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Volume 31 Issue 3
Jul.  2020
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Zhenqiang Ji, Chendong Ge, Mengyang Zhou, Nan Zhang. Quartz-Hosted Fluid Inclusions Characteristics and Their Implications for Fluvial Deposits along the Changjiang River. Journal of Earth Science, 2020, 31(3): 571-581. doi: 10.1007/s12583-020-1275-0
Citation: Zhenqiang Ji, Chendong Ge, Mengyang Zhou, Nan Zhang. Quartz-Hosted Fluid Inclusions Characteristics and Their Implications for Fluvial Deposits along the Changjiang River. Journal of Earth Science, 2020, 31(3): 571-581. doi: 10.1007/s12583-020-1275-0

Quartz-Hosted Fluid Inclusions Characteristics and Their Implications for Fluvial Deposits along the Changjiang River

doi: 10.1007/s12583-020-1275-0
Funds:

the National Basic Research Program of China 2013CB956504

More Information
  • The characteristics of quartz-hosted fluid inclusions in fluvial sediments from five locations in the upstream, midstream, and estuary of the Changjiang River, China, are analyzed. The sources of sediments are discussed concerning their differences in the shape, size, number, gas percentage and genetic type of quartz-hosted fluid inclusions. From upstream to downstream, the characteristics of quartz-hosted fluid inclusions in sediments are different. The fluid inclusion types in the samples from upstream to estuary are gradually enriched. The sediment influx from the tributaries of the Changjiang River makes new types of quartz-hosted fluid inclusions in the downstream and estuary. In terms of the number and size, most quartz-hosted fluid inclusions are concentrated in the range of 2-4 μm in diameters and 10-150 in number per 10-3 mm3. The number and size ranges of the fluid inclusions from different positions are also different. The fluid inclusions in the sample collected from the Shigu, upstream of the Changjiang River, are 2-18 μm in size, with the number of 2-166 per 10-3 mm3. Among the samples collected from Yibin, Yichang and Wuhan, the sizes of fluid inclusions are 2-15, 2-10, 2-12 μm, with the number of 1-270, 2-220, and 1-308 per 10-3 mm3, respectively. The proportion of primary fluid inclusions in the sample of the upstream (14%) is higher than that of the midstream (6%-8%) and the estuary (5%), suggesting that different types of source rocks have been input into the river by the tributaries. The characteristics of quartz-hosted fluid inclusions in the fluvial sediments could offer a new perspective for exploration of the source of sediments.
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  • Bodnar, R. J., 1983. A Method of Calculating Fluid Inclusion Volumes Based on Vapor Bubble Diameters and P-V-T-X Properties of Inclusion Fluids. Economic Geology, 78(3):535-542. https://doi.org/10.2113/gsecongeo.78.3.535 doi:  10.2113/gsecongeo.78.3.535
    Brookfield, M. E., 1998. The Evolution of the Great River Systems of Southern Asia during the Cenozoic India-Asia Collision:Rivers Draining Southwards. Geomorphology, 22(3/4):285-312. https://doi.org/10.1016/s0169-555x(97)00082-2 doi:  10.1016/s0169-555x(97)00082-2
    Chen, Z. Y., Li, J. F., Shen, H. T., et al., 2001. Yangtze River of China:Historical Analysis of Discharge Variability and Sediment Flux. Geomorphology, 41(2/3):77-91. https://doi.org/10.1016/s0169-555x(01)00106-4 doi:  10.1016/s0169-555x(01)00106-4
    Cheng, T. W., Zhao, C. N., 1985. Runoff Volumes and Sediment Discharges of Large Rivers in China and Their Influence on the Coastal Zone. Acta Oceanologica Sinica, 7(4):460-471 (in Chinese with English Abstract)
    Fan, D., Wang, Y. Y., Wu, Y. Z., 2012. Advances in Provenance Studies of Changjiang Riverine Sediments. Advances in Earth Science, 27(5):515-528 (in Chinese with English Abstract) http://d.old.wanfangdata.com.cn/Periodical/dqkxjz201205004
    Galy, A., France-Lanord, C., 2001. Higher Erosion Rates in the Himalaya:Geochemical Constraints on Riverine Fluxes. Geology, 29(1):23. https://doi.org/10.1130/0091-7613(2001)029<0023:herith>2.0.co;2 doi:  10.1130/0091-7613(2001)029<0023:herith>2.0.co;2
    Goldstein, R. H., 2001. Fluid Inclusions in Sedimentary and Diagenetic Systems. Lithos, 55(1/2/3/4):159-193. https://doi.org/10.1016/s0024-4937(00)00044-x doi:  10.1016/s0024-4937(00)00044-x
    He, M. Y., Zheng, H. B., Huang, X. T., et al., 2011. Clay Mineral Assemblages in the Changjiang Drainage and Provenance Implications. Acta Sedimentologica Sinica, 29(3):544-551 (in Chinese with English Abstract) https://www.sciencedirect.com/science/article/pii/S0025322703002135
    He, M. Y., Zheng, H. B., Jia, J. T., 2013. Detrital Zircon U-Pb Dating and Hf Isotope of Modern Sediments in the Changjiang River:Implications for the Sediment Provenance. Quaternary Sciences, 33(4):656-670 (in Chinese with English Abstract)
    Huang, X. T., Zheng, H., Chappell, J., et al., 2013. Characteristics of Cosmogenic Nuclide 10Be in the Changjiang Riverine Sediments and Estimations of Erosion Rate. Quaternary Science, 33(4):67l-683 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-DSJJ201304005.htm
    Jia, J., Zheng, H. B., Yang, S., 2010. Rock Types in Changjiang Drainage and Their Implications for Zircon U-Pb Provenance Study of Changjiang Sediments. Journal of Tongii University (Natural Science), 38(9):1375-1380 (in Chinese with English Abstract) doi:  10.3969/j.issn.0253-374x.2010.09.024
    Land-Ocean Interactions in the Coastal Zone, 2005. Land-Ocean Interactions in the Coastal Zone: Science Plan and Implementation Strategy. In: Kremer, H. H., Le Tissier, M. D. A., Burbridge, P. R., eds., IGBP Report 51/IHDP Report 18. IGBP Secretariat, Stockholm
    Lu, H. Z., 2014. Fluid Inclusion Petrography:A Discussion. Geological Journal of China Universities, 20(2):177-184 (in Chinese with English Abstract) http://d.old.wanfangdata.com.cn/Periodical/kwysdqhxtb201001003
    Lu, H. Z., Fan, H. R., Ni, P., et al., 2004. Fluid Inclusions. Science Press, Beijing. 147-170 (in Chinese)
    Lu, H. Z., Li, B. L., 1990. Inclusion Geochemistry. Geological Publishing House, Beijing. 61-74 (in Chinese)
    Lü, X. B., Zhao, P. D., Yao, S. Z., 1998. Geological Anomaly and Mineralization in the Middle-Lower Reaches of the Changjiang River. Acta Geologica Sinica, 72(3):260-266 (in Chinese with English Abstract)
    Meng, X. W., Du, D. W., Chen, Z. H., et al., 2000. Factors Controlling Spatial Variation of 87Sr/86Sr in the Fine-Grained Sediments from the Overbanks of the Yellow River and Changjiang River and Its Implication for Provenance of Marine Sediments. Geochimica, 29(6):562-570 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQHX200006007.htm
    Milliman, J. D., Shen, H. T., Yang, Z. S., et al., 1985. Transport and Deposition of River Sediment in the Changjiang Estuary and Adjacent Continental Shelf. Continental Shelf Research, 4(1/2):37-45. https://doi.org/10.1016/0278-4343(85)90020-2 http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=kVEMHXGqC0rRW090C1KeiLMjsw5J08lGSFH4nNGsv9w=
    Roedder, E., 1984. The Fluids in Salt. American Mineralogist, 69:5-6 http://d.old.wanfangdata.com.cn/OAPaper/oai_pubmedcentral.nih.gov_439405
    Shao, L., Li, C., Yuan, S. Y., et al., 2012. Neodymium Isotopic Variations of the Late Cenozoic Sediments in the Jianghan Basin:Implications for Sediment Source and Evolution of the Yangtze River. Journal of Asian Earth Sciences, 45:57-64. https://doi.org/10.1016/j.jseaes.2011.09.018 doi:  10.1016/j.jseaes.2011.09.018
    Syvitski, J. P. M., Kettner, A., 2011. Sediment Flux and the Anthropocene. Philosophical Transactions of the Royal Society A:Mathematical, Physical and Engineering Sciences, 369(1938):957-975. https://doi.org/10.1098/rsta.2010.0329 doi:  10.1098/rsta.2010.0329
    Wang, G. Q., Shi, X. F., Li, C. X., 2006. A Review on Late Quaternary Sedimentary Geology of the Changjiang River Delta. Marine Geology & Quaternary Geology, 26(6):131-137 (in Chinese with English Abstract)
    Wang, L. C., Zhang, J. X., Chen, X. L., et al., 1998. A Contrast Analysis on the Load Character of the Changjiang River and the Huanghe River. Chinese Geographical Science, 8(4):317-325. https://doi.org/10.1007/s11769-997-0037-6 doi:  10.1007/s11769-997-0037-6
    Wang, P., 2005. Cenozoic Deformation and History of Sea-Land Interactions in Asia. Earth Science-Journal of China University of Geosciences, 30(1):1-18 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqkx200501001
    Wang, Y. H., Shen, H. T., Zhang, W. G., 2004. A Preliminary Comparison of Magnetic Properties of Sediments from the Changjiang and the Huanghe Estuaries. Acta Sedimentologica Sinica, 22(4):658-663 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=cjxb200404016
    Wang, Z. B., Yang, S., Li, P., et al., 2006. Detrital Mineral Compositions of the Changjiang River Sediments and Their Tracing Implications. Acta Sedimentologica Sinica, 24(4):570-578 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=cjxb200604015
    Wang, Z. B., Yang, S. Y., Wang, R. C., et al., 2007. Magnetite Compositions of Changjiang River Sediments and Their Tracing Implications. Geochimica, 36(2):176-184 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqhx200702007
    Xu, J. X., 2007. Sediment Deposition in Yichang-Hankou Reach of Changjiang River as Influenced by Sediment Yield from Different Source Areas. Journal of Sediment Research, (1):36-43 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=nsyj200701006
    Xu, Q., 1996. Fluid Inclusion Study in Metamorphic Rocks:Several Key Points. Earth Science Frontiers, 3(3/4):216-220 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-DXQY604.007.htm
    Xu, J. X., 2005. Response of Channel Sediment Budget to Flow and Sediment Inputs:An Example of the Yichang-Wuhan Reach, Changjiang River. Acta Geographica Sinica, 60(2):337-348 (in Chinese with English Abstract)
    Yang, S. Y., 2006. Advances in Sedimentary Geochemistry and Tracing Applications of Asian Rivers. Advances in Earth Science, 21(6):648-655 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=dqkxjz200606013
    Yang, S. Y., Jiang, S. Y., Ling, H. F., et al., 2007. Sr-Nd Isotopic Compositions of the Changjiang Sediments:Implications for Tracing Sediment Sources. Science in China Series D:Earth Sciences, 50(10):1556-1565. https://doi.org/10.1007/s11430-007-0052-6 doi:  10.1007/s11430-007-0052-6
    Yang, S., Li, C. X., 1999. Characteristic Element Compositions of the Changjiang and Yellow River Sediments and Their Geological Background. Marine Geology & Quaternary Geology, 19(2):19-26 (in Chinese with English Abstract)
    Zhang, Z. J., Tyrrell, S., Li, C. A., et al., 2014. Pb Isotope Compositions of Detrital K-Feldspar Grains in the Upper-Middle Yangtze River System:Implications for Sediment Provenance and Drainage Evolution. Geochemistry, Geophysics, Geosystems, 15(7):2765-2779. https://doi.org/10.1002/2014gc005391 doi:  10.1002/2014GC005391
    Zhou, X. J., Gao, S., Jia, J. J., 2003. Preliminary Evaluation of the Stability of Changjiang Clay Minerals as Fingerprints for Material Source Tracing. Oceanologia et Limnologia Sinica, 34(6):683-692 (in Chinese with English Abstract) http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hyyhz200306013
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Quartz-Hosted Fluid Inclusions Characteristics and Their Implications for Fluvial Deposits along the Changjiang River

doi: 10.1007/s12583-020-1275-0
Funds:

the National Basic Research Program of China 2013CB956504

    Corresponding author: Chendong Ge, ORCID:0000-0002-8749-8408, gcd@nju.edu.cn

Abstract: The characteristics of quartz-hosted fluid inclusions in fluvial sediments from five locations in the upstream, midstream, and estuary of the Changjiang River, China, are analyzed. The sources of sediments are discussed concerning their differences in the shape, size, number, gas percentage and genetic type of quartz-hosted fluid inclusions. From upstream to downstream, the characteristics of quartz-hosted fluid inclusions in sediments are different. The fluid inclusion types in the samples from upstream to estuary are gradually enriched. The sediment influx from the tributaries of the Changjiang River makes new types of quartz-hosted fluid inclusions in the downstream and estuary. In terms of the number and size, most quartz-hosted fluid inclusions are concentrated in the range of 2-4 μm in diameters and 10-150 in number per 10-3 mm3. The number and size ranges of the fluid inclusions from different positions are also different. The fluid inclusions in the sample collected from the Shigu, upstream of the Changjiang River, are 2-18 μm in size, with the number of 2-166 per 10-3 mm3. Among the samples collected from Yibin, Yichang and Wuhan, the sizes of fluid inclusions are 2-15, 2-10, 2-12 μm, with the number of 1-270, 2-220, and 1-308 per 10-3 mm3, respectively. The proportion of primary fluid inclusions in the sample of the upstream (14%) is higher than that of the midstream (6%-8%) and the estuary (5%), suggesting that different types of source rocks have been input into the river by the tributaries. The characteristics of quartz-hosted fluid inclusions in the fluvial sediments could offer a new perspective for exploration of the source of sediments.

Zhenqiang Ji, Chendong Ge, Mengyang Zhou, Nan Zhang. Quartz-Hosted Fluid Inclusions Characteristics and Their Implications for Fluvial Deposits along the Changjiang River. Journal of Earth Science, 2020, 31(3): 571-581. doi: 10.1007/s12583-020-1275-0
Citation: Zhenqiang Ji, Chendong Ge, Mengyang Zhou, Nan Zhang. Quartz-Hosted Fluid Inclusions Characteristics and Their Implications for Fluvial Deposits along the Changjiang River. Journal of Earth Science, 2020, 31(3): 571-581. doi: 10.1007/s12583-020-1275-0
  • Rivers are the main channels for transportation of land-derived materials to the sea, which are affected by both tectonics and climate (Yang, 2006). River systems record the evolution of basin structure and climate, while river sediments carry information on the erosion, transport, and source areas of river basins (Fan et al., 2012). Furthermore, rivers play an important role in the Earth's hypogene processes; therefore, investigation of the source-to-sink process of river sediments has become one of the four key research projects of the "NSF MARGINS Program Science Plan 2004" (Land-Ocean Interactions in the Coastal Zone, 2005).

    River sediment provenance tracing is one of the core elements of land-sea interaction research (Fan et al., 2012; Yang, 2006). As a result of the collision between the Indian Plate and the Cenozoic Eurasian Plate, the Himalaya-Tibetan Plateau was uplifted, forming an extremely large topographic slope. The newly uplifted strata have been affected by strong monsoon rainfall, weathering, and denudation, and sediments have been continuously transported to the sea through the Changjiang River and other rivers (Wang, 2005; Galy and France-Lanord, 2001; Brookfield, 1998). Rivers originating from the Tibetan Plateau transport approximately one third of the worldʼs total sediments to the sea each year, directly altering the Asian marginal basin (Syvitski and Kettner, 2011). In particular, the Changjiang River, as the largest river originating from the Tibetan Plateau, carries a large amount of sediments into the sea every year. The river is controlled by the Asian monsoon climate, with numerous tributaries and complex geological and geomorphological conditions (Cheng and Zhao, 1985). Study of its provenance and the modern sediment source-to-sink process in the Changjiang River sediment area is of considerable significance to investigations of the evolution of the Changjiang River Basin, and is also a key element of the study of land-sea interaction (Fan et al., 2012; Yang, 2006).

    Different methods have been used in the previous studies on sediment provenance in the Changjiang River Basin, including analyses of clastic mineral assemblages (Wang et al., 2006), isotope geochemistry (Yang et al., 2007; Meng et al., 2000), clay mineral assemblages (He et al., 2011; Zhou et al., 2003), and environmental magnetic characteristics (Wang et al., 2004). Based on the regional geological and bioclimatic conditions of the Changjiang River, the end-element characteristics have been established for identifying the source of the Changjiang River, Yellow River, and other rivers entering the East China Sea (Wang et al., 2006; Milliman et al., 1985). The Changjiang River Basin covers a wide area encompassing complex source rock types and mineral compositions. The effects of sediment differentiation, biogeochemistry, and early diagenesis should be considered in the study of sediment provenance since the river sediment source materials have undergone complex processes such as weathering, denudation, and transportation of the rock mass before sedimentation.

    Fluid inclusions in minerals are the most direct original diagenetic and mineralized types of fluid retained to date (Lu et al., 2004). Different types of fluid inclusions provide fluid information on their different sources (Lu et al., 2004). In particular, the quartz particles found in river sediments are derived from weathering and denudation products of various rocks and ores along the river basin. The fluid inclusions in these quartz particles record the properties of their different source areas. Notably, the morphological characteristics and generational classifications of fluid inclusions are consistently preserved after formation (Roedder, 1984). Furthermore, quartz grains from different sources have different fluid inclusion characteristics and generation classifications, which could reflect the characteristics of the source rocks and indicate the river sediment provenance. Therefore, study of the quartz-hosted fluid inclusions in sediments could be an approach to probe into the sediment provenance.

    Optical microscopy remains one of the most effective methods of studying fluid inclusions (Lu, 2014; Lu and Li, 1990), and the current microscopy-based method of fluid inclusion analysis is very mature. Lu and Li (1990) formulated the main procedure and method of microscopic observation and developed a fluid inclusion classification system. The formula for calculating the volumes of inclusions with irregular morphologies previously developed by Bodnar (1983) is also used.

    Fluid inclusions with different origins have different morphological characteristics and can be divided into primary, secondary, and pseudo-secondary fluid inclusions. Primary and pseudo-secondary inclusions develop at different stages of mineral formation, preserving fluids of different qualities (Lu, 2014; Lu and Li, 1990). That is, these inclusions capture the mother liquor of the forming main minerals. In contrast, secondary inclusions capture late fluids unrelated to the main minerals. Therefore, the proportion of different genetic types in a quartz grain can reflect the environmental characteristics of the source rocks to a certain extent.

    In this study, the morphological characteristics, quantities, sizes, and distributions of fluid inclusions in quartz particles of sediments from Changjiang River were observed and analyzed by the microscopic observation method. Hence, the fluid inclusions in the quartz particles were classified and counted. The morphological characteristics of quartz inclusions in sediments from the upstream, midstream, and estuary of the Changjiang River were analyzed. This study provides a new method for study of the sediment provenance of the Yellow Sea and the East China Sea.

  • The Changjiang River is the largest river in Asia, with a length of 6 300 km, covering an area of 1.8×106 km2, and an average sediment discharge of 480×106 ton/yr (Zhang et al., 2014). The river originates from the eastern Tibetan Plateau. The drainage basin is divided into three parts, the upper, the middle, and the lower reaches. The upper reaches span the area from the source to Yichang, the middle reaches stretch from Yichang to Hukou, while the area from Hukou to the delta region constitutes the lower reaches (Fig. 1). The Changjiang River is mainly situated on the Yangtze Craton and is surrounded by several geotectonic units, including the Qiangtang Block, the Songpan-Ganzi terrane, the Qinling-Dabie orogenic belt, and the Cathaysia Block (Shao et al., 2012).

    Figure 1.  Map of Changjiang River Drainage Basin showing main tributaries, major blocks, and sampling sites collected in this study (modified from Shao et al., 2012). ① SGJS-01; ② YBCJ-01; ③ YZD-67; ④ YZD-63; ⑤ YZD-46; ⑥ YZD-18; ⑦ YZD-10; ⑧ HK-01.

    The basement rocks are rarely exposed in the Yangtze Craton. The exposed rocks mainly consist of Proterozoic rocks with rare Archean outcrops (Zhang et al., 2014). The main outcropped rocks in the upper reaches of the Changjiang River are Mesozoic carbonate rocks with predominantly acid-intermediate-acid igneous rocks. The plains in the middle and lower reaches are mainly composed of Quaternary sediments and Paleozoic sedimentary rocks with red clastic rocks, intermediate-acid granite, and Cretaceous metamorphic rocks (Jia et al., 2010). The lithological characteristics vary from tributary to triburary in the Changjiang River Basin. The Yalong, Dadu, and Minjiang River basins are dominated by carbonate rocks with a small amount of granite. Wujiang River is dominated by carbonate rocks with basalt distributions. The upper reaches of Jialing River are dominated by clastic rocks with a little granite, while the lower reaches are interbedded with clastic rocks and carbonate rocks. The Hanjiang River Basin is dominated by Paleozoic metamorphic rocks, and the Changjiang River Basin is dominated by granite. Granite, sandstone and shale are dominant all over the Changjiang River Basin (Jia et al., 2010; Chen et al., 2001).

  • Eight samples were collected from surface sediments of the Changjiang River Valley from upstream to estuary in 2012 (Fig. 1). Five of them were selected for this study. They are SGJS-1 (Shigu) and YBCJ-1 (Yibin) in the upper reaches, YZD-63 (Yichang) and YZD-10 (Wuhan) in the middle reaches, and HK-1 (Chongming) in the estuary.

  • From each sediment sample, 100 quartz particles were randomly selected for observation. The fluid inclusions in quartz were observed and counted with a polarizing microscope (Nikon, Eclipse E400 POL) at the Fluid Inclusion Laboratory of the State Key Laboratory of Metal Deposits Research, Nanjing University.

    In order to ensure a good observation effect, the water droplets are placed on the surface of quartz particles during the experiment and then observed under a microscope. The observation effect is similar to that of immersion oil on the surface of quartz particles, which is simple and easy, and avoids the damage that the toxicity of immersion oil may bring to the observer. In the process of observation, all inclusions in quartz sand can be observed by using wooden or bamboo sticks to move quartz particles.

    The fluid inclusions in each quartz particle were photographed, recorded, and counted, described with shape, size, distributions and types etc. Genetic type classification was performed based on their morphological characteristics and divided into primary, secondary, and pseudo-secondary inclusions according to the system proposed by Lu and Li (1990).

    The sizes, number, and gas percentage of the fluid inclusions in the quartz particles were measured. The fluid inclusion size was taken as the length of the major diameter D as measured using a micrometer. The quantity of fluid inclusions in a quartz sample was counted using a counter positioned beneath the microscope. In order to compare, the number of fluid inclusions per volume of a quartz particle was used to indicate the quantity. The unit is number per 10-3 mm3.

  • The quartz-hosted fluid inclusions in all sediment samples are usually very small, generally ranging from 2 to 10 µm in size. A few of them are relative larger, about 15 µm in length.

    Three types of fluid inclusions in quartz are observed. The main type is liquid-rich aqueous fluid inclusion (Figs. 2a-2e), which comprises two phases (liquid+vapor H2O) at room temperature with 5%-30% of gas. Vapor-rich aqueous fluid inclusions are also observed in the quartz particles with 50%-90% gas (Figs. 2f-2g); daughter-mineral-bearing aqueous fluid inclusion is rare (Fig. 2h), which consists of H2O liquid, H2O vapor, and a daughter mineral phase.

    Figure 2.  Microphotographs showing typical quartz inclusions of the Changjiang River Drainage Basin. (a) Primary fluid inclusions with necking, SGJS-01; (b) randomly distributed primary fluid inclusions, YBCJ-01; (c) regionally dispersed primary fluid inclusions, YZD-63; (d) secondary fluid inclusions, YZD-10; (e) banded pseudo-secondary fluid inclusions, HK-01; (f) vapor-rich fluid inclusions, HK-01; (g) vapor-rich fluid inclusions, HK-01; (h) isolated primary fluid inclusions, HK-01.

    Most of the fluid inclusions are of regular elliptical, circular, or rectangular shape. As regards arrangement, the fluid inclusions mainly appear in clustered (Fig. 2b), zoned (Fig. 2e), and isolated distributions (Figs. 2a, 2h), of which zoned distribution is the most common. Fluid inclusions in the same zone generally have the same long-axis orientation and similar shapes and sizes. Some of them appears along pseudo-secondary trails (Fig. 2d).

    As detailed in Table 1, from the upper to lower reaches of the Changjiang River, there are also some differences in the overall characteristics of the fluid inclusions in the sediments. For the SDJS-01 samples collected from the Shigu area in the upper reaches, irregularly shaped inclusions are bigger, mostly formed by necking, and few secondary inclusions with irregular shapes are present. Most fluid inclusions are distributed in bands, some are massed or isolated. The sizes range of 2-14 μm.

    Fluid inclusion characteristics Sample name and location
    SGJC-1 YBCJ-1 YZD-63 YZD-10 HK-01
    Shigu Yibin Yichang Wuhan Chongming
    Size (μm) 2-14 2-12 2-10 2-12 2-9
    Shape Most regular Regularly shaped fluid inclusions predominate
    Few irregular
    Arrangement Mostly in bands, some in mass or isolated Mostly in mass and bands, a few isolated Bands, mass and isolated, all occur

    Table 1.  Morphological characteristics of quartz-hosted fluid inclusions in the Changjiang River Basin

    The YBCJ-01 and YZD-63 samples from Yibin and Yichang respectively, were found to have similar fluid inclusion characteristics. Most fluid inclusions are regular and occasionally irregular in shape. The fluid inclusions are mostly banded or massed, a few of them show isolated distribution pattern. The inclusions are smaller than those in SGJS-01 samples.

    The YZD-10 samples from Wuhan are similar with HK-01 samples from Chongming in estuary, mainly exhibiting regularly shaped fluid inclusions. Mass, bands and isolated inclusions distribution pattern all occured.

  • The main characteristics of quartz-hosted fluid inclusions in the upper, middle and lower reaches of the Changjiang River are listed in Table 1 and shown in Figs. 3-5.

    Figure 3.  Microphotographs showing typical quartz inclusions in sample SGJS-01.

    Figure 4.  Microphotographs showing typical quartz inclusions in samples YBCJ-01 (a)-(b), YZD-63 (c)-(d), and YZD-10 (e)-(f).

    Figure 5.  Microphotographs showing typical quartz inclusions in sample HK-01.

    The types of quartz inclusions in the SGJS-01 sediment collected from Shigu, Yunnan Province are shown in Fig. 3. There are five types of fluid inclusions in quartz (Figs. 3a-3e). Type 1 is a primary inclusion in origin, which is characterized by a negative crystal in shape, with a size of 12-18 μm, and contains about 50% of gas (Fig. 3a); Type 2 is a primary inclusion with 3-5 μm in diameter with 10% of gas and regular shape (Fig. 3b). Type 3 is a fluid inclusion with necking. They have 10-18 μm in diameter and contain 10% of gas (Fig. 3c). Type 4 is an isolated vapor-rich fluid inclusion with 80% of gas and 5 μm in diameter (Fig. 3d). Type 5 is a linear distribution of secondary inclusions with 3-5 μm in diameter and less than 10% of gas (Fig. 3e), which is the dominant type of fluid inclusions in the upstream.

    The quartz-hosted fluid inclusions in the YBCJ-01, YZD-63 and YZD-10 samples from Yibin, Yichang and Wuhan are different from those in the Shigu sample (SGJS-01). For the primary fluid inclusions, they are isolated and have negative crystal in shape (Figs. 4a, 4b), which are similar to the primary fluid inclusions in the Shigu sample (SGJS-01). In addition, some new types of primary fluid inclusions have been found (Figs. 4c, 4d). They have 10%-50% of gas and are 6-10 μm in diameter. Secondary fluid inclusions with 5-10 μm in diameter also have been found in these samples (Figs. 4e-4f), which are similar to the Shigu sample (Fig. 3e). Compared with Shigu samples, there are more types of quartz-hosted fluid inclusions collected from Yibin, Yichang and Wuhan, and the types of primary fluid inclusions in the Shigu samples can also be found in the middle reaches. Therefore, it can be inferred that the inflow of tributaries from the upstream to the middle reaches brings new types of quartz inclusions, which enrich the types of fluid inclusions in the middle reaches. The middle reaches also receive sediment input from the upstream.

    The type of fluid inclusions in quartz of the sediments (HK-01) collected from the Changjiang Estuary is also different from other sites. Figure 5 shows the types of quartz-hosted fluid inclusions in HK-01 samples. The same types of quartz-hosted fluid inclusions from the upper and middle reaches also have been found in HK-01 samples (Figs. 5a-5d, 5g). In addition, two new types of fluid inclusions are found in the estuarine samples. One has a rod-like shape with 10 μm in diameter and contains less than 10% of gas (Fig. 5e). Another is vapor-rich fluid inclusions with a size of 15 μm and more than 80% of gas (Fig. 5f). It can be inferred that the sediments in estuarine were sourced from the downstream tributaries as well as from the upper and middle reaches.

  • The statistical characteristics of quartz-hosted fluid inclusions in the Changjiang River sediments are indicated by the fluid inclusion size, number, and gas percentage (Table 1). The upstream sample (SGJS-01) has larger size of 2 to 14 µm. The number of fluid inclusions is in the range of 2-166 per 10-3 mm3, and the gas percentage is 10% to 90%. For the YBCJ-1 sample collected from Yibin, located in the lower part of the upper reaches, the size and the gas percentage of fluid inclusions are similar to those of the SGJS-01, ranging from 2 to 12 μm and 10% to 80%, respectively. The number of fluid inclusions increases obviously from 1 to 270 per 10-3 mm3. This indicates a change in the sediment source from Shigu to Yibin along the mainstream of the Changjiang River. On the Shigu site the sediments most likely have been input from the Jinshajiang River because the Jinshajiang River is the only main river (Fig. 1), whereas on Yibin site the sediments have been input partially from the Yalongjiang, Daduhe, and Minjiang rivers because the quartz there has more fluid inclusions than that on the Shigu site, which may be derived from more sources by tributaries. For the YZD-63 samples collected from Yichang (the middle reaches), the size of fluid inclusions range from 2 to 10 µm with 10%-80% of gas. The fluid inclusion numbers range from 2 to 220 per 10-3 mm3, which are similar to those in the upper reaches. For the YZD-10 sample collected from Wuhan in the middle reaches, the size of fluid inclusions ranges from 2 to 12 µm, but both the number and the gas percentage of fluid inclusions vary. The number range of fluid inclusions is wider from 1 to 308 per 10-3 mm3, and the gas percentages are from 5% to 70%. These features suggest that some sediments may be input from the Hanjiang River Basin. The upper reaches of the Hanjiang River Basin correspond to a loess area with notably different sediment supply. In the HK-01 sample of the Chongming in the estuary, the sizes of fluid inclusions range from 2 to 9 µm with 10%-80% of gas. The fluid inclusion numbers range from 2 to 116 per 10-3 mm3.

    The statistical data of number and size of the quartz-hosted fluid inclusions are shown in Table 2 and Fig. 6. There are some similarities in the size and the number of fluid inclusions. The size of quartz-hosted fluid inclusions in the sediments of the Changjiang River Basin is mostly concentrated in 2-5 μm in diameters, and the number is 10-200 per 10-3 mm3. Only a few quartz-hosted fluid inclusions are larger than 5 μm in diameter and more than 200 per 10-3 mm3. However, there are differences in the number and size of fluid inclusions between the upper, middle, and lower reaches of the Changjiang River Basin. The samples from Shigu, Yichang, and Yibin, which are located at the upper and middle reaches of the Changjiang River, exhibit greater size (up to 18 μm) and the number ranges of fluid inclusions (up to 270 per 10-3 mm3), whereas the fluid inclusions in the samples (HK-01) from the Chongming estuary are concentrated in 2-4 μm with 2-116 per 10-3 mm3 of fluid inclusions, indicating that not all the sediments in the upper reaches of the Changjiang River reach the middle and lower reaches and the estuary area, while the sediments in the estuary area mainly receive the input from the sediments in the upper, middle and lower reaches of the Changjiang River.

    Sample Size (μm) Number of fluid inclusions per volume (number per 10-3 mm3) Gas percentages
    SGJS-1 2-14 2-166 10%-80%, 10%-20% mainly, 7% vapor-rich
    YBCJ-1 2-12 1-270 10%-80%, 5%-20% mainly, 4% vapor-rich
    YZD-63 2-10 2-220 10%-80%, 10%-20% mainly, 5% vapor-rich
    YZD-10 2-12 1-308 5%-70%, 10%-20% mainly, 3% vapor-rich
    HK-01 2-9 2-116 10%-80%, 10%-50% mainly, 4% vapor-rich

    Table 2.  Statistical characteristics of quartz-hosted fluid inclusions of the Changjiang River Basin

    Figure 6.  Diagram showing size vs. number of fluid inclusions per volume for five different sediment samples from the Changjiang River.

  • The fluid inclusions in the Changjiang River sediment samples were classified into two genetic types, as shown in Fig. 7.

    Figure 7.  Genetic type proportions of quartz inclusions in different samples from the Changjiang River Drainage Basin.

    The Shigu sample (SGJS-01) contains 14% of primary fluid inclusions. From Shigu to Yibin, the number of primary fluid inclusions decreases significantly to 6%. The YZD-10 samples, collected from Wuhan, the number of primary fluid inclusions is 6%. The estuary sample (HK-01) contains 5% of primary fluid inclusions. The genetic types of sediment samples in Wuhan is similar to the samples in Changjiang Estuary, indicating that the source of sediment in the estuary is quite similar to that in Wuhan. This difference in quartz inclusion type reflects the different sources of sediments in the upper and lower reaches of the Changjiang River.

  • The Changjiang River Basin is a vast area with complex geological and tectonic settings, including the South China orogenic belt, Yangtze Platform, Qinling-Dabie orogenic belt, and Sanjiang Paleo-Tethys orogenic belt, which have various and complex rocks (Fig. 1). The outcropped rocks in the upper reaches of the Changjiang River mainly consist of carbonate, basalt, granite, and terrigenous clastic rocks (Fig. 1). In the middle reaches of the Changjiang River, the exposed rocks include schist, geneiss, granite, and clastic rocks. Cretaceous intermediate-acid intrusions and associated volcanic rocks are exposed in the lower reaches of the Changjiang River (Lü et al., 1998). These rocks are the main sources of fluvial sediments for the Changjiang River (Yang and Li, 1999).

    The characteristics of the quartz-hosted fluid inclusions in different areas of the Changjiang River Basin reflect the differences in the source rocks of the sediments. The number, size, gas percentage, and genetic type of fluid inclusions in the Shigu, Yunnan Province, in the upper reaches of the Changjiang River, are obviously different from those of the middle and lower reaches. The lithology in the upper reaches of the Changjiang River basin is dominated by clastic rocks, with a small number of granite and metamorphic rocks. Indeed, weathering and denudation products of rocks in the upper reaches of the Changjiang River Basin are the main source of sediments in the Changjiang River (Shao et al., 2012; Wang et al., 2006). In addition to the upper reaches, sediments are also imported into the middle and lower reaches of the river by several important tributaries.

    Jinsha River is the main source of coarse-grained sediments in the upper reaches of the Changjiang River (Shao et al., 2012; Xu, 2007), where clastic rocks and granite are the main outcropped source rocks. The quartz-hosted fluid inclusions in the fluvial sediments are characterized by larger size, and higher gas percentage, and have more primary fluid inclusions compared to other sites, suggesting that the outcropped rocks is the main source of fluvial sediments of the upper reaches of the Changjiang River.

    In the upper reaches from Shigu to Yibin, the exposed rocks in the area mainly consist of clastic rocks (Fig. 1). These rocks were input into the Changjiang River by the main tributaries of the Yalongjiang, Daduhe, and Minjiang rivers. The characteristics of the quartz-hosted fluid inclusions in the sediments at the Yibin site are different from those of the Shigu site. The number of primary fluid inclusions decreases obviously from 14% at the Shigu site to 6% at the Yibin site. The influx of tributaries may change the characteristics of the quartz-hosted fluid inclusions in the fluvial sediments.

    The exposed rocks in the Jialingjiang and Wujiang river basins are dominated by clastic rocks, with a small amount of granite (Fig. 1). The characteristics of the quartz-hosted fluid inclusions of the sediments at Yichang are very close to those of the Yibin site in terms of type, size, number, and gas percentage.

    The fluid inclusion characteristics of the sediment samples from Wuhan are significantly different from those mentioned above. The fluid inclusions have middle size (2 to 12 μm), higher gas percentage (5% to 80%), and the number (up to 308 per 10-3 mm3). Compared with the sediment samples collected from Yichang, the gas percentage of fluid inclusions decreases significantly and the number range increases significantly. The lithology of the tributaries along the middle reaches of the Changjiang River is more complex than the cases discussed above, but the main tributary that transports sediments to the main stream is the Hanjiang River. Indeed, more than 90% of the tributary sediments comes from the Hanjiang River (Xu, 2007, 2005). Therefore, the main reason for the changes in the quartz-hosted fluid inclusion characteristics of the sediments is the sediment input of the Hanjiang River. The sediment composition of the Hanjiang River is obviously different from that of the upper reaches of the Changjiang River at Yichang. This leads to significant differences in the fluid inclusion characteristics of the YZD-10 sediment samples.

    The lower reaches of the Changjiang River from Wuhan to the estuary are influenced by the Ganjiang River and the near-source materials of the main stream. In addition, they inherit the sediments of the upper and middle reaches. The quartz-hosted fluid inclusions in the HK-01 sediments located in the estuary area are characterized by the mixing of the upper, middle, and lower reaches.

  • In the previous studies, various methods were used to study the sources of fluvial sediments of the Changjiang River Basin, including clay mineral assemblages (He et al., 2013), Sr-Nd isotopes (Yang et al., 2007), magnetite chemical composition (Wang et al., 2007), and cosmogenic nuclide 10B (Huang et al., 2013). It was concluded that the materials of the upper reaches are the main contributions to the Changjiang River Basin.

    The quartz-hosted fluid inclusions in the fluvial sediments can be preserved stably for a long time without being affected by biochemical processes during sediment transport. The size, number, gas percentage, and genetic type of the fluid inclusions are controlled only by sediment source rocks. Wang et al. (1998) noted that the quartz-hosted fluid inclusions in the sediments of the Changjiang and Yellow rivers have distinct characteristics. Fluid inclusions in the sediments of the Changjiang River Basin show higher gas percentage, reflecting the fact that the mineralization temperature of the quartz sands in the Changjiang River is higher than that in the Yellow River.

    In this study, the characteristics of the fluid inclusions in the quartz grains from the Changjiang River Basin show some similarities and differences among the upper, middle, and lower reaches of the Changjiang River. In the upstream, quartz particles in the sediments have more primary, higher gas percentage and larger size of fluid inclusions, reflecting that the quartz particles were formed at higher temperature of rocks and/or quartz-rich mineral deposits, which mainly come from the intermediate-acid igneous rocks along the Jinshajiang River. From Shigu to the mouth of the Changjiang River, the main stream receives tributary sediment input continuously, the types of quartz inclusions are more abundant, reflecting that the sediment source in the Changjiang River Basin comes from the upstream material input, and also from the tributary sediment input.

    In addition, necking of fluid inclusions was found to be more common in the upper reaches of the Changjiang River than in the middle and lower reaches. Necking refers to changes in the fluid inclusion shapes after they are captured (Goldstein, 2001). Extrusion deformation of the main minerals at higher temperatures induces elongation or necking of existing fluid inclusions, causing changes in the fluid inclusion volume. The necking phenomenon differences observed in the quartz-hosted fluid inclusions examined in this study also reflects differences in the source rock properties corresponding to the upper, middle, and lower reaches of the Changjiang River (Goldstein, 2001; Xu, 1996).

  • The following conclusions are drawn from the analysis of the quartz-hosted fluid inclusions in the sediments of the Changjiang River Basin.

    The characteristics of the quartz-hosted fluid inclusions in the sediments from the upper, middle, and lower reaches of the Changjiang River show differences in term of number, size, and gas percentage. The characteristics of fluid inclusions are mainly controlled by the nature of the source rocks along the Changjiang River Basin.

    Quartz particles in the sediments of the upstream contain more primary, higher gas percentage and larger size of fluid inclusions, which were formed at higher temperature of rocks and/or quartz-rich mineral deposits, possibly from the intermediate-acid igneous rocks along the Jinshajiang River. In the middle and the mouth of the Changjiang River, the type of quartz-hosted fluid inclusions is more abundant, suggesting that the sediment source in the Changjiang River Basin not only comes from the upstream material input, but also from the tributary sediment input.

    The proportion of primary fluid inclusions in the sample of the upstream (14%) is higher than those of the midstream (6%-8%) and the estuary (5%), suggesting that the different types of source rocks have been input into the Changjiang River by the tributaries.

  • This study was supported by the National Basic Research Program of China (No. 2013CB956504). The authors express thanks to Prof. Zhongyuan Chen from East China Normal University for sample support, Prof. Pei Ni and Dr. Junying Ding from the School of Geosciences and Engineering, Nanjing University, for their guidance with fluid inclusion identification. The final publication is available at Springer via https://doi.org/10.1007/s12583-020-1275-0.

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