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A potentially new early Ediacaran glaciation
Zhongwu Lan, Magdalena H. Huyskens, Rong Ren, Qing-Zhu Yin
 doi: 10.1007/s12583-024-1979-7
[Abstract](17) [PDF 491KB](1)
Abstract:
Multiple episodes of Neoproterozoic glaciation, namely the Beiyixi, Altungol, Tereeken and Hankalchough glaciations, are recorded in the Kuruktag area of northeastern Tarim Craton, NW China. The Tereeken glaciation was previously correlated with the global Marinoan glaciation based on sedimentary and chemostratigraphic features recorded in the cap dolostone immediately overlying the glaciogenic diamictite, as well as less precise radiometric age constraints. In this study, we obtained chemical-abrasion isotope dilution isotope ratio mass spectrometry (CA-ID-IRMS) U-Pb age of 624.03 ± 0.1 Ma from zircons extracted from a tuff lava interbeded within the diamictite of the Tereeken Formation, which suggests an early Ediacaran age for the Tereeken glaciation. Such newly discovered early Ediacaran glaciation in the Tarim region could have induced the negative δ13Ccarb excursions between 625-605 Ma by providing oxygen and other oxidants to invoke remineralization of a deep ocean dissolved organic carbon (DOC) reservoir.
Detrital zircon U-Pb age analysis of Late Pliocene deposits from the lower Yangtze River, South China: Implications for sedimentary provenance and evolution of the Yangtze River
Xu Lin, Chang’an Li, Jing Liu-Zeng, Jovliet Marc, Haijin Liu, Lingling Li, Chengwei Hu, Xiaokang Chen, Jixin Chen
 doi: 10.1007/s12583-023-1961-9
[Abstract](168) [PDF 5297KB](46)
Abstract:
The Yangtze River, with a length of approximately 6,300 km, holds the distinction of being the largest river in East Asia that empties into the Pacific Ocean. Its formation is intricately linked to regional tectonic activity and climate fluctuations. However, the exact timeline for the formation of the Yangtze River remains elusive. This study investigates the provenance of the late Cenozoic strata in the Wangjiang Basin, situated in the lower Yangtze River, through the application of detrital zircon U-Pb dating. A total of seven sand samples were analyzed, leading to the identification of new U-Pb detrital zircon ages (n = 577). Our study reveals that the sand materials found in the Pliocene gravel beds of the Anqing Formation originate predominantly from the Yangtze River. The findings of our study, along with the provenance tracing of boreholes in the Yangtze River Basin and the shelf sea in East China, provide compelling evidence for the continuous presence of the Yangtze River throughout the Pliocene period. The development of the Yangtze River during the Pliocene is intricately connected to both the tectonic adjustments occurring at the southeastern margin of the Tibetan Plateau and the intensification of the Asian Monsoon.
Application of Synthetic Iron Oxyhydroxide with Influencing Factors for Removal of As(V) and As(III) from Groundwater
Shakeel Ahmed Talpur, Muhammad Yousuf Jat Baloch, Chunli Su, Javed Iqbal, Aziz Ahmed, Hafeez Ahmed Talpur
 doi: 10.1007/s12583-023-1862-y
[Abstract](162) [PDF 1684KB](22)
Abstract:
Synthesized iron oxyhydroxide was applied for the adsorptive removal of As(V) and As(III) from the aquas media. Additionally, this investigation highlighted the synergistic effect of calcium carbonate in conjunction with iron oxyhydroxide, resulting in enhanced removal efficiency. The experiment was conducted under various conditions: concentration, dosage, pH, agitation, and temperature. Material characterizations such as Brunauer Emmett Teller, X-ray Diffraction, Scanning Electron Microscopy, and Fourier Transform Infrared Spectroscopy were implied to understand adsorption mechanisms. The Langmuir model revealed optimal concentrations for As(V) = 500 μg/L at pH-5 and As(III) = 200 μg/L at pH-7, resulting in 95% and 93% adsorption efficiencies, respectively. Maximum adsorption capacities "qm" were found to be 1266.943 μg/g for As(V) and 1080.241 μg/g for As(III). Freundlich model demonstrated favorable adsorption by indicating "n>1" such as As(V) = 2.542 and As(III) = 2.707; similarly, the speciation factor “RL<1” for both species as As(V) = 0.1 and As(III) = 0.5, respectively. The kinetic study presented a pseudo-second-order model as best fitted, indicating throughout chemisorption processes for removing As(V) and As(III). Furthermore, incorporating calcium carbonate presented a significant leap in the removal efficiency, indicating As(V) from 95% to 98% and As(III) from 93% to 96%, respectively. Our findings offer profound motivation for developing effective and sustainable solutions to tackle arsenic contamination, underscoring the exceptional promise of iron oxyhydroxide in conjunction with calcium carbonate to achieve maximum removal efficiency.
Multi-scale structural geological model and quantification of stability evaluation for a high-steep fractured rock slope
Jia Wang, Wen Zhang, Donghui Chen, Han Yin, Junqi Chen
 doi: 10.1007/s12583-023-1953-9
[Abstract](51) [PDF 20246KB](29)
Abstract:
This study aims to evaluate the stability of a high-steep fractured rock slope on the right bank of Dongcuo River, Southeast Tibetan Plateau by establishing a multi-scale structural geological model. Multi-scale discontinuity information was first identified via the unmanned aerial vehicle photogrammetry. The multi-scale structural geological model for the cross section of the slope was established by multi-scale discontinuity processing. In particular, large-scale discontinuities were directly embedded into the model, medium-scale discontinuities were realized via discrete fracture network simulation technology, and small-scale discontinuities were implicitly considered in the equivalent rock parameter calculation. A staged scheme for searching the shortest paths of the multi-scale structural geological model via Dijkstra's algorithm was established. The searched shortest path with the largest discontinuity persistence passes the most fractures and processes the lowest shear strength, which can represent the critical slip surface (CSS). Three potential CSSs were selected for the quantification of the factor of safety (FOS) using the transfer coefficient method. Modified Jennings' criteria were proposed to estimate the equivalent shear strength of the CSS composed by rock bridges and discontinuities. Finally, FOS is calculated as 3.81, implying that the studied rock slope remains stable
First record of Middle Eocene elephant ancestors' footprints in the Gonjo Basin, East Tibet Plateau
TAHIR Asma, Huazhou Yao, KHAN Junaid, Yangui Li, He Zhao, Yue Yu
 doi: 10.1007/s12583-023-1946-6
[Abstract](39) [PDF 2407KB](17)
Abstract:
It is the first time that the fossil footprints of a group of middle Eocene elephant ancestors have been discovered in the Gonjo Basin, east Tibet Plateau. The Gonjo Formation is attributed to the middle Eocene epoch (U-Pb age = 44.7 ± 1.2 Ma) and consists mainly of purplish-red, medium- to coarse-grained sandstones, siltstones interbedded with mudstones, and conglomerates with sedimentary structures like ripple marks, rip-up clasts, and trough-cross bedding, suggesting fluvial-lacustrine systems. The group of fossil footprints has a characteristic oval-concave shape, and the toe impressions are absent. Some fossil footprints are overstepped with a pockmarked texture resembling Proboscipeda enigmatica. More than 165 fossil footprints of the group are relatively well-preserved with different diameters, which is evidence of highly social behavior and trackmakers of different ages, including calves, juveniles, adolescents, and adults. The size frequency of the fossil footprints enabled us to deduce the body mass, shoulder height, and hip-height distribution of the trackmakers that crossed the east Tibet Plateau 44.7 million years ago. The trackmakers comprised an estimated average hip-height of 111.8 cm, an average shoulder height of 172.8 cm for males/155.9 cm for females, and an average body mass of approximately 1218.1 kg for males/907.8 kg for females. The abundance of fossil footprints reveals that in the middle Eocene epoch, the environment was extraordinarily conducive for the elephant ancestors to live in the East Tibet region.
Investigation of oil content in lacustrine shale-oil systems: Insights from two different pyrolysis
YUPING WU, Chinglin Liu, Fujie Jiang, Tao Hu, Chenxi Zhang, Jiahao Lv, Renda Huang, Meiling Hu, Guanyun Wu, Rizwan Sarwar Awan
 doi: 10.1007/s12583-023-1814-6
[Abstract](895) [PDF 1935KB](63)
Abstract:
This research has investigated the oil content of lacustrine shale-oil systems from the Junggar Basin. Twenty-eight samples are used for different pyrolysis experiments to study the characteristics of shale oil occurrence and the difference between various evaluation methods. Additionally, the factors affecting the physical states of shale oil are discussed. Compared with the standard Rock-Eval, the two-step pyrolysis and multi-step pyrolysis can eliminate the influence of the carryover effect. Therefore, these two types of pyrolysis are used to obtain the total, free, and adsorbed oil yield of the shale. The results demonstrate that the total oil yield acquired by multi-step pyrolysis is quite similar to that obtained by two-step pyrolysis. Both of them can prevent the retained oil yield from being underestimated by more than 50%. However, the free oil yield obtained by multi-step pyrolysis is significantly higher than that obtained by two-step pyrolysis. The multi-step pyrolysis can easily exaggerate the real free oil yield in resource evaluation. Therefore, this article suggests using the two-step pyrolysis to evaluate the characteristics of petroleum in shales. Furthermore, the amount of hydrocarbons within shales is related to organic matter properties. The higher the organic matter richness, the higher the total/adsorbed oil yield within the shale before reaching the adsorption saturation. The better the kerogen type, the higher the amount of liquid hydrocarbons within shales. As the thermal evolution of shales increases, the free oil proportion and the mobility of petroleum increase. This study compared different pyrolysis methods, which provided new insight for obtaining the oil content of shales, a key parameter of shale oil resource evaluation.
Application of unmanned aerial vehicle remote sensing on dangerous rock mass identification and deformation analysis: case study of a high-steep slope in an open pit mine
Wenjie Du, Qian Sheng, Xiaodong Fu, Jian Chen, Jingyu Kang, Xin Pang, Daochun Wan, Wei Yuan
 doi: 10.1007/s12583-023-1813-7
[Abstract](378) [PDF 4237KB](108)
Abstract:
Source identification and deformation analysis of disaster bodies are the main contents of high-steep slope risk assessment, the establishment of high-precision model and the quantification of the fine geometric features of the slope are the prerequisites for the above work. In this study, based on the UAV remote sensing technology in acquiring refined model and quantitative parameters, a semi-automatic dangerous rock identification method based on multi-source data is proposed; In terms of the periodicity UAV-based deformation monitoring, the monitoring accuracy is defined according to the relative accuracy of multi-temporal point cloud. Taking a high-steep slope as research object, the UAV equipped with special sensors was used to obtain multi-source and multi-temporal data, including high-precision DOM and multi-temporal 3D point clouds. The geometric features of the outcrop were extracted and superimposed with DOM images to carry out semi-automatic identification of dangerous rock mass, realizes the closed-loop of identification and accuracy verification; changing detection of multi-temporal 3D point clouds was conducted to capture deformation of slope with centimeter accuracy. The results show that the multi-source data-based semi-automatic dangerous rock identification method can complement each other to improve the efficiency and accuracy of identification, and the UAV-based multi-temporal monitoring can reveal the near real-time deformation state of slopes.
Organic matter occurrence and its effects on pore structure and methane adsorption capacity capacity: A case study of the Niutitang black shale in Guizhou, China
Peng Xia, Fang Hao, Jinqiang Tian, Yong Fu, Chuan Guo, Zhen Yang, Yuliang Mou, Ke Wang
 doi: 10.1007/s12583-022-1688-z
[Abstract](1210) [PDF 5313KB](95)
Abstract:
The black shale samples from the Niutitang Formation in the Yangtze Block were sequentially treated using organic solvent extraction and wet chemical oxidation. The organic matter (OM) in the shales includes physically mobile OM (PmOM), chemically mobile OM (CmOM), and stable OM (StOM). The CmOM has the strongest CH4 adsorption capacity because it has the largest volume of micropores and mesopores. In contrast, the PmOM has a very negative effect on the CH4 adsorption because it is poreless. The XD shale is a siliceous shale, in which the quartz particles wrap partly OM, preventing extraction and oxidation. The SL shale is an argillaceous shale, in which most of the OM is combined with clay minerals to form organo-clay composites. In both the SL and XD shales, the OM that is extractable via organic solvents is distributed among the mineral particles and is interconnected. The conceptual model of marine black shale in different environments needs to be perfected in the future because quantitative and qualitative methods should be combined to clarify the relationship between the known OM types (e.g., pyrobitumen, solid bitumen, and solid kerogen) and the OM types identified in this study.
Multivariate statistical analysis of dominating groundwater mineralization and hydrochemical evolution in Gao, northern Mali
TRAORE ADIARATOU, Xumei Mao, Alhousseyni Traore, YAHAYA YAKUBU, Aboubacar Sidibe
 doi: 10.1007/s12583-022-1689-y
[Abstract](203) [PDF 1783KB](36)
Abstract:
Population growth and expanding urbanization have caused persistent shortages and contamination of groundwater resources in Mali, Africa. The increase in groundwater salinity makes it more difficult for residents to obtain drinking water, it is necessary to clarify the causes and control factors of groundwater mineralization in Gao region, northern Mali. Based on the analysis of the hydrochemical composition of groundwater in 24 boreholes, Piper and Schöeller diagrams, principal component analysis (PCA) and hierarchical cluster analysis (HCA) are used to carry out multivariate statistical analysis on the main ions. The results show that the groundwater samples are weakly alkaline, with pH values ranging from 5.83 to 8.40, and the average values of boreholes are 7.50, respectively. The average electrical conductivity (EC) value is 354.4 (µS/cm), and the extreme value is between 124.0 and 1247 (µS/cm). Water is usually mineralized and presents nine types of water phase. The three principal components explain 84.42% of the total variance for 13 parameters. The factor F1 (58.85%), the factor F2 (16.88%) and the factor F3 (8.69%) present for the majority of the total data set. In addition, multivariate statistical analysis confirmed the genetic relationship among aquifers and identified three main clusters. Clustering related to groundwater mineralization (F1), clustering related to oxide reduction and iron enrichment (F2), and clustering of groundwater pollution caused by nitrate and magnesium (F3). We found that agriculture, weathering activities and dissolution of geological materials promote the mineralization of groundwater. Groundwater quality in the Gao region is becoming less and less potable because of increasing salinity.
Spatial and temporal evolution of lithospheric mantle beneath the eastern North China Craton: Constraints from mineral chemistry of peridotite xenoliths from the Miocene Qingyuan basalts and a regional synthesis
Jian-Fang Guo, Qiang Ma, Jianping Zheng, Yuping Su
 doi: 10.1007/s12583-022-1691-4
[Abstract](164) [PDF 5165KB](50)
Abstract:
Mineralogical data are presented for the peridotite xenoliths from Miocene (~19Ma) Qingyuan basalts in the eastern North China Craton (NCC), with the aim of constraining on property of the sub-continental lithospheric mantle (SCLM) beneath the northern Tan-Lu Fault zone (TLFZ) during the Cenozoic. The Qingyuan peridotites are dominated by spinel lherzolites with moderate-Mg# olivines (89.4 to 91.2), suggesting that the regional SCLM is mainly transitional and fertile. Light rare earth element (LREE)-depleted, slightly depleted and enriched clinopyroxenes (Cpx) are identified in different peridotites. Chemical compositions of the LREE-enriched Cpx and the presence of phlogopite suggest that the Qingyuan SCLM has experienced silicate-related metasomatism. The synthesis of available mineral chemical data of the mantle xenoliths across the NCC confirms the SCLM beneath the NCC is highly heterogeneous in time and space. The Mesozoic-Cenozoic SCLM beneath the TLFZ and neighboring regions are more fertile and thinner than that beneath the region away from the fault zone. The fertile and refractory peridotite xenoliths experienced varying degrees of silicate and carbonatite metasomatism, respectively. The spatial-temporal lithospheric mantle heterogeneity in composition, age and thickness suggest that the trans-lithosphere fault zone played an important role in heterogeneous replacement of refractory cratonic lithospheric mantle.
Limitation of the Application of Heat Tracer in Investigating Groundwater and River Interactions under Dynamic Flow Conditions
Mengyan Ge, Rui Ma, Ziyong Sun
 doi: 10.1007/s12583-022-1683-4
[Abstract](138) [PDF 3970KB](23)
Abstract:
The groundwater (GW) in the floodplain riparian area frequently interacts intensely with surface water (SW). Heat as a tracer is one of the hot research fields in investigating GW-SW interactions, and analytical approaches have been proposed for the calculation of exchange flow velocity. However, few studies have considered the effects of very dynamic flow conditions and monitoring instrumentation on the calculation with field measured data. Herein, taking the middle reaches of the Heihe River as the study area, different types of monitoring wells were constructed under the riverbed and near the river, and multiple methods (Darcy’s law, heat tracing, and isotopic mixing methods) were employed to trace the exchanges between the river and groundwater. The results indicate that different methods demonstrate diverse information with obvious unevenly distributed flux along the vertical direction. And the combination of multiple methods has an important role in studying the interaction between GW and SW. Fully screened wells produce intraborehole flow and disturb the heat transport, which is relevant to flow velocity, and further affects the temperature distribution, impacting the temperature-based flow velocity calculation. Dynamic flow conditions aggravate riverbed sediment disturbances, e.g., scour and deposition, and additionally affect the interaction and monitoring data.
Geochemical Modeling of Fluid–Rock Interactions in Shallow buried Carbonate Reservoirs based on the Water Bath Instrument
Jiayi Ma, Anjiang Shen, Shuyun Xie, Min She, Huayun Tang, Emmanuel M. CARRANZA, Tianfu Zhang
 doi: 10.1007/s12583-022-1690-5
[Abstract](147) [PDF 2439KB](21)
Abstract:
Fluid–rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space. In the diagenetic stage of shallow burial, the dissolution of carbonate rocks by acidic fluids is conducive to the development of secondary pore space in reservoirs. In contrast, the free drift experiment based on water bath instrument can simulate the dissolution process of carbonate rocks in shallow burial environment effectively. In order to study the shallow burial dissolution mechanism of carbonate rocks in different acid solutions, 14 samples of typical carbonate rocks of Sinian, Cambrian, Ordovician, Permian and Triassic ages in the Tarim and Sichuan Basins, China were used. The dissolution experiments on carbonate rocks in sulfuric acid, acetic acid, hydrochloric acid, silicic acid and carbonic acid at shallow burial temperature (30℃≤T≤90℃) were carried out using a water bath instrument. The PHREEQC software was used to simulate the dissolution of carbonate minerals, in order to compare the results of constant temperature water bath experiment. The results show that acid solutions have significant dissolution effect on shallow burial carbonate rocks when T = 50–60℃, which corresponds to the burial depth of 1500–2000 m in the Tarim Basin and 1110–1480 m in the Sichuan Basin. However, there were obvious differences in the dissolution and reformation of carbonate rocks in different acids. In particular, sulfuric acid solution produced by thermochemical sulfate reduction can significantly promote the dissolution of carbonate rocks, especially dolomitic limestone. Moreover, the dissolution of limestone reservoirs is stronger than that of dolomite reservoirs in shallow burial. The results will provide new insights into the study of dissolution laws and influencing factors of carbonate reservoir space and the evaluation and prediction of carbonate reservoir in China.
Chronology, geochemistry and isotopic compositions of the Cretaceous Zhangjiakou diabase: Magmatic derivation and geodynamic implications
peng li, Dazhao Wang, guanzhong shi
 doi: 10.1007/s12583-022-1684-3
[Abstract](133) [PDF 6259KB](21)
Abstract:
Zircon U–Pb ages, major and trace elements and Sr–Nd–Hf isotope data of the diabase in the Zhangjiakou district were studied to investigate its derivation and tectonic implications. Zircon U–Pb ages indicate that the diabase was emplaced at ~130 Ma or younger, and captured zircons cluster at ~147 Ma, ~240 Ma, ~430 Ma and ~465 Ma. The diabase is characterized by minor variations in SiO2 (49.35–52.10 wt.%), TiO2 (1.65–1.77 wt.%), Al2O3 (17.00–18.26 wt.%), MgO (4.28–4.93 wt.%), CaO (6.69–7.90 wt.%) and Mg# (48–54). It has no significant Eu anomaly and displays enrichment in large ion lithophile elements (Rb, Ba and Sr) and depletion in high field strength elements (Nb, Ta, P and Ti). The diabase exhibits homogeneous Sr ((87Sr/86Sr)i = 0.70606–0.70701) and Nd (εNd(t) =–13.6 to –13.2) isotopic compositions. These features suggest that the parental magma was derived from partial melting of the ancient lower crust, relating to mantle upwelling that triggered by stagnant slabs or lithospheric detachment associated with the westward subduction of the Paleo-Pacific Plate. The Early Paleozoic inherited igneous zircons in the diabase suggest that the northern margin of the North China Craton (NCC) likely underwent southward subduction of the Paleo-Asian Ocean.
Characteristics of connected pores and evaluation of shale oil mobility in the Qianjiang Formation, Qianjiang Sag, Jianghan Basin,China
SUN Zhongliang, LI Zhiming, HE Chencheng, ZHU Feng, SHEN Baojian, LU Longfei
 doi: 10.1007/s12583-022-1699-9
[Abstract](382) [PDF 2527KB](37)
Abstract:
The connectivity of shale pores and the occurrence of movable oil in shales have long been a focus of research. In this paper, samples from Wells BX7 and BYY2 in the Eq34-10 cyclothem of Qianjiang Formation in the Qianjiang Depression, were analyzed. A double mercury injection method was used to distinguish between invalid and effective connected pores. The pore characteristics for occurrence of retained hydrocarbons and movable shale oil were distinguished based on comparison of pore changes in low temperature nitrogen adsorption and high pressure mercury injection experiments before and after extraction and the change in the mercury injection amounts in the pores between two separate mercury injections.. The results show that less than 50% of the total connected pores in the Eq34-10 cyclothem samples are effective. The development of effective connected pores affects the mobility of shale oil but varies with different lithofacies. The main factor limiting shale oil mobility in Well BX7 is the presence of pores with throat sizes less than 15nm. In Well BYY2, residual mercury in injection testing of lamellar dolomitic mudstone facies was mainly concentrated in pores with throats of 10~200 nm, and in bulk argillaceous dolomite facies it was mainly concentrated at 60~300nm. The throats of hydrocarbon-retaining pores can be 5nm or even smaller, but pores with movable shale oil in the well were found to have have throat sizes greater than 40nm. Excluding the influence of differences in wettability, the moveability of shale oil is mainly affected by differences in lithofacies, the degree of pore deformation caused by diagenesis, the complexity of pore structures, and the connectivity of pore throats. Dissolution and reprecipitation of halite also inhibit the mobility of shale oil.
Formation Mechanism of the Paleocene basal conglomerate, southwest Tarim Basin
yong Yue, Jingchun Tian, Chuanyan Huang
 doi: 10.1007/s12583-022-1696-z
[Abstract](130) [PDF 8039KB](19)
Abstract:
Abstract: Most knowledge about the Cretaceous-Paleogene strata in the Tarim Basin is mainly inferred from the outcrops at the basin’s margin,but first time in the basin. The formation mechanism of the Paleocene basal conglomerate was determined using geochemical isotopes of the breccia from well PBX1 in the southwestern Tarim Basin. The results showed that the global K/Pg (i.e., Cretaceous/Paleogene) clay layer boundary was located in the middle of the Paleocene basal conglomerate at the depth of 7066.75m in well PBX1. In the Late Cretaceous, associated with volcanic activities and earthquakes, the caldera in the PBX1 well block formed an annular depression with large elevation differences in response to the Pamir block collision. As a result, the collapsed breccia with storm tide genesis deposited at the periphery and inside of the depression, characterized by syn-sedimentary deformation. During the Paleocene, multiple sets of interbedded carbonate and collapsed breccia deposited in response to multi-phased transient transgression-regression cycles. The transportation of breccia exhibited near-source accumulation/extremely close or in-situ rapid accumulation. The studied region is located in the eastern end of the Tethys Sea, the Late Cretaceous-Early Paleocene breccia is of great significance for reconstructing the paleogeography of the Tarim basin in Tethys. Key words: South-western Tarim;Paleogene system;Breccia;Attribution and genesis
Contrasting behavior for Li-Mg isotopes during subduction: Insights from garnet in the Yardoi schists, Tibet
Xing Li, Yilin Xiao, Olivier Nadeau, Dongyong Li, Haiyang Liu, Zhang Zeming, Zhenhui Hou
 doi: 10.1007/s12583-022-1697-y
[Abstract](208) [PDF 4022KB](66)
Abstract:
It has long been recognized that garnet has the capacity to preserve the trace element and isotopic signature of distinct metamorphic growth zones because of its high closure temperature. Combined with the large size of certain garnet porphyroblast, this allows investigating variations in metamorphic conditions such as pressure, temperature, deviatoric stress, and fluid composition, which occur during subduction-related metamorphism. Here, one garnet porphyroblast of 6 cm diameter was sampled from the Yardoi schists of Tibet, and the major-, trace-, and Li-Mg isotopic compositions of distinct growth zones were determined in situ. The δ7Li values range from +6.0 ‰ to +4.1 ‰ and follow ‘S-shape’ patterns on both sides of the garnet’s core, revealing a two-stage growth process corresponding to the fluid-assisted sequential recrystallization of chlorite and micas during prograde metamorphism. By contrast, once corrected for the overprinting by retrograde metamorphism, the δ26Mg values vary monotonously from -1.73 ‰ in the core to -1.32 ‰ in the outer rim, reflecting a single-step process interpreted to result from increasing temperature and the solid-state recrystallization of chlorite-biotite during prograde metamorphism. This different behavior of Li and Mg isotopes is interpreted to result from the fact that Li is more fluid-mobile than the major element Mg.
Provenance of the southeastern South China Block in the Late Triassic and initiation of Paleo-Pacific subduction: Evidence from detrital zircon U–Pb geochronology
Jintao Kong, zhongjie Xu, Rihui Cheng, Duo Wan
 doi: 10.1007/s12583-022-1694-1
[Abstract](116) [PDF 7438KB](21)
Abstract:
During the late Paleozoic–early Mesozoic era, the sediment transport system and tectonic regime in the southeastern margin of the South China Block (SESCB) all changed, significantly affected by the Paleo-Pacific subduction. This study uses detrital zircon geochronology to discuss the Late Triassic source-to-sink system in the SESCB and provides some references for the Paleo-Pacific subduction process. The paleogeography and similarity of detrital zircon age distribution reveal three sinks in the SESCB during the Late Triassic: 1. the Yangchun–Kaiping–Gaoming area, comprising major age ranges of 260–220, 460–400, and 1,200–800 Ma, which might be sourced from the Yunkai Terrane; 2. the Jiexi–Kanshi–Nanjing area, characterized by the significant age component of 2,000–1,800 Ma, which corresponded to the Wuyi Terrane; 3. the Xinan area, consisting of significant age groups of 290–250 Ma and 380–320 Ma, which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific subduction. The Upper Triassic strata contain many 290–250 Ma zircons, and their trace elements suggested a magmatic arc existed near the SESCB during the 290–250 Ma. Thus, we propose that the Paleo-Pacific subduction might have begun in the Early Permian.
Ore geology, H–O–C isotopes and 40Ar–39Ar dating of the Wutonggou iron deposit, eastern Tianshan, NW China: Implications for the source, timing, and genesis of hydrothermal mineralization in a sedimentary iron deposit
Chun-Long Wang, Yi‑Tian Wang
 doi: 10.1007/s12583-022-1686-1
[Abstract](152) [PDF 6300KB](31)
Abstract:
The Wutonggou iron deposit is located in the well-known iron metallogenic belt in the eastern Tianshan, NW China, and has been regarded as a sedimentary iron deposit. Hydrothermal overprinting could play indispensable roles in the formation of high-grade iron ores in sedimentary iron deposits, thus the nature and evolution of hydrothermal fluids have important implications on the genesis of these deposits. Consequently, an integrated study of ore geology, H–O–C isotopes and 40Ar–39Ar dating, is conducted on the Wutonggou deposit, in order to reveal the features, source, and timing of hydrothermal mineralization. The studied deposit includes two mining sections namely the Jianshan and Wutonggou. The δ18O values of early magnetite from the Jianshan section range from +3.0‰ to +5.8‰ that nearly consistent with classic magmatic magnetite, while increase to 6.3‰–8.0‰ in the late stage. Quartz from the two sections shows comparable H–O isotopic compositions and identical fractionation trends, and is plotted in or periphery to the primary magmatic water area. Calcites from the two sections are broadly similar in carbon and oxygen isotopic compositions, and siderite from the Wutonggou section is plotted in the same region. Thus, comparable stable isotopic compositions and evolution trends indicate similar magmatic fluids contributed hydrothermal iron mineralization in the two mining sections. Moreover, water-rock interactions of varying degrees generated distinct mineralization styles in the Jianshan and Wutonggou sections, and caused the isotopic fractionation in late stages. Biotite extracted from a hydrothermal siderite ore yielded a 40Ar–39Ar plateau age of 299.5 ± 2.0 Ma, indicating the timing of hydrothermal iron mineralization is corresponding to the emplacement of vicinity granitoids. Taken together, the hydrothermal mineralization in the Wutonggou iron deposit was the product of remobilization and upgrading of early sedimentary iron ores, and ore-forming fluids were most probably originated from regional granitic magmatism.
Characteristics and formation analysis of earth fissure in Anren area in Wei River Basin, China
Jianwei Qiao, Zhenjiang Meng, Yuyun Xia, Cong Liu, Quanzhong Lu, Feiyong Wang, Yuanqiang Zhou, Haiyuan Zhao
 doi: 10.1007/s12583-022-1653-x
[Abstract](296) [PDF 3547KB](24)
Abstract:
Since the 1950’s, 212 earth fissures have been discovered in the Wei River Basin. During a field survey in 2016, an additional 48 earth fissures were discovered in Anren area, northeast of the Wei River Basin. The characteristics and formation mechanisms of these fissures were studied through field investigations, measurements, trench excavation, and drilling. On-site investigations indicated that these earth fissures were distributed along a fault-controlled geomorphic boundary. Fissures trended at 60°–80° NE and were divided into five groups. Trenches revealed multiple secondary fissures, exposing severe soil ruptures in the shallow earth surfaces. Drilling profiles revealed that earth fissures dislocated several strata, and resembled synsedimentary faults. Seismic reflection profiles revealed buried faults beneath the earth fissures. The Anren area fissures formed in the following three stages: regional extension that initially generated multiple buried faults; seismic activity rupturing multiple strata, resulting in multiple buried fractures; and finally, erosion processes that propagated the buried fractures to the surface, forming the current earth fissures.
Geochronology and geochemistry of Permian Dashizhai Basin in Xing’an–Inner Mongolia Orogen: Implications for the evolution of the Paleo-Asian Ocean
Chi Zhang, Guosheng Wang, Zhiguang Zhou, Shen Gao, Neng Zhang, Liudong Wang, Erqiang Bo
 doi: 10.1007/s12583-022-1651-z
[Abstract](151) [PDF 21807KB](26)
Abstract:
The Xing’an–Inner Mongolia Orogen is a critical tectonic unit for constraining the evolution of the Paleo-Asian Ocean. However, the location and time for the closure of the Paleo-Asian Ocean are still debated. Here, we select a representative basin in Dashizhai in northeastern China, using U-Pb zircon geochronology and geochemistry to analyze the sedimentary facies, depositional ages, and provenance. The results show that the age of the Dashizhai Formation range from 400 to 347 Ma, the Shoushangou Formation range from 400 to 348 Ma, the Zhesi Formation range from 307 to 252 Ma, and the Linxi Formation range from 299 to 241 Ma. The Dashizhai Formation is composed of metamorphic andesite and clastic rocks. The Shoushangou Formation comprises siltstone, rhyolite, and argillaceous siltstone. The Zhesi and Linxi Formations are composed of mudstone and argillaceous siltstone. Geochemical data shows that these rocks are enriched in light rare earth elements and depleted in Eu with various La/Sc, Th/Sc, and La/Co ratios. The Permian Dashizhai Basin is from Permian volcanic and felsic igneous rocks from the Ergun, Xing’an, and Songliao blocks. The absence of the Late Carboniferous strata in the Dashizhai Basin indicates an extension setting during this period. Furthermore, we suggest the Xing’an–Inner Mongolia Orogen was an uplifting process associated with evolution the Paleo-Asian Ocean during the Late Permian.
Effect of Reclamation on the Groundwater-Lake Water Interaction in Chen Lake
Kun Lei, Teng Ma, Liu Chen, Zhen Li, Yu Chen
 doi: 10.1007/s12583-022-1652-y
[Abstract](135) [PDF 3200KB](29)
Abstract:
Chen Lake has been seriously modified by reclamation to expand the residential and agricultural area. Lake reclamation can decrease water quantity, cause water quality problems, and degrade water ecological function. To clarify the interaction between groundwater and lake water influenced by reclamation, water level and hydrochemical characteristics of five groundwater nests and three lake sites were monitored. Results emphasize that the seasonal fluctuations of lake water level is an important factor for both recharge and maintaining groundwater levels in study area. Groundwater in reclaimed farmland have seasonal patterns following lake water with a lag time. Noteworthy, the lag time of porewater in reclaimed farmland is one month longer than confined water. HCA showed that lake water and groundwater samples in same cluster were characterized by high δD, δ18O, Cl- and K+, suggesting the provision of lake to groundwater systems and the transfer of chemical signature. Other Cluster was dominated by reclaimed farmland groundwater samples and enriched in Ca2+, HCO3-, Si. This finding interpreting that water-rock interaction is the predominant process in reclaimed farmland. As a result, there is a high degree of connectivity between lake water and underlying groundwater. However, porewater hydrodynamic conditions gradually weaken and groundwater recharge in reclaimed farmland is modified after large-scale reclamation.
3D Distinct Element Back Analysis Based on Rock Structure Modelling of SfM Point Clouds: The Case of the 2019 Pinglu Rockfall of Kaili, China
Zhen Ye, Qiang Xu, Qian Liu, Xiujun Dong, Feng Pu
 doi: 10.1007/s12583-022-1667-4
[Abstract](140) [PDF 9435KB](20)
Abstract:
This paper introduces the use of point cloud processing for extracting 3D rock structure and the 3DEC -related reconstruction of slope failure, based on a case study of the 2019 Pinglu rockfall. The basic processing procedure involves: (1) computing the point normal for HSV-rendering of point cloud; (2) automatically clustering the discontinuity sets; (3) extracting the set-based point clouds; (4) estimating of set-based mean orientation, spacing, and persistence; (5) identifying the block-forming arrays of discontinuity sets for the assessment of stability. The effectiveness of our rock structure processing has been proved by 3D distinct element back analysis. The results show that SfM modelling and rock structure computing provides enormous cost, time and safety incentives in standard engineering practice.
Late Miocene elevated horizontal karst caves and landform evolution as a response to tectonic uplift along with regional integration of fluvial drainage in Southwestern China
Min Zhai, Xinggong Kong, Yuanhai Zhang, Philip Rowsell, Zhijun Zhao, Baojian Huang, Jing Zhang
 doi: 10.1007/s12583-022-1656-7
[Abstract](251) [PDF 14363KB](20)
Abstract:
In Southwestern China, the development of karst landforms and the planation surfaces is closely related to local tectonics, fluvial incision and base level change, as well as climate change. While researches on when these karst landforms and planation surfaces formed and how they evolved along drainage development are scarce. Fortunately, horizontal caves with numerous fluvial deposits in high karst mountains can be used as time markers in landform evolution. Here we select large horizontal caves to perform studies of geomorphology, sedimentology and geochronology. Field work shows that more than 25 km long horizontal cave passages are perched 1500 m higher than the local base level, but filled with several phases of fluvial sediments and breakdown slabs. The first phase of fluvial gravels and related cave drainage were dated back to 6.4 Ma using cosmogenic nuclide burial dating, and the stalagmite covering the cave collapse was dated by the U-Pb method , older than 1.56 Ma. These results show that the continuous horizontal cave drainage system and the planation surface were developed prior to the Late Miocene. The lowering process of the base level as a result of the sharp fluvial incision and water level lowering, along with the regional uplift, led to the abandonment of the horizontal cave and the elevated planation surface at the Late Miocene . After that, the phase of cave collapse , thick fluvial sand and clay sediments in the caves from the recharge of the cave deposited at around 1.6 Ma and during the Middle Pleistocene, respectively. Subsequently, speleothems widely deposited on the collapse and clay sediment during the period from 600 to 90 ka ,whereas the deposition of cave fluvial sediments terminated suddenly. The tectonic could control the denudation of surface caprock and the development of karst conduits prior to the Late Miocene, whereas the river incision acted as the main driver for the base level lowering and the destruction of the horizontal cave drainage at high altitude. In addition, the rapid incision and the retreat of Silurian gorges finally caused the formation of karst mesa in the Middle Pleistocene.
Source-to-sink relationships between the Qaidam Basin (North Tibet) and its surrounding mountain ranges: New insights from detrital zircon U–Pb ages in modern river sediments
Xu Zhang, Bowen Song, Tinglu Yang, Yafei Hou, Yibo Yang, Keke Ai, Jiaxuan Wang, Zhang Kexin
 doi: 10.1007/s12583-022-1666-5
[Abstract](245) [PDF 7269KB](43)
Abstract:
The Cenozoic source-to-sink history of the Qaidam Basin is crucial for understanding of the basin-filling architecture, mountain-building processes and even the dynamics of the Tibetan plateau growth. However, the provenance history of Cenozoic strata in the Qaidam Basin remains ambiguous, especially in the northern Qaidam Basin. This controversy highlights the importance of obtaining the spatial source-to-sink relationships between the Qaidam Basin and its surrounding mountain ranges. In this study, we investigated the detrital zircon U–Pb ages of modern fluvial systems draining the Eastern Kunlun Shan. Their detrital zircon age distributions fall into five age groups: 300-190, 530-360, 1000-560, 2000-1100 and 2650-2000 Ma. The dominant age groups are 530-360 and 300-190 Ma, which represent the successive subduction of the Proto-Tethys and Paleo-Tethys Oceans and the subsequent continental collisions, respectively. Combining these new detrital zircon U–Pb ages with available age datasets, we finally obtained complete detrital zircon age information for modern fluvial systems in the whole Qaidam Basin. The U–Pb age distributions of modern river sands reveal that the zircon age signature of basement rocks in the Eastern Kunlun Shan is significantly different from that in the South Qilian Shan but is similar to that in the Altyn Tagh Shan. Moreover, these zircon age observations were confirmed by the significant difference in the Nd isotopic signature of modern river sands, which reveals a significant difference between the Eastern Kunlun Shan and South Qilian Shan in the formation and evolution process.
Karst trough control of solute transport processes at two karst groundwater flow systems, Western Hubei, Central China
Yi'an Wang, Ruichao Zhao, Lin Ding, Shuai Xiong, Yin Li, Jianwei Bu, Wei Chen, Hong Zhou, Wei Liu
 doi: 10.1007/s12583-022-1665-6
[Abstract](319) [PDF 3313KB](66)
Abstract:
To investigate groundwater flow and solute transport characteristics of the karst trough zone in China, tracer experiments were conducted at two adjacent typical karst groundwater flow systems (Yuquandong (YQD) and Migongquan (MGQ)) in Sixi valley, western Hubei, China. High-resolution continuous monitoring was utilized to obtain breakthrough curves (BTCs), which were then analyzed using the multi-dispersion model (MDM) and the two-region nonequilibrium model (2RNE) with basic parameters calculated by CXTFIT and QTRACER2. Results showed that: (1) YQD flow system had a complex infiltration matrix with overland flow, conduit flow and fracture flow, while the MGQ flow system was dominated by conduit flow with fast flow transport velocity, but also small amount of fracture flow there; (2) they were well fitted based on the MDM (R2=0.928) and 2RNE (R2=0.947) models, indicating that they had strong adaptability in the karst trough zone; (3) conceptual models for YQD and MGQ groundwater systems were generalized. In YQD system, the solute was transported via overland flow during intense rainfall, while some infiltrated down into fissures and conduits. In MGQ system, most were directly transported to spring outlet in the fissure-conduit network.
Physical prediction model of compound hydrodynamic unload-load response ratio and its application in reservoir colluvium landslide
Lu Guo, Keqiang HE, Honghua Liu, Fandi Meng, Xuchun Wang
 doi: 10.1007/s12583-022-1662-9
[Abstract](108) [PDF 1406KB](14)
Abstract:
It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall. Based on the systematic analysis of the change law of reservoir water level, rainfall and displacements of reservoir colluvium landslide, this paper proposes the compound hydrodynamic action of rainfall and reservoir water as the unload-load parameter, and the landslide displacement as the unload-load response parameter. Based on this, a physical prediction model of the compound hydrodynamic unload-load response ratio of reservoir colluvium landslide was established, and the quantitative relationship between the compound hydrodynamic unload-load response ratio and its stability evolution was in-depth analyzed and determined. On the basis of the above research, taking Shuping landslide, a typical hydrodynamic pressure landslide as an example, the unload-load response ratio model is used to systematically evaluate and predict the stability evolution law and the change trend of the landslide under compound hydrodynamic action. The prediction result shows that the variation law of the compound hydrodynamic unload-load response ratio is consistent with the dynamic evolution law of its stability. Therefore, the above studies show that the compound hydrodynamic unload-load response ratio parameter is an effective displacement dynamic evaluation parameter for reservoir colluvium landslides, so it can be used in the prediction of the reservoir colluvium landslides.
Effect of the tectonic inversion on the Source-to-sink system evolution in a lacustrine rift basin, a case study of South Yellow Sea Basin, East China.
Xue Fan, Chao Fu, Shengli Li, Shunli Li
 doi: 10.1007/s12583-022-1664-7
[Abstract](148) [PDF 10495KB](29)
Abstract:
The complex plate collision process led the South Yellow Sea Basin (SYSB) to go through an intensity tectonic inversion during the early Cenozoic, which led to a regional unconformity surface development. As a petroliferous basin, SYSB saw intensity denudation and deposition process, making it hard to characterize their source-to-sink system(S2S), and this study provided a new sight to reveal them quantitatively. According to the seismic interpretation, it was found that two types of tectonic inversion led to the strata shortening process, which was classified according to their difference in planar movements, dip-slip faults, and strike-slip ones. As for dip-slip faults, the inversion structure was primarily formed by the dip-slip movement and many fault-related folds developed, which mainly developed in the North Depression Zone of the SYSB. The strike-slip ones, accompanying developed with some negative flower structures, are dominated in the South Depression Zone of the SYSB. Then, to reveal its source-to-sink system in the tectonic inversion basin, we speculated the sediments’ provenance area and their migration distance, referring to the zircon U-Pb data and heavy mineral assemblage. As for the North Depression Zone, it is shown that fewer distal sediments from the West Sulu Orogenic Belt are infilled, and proximal slump or fan delta are prominently developed during the tectonic inversion stage. The provenance rebuild in the South Depression Zone shows increasing sediments from the proximal area (Central Uplift Zone in SYSB and Wunansha Uplift) and the prograding delta long-axis parallel to these boundary faults during the tectonic inversion stage. Calculations were conducted on the coarse sediments content, faults displacements, catchment relief, sediments migration distance, and discussions about the impact factors to the Source-to-sink system developed in various strata shortening patterns with a statistical method. It was found that, within the dip-slip faults-dominated zone, the volume of the sediment routing system and the ratio of coarse-grained sediments merely has a relationship with the amount of sediment supply and average faults broken displacement. Compared with the strike-slip faults-dominated zone, the source-to-sink system shows a lower level of sandy sediment influx, and its coarse-grained content is mainly determined by the average faults broken displacement.
System reliability analysis of reservoir landslides: Insights from long-term reservoir operation
Kang Liao, Yiping Wu, Fasheng Miao
 doi: 10.1007/s12583-022-1668-3
[Abstract](175) [PDF 4819KB](28)
Abstract:
The reservoir operation awakens numerous landslides with multiple sliding surfaces known as reservoir landslides, and the systematic stability analysis for such landslides is becoming increasingly urgent. Taking the Majiagou landslide as an example, this paper analyses the comprehensive performance of the landslide from a probabilistic point of view. Under a reservoir operation cycle, a series of numerical analyses are carried out to simulate the migration of the seepage field, then the dynamic stability of the landslide is quantified accordingly. Subsequently, the wetting-drying cycles test is used to model the weakening of strength parameters in hydro-fluctuation belt under the long-term reservoir operation. Considering the weakening effect of long-term reservoir operation on the hydro-fluctuation belt, the system reliability is evaluated using the Ditlevsen's bounds. The results suggest that the reservoir operation can affect the stability of the landslide by changing the seepage field. The system failure probability gradually rises as the number of wetting-drying cycles increases. Compared with conventional probabilistic analysis that calculates the failure probability of each sliding surface mechanically, analyzing the landslide in terms of system reliability can effectively narrow the failure probability range, which provides an insightful idea for evaluating the systematic stability of analogous reservoir landslides.
In-situ horizontal extrusion test of herbaceous root–soil with different root types
Fangcui Liu, Shengwen Qi, Shenglin Qi, Xiaokun Hou, Yanrong Li, Guangming Luo, Lei Xue, Xueliang Wang, Juanjuan Sun, Songfeng Guo, Bowen Zheng
 doi: 10.1007/s12583-022-1661-x
[Abstract](210) [PDF 7426KB](30)
Abstract:
The influence of different types of roots on the soil is complex and still remains unclear. Four in-situ extrusion tests were conducted on two types of root systems, namely fibrous and tap root system, for three plants (i.e. Eleusine indica, Potentilla anserine and Artemisia argyi), according to the classification in Botany, and the thrust–displacement curves and failure patterns of different samples were analysed by comparison to fill the aforementioned gap. Results reveal that the roots can reduce the characteristics of soil brittleness and enhance its capability to resist large deformation, and different root types contribute different effects on the strain-hardening behaviour of the root–soil mass. The contribution of the fibrous root system on strength is limited, whilst the tap root system substantially enhances strength and stiffness. Results of failure patterns show that fibrous and tap root systems affect soil solidification and surface cracking reduction. However, the effect of the tap root system depends on the composition of lateral and tap roots: long and rich lateral roots are effective for resisting the creation of cracks, but thick tap roots with few and thin lateral roots may lead to several surface cracks.
Mechanism of interaction between anchored slide-resistant piles and landslides with weak-hard interbedded bedrock:model tests and theoretical interpretation
Guihua Wang, Changdong Li, Xin He, Taijiang Chen, Jie Meng, Wenmin Yao, Yongquan Zhang, HUAWEI ZHANG
 doi: 10.1007/s12583-022-1663-8
[Abstract](275) [PDF 3551KB](19)
Abstract:
Interactions between anchored slide-resistant piles and landslides with weak-hard interbedded bedrock have not yet been systematically studied. Physical models of landslides reinforced by anchored slide-resistant piles are investigated based upon the self-developed testing system. The landslide system evolution with increasing loading force is revealed; the internal force and deformation of anchored slide-resistant piles in weak-hard interbedded bedrock are analyzed. A single anchored pile in weak-hard interbedded bedrock is analyzed theoretically, and an optimized calculation method for the axial force of the anchor cable is proposed. The results show that (1) The landslide system evolves through four stages: creeping, coordinated deformation, uncoordinated deformation, and failure. (2) The thrust sharing ratio of the pile-anchor first increases, then decreases slightly, and finally stabilizes; the maximum thrust sharing ratio is 12.22. (3) The anchoring force provided by weak-hard interbedded bedrock is between those of homogeneous hard and homogeneous weak rocks. The horizontal displacement of the pile in homogeneous hard rock is small, but more thrust is borne by the pile, and vice versa. (4) The theoretical value for a single anchored pile calculated by the optimized method is close to the measured value. These findings provide a scientific basis for landslide control projects in areas with weak-hard interbedded bedrock.
Applications of deep learning in mineral discrimination: a case study of quartz, biotite and K-feldspar from granite
Wei Lou, Dexian zhang
 doi: 10.1007/s12583-022-1672-7
[Abstract](91) [PDF 5838KB](32)
Abstract:
Mineral recognition and discrimination play a significant role in geological study. Intelligent mineral discrimination based on deep learning has the advantages of automation, low cost, less time consuming and low error rate. In this manuscript, characteristics of quartz, biotite and K-feldspar from granite thin sections under cross-polarized light were studied for mineral images intelligent classification by Inception-v3 deep learning convolutional neural network (CNN), and transfer learning method. Dynamic images from multi-angles were employed to enhance the accuracy and reproducibility in the process of mineral discrimination. Test results show that the average discrimination accuracies of quartz, biotite and K-feldspar are 100.00%, 96.88% and 90.63%. Results of this study prove the feasibility and reliability of the application of convolution neural network in mineral images classification. This study could have a significant impact in explorations of complicated mineral intelligent discrimination using deep learning methods and it will provide a new perspective for the development of more professional and practical mineral intelligent discrimination tools.
Origin of burrow-associated dolomites and its reservoir implications: A case study from the Lower-Middle Ordovician carbonates of Tarim Basin (NW China)
Chuan Guo, Daizhao Chen, Yong Fu, Xiqiang Zhou, Cunge Liu
 doi: 10.1007/s12583-022-1673-6
[Abstract](74) [PDF 11140KB](39)
Abstract:
The Yingshan Formation of the Lower-Middle Ordovician in the Tarim Basin (NW China) was mainly deposited in a shallow platform, which was intensely bioturbated with burrows filled with both dolomites and calcites. This study aims to figure out the controls on the dolomitization of burrow infills and the effects on petroleum reservoir quality based on petrographic examination, fluid inclusion microthermometry, and isotopic (C-O-Sr) geochemical analyses. The differentiation of burrow-associated carbonates (dolomites and calcites) was likely controlled by the interactions of sea-level oscillations of variable orders and depositional environments. The burrow-associated dolomites (BADs) were precipitated in a relatively restricted (i.e., lagoon) depositional environment during the lowstand of long-term sea level. In contrast, the burrow-associated calcites (BACs) were formed in a water circulation-improved lagoonal environment during the transgression of long-term sea level. Isotopic geochemical data indicate that the BADs in the Yingshan Formation were formed from slightly saline (i.e., mesosaline to penesaline) seawater, whereas the BACs were precipitated from nearly normal seawater. In addition to the anoxic condition, the presence of marine-sourced organic matter and sulfate-reducing bacteria, and a sufficient supply of dolomitizing fluids enriched in magnesium ions (Mg2+) and their Mg2+ concentration may have played a critical role in the formation of BADs. In the more permeable and disturbed burrow sediments as a result of burrowing, penetrating fluids with higher salinities and higher Mg2+ concentration relative to seawater favored dolomite precipitation. The fluids with seawater-like Mg2+ concentration, however, would lead to calcite precipitation. The progressive dolomitization of these burrowed sediments could have propagated the dolomitizing fronts and extended into ambient limestones, leading to the development of extensive dolomites. This dolomitization process can improve the petrophysical properties (porosity and permeability) and the potential as hydrocarbon reservoirs during the emplacement of hydrocarbons from underlying source rocks of the Cambrian to Lower Ordovician.
U-Pb ages and europium anomalies of detrital zircons from sediments in the West Kunlun Orogenic Belt: implications for the Proto-Tethys Ocean evolution
Yinggang Zhang, Xizhu Yao, Jin Wang, Wenqing Pan, Yongquan Chen, Baoshou Zhang, Tao Yang
 doi: 10.1007/s12583-022-1671-8
[Abstract](289) [PDF 5722KB](44)
Abstract:
The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt (WKOB), and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks in the WKOB. Sedimentary rocks in the WKOB received little attention in the past; however, they could provide important constraints on the evolution of the oceanic lithosphere. Here, a series of shales and greywackes found in the Kudi area of WKOB were studied to constrain their depositional ages and explore their significance in the evolution of the Proto-Tethys oceanic crust. U-Pb dating and europium anomaly (Eu/Eu*) were analyzed for detrital zircons from greywackes interlayers, while bulk rare earth elements and yttrium (REY) of the shales were measured. Detrital zircons U-Pb ages yielded a maximum depositional age of 436 Ma for the greywackes and black shales, while the REY distribution patterns of the black shales are similar to those of the Tarim Ordovician Saergan shales. Accordingly, the studied WKOB black shales were deposited in the Proto-Tethys Ocean during the Late Ordovician-Early Silurian period. The maximum depositional age at 436 Ma may represent a minimum closure time of the Proto-Tethys Ocean, which is also supported by the absence of increases in Eu/Eu* values during the Late Ordovician-Early Silurian. Besides, our Eu/Eu* values in detrital zircons indicate diminished orogenesis during the Archean to Mesoproterozoic, subduction-related accretion at the margins of the supercontinent Rodinia during the Neoproterozoic.
Fe-Ti oxide mineralization in the XV intrusion, Bafq mining district, Central Iran: insights from mineralogy, mineral chemistry and S isotopic data
Sakine Amraei, Majid Ghasemi Siani, Mohammad Yazdi, Liang Qiu, Bertrand Moine, Minghua Ren
 doi: 10.1007/s12583-022-1675-4
[Abstract](138) [PDF 5984KB](12)
Abstract:
The mafic-ultramafic intrusion in the XV anomaly area, which contains magmatic Fe-Ti oxide-(P) ore, is located in the Bafq mining district in the Central Iran. It consists of cumulate and layered Fe-Ti-bearing gabbros and pyroxenites. The mineral assemblages include clinopyroxene, Fe-Ti oxides, plagioclase, amphibole, apatite and sulfides (pyrite and chalcopyrite). The Fe-Ti oxides mainly consist of magnetite-titanomagnetite and ilmenite, which occur as disseminated, intergrowth, lamellae (trellis and sandwich textures) and inclusions. Magnetite in the gabbroic rocks is from the near end-member of Fe3O4 (<1 wt. % TiO2) to titanomagnetite containing up to 8 wt. % TiO2 (about 3.73 to 26.84 % Ulvospinel (XUsp)). Magnetite in pyroxenite rocks is characterized with TiO2 range from 0.46 to 3.14 wt. % (XUsp varied from 1.76 to 10.46 %). The abundances of V2O3 range from 0.03 to 1.29 and 0.24 to 1.00 wt. % for gabbro and pyroxenite, respectively. XUsp contents of magnetite show insignificant correlations with Al2O3 and MgO. The average XIlm in the ilmenite of gabbro is 92 %, whereas it is 90.37 % in the pyroxenite rocks. The MgO and V2O3 contents show a slightly positive correlation with TiO2 in ilmenite. The composition of clinopyroxenes in gabbro and pyroxenite rocks fall in the diopside to augite field with Mg# ranging from 67 to 98 and 74 to 96, respectively. In both rock types, amphiboles are mainly pargasite and rarely actinolite. Plagioclase in pyroxenite rocks are clustered in the labradorite to andesine fields with a compositional ranges of An46-69 and in gabboic rocks fall in two fields with compositional ranges of albite with An0.65-5.95 and labradorite with An50-63. The δ 34S isotopic values cover a limited range from +3.15 ‰ to +4.10 ‰ V-CDT consistent with magmatic origin. Fe-Ti mineralization are formed in two stages, minor inclusions of Fe–Ti oxide minerals in the pyroxene and plagioclase crystallized in the early magmatic stage, whereas interstitial oxides formed by fractional crystallization processes that accumulated by gravitational settling in the later stage as intercumulus phase. Gravitational settling process is supported by the observation of decreasing the amount of Fe-Ti oxides from Fe-Ti oxide- rich pyroxenite to weak mineralized gabbro (base to top). The high contents of H2O, phosphorate and high initial Ti-Fe in parental magma are the crucial factors controlling the Fe-Ti oxides enrichment and mineralization.
monitoring multi-temporal changes of lakes on the tibetan plateau using multi-source remote sensing data from 1992 to 2019: a case study of lake zhari namco
juan wu, chang-qing ke, yu cai, zheng duan
 doi: 10.1007/s12583-022-1639-8
[Abstract](196) [PDF 7604KB](14)
Abstract:
lake level, area and volume are sensitive indicators of climate change. at present, many studies have focused on the interannual water balance of lakes, but lake level and area can change remarkably with seasons, especially for lakes with seasonal ice cover. zhari namco, a seasonal frozen lake, was selected as an example to investigate its seasonal water balance. multi-source altimetry and landsat data were used to obtain the seasonal lake level and area from 1992 to 2019, and seasonal lake volume variations were also estimated. the results indicated the average lake level, area and volume in autumn were the largest. the lake level, area, and volume experienced three turning points approximately in 2000, 2010, and 2016, and showed an overall increasing trend from 1992 to 2019, with slopes of 0.15 m/year, 2.17 km2/year, and 0.14 km3/year, respectively. the lake area expanded significantly in autumn, which was related to the abundant precipitation. delay time of land surface runoff, increased temperature, and evaporation may be the reason for the low lake level and volume in summer. the precipitation was the dominant factor of water balance, which explained 62.09%, 62.43%, and 62.10% of the variations in lake level, area, and volume, respectively.
stochastic modeling of folded structures in scarce data scenarios using transiogram with locally varying anisotropy
yabo zhao, weihua hua, guoxiong chen, liang dong, zhipeng liu, xiuguo liu
 doi: 10.1007/s12583-022-1646-9
[Abstract](162) [PDF 3963KB](7)
Abstract:
sampling is usually scarce in geological modeling, and hence, complex and continuous geological phenomena are difficult to simulate when anisotropy changes locally. the current study aimed to present a method for modeling folded structures using transiogram with locally varying anisotropy in scarce data scenarios. based on the direction fields of locally varying anisotropy, a pathline-based algorithm was proposed to simulate the folds that are flattened and calculate the relative position of any two random points thereafter. compared to the traditional two-point spatial continuity measures (such as the variogram), the locally varying anisotropy transiogram could not only describe the high order markovian of the spatial distribution of geological bodies, but also do so with explicable physical implication. the report revealed that the locally varying anisotropy transiogram of horizontal strata can be directly obtained if the stratigraphic sequence and stratum thickness are known. in the case study, only one geological map was used in a real complex-fold area to successfully simulate the 3-d stratigraphic model.
gastropod fauna of the zuodeng permian-triassic boundary section in the nanpanjiang basin and its geometric-based morphological disparity analysis
xin sun, li tian, xincheng qiu, kaiping guan, erik tihelka, haijun song, jinnan tong, hao yang
 doi: 10.1007/s12583-022-1645-x
[Abstract](114) [PDF 4539KB](9)
Abstract:
gastropods, as one of the most common invertebrates in shallow marine environments, were heavily impacted by the permian-triassic mass extinction (ptme), with severe loss of diversity and remarkable dwarfism of body size. here, we report a new gastropod fauna from the permian‒triassic carbonates of zuodeng, guangxi province, south china. five species belonging to five genera and two indeterminate taxa are identified. the zuodeng fauna is dominated by paleozoic holdover taxa, including holopea teres, protostylus sp., and wannerispira shangganensis although most of them are found in the basal triassic microbialites. three gastropod communities have been recognized by cluster analysis. further morphological analyses show that the changing pattern of disparity, with diversity decreasing from community ⅱ to ⅲ, fits the interior-reduction model. in addition, the morphospace of community in microbialites is higher than those in non-microbialite bearing beds at zuodeng, shedding new light on the ecological role of microbialites during the permian-triassic environmental stress.
susceptibility mapping of ground collapse caused by anthropogenic activities
zhongmin mao, yuyong jiao, fei tan, xin qi, cong zeng
 doi: 10.1007/s12583-022-1644-y
[Abstract](101) [PDF 4967KB](3)
Abstract:
frequent ground collapses resulted by anthropogenic activities occur due to rapid urbanization. accurate susceptibility mapping is critical for disaster prevention and control. in this study, 1198 ground collapse cases were collected from 2017 to 2020 in shenzhen. after multicollinearity testing, eight effective factors (elevation, relief, clay proportion, average annual precipitation, distance from water, land use type, building density, and road density) were selected to construct an evaluation index system. ground collapse susceptibility was analyzed and mapped using the normalized frequency ratio (nfr), logistic regression (lr), and nfr-lr coupling models. finally, the rationality and performance of the three models were compared using the frequency ratio (fr) and receiver operating characteristic (roc) curve, respectively. all three models could effectively evaluate the ground collapse susceptibility (area under the roc curve (auc) > 0.7), though the result of nfr-lr model was more rational and had the highest performance (auc = 0.791) among the three models. shenzhen possessed ground collapses mainly in built-up areas, the greater the intensity of anthropogenic activity in a location, the higher the likelihood of a disaster. the high and very high susceptibility zones covered a total area of 546.76 km2 and involved the nanshan, luohu, and futian districts, as well as some areas of the baoan, guangming, and longgang districts.
Protoconodonts and Paraconodonts from the Machari Formation (upper Series 3 and Furongian) in the Eodungol Section, Yeongwol, Korea
Byung-su LEE
[Abstract](292) [PDF 2509KB](32)
Abstract:
The Machari Formation ranges from the “upper Series 3” (Middle Cambrian) to Furongian (Upper Cambrian) in the Yeongwol area, Korea. It has been known to yield relatively diverse invertebrate fossils. Particularly trilobite biozones of the formation have been well defined. On the other hand, little has hitherto been studied on conodont microfossils for the formation. This paper reports a diverse and well preserved protoconodonts and paraconodonts of Series 3 from the formation in the Eodungol section, exposed along a southern mountain trail of Mt. Sambangsan, Yeongwol, Korea. Five of the thirteen samples collected for conodont contain a rich protoconodont and paraconodont assemblage and numerous shelly fossils including trilobites, brachiopods, sponge spicules, hyolithids and incertae sedis. Sample Eo5 is extremely fossiliferous (465 elements, 96.5 % of total collection), and the most abundant species was Phakelodus elongatus (236 elements, 62 % of the Eo5 collection). The preservation is relatively good, but some specimens are corroded and fragmentary. Some of protoconodonts are exfoliated. Relatively larger ones were commonly preserved as phosphatized internal molds, particularly in specimens of Furnishina bigeminata, Furnishina leei n. sp., Muellerodus pomeranensis, Nogamiconus sinensis and westergaardodids. Phakelodids were commonly preserved as clusters. Among twenty species referable to nine genera, Furnishina bigeminata, Furnishina leei n. sp., Nogamiconus sinensis, Huayuanodontus tricornis, Proscandodus obliquus, and Westergaardodina grandidens were previously undescribed species in Korea. This assemblage is named herein as the Westergaardodina matsushitai Zone, which is new biozonal name replacing the old one i.e., Gapparodus bisulcatus-Westergaardodina matsushitai-Westergaardodina moessebergensis Assemblage. The W. matsushitai Zone corresponds to the Lejopyge armata trilobite Zone, and is well correlated with the upper Series 3 conodont biozones of the Westergaardodina matsushitai-Westergaardodina grandidens Zone of South China, and the Westergaardodina matsushitai Zone of North China, respectively. The present data allow a useful correlation to China and Baltica in relation to new subdivision of the Cambrian. Furnishina leei n. sp. is newly described.
Uranium Isotope Variations (234U/238U and 238U/235U) and Behavior of U-Pb Isotope System in the Vershinnoe SandstoneType Uranium Deposit, Vitim Uranium Ore District, Russia
V. N. Golubev, I. V. Chernyshev, B. T. Kochkin, N. N. Tarasov, G. V. Ochirova, A. V. Chugaev
 doi: doi.org/10.1007/s12583-021-1436-9
[Abstract](28) [PDF 5507KB](17)
Abstract:
The U-Pb isotope system and uranium isotope composition (235U/238U and 234U/238U) were studied in a number of samples from the vertical section of the uranium ore body at the Vershinnoe sandstone-type deposit, Vitim uranium ore district, Russia. These parameters were determined to broadly vary. Deviations of the 234U/238U ratio from the equilibrium value indicate that the uranium ore was not completely conserved during the postore stage, and uranium was determined to continue mi‐grating at the deposit. Comparison of the U-Pb isotope age value and 234U/238U isotope ratio provides an insight into the migrate direction of uranium in the ore body. The broad variations (137.377–137.772) in the 238U/235U ratio over the vertical section of the ore body can be explained by the different settings of the samples relative to the ore deposition front and changes in the redox conditions when this front shifted. The fact that the δ238U and K234/238 values are correlated indicates that the transfer of the 234U iso‐tope into the aqueous phase may have been coupled with isotope fractionation in the 238U-235U system during the postformation uranium migration within the orebody.
Association of Sandstone-Type Uranium Mineralization in the Northern China with Tectonic Movements and Hydrocarbons
Yin Chen, Peisen Miao, Jianguo Li, Ruoshi Jin, Hualei Zhao, Lulu Chen, CongWang, Haoyu Yu, Xiaoru Zhang
 doi: doi.org/10.1007/s12583-021-1493-0
[Abstract](77) [PDF 50719KB](27)
Abstract:
In the continental basins of Northern China (NC), a series of energy resources commonly co-exist in the same basin. As the three typical superimposed basins of different genesis in the NC, the Junggar, Ordos, and Songliao basins were chosen as the research objects. The favorable uraniumbearing structures are generally shown as a basin-margin slope or transition belt of uplifts with the de‐velopment of faults, which are conducive to a fluid circulation system. The Hercynian, Indosinian, and Yanshanian movements resulted in the development of uranium-rich intrusions which acted as the sig‐nificant uranium sources. The main hydrocarbon source rocks are developed in the Carboniferous, Permian, Jurassic and Cretaceous. The mature stage of source rocks is concentrated in the Jurassic–Cretaceous, followed by the multi-stage expulsion events. Influenced by the India-Eurasian collision and the subduction of the Pacific Plate, the tectonic transformation in the Late Yanshanian and Himala‐yan periods significantly influenced the sandstone-type uranium mineralization. The hydrocarbon reser‐voirs are spatially consistent with sandstone-type uranium deposits, while the hydrocarbon expulsionevents occur in sequence with sandstone-type uranium mineralization. In the periphery of the faults or the uplifts, both fluids met and formed uranium concentration. The regional tectonic movements moti‐vate the migration of hydrocarbon fluids and uranium mineralization, especially the Himalayan move‐ment.
An investigation of dislocation in olivine phenocrysts from the Hawaiian basalts
Zhuo-Yue Li, Da-Peng Wen, Yong-Feng Wang, Xiang-Wen Liu
 doi: 10.1007/s12583-020-1030-6
[Abstract](2057) [PDF 7048KB](157)
Abstract:
Intracrystalline distortions (like undulose extinction, dislocations, and subgrain boundaries) in olivine from naturally-deformed peridotites is generally taken as a sign of dislocation creep. However, similar features in olivine phenocrysts that were found in basaltic magmas are still not well understood. In particular, whether subgrain boundaries in olivine phenocrysts arise from plastic deformation or grain growth is still debated (In the latter case, they are essentially grain boundaries but not subgrain boundaries. Therefore, we used hereinafter subgrain-boundary-like structures instead of subgrain boundaries to name this kind of intracrystalline distortion). Here we carried out a detailed study on dislocations and subgrain-boundary-like (SG-like) structures in olivine phenocrysts from two Hawaiian basaltic lavas by means of petrographic microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). Abundant and complex dislocation substructures (free dislocations, dislocation walls, and dislocation tangles) were observed in the decorated olivine grains, similar to those in olivine from peridotite xenoliths entrained by the Hawaiian basalts. The measured average dislocation density is 2.9 ± 1.3 × 1011 m-2, and is three to five orders of magnitude higher than that in laboratory-synthesized, undeformed olivine. TEM observations on samples cut across the SG-like structures by FIB (focused ion beam) demonstrated that this kind of structures is made of an array of dislocations. These observations clearly indicate that these structures are real subgrain boundaries rather than grain boundaries. These facts suggested that the observed high dislocation densities and subgrain boundaries were not resulted from crystal crystallization/growth, but were formed by plastic deformation. These deformation features do not prove that the olivine phenocrysts (and implicitly mantle xenoliths) were deformed after their capture by the basaltic magmas, but can be ascribed to a former deformation event in a dunitic cumulate, which was formed by magmatic fractionation, then plastically deformed, and finally disaggregated and captured by the basaltic magma that brought them to the surface.
Central Asia––A Global Model for the Formation of Epigenetic Deposits in a Platform Sedimentary Cover
Igor Pechenkin, Vladislav Petrov
 doi: doi.org/10.1007/s12583-021-1581-1
[Abstract](11) [PDF 8469KB](7)
Abstract:
Metallogenic specialization of sedimentary cover in Central Asia is determined by its tec‐tonic setting that governs the hydrodynamic regime (exfiltrational or infiltrational) and as a consequence, the hydrogeochemical zonality (type of water and its gaseous and microcomponent composition). Hydro‐dynamic conditions (distribution of recharge and discharge areas) determine the direction of stratal water flow and location of mineralization resulted from the change in geochemical, thermodynamic, litholog‐ical, structural and other conditions. The exfiltrational regime suggests a dependence of the epigenetic mineralization upon the distribution and degree of preservation of hydrocarbon occurrences. Often, hy‐drocarbon matter serves as a reducing barrier and ore-concentrating factor during the formation of polymineral concentrations related to stratal oxidation zone. The supergene epigenetic ore-forming pro‐cesses are induced by the interaction between the Earth’s sedimentary cover and hydrosphere. Sedimen‐tary rocks themselves commonly serve as a source of ore materials. The ore deposition zones on geochemi‐cal barriers and ore material source are often located significantly apart from each other. The trend of these processes is determined by the position of ore-bearing depressions in large tectonic blocks.
Theoretical System of Sandstone-Type Uranium Deposits in Northern China
Ruoshi Jin, Huajian Liu, Xiaoguang Li
 doi: doi.org/10.1007/s12583-021-1449-4
[Abstract](56) [PDF 19090KB](18)
Abstract:
Many theoretical results on sandstone-type uranium mineralization in northern China obtained by the uranium research team of the Tianjin Center of Geological Survey in recent years are presented. From the source sink system of uranium-producing basins, sedimentary environment of uranium-bearing rock series, ore-forming fluid information, evolution of tectonic events, basin forma‐tion and development, we redefine and classify uranium orebodies, redox zoning, and ore-controlling structural styles. We then systematically propose a theoretical system of sandstone-type uranium depos‐its in northern China. We conclude that sandstone-type uranium deposits in northern China are main‐ly found in sedimentary environments such as rivers, deltas, and alluvial fans in the Mesozoic and Cenozoic lowstand systems tract and in gray sandstone layers in the vertical redox zoning. The orebodies are controlled by the tectonic slope belt, which is in the shape of a strip on the plane, and spreads in a layer or plate on the section. Vertical (ups and downs) tectonic movement triggers large-scale phreatic flow in the basin, which is the real driving force for controlling the ore-forming fluid. The theoretical system of sandstone-type uranium deposits in northern China should be based on global tectonic move‐ment and environmental changes and take into account factors such as basins as a unit to study miner‐alization background, ore concentration areas as objects to study mineralization, and the correlation between regional tectonic movement and metallogenic process as a breakthrough point to study tecton‐ic events and metallogenic events. It should also be based on different basin types to establish metallo‐genic models. The innovative research results and ideas are summarized with the aim of promoting the continuous improvement of sandstone-type uranium mineralization theory in northern China.
U-Blacks Mineralization in Sandstone Uranium Deposits
Olga A. Doynikova
 doi: doi.org/10.1007/s12583-021-1451-x
[Abstract](20) [PDF 18000KB](12)
Abstract:
Ores of infiltration sandstone-hosted uranium deposits in the sedimentary cover are ubiquitous composed of dispersed soot powder mineralization of black, brownish-black colour. Longterm studies of such loose U-ores by analytical transmission electron microscopy (ATEM) proved their polymineral nature. Uranium blacks are composed by at least three different U-mineral forms: oxide (uraninite), silicate (coffinite) and phosphate (ningyoite) which are present in various proportions of ore compositions. Such high dispersed friable uranium formations are difficult to diagnose by tradition‐al mineralogical methods (optical, XRD, IR and X-ray spectroscopy, etc.) which analyze total sample composition (phases mixture); their results characterize the dominant sample phase, omitting both sharply subordinate and X-ray amorphous phases. All research results are based on ATEM methods (SAED+EDS), which are optimal for crystallochemical diagnostics in the mineralogical study of such uranium ores. The article presents the diagnostic characteristics under electron microscope (EM) of uranous minerals from different sandstone deposits with their origin being discussed.
Classification of Sandstone-Related Uranium Deposits
Michel Cuney, Julien Mercadier, Christophe Bonnetti
 doi: doi.org/10.1007/s12583-021-1532-x
[Abstract](106) [PDF 1583KB](26)
Abstract:
Sandstone type deposits are the most common type of uranium deposits in the world. A large variety of sub-types have been defined, based either on the morphology of the deposits (e.g., tabu‐lar, roll front, etc), or on the sedimentological setting (e.g., paleovalley, paleochannel, unconformity), or on tectonic or lithologic controls (e.g., tectonolithologic, mafic dykes/sills), or still on a variety of others characteristics (phreatic oxidation type, interlayer permeable type, multi-element stratabound infiltra‐tional, solution front limb deposit, humate type, etc.), reflecting the diversity of the characteristics of these deposits, but making it difficult to have a clear overview of these deposits. Moreover, uranium de‐posits occurring in the same sedimentological setting (e.g., paleochannel), presenting similar morpholo‐gies (e.g., tabular), may result from different genetic mechanisms and thus can be misleading for explora‐tion strategies. The aim of the present paper is to propose a new view on sandstone-related uranium de-posits combining both genetic and descriptive criteria. The dual view is indeed of primordial importance because all the critical characteristics of each deposit type, not limited to the morphology/geometry of the ore bodies and their relationships with depositional environments of the sandstone, have to be taken into account to propose a comprehensive classification of uranium deposits. In this respect, several key ore-forming processes, like the physical-chemical characteristics of the mineralizing fluid, have to be used to integrate genetic aspects in the classification. Although a succession of concentration steps, potentially temporally-disconnected, are involved in the genesis of some uranium mineralization, the classification here proposed will focus on the main mechanisms responsible for the formation and/or the location of ore deposits. The objective of this paper is also to propose a robust and widely usable ter‐minology to define and categorize sandstone uranium deposits, considering the diversity of their origin and morphologies, and will be primarily based on the temperature of the mineralizing fluid considered as having played the critical role in the transportation of the uranium, starting from synsedimentary ura‐nium deposits to those related to higher temperature fluids.
COVER
2024, 35(1)  
[Abstract](0) [PDF 23141KB](0)
Abstract:
CONTENTS
2024, 35(1)  
[Abstract](0) [PDF 241KB](0)
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Geochemistry and Mineral Deposits
Trace Element Mobility in Subducted Marble and Associated Eclogite: Constraints from UHP Rocks in the Shuanghe Area, Central-East China
Xingao Hou, Zhiqiang Yu, Shefa Chen, Lei Liu, Yilin Xiao
2024, 35(1): 1-15.   doi: 10.1007/s12583-022-1692-3
[Abstract](118) [FullText HTML](118) [PDF 7747KB](31)
Abstract:

In order to decipher element mobility in UHP meta-sedimentary rocks in the continental subduction zone, major and trace element compositions are investigated for a continuous profile from a representative UHP region in the Dabie Mountains. Among the lithologic contact zone, contents of K, Ca, LREE, and LILE exhibit varying degrees of downward trends in both marble and eclogite toward the contact zone, indicating that marble and their associated eclogite can release a large amount of K, Ca, and a small number of LILEs and LREEs. Titanite is the main Ti phase in both marble and eclogite. Titanite rims around rutile can occasionally be seen in eclogite. Contents of Ti and HFSE exhibit a well-coupled relation among marble and eclogite, indicating that substantial Ti and HFSEs were migrated from eclogite to marble, in accord with the capacity of a melt medium. Rutiles and titanites in marble exhibit a relatively limited variation in Nb/Ta ratios (12.9–16.2), similar to those of titanites in eclogite (14.2–16.7), which demonstrates that rutiles and titanites in marble were sourced from eclogite because of short-distance migrations of Ti and HFSEs. According to the P-T path and the temperature and pressure conditions of the peak metamorphism reported by previous studies, the eclogite associated with marble may not form supercritical fluids in the subduction zone because of the addition of carbonate minerals.

Insight into the Origin of Iron Ore Based on Elemental Contents of Magnetite and Whole-Rock Geochemistry: A Case of the Bipindi Banded Iron Formations, Nyong Complex, SW Cameroon
Landry Soh Tamehe, Huan Li, Sylvestre Ganno, Zuxing Chen, Yanick Brice Lemdjou, Safiyanu Muhammad Elatikpo
2024, 35(1): 16-28.   doi: 10.1007/s12583-022-1622-4
[Abstract](1) [FullText HTML](1) [PDF 9606KB](0)
Abstract:

The Bipindi iron ore district is located in the central section of the Nyong Complex at the northwestern margin of the Congo Craton in Southwest Cameroon. This iron district contains numerous iron mineralization hosted by the Mewongo, Bibole, Kouambo, and Zambi banded iron formations (BIFs). These BIFs contain magnetite as the main iron ore mineral associated with pyrite, and gangue minerals are quartz with minor chlorite and amphibole. The origin of iron ore from these BIFs was investigated using a combination of in-situ magnetite and whole-rock chemistry. The studied BIF ore samples have a narrow range of TFe between 30.90 wt.% and 43.20 wt.%, indicating a low-grade ore. The geochemical signatures of magnetite such as low contents of base metals (e.g., Cu, Co, V, and Zn) and low Co/Zn ratios < 0.85 indicate a hydrothermal origin. Combined with the geochemical features of these BIFs, e.g., high Fe/Ti and Fe/Al ratios (mean > 600 and > 75, respectively), we suggest that magnetite was derived from a mixture of seawater and ~0.1% low-temperature hydrothermal fluids in an oxidizing environment. Collectively, low-temperature hydrothermal and later metamorphic fluids were necessary for the transformation of the protolith Nyong Complex BIFs to iron ore.

A Deep Mantle Source for the Late Neoarchean Metamorphosed Basalts in Eastern Hebei, North China Craton: Insights from Whole-Rock Geochemistry and Sm-Nd Isotopes, and Zircon U-Pb-Hf Isotopes
Zhuang Li, Chunjing Wei, Chuan Yang, Xi Zhang
2024, 35(1): 29-40.   doi: 10.1007/s12583-023-1807-5
[Abstract](0) [FullText HTML](0) [PDF 16184KB](0)
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The basalts within the greenstone belt worldwide serve as an ideal target to decipher the nature of Archean mantle sources and further to extend the understanding of the early stages of Earth's evolution. To provide important insights into the issues, we carried out a detailed investigation of whole-rock geochemistry and Sm-Nd isotopes, and zircon U-Pb-Hf isotopes for the Late Neoarchean metamorphosed basalts in eastern Hebei, North China Craton. U-Pb isotopic dating using the LA-ICP-MS on zircons reveals that the basalts in eastern Hebei erupted at ca. 2.48–2.51 Ga and subsequently experienced multiple regional metamorphic events at 2 477 and 1 798 Ma, respectively. The metamorphosed basalts are featured by low SiO2, MgO, K2O + Na2O, and high FeO contents, endowed with the subalkaline and high-Fe tholeiitic affinities. The radiogenic initial Nd and Hf isotope values and correlations among V, Ni and Cr contents strongly imply that the basalts experienced significant clinopyroxene and olivine fractionation and minor crustal contamination during magma evolution. They are also characterized by the relatively low total REE contents and exhibit significant depletions to moderate enrichments in the LREE contents, indicating the derivation from a deep mantle source in an Archean proto-mantle plume setting.

Zircon Hf Isotope Mapping for Understanding Crustal Architecture and Its Controls on Mineralization during Early Cretaceous in the Southern Great Xing'an Range, NE China
Feng Yuan, Huanan Liu, Shengjin Zhao, Mingjing Fan
2024, 35(1): 41-50.   doi: 10.1007/s12583-020-1100-9
[Abstract](1) [FullText HTML](1) [PDF 1073KB](0)
Abstract:

Voluminous Early Cretaceous granitoids and associated large-scale ore deposits are distributed within the southern Great Xing'an Range (SGXR), NE China. Based on previously published geochronology and zircon Hf-isotope data, Hf isotope mapping is undertaken to improve our understanding of crustal architecture and its controls on ore deposits. The ore-related Early Cretaceous granitoids were sourced predominantly from juvenile crust, with the involvement of variable proportions of ancient crustal materials. The crustal architecture, as inferred from Hf isotopic contour maps, indicates two distinct Hf isotopic domains in SGXR, including (1) a higher-εHf (+7 to +11) juvenile crust containing minor ancient crustal material, and (2) a lower-εHf (+2 to +6) juvenile crust containing a greater proportion of ancient crustal materials.The Hf isotopic maps identify links between crustal architecture and regional metallogeny. Copper deposits and other deposits with significant Cu production are restricted mainly to the higher-εHf juvenile crustal regions in the northern and eastern SGXR. Deposits dominated by other metals (e.g., Mo, Sn, W, Pb, Zn, and Ag) occur mainly in the lower-εHf juvenile crustal regions in the southern and western SGXR. Interaction between juvenile crust-derived melts and ancient crustal components played an important role on the distribution of various ore metals.

Geochemical Characteristics and Development Significances of Constant and Trace Elements from Coalbed Methane Co-Produced Water: A Case Study of the Shizhuangnan Block, the Southern Qinshui Basin
Yang Li, Shuheng Tang, Jian Chen, Songhang Zhang, Zhaodong Xi
2024, 35(1): 51-61.   doi: 10.1007/s12583-022-1628-y
[Abstract](1) [FullText HTML](1) [PDF 2191KB](0)
Abstract:

As an unconventional natural gas resource, coalbed methane (CBM) development releases a large amount of CBM wells co-produced water. Geochemical characteristics of the co-produced water provide an essential foundation for the production dynamics of CBM reservoirs if the impacts of fracturing fluids and other aquifers can be ignored. In the Shizhuangnan Block of the southern Qinshui Basin, constant and trace elements in CBM co-produced water from the wellheads were collected and determined, which is applied to assess water source, fracturing fluid effect, and CBM production. Based on principle component analysis and hierarchical clustering analysis, the water samples are divided into four categories. It suggests that different characteristics affected by water-rock interaction, reservoir environment, aquifer recharge, and hydraulic fracturing result in the various ratios of Na+/Cl-, alkalinity (HCO3- + CO32-)/Cl- and other specific rules. Moreover, Cl- is selected as a dividing line for complete fracturing fluid flow back, associated with organic-bound chlorine complexes in the original coal seam water. Compared to constant elements, there is a significant correlation between Li and Sr concentrations and CBM productivity, so templates regarding trace elements can be used to distinguish various sources of the co-produced water.

Characterization of Arroyo Verde Epithermal Deposit: Paragenesis, Mineral Geochemistry, Geochronology and Fluid Inclusions in Lower Chon Aike Volcanism, Argentina
Cecilia Pavón Pivetta, Leonardo Benedini, Paulo Marcos, Ma. Agustina Cócola, Mercedes Virginia Barros, Daniel Gregori, Leonardo Strazzere, Anderson Costa dos Santos, Mauro C. Geraldes
2024, 35(1): 62-84.   doi: 10.1007/s12583-023-1823-5
[Abstract](3) [FullText HTML](3) [PDF 3264KB](0)
Abstract:

Arroyo Verde epithermal deposit, in the North Patagonia region of Argentina, is located within the Lower Chon Aike volcanism and is developed between 192.6 ± 2.5 Ma (mineralization host rock) and 189.5 ± 2.6 Ma (overlying lava). Marifil volcanic complex is the host rock for these veins, veinlets and breccias. This particular small deposit has developed low to intermediate sulphidation characteristics, with gangue mineral textures associated with several ore minerals. Electron probe microanalysis determines electrum, silver minerals such as acanthite, and tetrahedrite, related Ag-Cu minerals like jalpaite, mckinstryite, stromeyerite, and base metals like chalcopyrite, sphalerite, galena and pyrite. Fluid inclusions in quartz of two out of five events indicate that these Low Jurassic veins were formed due to subtle boiling and dilution mechanisms and by low-salinity (3.4 wt.% to 6.7 wt.% NaCl Eq) magmatic-hydrothermal fluid at 225 to 310 ℃. The fluid inclusion measurements that indicate boiling (Event 3) were plotted, and based on this data, we interpret that the Arroyo Verde deposit has been eroded between 550 and 700 m. This particular character has not been previously recorded for other sectors of the eastern north Patagonian region.

Structural Geology
SS-LASS Zircon Dating Deciphering Multiple Episodes of Anatexis in a Deeply-Subducted Continental Crust: An Example from Sulu Orogen, China
Peng Feng, Lu Wang, Xiawen Li, Wenjie Ding, Zhe Chen
2024, 35(1): 85-98.   doi: 10.1007/s12583-022-1797-8
[Abstract](1) [FullText HTML](1) [PDF 5601KB](0)
Abstract:

'Single shot' laser-ablation split-stream (SS-LASS) technique analyzing unpolished zircon grains makes their thin rims tenable for determination, which thus offers great potential in deciphering the timing of multiple and short-lived episodes of anatexis and metamorphism in deeply-subducted continental crusts. Dominated granitic gneisses in the deeply subducted continental crust undergoing considerable fluid-melt activities persist multistage growth of zircon. Therefore, a comparative study of SS-LASS and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) zircon dating was conducted on the granitic gneisses from the Sulu belt in this study. Zircons mostly show a core-mantle-rim structure with CL-bright rims thinner than 5 μm. For LA-ICP-MS dating, relict magmatic zircon cores yield protolith ages of ca. 756–747 Ma; whereas the dark mantles record syn-exhumation anatexis at ca. 214 Ma. By contrast, according to the U-Pb dates, trace element features, zircon crystallization temperatures and geological context, SS-LASS zircon petrochronology deciphers three episodes of anatectic events, as follows: (ⅰ) the first episode of anatexis at ca. 218–217 Ma dominated by phengite-breakdown melting, likely facilitating the exhumation of the UHP slice from mantle depth; (ⅱ) the second episode of anatexis at ca. 193–191 Ma indicating part of northern Dabie-Sulu belt was still "hot" because of buried in the thickened orogenic crust at that time; (ⅲ) the third episode of anatexis (ca. 162–161 Ma) consistent with the intrusion ages (ca. 161–141 Ma) of the Jurassic to Cretaceous granitoids in this orogen, suggesting the initial collapse of the orogenic root of the Sulu belt occurred at Late Jurassic due to the Izanagi plate initially subducting beneath the margin of Eastern Asia. This study sheds new light upon the utilization of SS-LASS petrochronology deciphering multiple anatectic events in the deeply-subducted continental crust and supports us in better understanding the tectonic evolution of Dabie-Sulu Orogen.

Cretaceous–Neogene Exhumation of the Daqing Shan, North China Constrained by Apatite Fission Track Thermochronology
Junlin Zhou, Yuhong Li, Wei Han, Yunpeng Zhang, Gaochao Chen, Qiao Zhang, Jianshe Wei, Yazhuo Niu
2024, 35(1): 99-111.   doi: 10.1007/s12583-021-1518-8
[Abstract](1) [FullText HTML](1) [PDF 2725KB](0)
Abstract:

The Daqing Shan (DQS) located in the Yinshan-Yanshan Orogenic Belt plays an important role in the Mesozoic to Cenozoic evolution of the North China Craton. However, the cooling and exhumation history since the Cretaceous is still controversial. Integrating the apatite fission track (AFT) data in both this study and previous works, a three-stage exhumation history from Cretaceous to Neogene of the DQS is proposed. (1) The first stage is composed of the early exhumation during Early Cretaceous driven by the collision between the North China and Siberia cratons (ca. 148–132 Ma) and the far-field effect of the subduction of the Pacific Plate (ca. 132–114 Ma). (2) Due to the subsidence of the Hetao Basin and the subsequent compensation between the DQS and the Hetao Basin, the DQS experienced the second rapid exhumation from Early Eocene to Early Oligocene (ca. 54–29 Ma). (3) Since the Late Miocene (ca. 13.5 Ma), the third rapid cooling and exhumation of the DQS occurred due to the far-field effect of the uplift of the Tibetan Plateau and the subduction of the Pacific Plate.

Formation of the Tibetan Plateau during the India-Eurasia Convergence: Insight from 3-D Multi-Terrane Thermomechanical Modeling
Jile Chen, Peimin Zhu, Yuefeng Yuan, Guifan Chen
2024, 35(1): 112-130.   doi: 10.1007/s12583-023-1931-0
[Abstract](1) [FullText HTML](1) [PDF 13323KB](0)
Abstract:

Various models exist to explain the formation of the Tibetan Plateau, including "tectonic escape", "pure shear thickening", "convective removal of the lithospheric mantle", and "lower crustal flow" model. The first two models are primarily constructed on pure mechanical models but are unable to reasonably explain the tension and shear phenomena inside the plateau. The latter two are rheological dynamic models based on deep geophysical observations. However, the spatial range of the lower crustal flow and its role in the plateau formation/uplift remain controversial. Five multi-terrane visco-plastic thermomechanical models were constructed to simulate the uplift and lithospheric structure change of the Tibetan Plateau during the post-collision stage (since 35 Ma) under the convergence of the Indian Plate. Results show that the plateau's formation begins with crustal thickening, blocked by strong terranes at the northern plateau, and expanded laterally to the east. The lithosphere thickens gradually and experiences delamination at its base, elevating temperature within the crust and forming partial melting layers in the central plateau. As convergence persists on the southern side, the northern plateau's lithosphere bends downward and undergoes delamination, further heating the crust and promoting the northward and eastward flow of partial melting layers, leading to secondary uplift around the plateau.

Evaluation of the Relative Tectonic Activity from the Faults in the Gengma-Lancang-Menghai Seismic Belt (Southwestern China)
Dan Wang, Youpu Dong, Zhipeng Xi, Dongyue Zhang, Jiaxin Duan, Huayu Yu, Liang Yu
2024, 35(1): 131-143.   doi: 10.1007/s12583-021-1565-1
[Abstract](0) [FullText HTML](0) [PDF 19856KB](0)
Abstract:

The Gengma-Lancang-Menghai seismic belt, the southernmost part of the North-South seismic belt, is controlled by four active faults: the Nantinghe fault (NTHF), the Sanjianshan fault (SJSF), the Hanmuba-Lancang fault (HMB-LCF), and the Heihe fault (HHF), from northwest to southeast. However, the tectonic activity of the faults in the Gengma-Lancang-Menghai seismic belt has not been fully studied yet. In the present work, we conducted tectonic geomorphic indices to analyze the relative tectonic activity along the faults in the seismic belt based on the digital elevation model. We interpreted asymmetric factor, index of drainage basin shape, hypsometric integral, normalized stream-length gradient, valley floor-to-width to height ratio, and longitudinal profiles to show that the relative tectonic activity is higher in the north and lower in the south, and is strong in the region from Shanjia to Huimin in the center of the seismic belt.

Hydrogeology and Environmental Geology
Characteristics of Paleontological Communities in Surface Sediments of the Southern South China Sea and Their Paleoclimatic and Paleoenvironmental Significance
Jing Zhao, Li Zhang, Xiaoyan Wang, Jinglian Ge, Min Xu, Wei Chen, Mao Luo, Qianyong Liang, Qiuhua Yu, Shuaibing Luo, Wenkun Qie
2024, 35(1): 144-154.   doi: 10.1007/s12583-023-1910-5
[Abstract](1) [FullText HTML](1) [PDF 30122KB](0)
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Understanding the spatial and temporal distribution of different paleontological communities in the southern South China Sea (SCS) is fundamental to explore its paleoclimatic and paleoenvironmental changes. In this study, foraminifera, pollen and diatoms from 100 surface sediment samples covering 40 000 km2 of sea floor in the southern SCS were comprehensively investigated in terms of their assemblage and distribution. The results showed the existence of abundant foraminifera and pollen in most of the samples, although diatom communities were relatively scarce. Foraminifera were dominated by G. sacculifer, G. menardii, G. ruber, while diatoms were characterized by T. simonsenii, T. nitzschioides and T. longissima, indicating a typical tropical marine environment. The pollen assemblages showed a better reflection of montane rainforest, tropical rainforest and mangrove. The spatial differences among foraminifera assemblages may indicate the effect of water depth and a warmer environment in the southeast part of the study area, while the spatial patterns of diatom and pollen assemblages imply the influence of coastal current. Our study also noted that the compositions of paleontological communities in the SCS can vary significantly in a short distance, and synthesized studies on multiple biological groups are needed to reconstruct the Quaternary climate and the oceanographic environment.

Hydrochemical Characterization, Controlling Factors and Water Quality of Surface Water in Shandong Province, North China
Ran An, Jiutan Liu, Zongjun Gao, Changsuo Li, Yuming Peng
2024, 35(1): 155-166.   doi: 10.1007/s12583-021-1441-z
[Abstract](0) [FullText HTML](0) [PDF 21136KB](0)
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In this study, 90 surface water samples were collected from Shandong Province (SDP) in the dry and wet seasons and analyzed using statistical analysis, hydrochemical methods and water quality index (WQI). The content of main ions showed seasonal variations, with a higher average value in the dry season than in the wet season. Sampling points exhibiting high contents of the main chemical components were mainly distributed in areas southwest of SDP, north of Weifang, and around Jinan. The saturation index of carbonate minerals was greater than zero, while that of evaporite minerals was less than zero. The hydrochemical characteristics of surface water are mainly dominated by rock weathering as well as cation exchange. In addition, surface water in SDP has significantly been affected by anthropogenic factors. Most of the surface water could be classified as weakly alkaline soft-fresh water, with the hydrochemical types of SO4·Cl-Ca·Mg and SO4·Cl-Na. In terms of WQI, 47.88% and 37.88% of the water samples in SDP were classified as poor water in the dry and wet seasons, respectively. On the whole, the water quality is higher in the wet season than in the dry season, and surface water in SDP is generally suitable for agricultural irrigation.

A Novel Gymnosperm Wood from the Lopingian (Late Permian) in Zhangzi, Shanxi, North China and Its Paleoecological and Paleogeographic Implications
Xiao Shi, Jianxin Yu, Yuewu Sun, Zhen Xu, Hui Li
2024, 35(1): 167-176.   doi: 10.1007/s12583-021-1510-3
[Abstract](0) [FullText HTML](0) [PDF 47474KB](0)
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The Permian-Triassic transition saw extreme climatic changes that severely impacted the terrestrial ecosystem. Fossil plants, particularly fossil woods, are sensitive to climatic changes, and they, therefore, are unique materials revealing extreme environmental and climatic changes on land at that time. Abundant conifer woods were discovered in the Lopingian (Late Permian) strata of the Sunjiagou Formation in Shanxi Province, North China. The newly finding permineralized woods record the unique landscape of Lopingian North China. They represent a new conifer genus and species: Shanxiopitys zhangziensis gen. et sp. nov. Analyses of growth pattern and anatomical characteristics of the fossil woods indicate these trees grew under optimal growing conditions, and without seasonal growth cessation. However, climate signals from leaf fossils, vertebrate fossils and sedimentary evidences indicate a strongly seasonal climate in North China during the Lopingian. Thus, it is speculated that these trees likely lived in the gallery forests, which were distributed along the paleo-rivers within a seasonal landscape in the central North China block during the Lopingian.

Influence of Sub-Cloud Secondary Evaporation Effects on the Stable Isotopes in Precipitation of Urumqi Glacier No. 1, Eastern Tianshan
Mengyuan Song, Zhongqin Li, Feiteng Wang, Xin Zhang
2024, 35(1): 177-189.   doi: 10.1007/s12583-021-1522-z
[Abstract](0) [FullText HTML](0) [PDF 1861KB](0)
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In arid regions, the stable hydrogen and oxygen isotopic composition in raindrops is often modified by sub-cloud secondary evaporation when they descend from cloud base to ground through the unsaturated air. As a result of kinetic fractionation, the slope and intercept of the δ2H-δ18O correlation equation decrease. The variation of deuterium excess from cloud base to the ground is often used to quantitatively evaluate the influence of secondary evaporation effect on isotopes in precipitation. Based on the event-based precipitation samples collected at Urumqi Glacier No. 1, eastern Tianshan during four-year observation, the existence and impact of secondary evaporation effects were analyzed by the methods of isotope-evaporation model. Under high air temperature, small raindrop diameter and precipitation amount, and low relative humidity conditions, the remaining rate of raindrops is small and the change of deuterium excess is large relatively, and the slope and intercept of δ2H-δ18O correlation equation are much lower than those of Global Meteoric Water Line, which mean that the influence secondary evaporation on precipitation enhanced. While on the conditions of low air temperature, high relative humidity, heavy rainfall, and large raindrop diameter, the change of deuterium excess is small relatively and the remaining rate of raindrops is large, and the slope and intercept of δ2H-δ18O correlation equation increase, the secondary evaporation is weakened. The isotope-evaporation model described a good linear correlation between changes of deuterium excess and evaporation proportion with the slope of 0.90‰/%, which indicated that an increase of 1% in evaporation may result in a decrease of deuterium excess about 0.90‰.

Characteristics and Genesis of Acid Drainage Contamination from a Rock Tunneling Project Site
Yanyun Li, Zejiao Luo, Shihua Qi
2024, 35(1): 190-200.   doi: 10.1007/s12583-021-1551-7
[Abstract](0) [FullText HTML](0) [PDF 10545KB](0)
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While acid mine drainage (AMD) issues have become a topic of global concern, few studies have focused on acid drainage problems of non-mining activities. We conducted field research and a series of laboratory experiments to investigate the characteristics, release processes and formation of acid drainage contamination. Spoil rock samples and adjacent surface water, groundwater, soil and sediment samples were collected at a railway tunnel construction site in central China, and various parameters, such as the pH, mineral ion concentrations, and heavy metal concentrations, were measured. Based on the measured concentrations, surface water and sediments were seriously contaminated by acids, sulfate salts and heavy metals. Contamination in surface water showed a decreasing tendency as the distance from the spoils increased, while that in sediments showed a greater influence of coprecipitation and adsorption processes of heavy metal ions. The eluviation experiments of three rock samples indicated that R2 (silty fine sandstone) was the most likely major acid drainage contributor. Thiobacillus ferrooxidans was cultured and isolated from contaminated water to study the oxidation conditions during the release processes. The significant release of acid drainage when air and bacteria were both in the culture container suggested that oxygen and bacteria were necessary to produce acid drainage from spoils.

First Record of Cyclocarya from the Early Oligocene Qaidam Basin, North Tibet: Implications for the Paleogeography and Paleoecology
Yafei Hou, Bowen Song, Xiangchuan Li, Fang Han, Xu Zhang, Kexin Zhang
2024, 35(1): 201-211.   doi: 10.1007/s12583-021-1580-2
[Abstract](0) [FullText HTML](0) [PDF 41393KB](0)
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As the largest intermontane basin in the northeastern Tibetan Plateau (TP), the Qaidam Basin provides unique insight into paleoclimatic change and its relationship with global change and uplift on the TP. In this study, based on morphological comparison, fossil fruit of Cyclocarya from the Early Oligocene Shangganchaigou Formation in the Qaidam Basin is assigned as Cyclocarya cf. weylandii. The discovery of Cyclocarya cf. weylandii demonstrates the occurrence of Cyclocarya in the Oligocene sediment in Qaidam Basin. This is the first record of Cyclocarya fossil of Early Oligocene Age in China and indicates that Cyclocarya has existed on the northeastern TP since at least the Early Oligocene. The living analogues of the current fossil now lives in sub-tropical China, where the East Asian Monsoon is prevalent. Integrating the new fossils and previously reported fossil remains of plants and fishes, it can be inferred that the Early Oligocene Qaidam Basin was primarily influenced by westerly circulation and had a relatively warm and humid climate, which was in sharp contrast to the present-day climate in Qaidam Basin.

Engineering Geology and Geo-hazards
Preliminary Results of the Seismicity Monitoring Experiment around the 2019 Mw5.4 Earthquake Epicenter in the Central South China Sea Basin
Wenfei Gong, Aiguo Ruan, Xiongwei Niu, Zhenjie Wang, Pingchuan Tan, Xiaodong Wei, Wei Wang, Zhengyi Tong, Liqun Cheng, Fansheng Kong, Shaoping Lu, Jianke Fan, Weiwei Ding, Jinyao Gao, Chunguo Yang, Jiabiao Li
2024, 35(1): 212-220.   doi: 10.1007/s12583-021-1604-y
[Abstract](0) [FullText HTML](0) [PDF 5639KB](0)
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On September 5, 2019, a moderate earthquake of Mw5.4 unexpectedly occurred in the apparently quiescent central basin of the South China Sea. We immediately carried out a seismicity monitoring experiment around the epicenter by using broadband ocean bottom seismometers (OBS) for the following three scientific targets. The first is knowing the earthquake seismogenic mechanism, fault structure and further development. The second is finding the role of the residual spreading ridge playing in earthquake processes and further revealing the deep structures of the ridge directional turning area. The third is confirming the existence and significance of the so called "Zhongnan fault". This paper reports the preliminary results of the first phase experiment. Five OBSs were deployed for seismicity monitoring with a duration of 288 days, but only three were recovered. Micro-earthquakes were firstly detected by an automatic seismic phase picking algorithm and then were verified by analyzing their seismic phases and time-frequency characteristics in detail. A total of 21, 68 and 89 micro-earthquakes were picked out from the three OBSs respectively within the distance of 30 km. The dominant frequency of these micro-earthquakes is 12–15 Hz, indicating tectonic fracturing. During the first two months after the mainshock the seismicity was relatively stronger, and micro-earthquakes were still occurring occasionally till the end of observation, indicating the epicenter area is active. We used Match & Locate method to locate 57 micro-earthquakes preliminarily. Their spatial distribution shows that the seismicity is developed mainly along the NE direction roughly parallel to the residual ridge with depth variations between 10–20 km.

Dynamic Effect of Landslides Triggered by Earthquake: A Case Study in Moxi Town of Luding County, China
Hongfu Zhou, Fei Ye, Wenxi Fu, Bin Liu, Tian Fang, Rui Li
2024, 35(1): 221-234.   doi: 10.1007/s12583-022-1806-y
[Abstract](0) [FullText HTML](0) [PDF 35647KB](0)
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The dynamic effect is a very important issue widely debated by scholars when studying the genetic and disaster-causing mechanisms of earthquake-triggered landslides. First, the dynamic effect mechanism and phenomena of earthquake-triggered landslides were summarized in this paper. Then, the primary types of dynamic effects were further used to interpret the Mogangling landslide in Moxi Town of Luding County, China. A field investigation, remote sensing, numerical calculation and theoretical analysis were carried out to illustrate the failure mechanism of slope rock masses affected by earthquakes. The interaction between seismic waves and slope rock masses and the induced dynamic effect of slope rock masses were primarily accounted for in the analysis. The slope topography, rock mass weathering and unloading characteristics, river erosion, regional seismogenic structure, and rock mass structure characteristics were also discussed. The results showed that the formation of the Mogangling landslide was mainly related to the high amplification effect of seismic acceleration and back slope effects, interface dynamic stress effects, and double-sided slope effects of seismic waves caused by the catastrophic Ms 7.75 Moxi Earthquake in 1786. The principles for the site and route selection of large-scale infrastructure in the planning stage and the scientific prevention of seismic geological disasters were proposed on the basis of the dynamic effect of earthquake-induced landslides.

Investigation on the Deformation and Failure Patterns of Loess Cut Slope Based on the Unsaturated Triaxial Test in Yan'an, China
Lina Ma, Shengwen Qi, Songfeng Guo, Qiangbing Huang, Xiaokun Hou
2024, 35(1): 235-247.   doi: 10.1007/s12583-021-1554-4
[Abstract](367) [FullText HTML](297) [PDF 13623KB](6)
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The large-scale implementation of the Gully Stabilization and Land Reclamation (GSLR) project induces various failures of loess slopes due to excavation in Yan'an, China. However, the deformation and failure behavior of these excavated loess slopes have not been fully understood. In this study, field investigation was undertaken for analyzing the distributions and failure features of excavation-induced loess slope failures. It is found that plastic failure mainly occurs in Q3 loess layers and brittle failure in Q2. To understand the underlying failure mechanism, a series of triaxial shear tests were conducted on intact Q3 and Q2 loess samples that with different water contents, namely natural water content (natural), dry side of the natural value (drying 5%), and wet side (wetting 5%). The characteristics of stress-strain curves and failure modes of the samples were analyzed. Results show that the stress-strain curves of Q2 samples are dominated by strain-softening characteristics, while Q3 samples mainly exhibit strain-harden features except in the drying state. Correspondingly, shear failures of Q3 specimens are mainly caused by shear crack planes (single, X or V-shaped). For Q2 loess, the dominance of tensile cracks is observed on the surface of damaged specimens. These disclose the different failure modes of excavated slopes located in different strata, that is, the arc sliding failure of Q3 loess slopes and the stepped tensile failure of Q2 loess slopes, and are helpful in the design and management of the ongoing GSLR projects in the Loess Plateau.

Dynamic Stability and Fuzzy Reliability Analysis of Toppling Perilous Rock Under Seismic Excitation
Linfeng Wang, Jixu Zhang, Wanchun Xia, Xiaoming Huang, Guojin Tan
2024, 35(1): 248-262.   doi: 10.1007/s12583-022-1740-z
[Abstract](60) [FullText HTML](60) [PDF 8182KB](9)
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To predict the occurrence of the collapse disaster in toppling perilous rock under the action of bidirectional earthquakes, the dynamic stability and fuzzy reliability calculation method of toppling perilous rock under the action of bidirectional earthquakes is proposed. First, the mass viscoelasticity model is used to simulate two main control surfaces of toppling perilous rock, the seismic dynamic response model and motion equation of toppling perilous rock are established based on the D'Alembert principle, and the Newmark-β method is used to solve the dynamic motion equation. Then, the instability event of toppling perilous rock is considered a fuzzy event, the membership function expression of the stability coefficient of toppling perilous rock is determined based on the fuzzy failure criterion, the calculation equations of the toppling perilous rock dynamic stability coefficient and fuzzy reliability are established, and the fuzzy reliability evaluation method based on the probability distribution of reliability is proposed. Finally, the influence of different superposition modes of seismic excitation on the fuzzy reliability of toppling perilous rock is analyzed. The calculation results of toppling perilous rock in the engineering case show that the fuzzy reliability calculated after considering the fuzzy failure criterion is reduced by 10.73% to 25.66% compared with the classical reliability. Considering the bidirectional seismic excitation, the fuzzy reliability of toppling perilous rock is reduced by 5.46% to 14.89%. Compared with using the acceleration peak time encounter mode to superpose the seismic excitation, the fuzzy reliability of toppling perilous rock is reduced by 3.4% when the maximum action effect time encounter mode is adopted.

Debris Flow Susceptibility Evaluation in Meizoseismal Region: A Case Study in Jiuzhaigou, China
Yongwei Li, Linrong Xu, Yonghui Shang, Shuyang Chen
2024, 35(1): 263-279.   doi: 10.1007/s12583-022-1803-1
[Abstract](0) [FullText HTML](0) [PDF 44320KB](0)
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Jiuzhaigou is situated on a mountain-canyon region and is famous for frequent tectonic activities. An abundance of loose co-seismic landslides and collapses were produced on gullies after the Jiuzhaigou Earthquake on August 8, 2017, which was served as material source for debris flow in later years. Debris flow appears frequently which are seriously endangering the safety of people's lives and properties. Even the earliest debris flow appeared in areas where no case ever reported before. The debris flow susceptibility evaluation (DFSE) is used for predicting the areas prone to debris flow, which is urgently required to avoid hazards and help to guide the strategy of preventive measures. Therefore, this work employs debris flow in Jiuzhaigou to reveal the characteristics of disaster-pregnant environment and to explore the application of machine learning in DFSE. Some new viewpoints are suggested: (ⅰ) Material density factor of debris flow is first adopted in this work, and it is proved to be a critical factor for triggering debris flows by sensitivity analysis method. (ⅱ) Deep neural network and convolutional neural network (CNN) achieve relatively good area under the curve (AUC) values and are 0.021–0.024 higher than traditional machine learning methods. (ⅲ) Watershed units combined with CNN-based model can achieve more accurate, reliable and practical susceptibility map. This work provides an idea for prevention of debris flow in mountainous lands.

Editorials
Quantitatively Evaluating the Erosion and Preservation of Supergene Oxide Zones: Evidence from the Yulong Porphyry Cu Deposit, Eastern Tibetan Plateau
Xiao-Dong Deng, Jian-Wei Li
2024, 35(1): 280-282.   doi: 10.1007/s12583-023-1952-x
[Abstract](0) [FullText HTML](0) [PDF 745KB](0)
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Building a More Sustainable Chinese Loess Plateau
Peiyue Li, Xiaomei Kou, Yong Wang, Le Niu
2024, 35(1): 283-287.   doi: 10.1007/s12583-024-1970-3
[Abstract](0) [FullText HTML](0) [PDF 7342KB](0)
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The Chinese Loess Plateau, a region of remarkable ecological and economic value, grapples with significant water management challenges due to its distinctive geology and climate. This perspective offers a short review of the eco-environmental protection measures undertaken in the Loess Plateau, underscoring the transformative impacts of initiatives such as the "Grain for Green" project. However, it also highlights the enduring challenges, including land degradation, water resources issues, socio-economic inequities, and the implications of climate change. Particularly, water management emerges as a pivotal issue with far-reaching repercussions for soil conservation, biodiversity, and human livelihoods. The paper concludes by proposing future actions, emphasizing the necessity for policy modifications, novel initiatives, and research to tackle these challenges and foster sustainable development in the Loess Plateau. The insights gained from this region could offer invaluable lessons for other regions confronted with similar challenges, thereby contributing to global efforts to mitigate desertification and champion sustainable development.

Identification and Characteristics Analysis of Micro-Seismic Signals in the Haima Seep Area
Xiangchun Wang, Bing Nie, Zhiyu Wu, Weiwei Wang, Hua Chen
2024, 35(1): 288-291.   doi: 10.1007/s12583-024-1968-x
[Abstract](0) [FullText HTML](0) [PDF 1928KB](0)
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Holocene Hydroclimatic Variations in the Asian Drylands: Current Understanding and Future Perspectives
Guoqiang Ding, Shengqian Chen, Yuanhao Sun, Shuai Ma, Jianhui Chen
2024, 35(1): 292-295.   doi: 10.1007/s12583-023-1958-4
[Abstract](0) [FullText HTML](0) [PDF 1385KB](0)
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Integrating Shipborne Images with Multichannel Deep Learning for Landslide Detection
Pengfei Feng, Changdong Li, Shuang Zhang, Jie Meng, Jingjing Long
2024, 35(1): 296-300.   doi: 10.1007/s12583-023-1957-5
[Abstract](0) [FullText HTML](0) [PDF 17007KB](0)
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An Advanced Image Processing Technique for Backscatter-Electron Data by Scanning Electron Microscopy for Microscale Rock Exploration
Zhaoliang Hou, Kunfeng Qiu, Tong Zhou, Yiwei Cai
2024, 35(1): 301-305.   doi: 10.1007/s12583-024-1969-9
[Abstract](0) [FullText HTML](0) [PDF 2234KB](0)
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Backscatter electron analysis from scanning electron microscopes (BSE-SEM) produces high-resolution image data of both rock samples and thin-sections, showing detailed structural and geochemical (mineralogical) information. This allows an in-depth exploration of the rock microstructures and the coupled chemical characteristics in the BSE-SEM image to be made using image processing techniques. Although image processing is a powerful tool for revealing the more subtle data "hidden" in a picture, it is not a commonly employed method in geoscientific microstructural analysis. Here, we briefly introduce the general principles of image processing, and further discuss its application in studying rock microstructures using BSE-SEM image data.

A Three-Dimensional DEM Method for Trajectory Simulations of Rockfall under Irregular-Shaped Slope Surface and Rock Blocks
Liang Chen, Weiqian Zeng, Xianbiao Wang, Yang Ye, Yunfeng Ge, Dongming Gu, Shan Dong
2024, 35(1): 306-312.   doi: 10.1007/s12583-023-1959-3
[Abstract](0) [FullText HTML](0) [PDF 6120KB](0)
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Groundwater Quality and Vulnerability Assessment in a Semiarid Karst Region of Northern China
Ran An, Shu Wang, Zongjun Gao, Zhenyan Wang, Wei Li, Qijun Deng, Lü Lin, Yuanqing Liu
2024, 35(1): 313-316.   doi: 10.1007/s12583-021-1538-4
[Abstract](0) [FullText HTML](0) [PDF 9886KB](0)
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Vol 35, No 1 , 2024

ISSN 1674-487X

CN 42-1788/P

Editor in Chief: Yanxin Wang

Managing Editors: Zhong-Qiang Chen, Shao-Yong Jiang

Associate Editor:

Shu Jiang,Changdong Li,Rui Ma 
Qiliang Sun,Timothy M. Kusky,Dun Wang 
Lunche Wang,Long Xiao,Xin-Fu Zhao
Keqing ZongRenguang Zuo

2022 Impact Factor 3.3