The Getang is a representative Carlin-type gold deposit in Southwest China. It has a proven reserve of about 30 tonnes at an average grade of 5.1 g/t Au. The orebodies occur as stratabound lenses, and are structurally controlled by shallow NWW- and NE-trending fold-fault systems and the unconformity between the Upper and Middle Permian. In this study, the regional- and deposit-scale structural investigations, joints and finite strain measurements, and stress and dynamic analysis were conducted with an aim to reveal the structural process of the Getang gold deposit and clarify the relationship between the gold mineralization and structures. Three phases of deformation were identified in the deposit: (1) paleokarst was generated by a crustal uplift when the Youjiang Basin experienced extension at the end of the Middle Permian, laying the foundation for the unconformity; (2) the NW-trending structures were formed under a NNE-SSW compression during the Indochina-South China collision (Indosinian orogeny) in Triassic; (3) the NE-trending structures were generated or reactivated under a NW-SE-oriented compression during the Yanshanian intracontinental orogeny. The unconformity recorded two episodes of tectonic evolution in the NNE-SSW and NW-SE directions. Structural analyses and geochronology data suggest that the Getang gold deposit was formed as a result of tectonic transition from compression to extension during the Yanshanian intracontinental orogeny.
It has been suggested that the ore-forming process and geometry of ore domains are results of tectonic evolution, and structure is a crucial controlling factor to form high-grade orebodies at shallow crustal levels (Micklethwaite, 2009; Berger et al., 2003; Sibson, 1996). Structural deformation that predates or is synchronous with mineralization can constrain the location of the ore-forming fluids trapped, or ore minerals precipitated, while later structural deformation may offset or remobilize mineralization (Bell et al., 2018 and references therein). Hence, structure is the predominant controlling factor for the geometry and distribution of orebodies (Micklethwaite, 2011; Páez et al., 2011; Blenkinsop, 2004). For example, the ore-shoots of the Carlin-type gold deposits in Nevada were suggested to be primarily controlled by structural culminations and intersections between calcareous strata and steep fractures (Cassinerio and Muntean, 2011).
Carlin-type gold deposits are significant gold producers in the world (Groves et al., 2016; Large et al., 2016; Cline et al., 2005). As a principal part of the Dian-Qian-Gui "Golden Triangle" in China, the northern margin of the Youjiang Basin is a well-known crucial producing district of Carlin-style gold deposits (Hu R Z et al., 2017a, b, 2002; Tu, 1990). More than 100 gold deposits and occurrences with an endowment estimated as > 800 t have been discovered since 1978 (Su et al., 2018). The Shuiyindong (Su et al., 2012), Jinfeng (Lannigou) (Chen et al., 2007), Zimudang (Liu et al., 2015), and Getang (Hu et al., 2018a) gold deposits are the most remarkable Carlin-type gold deposits in the northern Youjiang Basin. The regional structural framework was depicted with evidence from the geology, seismic reflection, gravity, and airborne magnetics (Hu R Z et al., 2017a, b; Wang et al., 1994; Wang, 1992). Based on geological survey, the styles and distribution of the structures in these gold deposits were summarized (Wu et al., 2016; Luo, 2015, 1997a, b; Fu et al., 2008; Liu et al., 2008; Peters et al., 2007; Mao et al., 1990). After a solid research on the Huijiabao gold orefield, a "two-story-building model" was constructed to describe the gold mineralization styles in the Huijiabao gold orefield (Guo and Zhou, 2006). The unconformtiy between the Upper and Middle Permian (also termed as "SBT") was determined as one of the most important ore-controlling structures (Liu J Z et al., 2014, 2010, 2006; Liu S et al., 2013). Combining structural analysis with geochemistry study, the structural control on the location of gold deposits (Tan et al., 2017; Luo, 1997b) and fluid migration within the Shuiyindong and Jiadi (Zeng et al., 2018; Tan et al., 2015) was disscussed. The regional tectonism and metallogenesis were summarized based on the large scale mapping and structural analysis in the Jinfeng deposit (Chen et al., 2011, 2007).
The Getang gold deposit is a large-scale Carlin-type deposit, containing a proven reserve of about 30 tonnes at an average grade of 5.1 g/t Au (Hu et al., 2018a; Liu et al., 2013; Zhang et al., 2003). However, the deposit-scale structural features and their control on the ore-forming process remain poorly understood. Recently, some primary gold orebodies are revealed, providing a valuable opportunity to study the structural control on the gold deposit. In this study, detailed deposit-scale structural investigations and analyses were conducted to help clarify the structural evolutionay process of the Getang gold deposit. Joints and finite strain measurements were performed to determine relationship between the gold mineralization and structures. This study will help understand the structural control of gold mineralization in the Getang deposit.
1.
GEOLOGICAL SETTING
The northern margin of the Youjiang Basin (Zhang et al., 2003; Hu et al., 2002; Figure 1a) is bounded by the NE-trending Mile-Shizong fault (MSF) to the northwest, the NW-trending Ziyun-Yadu fault (ZYF) to the northeast, and the NEE-trending Youjiang fault (BF) to the south (Figure 1b). The Youjiang Basin was produced by the rifting on the southwest margin of the Precambrian Yangtze Craton during the Devonian (Meng et al., 2020; Ren et al., 2020; Zhang et al., 2020; Su et al., 2018). The generated NW- and NE-trending rifts established the regional structural framework (Lai et al., 2014; Du et al., 2013). Following the passive margin evolution, slab-pull extension driven by the southwestward subduction of the Paleo-Tethys ocean beneath the Indochina Block during the Permian (Qiu et al., 2017; Lai et al., 2014; Du et al., 2009) may reactivated the NW and NE-striking basement structures in the Youjiang Basin (Su et al., 2018). Continued southwest subduction eventually caused the Indochina-South China collision (Indosinian orogeny) along the Song Ma Suture (Zaw et al., 2014), which resulted in a Triassic foreland fold-and-thrust belt in the Youjiang Basin represented by the NW-NWW-trending open folds and thrust faulting (Chen et al., 2019; Li et al., 2017; Qiu et al., 2016). The Indosinian deformation was subsequently overprinted by the Late Jurassic–Cretaceous NW-SE thrusting generated by the subduction of the Pacific Plate beneath the Eurasian Plate (Yanshanian orogeny) (Zeng et al., 2018; Qiu et al., 2016 and references therein). During Yanshanian Orogeny, the Youjiang Basin was characterized by extension and emplacement of dykes (Su et al., 2009b; Fang et al., 2006). The tectonic events during the Middle–Late Triassic and the Late Jurassic–Early Cretaceous were suggested to be geneticly related to the gold mineralization in the Youjiang Basin (Su et al., 2018).
Figure
1.
(a) Simplified tectonic map of Southwest China and North Vietnam showing the location of the Youjiang Basin (modified after Su et al., 2018); (b) Geological map of the Southwest Guizhou showing the geology, structure, and distribution of the representative Carlin-type gold deposits (modified after Luo and Zeng, 2018). ASRR. Ailaoshan-Red River shear zone; MSF. Mile-Shizong fault; ZYF. Ziyun-Yadu fault; NPF. Nanpanjiang fault; BF. Youjiang fault; GFF. Guangnan-Funing fault; PNF. Pingxiang-Nanning fault; NVB. North Vietnam Block. Gold deposits: SYD. Shuiyindong; ZMD. Zimudang; LNG. Lannigou; LWC. Laowanchang; JD. Jiadi; NB. Nibao; GT. Getang; XW. Xiongwu; YT. Yata; BQ. Banqi; BD. Baidi.
The outcropped lithologies in the study area are predominantly Devonian to Triassic in age. The Triassic rocks are the most widely distributed, followed by the Permian, while the Devonian and Carboniferous sequences are sporadically exposed in the cores of some anticlines or domes (Qiu et al., 2019; Luo, 2015). The Triassic system in the northern Youjiang Basin has been divided into two sedimentary units including the northern shallow-water platform and the southern deep-water basin (Chen et al., 2011). The northern shallow-water platform consists of limestone, bioclastic limestone, dolomite, and argillite. In contrast, the southern deep-water basin is composed mainly of sandstone, siltstone, argillite, marl, and black shale.
Magmatic rocks account for a minor volume of the surface on the northern Youjiang Basin, mainly including the late Permian Emeishan flood basalts, the diabase sill (Figure 1a), and alkaline ultramafic pipes and dykes (Figure 1b). The Emeishan flood basalts in the northwestern part are composed of basaltic lava, pyroclastics, and breccias. Two phases of diabase-sill forming magmatism were emplaced during the Early Triassic (ca. 260–250 Ma) and Early Jurassic (ca. 190 Ma), and are exposed within the Badu anticline (Qiu et al., 2019) and the Luodian area (Huang et al., 2019). The alkaline ultramafic pipes and dykes in the eastern part were emplaced during the Late Cretaceous (ca. 88–85 Ma, Su et al., 2018; Luo, 2015; Liu et al., 2010) and principally distributed along the inferred NS-trending Puding-Ceheng fault (Su et al., 2009b; Figure 1b). In addition, extensive concealed granitic and mafic intrusions were speculated according to the magnetic and gravitational anomalies (Wang et al., 2009).
Since the 1990s, a lot of geochronology data were reported on the Carlin-type gold deposits in the Youjiang Basin. The ages reported before 2006 exhibited a wide range from 276 Ma to as young as 82 Ma (Chen et al., 2006), which impeded a consensus on the dynamic mechanism of the gold mineralization. High precision dating methods (Qiu and Bai, 2019), including Re-Os of sulphide (Chen et al., 2015), 40Ar-39Ar of sericites (Chen et al., 2009), Sm-Nd of calcite (Wang et al., 2021; Tan et al., 2019; Jin, 2017; Su et al., 2009a), and U-Pb of rutile (Pi et al., 2017) yielded age populations of 220–190 and 150–130 Ma, indicating a genetic relationship between gold mineralization and the Indosinian and Yanshanian orogeny. Recently, some precise ages dated by apatite SIMS Th-Pb and zircon (U-Th)/He range from 160 to 132 Ma, which raised questions about age data between 220 and 190 Ma and suggested that gold mineralization might occur at 150–130 Ma (Chen et al., 2019; Huang et al., 2019). In addition, the contact relations of stratigraphy or intrusions in Youjiang Basin also support that the gold mineralization can be constrained to 150–135 Ma (Wang et al., 2021).
2.
DEPOSIT GEOLOGY
The Getang gold deposit is situated at the southeastern segment of the Getang anticline (Figure 1b). Sedimentary rocks in the deposit are mainly Middle Permian to Middle Triassic in age (Figure 2). The Maokou Formation of the Middle Permian is featured by thickly bedded massive bioclastic limestone. Four lithologic units of the Late Permian Longtan Formation were recognized from the bottom to upper in the Getang District. The lowest unit is composed of black carbonaceous argillite locally intercalated with coal seams. The second unit includes gray laminated argillite and siltstone with lenticular coal bed and muddy limestone. The third unit is mainly gray silicified limestone and subordinate siltstone, sandstone, and argillite. The highest unit is dominated by the interbeds of laminated siltstone, sandstone, and argillite. The Changxing and Dalong formations of the Late Permian display chert limestone with greyish-green argillite and muddy limestone. The Early Triassic lithology consists of variegated shale intercalated with muddy limestone. The Middle Triassic lithology is mainly dolomite and dolomitic limestone. The unconformity was developed along the paleokarst surface between the Upper and Middle Permian series and consists of silicified and brecciated argillite and limestone.
Figure
2.
Simplified geological map of the Getang gold deposit (modified after BGMG, 2014).
The Getang gold deposit extends discontinuously over an area of about 15 km2 in the direction of NW-SE. It is composed of several ore blocks, including Getang, Erlongkou, Kesa, and Kehua (Figure 2). More than 30 gold orebodies with highly variable thicknesses from 0.5 to 30.4 m have been discovered along the unconformity (Figure 3). The orebodies occur as long elliptic to nearly round morphologies in the plane and stratified or lenticular shapes in the profile. Some ores were oxidized and exploited because of pervasive weathering, while the remainder ores are mainly primary with Au grade ranging from 2 to 4 g/t (Liu et al., 2013; Zhang et al., 2003).
Figure
3.
(a) Photograph of stopes showing occurrences of the primary and oxidized ores in the unconformity; (b) geological section presenting the spatial relationship of the Maokou Formation, unconformity, and the Longtan Formation; (c), (d) geological sections illustrating the features of mineralization in the Getang gold deposit.
The primary ores are mainly disseminated, stockwork, and brecciated. In disseminated ores, pyrite, arsenopyrite, and other sulfides are disseminated sparsely in the form of fine particles. Stringer veins of pyrite and quartz characterize the stockwork ore. The brecciated ores are silicified and cemented by chalcedony, and gold-bearing arsenian pyrite and arsenopyrite. Overall, the primary ore mineral is arsenian pyrite, with minor amounts of arsenopyrite, stibnite, realgar, and orpiment. Goethite, jarosite, and anhydrite were detected in oxidized ores. Gangue minerals consist of quartz, fluorite, calcite, illite, and kaolinite.
Hydrothermal alteration is pervasive and involves silicification, sulfidation, illitization, and carbonatization. Silicification is typically identified as jasperoid quartz grains and minor quartz veinlets. Carbonatization is widespread and preferentially expresses as calcite veins in carbonate host rocks. An alteration zoning across the unconformity was identified from bottom to top: carbonatization through silicification-sulfidation-illitization and realgar (orpiment)-stibnite-fluorite to carbonatization. And the silicification, sulfidation, and illitization are spatially and temporally close to gold mineralization.
According to the textures, crosscutting relationships, and mineral assemblages, four hydrothermal stages can be recognized in the Getang gold deposit (Hu et al., 2018a). The early ore stage (pyrite-arsenopyrite) is dominated by massive or dense disseminated ores composed of pyrite and minor arsenopyrite. The intermediate ore stage (chalcedony-arsenian pyrite) is characterized by brecciated ores silicified and cemented by jasperoid quartz, and fine-grained arsenian pyrite contains the most Au resource of this deposit. The late ore stage (pyrite-calcite) occurs as calcite veins with or without pyrite, and the Au grade of this stage is low. Fluorite of the post-ore stage (fluorite-realgar-orpiment) is mainly expressed as veinlets that cut the disseminated ores of the previous stages. The distribution of realgar and orpiment is heterogeneous. Realgar is nodular and spotted, while orpiment occurs as veinlets and stockworks, though they are intergrowth locally along the unconformity. The characteristics of gold mineralization were detailedly described by Hu et al. (2018a).
3.
REGIONAL STRUCTURES
Considering the location of the Getang gold deposit, the regional structures refer to structural elements that extend throughout the northern Youjiang Basin. The northern Youjiang Basin is characterized by a fold-and-fault system superimposed by regional NW- and NE-trending structures, which mainly include gently folds and brittle fractures (Zeng et al., 2018, Luo et al., 2016 and references therein). Besides, as the wide distribution of the paleokarst above the Middle Permian Maokou limestone, the unconformity is also an important regional structure in the northern Youjiang Basin (Hu et al., 2018b; Chen et al., 2011; Peters et al., 2007).
3.1
NW-Trending Structures
The NW-trending structures are common in the eastern portion of the northern Youjiang Basin, including the NW to NWW-trending Dayakou, Getang, and Huijiabao anticlines and accompanying oblique faults. These NW to NWW-trending anticlines are usually open folds with gentle limbs. These anticlines usually extend for several to dozens of kilometers along the axes. The anticlinal cores are predominated by the Middle to Upper Permian rocks, while their limbs are covered by the Triassic rocks. The previous investigation suggested that these NW to NWW-trending anticlines are the first order ore-controlling structures in the gold orefields in the eastern portion of the northern Youjiang Basin, such as the Huijiabao and Getang orefields.
The NW-trending faults are usually developed with the adjacent homoaxial anticlines and cut the limbs of the anticlines. The reverse faults F101 and F105 are most representative in the Huijiabao orefield. They strike NWW and dip steeply to the north and south, respectively (Tan et al., 2015).
3.2
NE-Trending Structures
The NE-trending folds are dominated in the western part of the northern Youjiang Basin, including the Lianhuashan, Xiongwu, and Nibao anticlines. These NE-trending anticlines extend for 40 km in length at 40°–45° and 10–20 km in width with gentle limbs, and their fold axes are usually disrupted the later tectonic events (Zeng et al., 2018). The rocks in the anticlinal cores are Devonian to Permian in age, while the limbs are dominated by Triassic detrital rocks. In the orefield-scale, these NE-trending anticlines are proposed to be the principal ore-controlling structures in the western portion of the northern Youjiang Basin. Besides, there are also some locally developed outcrop-scale NE-trending folds superposed on the NW to NWW-trending anticlines in the eastern portion of the northern Youjiang Basin (Li et al., 2017; Qiu et al., 2016).
The NE-trending faults are extensive throughout the northern Youjiang Basin. The NE-trending faults are commonly steep normal faults, and some faults have a dip-slip displacement of hundreds of meters and can extend about 10 to 38 km along the NE direction. The NE-trending faults developed along the NE-trending folds and usually intersected the early NW- to NWW-trending structures and disrupted the NW- to NWW-trending fold axes.
3.3
Unconformity
The unconformity is widely distributed in the northern margin of the Youjiang Basin. According to the overlying rocks, the unconformity can be divided into two regions: (1) the Longtan Formation region and (2) the Emeishan basalt series region (Liu et al., 2014). It was suggested to result from a combination of tectonic events, fluid flow, and hydrothermal alteration (Liu et al., 2010). The thickness varies greatly from 0 to 70 m with extensive breccia. The breccias vary in size and are complex in composition, including weakly silicified, strongly silicified, and strongly brecciated limestone of the Middle Permian Maokou Formation, and silicified brecciated, and cataclastic argillite (basalt, tuff) of the Upper Permian sequences (Zeng et al., 2018; Liu et al., 2014). The unconformity is a remarkable ore-controlling structure in the northern Youjiang Basin (Liu et al., 2014) and provides a favorable depositing space for the gold and antimony deposits, including the Shuiyindong, Getang, Nibao gold deposits, and the Dachang large-scale antimony deposits.
4.
STRUCTURES WITHIN DEPOSIT
Structures in the Getang gold deposit are characterized by a superimposed system composed of NE- and NW-trending structures. Some outcrop-scale interlayer-gliding structures are developed in the Longtan Formation. The unconformity is also an important deposit-scale structure in the Getang gold deposit.
4.1
NW-Trending Structures
The NW-trending structures are represented by the Getang anticline, which is gentle in limbs with dip angles of 5°–15°. The Getang anticline is a superposed anticline (Figure 2) and presents as an upright gentle anticline (Figure 4). The northwestern segment is mainly covered by the Triassic rocks, and its axis orientation trends to nearly the E-W with a relatively stable occurrence. In contrast, the southeastern segment was lifted and denuded extensively, and the fold axis turns into NW-SE direction with the hinge plunging into the southeast (Figure 5). The core in the southeastern segment is dominated by Middle and Upper Permian rocks, and the limbs consist mainly of Triassic rocks.
Figure
4.A–A' and B–B' geological sections of the Getang gold deposit. The A–A' geological section showing an anticline that trends to the northeast; the B–B' geological section presenting an anticline that trends to the southeast.
The Guiluo fault is the most remarkable NW-trending fault in the east of the mining area. The Guiluo fault extends for several kilometers across the Getang District and is crosscut by NE-trending faults.
4.2
NE-Trending Structures
The NE-trending faults are more frequent than the NE-trending folds in the Getang gold deposit. The Haimagu, Shangheba, and Lugou faults are typical examples, which disrupt the Getang anticline into several segments and show a close relationship with gold mineralization (Figure 6).
Figure
6.
Structural features of the Haimagu fault. (a) Breccias in the Haimagu fault; (b) positive steps on the Haimagu fault plane; (c) limestone breccias enclosed by the early white calcite vein; (d) the late red calcite vein with steep attitudes.
The Haimagu fault is a regional fault zone, which extends about 40 km to the northeast and is donzes of meters to more than a hundred meters wide (Zeng et al., 2014). According to geological survey and a seismic reflection passed through the Getang gold deposit (Hu et al., 2017, 2012), the Haimagu fault is verified to be a high-angle reverse fault, dipping to the northwest at the shallow (Figure 2) and turning to the southeast at the deep (Zeng et al., 2014). And the fault displacement is 1.5–2 km, occurring as a major fault that cuts through the Devonian rocks. Field geological survey showed that the footwall is mainly Triassic rocks, while the hanging wall is Permian rocks.
The Haimagu fault is characterized by a variety of fragments caused by multi-phases movement. It is locally silicified with weak gold anomalies. The silicification and weak gold anomalies indicate activation during the gold ore-forming process. A large number of fault breccias with various sizes and randomly orientation is developed in the fault zone (Figure 6a). And a set of positive steps developed on the fault plane (Figure 6b). Besides, two stages of calcite veins in its secondary faults are determined with the mineral occurrences and intersecting relationship. Calcites in the early stage are mainly white coarse-grained euhedral, and the white calcite veins can occur as steep coarse veins or relatively gentle veins. Breccias of wall rocks cemented by the calcite veins are also very common (Figure 6c). Calcites of the later stage are red and fine-grained. The later calcite veins are steep veinlets with a slow wavy plane (Figure 6d).
The Shangheba fault is located in the southeast of the Getang gold deposit. It extends for about 4.4 km along the strike, dips steeply to the NW with an average angle of 70°–75°, displaying a vertical fault distance of 5–20 m. The Lugou fault is located 500–900 m southeast of the Shangheba fault, striking roughly parallel to the Shangheba fault with 4.1 km, dipping to the southeast with a steep angle of 70°–80° and showing a vertical fault distance of 50–120 m. Both the Shangheba and Lugou faults are normal faults crosscutting the Maokou limestone and ore-bearing unconformity. Besides, many small faults in the stopes crosscut the ore-bearing unconformity. These faults suggest extensive structural events post gold mineralization in the region.
The NE-trending folds developed in the Getang gold deposit are usually outcrop-scale and overprint the NW-trending Getang anticline. These NE-trending folds curve the Upper Permian siltstone and argillite and are generally several to dozens of meters wide, presenting as upright open folds. The plunge angles are small, the axial planes are relatively upright, and both limbs are relatively gentle, with dip angles between 10° and 25° (Figure 7). The NE-trending folds maybe the local occurrences of NE-trending structures in the northern margin of the Youjiang Basin.
Figure
7.
NE-trending folds in the Getang gold deposit. (a) Photograph showing a NE-trending syncline in the Erlongkou Block; (b) photograph showing NE-trending folds in the Erlongkou Block; (c) photograph showing NE-trending folds in the Kehua Block; (d) photograph showing NE-trending folds in the Kehua Block.
The interlayer-gliding structures (Figures 8a, 8b) in the Getang gold deposit are also well developed. These structures are mainly developed in the Longtan Formation of the Upper Permian and showed by folds of the sandstone layers. The occurrence and thickness of rocks close to the unconformity change greatly, while they tend to be stable away from the unconformity (Figures 8c, 8d). Therefore, the unconformity is supposed to be the principal slip interface (Hu Y Z et al., 2017; Zeng et al., 2014). According to the geological survey, the axes of these structures strike roughly to the NE 60°–85° (Figures 8a, 8b), suggesting a genetic relationship with the NW-SE tectonic stress. Combining with the Yanshanian intercontinental orogeny, the interlayer-gliding structures may be a product of the compression from the NW-SE.
Figure
8.
Interlayer-gliding structures in the Getang gold deposit. (a) Photograph illustrating the interlayer-gliding structure in the Longtan Formation; (b) photograph illustrating the interlayer-gliding structure in the Longtan Formation; (c) photograph illustrating the interlayer-gliding structure close to the unconformity in the Kehua Block; (d) photograph illustrating the interlayer-gliding structure close to the unconformity in the Kehua Block.
The unconformity serves as the most crucial ore-bearing structure in the Getang gold deposit and offers a migrating channel and perfect depositing space for ore-forming fluids. During the hydrothermal mineralization process, pyrite in the early stage is mainly distributed in argillite or carbonaceous shale in the form of dissemination or aggregates (Figures 9a, 9b). The mass and aggregate of pyrite were broken into breccias, which are angular, poorly sorted, disorganized, and cemented by masses of silica and minor pyrite of later stage (Figures 9b, 9c). The pyrite of the later stage developed as a comb structure in pyrite-quartz veins (Figure 9d), which crosscut the mineralized carbonaceous shale. The brecciated ore and patterns of pyrite indicate a tensional kinetics property. Subsequently, the veined and stockwork fluorite, realgar, and orpiment also gradually developed in the unconformity with the evolution of ore-forming fluids (Figures 9e, 9f).
Figure
9.
Featured photos of the unconformity. (a) Disseminated pyrites in the argillite; (b) massive pyrite in the silicified carbonaceous shale; (c) breccias in the unconformity; (d) comb structure of the pyrite-quartz veins; (e) fluorite stockworks in the unconformity; (f) orpiment stockworks and realgar aggregate in the unconformity.
Extensive joints filled by calcite and quartz are developed in limestone of the Middle Permian and the Early Triassic around the Getang gold deposit, 1 755 dip directions and dip angles of joints were measured at 9 locations in the periphery of the gold deposit, including the Gaoloubei, Yangtouzhai, Baobaoshang, Dalongche, Mozhai, Mozhaibeixi, Shangbeiba, Shuiku, and Shuitougou (Table 1). Meanwhile, 100 to 300 joints were measured at each position and were classified according to properties and filling. On this basis, stereograms of joints of different categories were plotted, respectively, using the software Georient v9.4.4 (Páez et al., 2011; Holcombe, 2009).
Table
1.
Parameters of joints measurement from the Getang gold deposit
On the stereograms, shear joints filled by white calcite-quartz from the Gaoloubei, Baobaoshang, Dalongche, Mozhai, Shangheba, Shuiku, Shuitougou show roughly the same characteristics (Figures 10a–10g). Their poles on the stereograms are concentrated in two areas, respectively corresponding to two major occurrences of the white quartz-calcite veins. One group trends to the NE-NNE and dips to the NW-NWW, while the other group trends to the NE-NEE and dips to the SE-SSE, presenting conjugate characteristic with a steep angle. Given that the quartz-calcite veins formed under the pure shear model, the conjugate characteristic indicates that the directions of maximum principal stress (σ1) range from NNE to NEE. Poles of quartz-calcite veins from the Yangtouzhai are concentrated in one area, presenting a group of shear joints (Figure 10h). These shear joints dip ~61° to NE with an average dip angle of 13°, suggesting a NE-SW-oriented maximum principal stress (σ1).
Figure
10.
Stereograms of joints of the Getang gold deposit.
The shear white quartz-calcite veins from the Mozhaibeixi can be divided into two groups (Figure 10i). One group strikes to NWW, and dips to NNE with a high angle. The other group trends to SEE, and dips to SSW with a steep angle. These two groups of joints present a conjugate feature, indicating a NWW-SEE direction of maximum principal stress (σ1).
The shear joints filled by red calcite and quartz from the Shangheba are dominanted by the occurrence of 142° in the dip and 76° of the dip angle (Figure 10j). Due to the absence of conjugate veins, it is difficult to infer the direction of maximum principal stress (σ1).
Tensional joints filled by white calcite and quartz from the Dalongche, Mozhai, Shuiku, Shuitougou share similar features (Figures 10k–10p). The overall occurrences of the tensional joints from these 4 locations are 49°–82° in the strike and 51°–79° in the dip. Given a pure shear model, these tensional joints supposed to be formed under the maximum principal stress (σ1) of NE-SW, which is consistent with the shear joints. While the joints with the same mineral assemblage from the Baobaoshang, Mozhaibeixi have a strike range of 208°–302° and dip range of 61°–89°, which suggests that the direction of maximum principal stress (σ1) is NWW-SEE.
5.1.2
Finite strain
Thirteen directional samples were collected from the orebodies as well as their hanging wall and footwall. Assuming that the occurrences of beds correspond with axes by X||trend, Y||dip, Z⊥XY plane in the rectangular coordinates system. Twenty-six thin directional sections in XY and YZ planes were polished to observe and photograph directionally with the microscope. On this basis, the right orientation of these micrographs was preset as 0° to outline the equiaxial minerals or detritus, and two dimension strain ellipses were generated automatically based on the statistical analysis of the outline of mineral or detritus using the software Straindesk 1.1. The real two-dimension strain ellipses were corrected according to the primary attitudes in the field (Li and Zeng, 2006).
(1) El-57 and EL-58 are the Maokou limestone collected from the footwall with the dominant mineral of calcite. According to the real strain ellipse, the finite strain in XY plane is 1.177 and 1.308, and the elongated axes are 5.2° and 60.4°, indicating that the footwall was affected by tectonic stress in the direction of nearly E-W and NW-SE. The finite strain in the YZ plane is 1.005 and 1.115, and the inclined angles between the dipping and long axes are 45.7° and 89.2°, respectively (Table 2).
Table
2.
Parameters of directional thin sections from the Getang gold deposit
(2) Samples El-44, EL-46, and EL-54 were collected from the hanging wall, and are dominated by the siltstones and carbonaceous siltstones with quartz and bioclastic particles within the Longtan Formation. The finite strain in the XY plane is 1.07–1.218, with a wide range of long axes 48.7°, and 313.9°–347.4°, reflecting the maximum principal compressive stress is NE-SW to NW-SE. The finite strain in the YZ plane of the three samples is 1.232–1.529, and the inclined angles between the dipping angle and the elongated axes are 0.3°–9.2° and 48.8° (Table 2).
(3) Eight samples (EL-48, EL-49, EL-50, EL-51, EL-55, EL-56, EL-64, and EL-65) collected from orebodies were strongly silicified, and the mineral particles are mainly euhedral to subhedral quartz. The finite strain in the XY plane is 1.051–1.210. The long axes are 7.9°–71.9° and 272.4°–294.9°, indicating that the maximum principal compressive stress is NW-SE and is partially affected by the nearly S-N compression. The finite strain in the YZ plane is 1.065–1.258, and the inclined angles between the dipping angle and the long axes are 6.3°–24.8° and 58.3°–67.4° (Table 2).
To analyze the dynamic characteristics of the tectonic event, the true strain difference (ε), vorticity (Wk), thickness ratio (S) vertical to shear direction, and eigenvector ordinate ratio of polar-Mohr (ξ1/ξ2) were calculated with the Rs (a/b) and included angle of the thin section in YZ plane (Table 3).
Table
3.
Parameters of finite strain from the Getang gold deposit
When materials fracture under brittle deformation, it is said to exhibit brittle failure. The stress conditions at the point of failure are known as the stress criteria of brittle strength (Fossen, 2010). It is found that, in general, two sets of planar shear fractures are formed which intersect in a line parallel to the intermediate principal stress axis σ2. Moreover, the acute angle between the shear fractures is bisected by the maximum principal stress axis σ1 (Price and Cosgrove, 1990).
According to the stress criteria of brittle strength, it is suggested that the formation of joints in the Getang gold deposit should generally be caused by compression with the maximum principal stress axis σ1 in the direction of NNE-SSW, based on the stereograms of joints (Section 5.1.1) at 9 locations. The slight differences in the direction of the maximum principal stress axis at each point may be related to the influence of adjacent higher-level faults. The maximum principal stress axis in the Mozhaibeixi is NWW in direction, which may be related to the transformation of the NW-trending Guiluo fault.
To present the tectonic stress field that controlled joint formation, the stereograms of joints were plotted on the geological map of the Getang gold deposit (Figure 11). And the stress trajectories were outlined to present the NNE-SSW tectonic stress field that caused fractures in the Getang gold deposit.
Figure
11.
Stress trajectories showed by stereograms of joints on the geological map of the Getang gold deposit.
Since a strain results from the action of stress, we can illustrate the geometrical relationship between the two regarding a homogeneous strain of pure shear. In the case of pure shear, the orientation of the principal stress axes corresponds with X||σ3, Y||σ2, Z||σ1; that is, the direction of greatest extension corresponds to the direction of minimum stress, and the direction of least extension or greatest shortening corresponds to the direction of maximum stress (Ramsay and Huber, 1983).
The strain ellipses of orebodies and its hanging wall and footwall indicate that structures in the Getang gold deposit were jointly controlled by tectonic stresses in the direction of NNE-SSW and NW-SE (Figure 12). The limestone in the footwall (Maokou Formation) is competent and weakly affected by lateral tectonic movement. The orebodies and hanging wall were jointly affected by tectonic stresses in the NNE-SSW and NW-SE direction, and the tectonic stress in the NNE-SSW direction as a more substantial effect on the hanging wall than that of the tectonic stress in the NW-SE direction.
The inclined angles between the dipping angle and the long axes of the true strain ellipses in the dipping thin section can be used to judge the tectonic property that minerals or detritus experienced. The inclined angle < 45° indicates that the tectonic property may be compressive and shear, while the inclined angle > 45° suggests that the tectonic property should be tensional and shear. The inclined angles of the footwall (45.7° and 89.2°) in the Getang gold deposit are greater than 45°, indicating a tensile property. The inclined angles of the hanging wall (0.3°–9.2° and 48.8°) are less than or close to 45°, reflecting a compressional property. And the inclined angles of orebodies (6.3°–24.8° and 58.3°–67.4°) are in a wide range, which indicates the tectonic property during gold mineralization changed considerably and varied from compression to extension.
The vorticity (Wk) of finite strain is often selected as an index for the tectonic property: Wk = 0 suggests that a pure shear dominated; Wk = 0.71–0.75 indicates that pure shear is comparable to simple shear; (Wk) = 1 indicates that a simple shear matter (Tikoff and Fossen, 1995; Means et al., 1980). In the Getang gold deposit, the vorticities (Wk) of the footwall (0.020 6 and 0.941 2), the hanging wall (0.018 4 and 0.522 1–0.887 9), and the orebodies (0.354 5–0.930 0) varied in a wide range. This feature reflects that the gold mineralization related rocks are controlled by simple shear and pure shear in different periods or parts, or its dynamic properties changed with the development of tectonic activities.
The thickness ratio (S) vertical to shear direction reflects the thickness changes of rocks: S < 1 means that rocks are thinned by tectonic movement, S = 1 means that rocks remain unchanged, and S > 1 means that rocks are thickened. The thickness ratios (S) of orebodies (0.621 7–0.865 2 and 1.250 2–1.313 3) indicate that orebodies are locally thinned and thickened, which may be related to the uneven distribution of tectonic stress.
6.
STRUCTURAL CONTROL ON GOLD MINERALIZATION
6.1
Structural Evolution
As the ore-forming process and geometry of ore domains are components of tectonic evolution, clarifying the structural process of the Getang gold deposit is critical to identify the structural control on the gold mineralization. Based on the tectonic evolution and structural features within deposit, three structural processes can be identified:
(1) The thickly bedded massive bioclastic limestone of the Maokou Formation suggests that the Getang District was a shallow-water platform when the Youjiang Basin performed as a rift basin before the Middle Permian (Wang et al., 1995). The paleokarst indicates a crustal uplift associated with emplacement of the Emeishan plume at the end of the Middle Permian (He et al., 2003) when the Youjiang Basin experienced extension driven by slab-pull of the Paleo-Tethys Ocean (Qiu et al., 2017; Lai et al., 2014; Du et al., 2009). After sedimentation of the siliceous clastic rocks of the Late Permian, the paleokarst served as a physicochemical transition interface and laid a foundation for the unconformity (Liu J Z et al., 2014, 2010, 2006).
(2) The NWW-trending Getang anticline and the NW-trending faults are supposed to form under compression in the NNE-SSW direction caused by the Indochina-South China collision (Indosinian orogeny) along the Song Ma Suture (Zaw et al., 2014), which resulted in a NW-NWW trending foreland fold-and-thrust belt in the Youjiang Basin (Chen et al., 2019; Li et al., 2017; Qiu et al., 2016). This tectonic stress field was also evidenced by the joint measurement, which suggested that the fractures in the Getang District were also formed under a NNE-SSW tectonic stress field.
(3) The two stages of calcite veins in the Haimagu fault indicate multi-stage tectonic events of the NE-trending faults. The NE-trending faults (such as the Haimagu fault) are verified to sinistral offset and rotate the NWW-trending Getang anticline and NW-trending faults (such as Guiluo fault). This intersecting relationship indicates that the NE-trending structures were formed or reactivated after the NW-trending structures in the Getang District. The NE-trending folds superposed on the NWW-trending Getang anticline and the interlayer-gliding structures developed in the detrital rock of the Longtan Formation are evidence for the NW-SE tectonic stress generated by the Late Jurassic–Cretaceous NW-SE thrusting during the subduction of the Pacific Plate beneath the Eurasian Plate (Yanshanian orogeny) (Zeng et al., 2018; Qiu et al., 2016 and references therein).
The strain ellipses of the orebodies suggest that the unconformity was jointly affected by tectonic stresses in the NNE-SSW and NW-SE directions. It means that the unconformity developed during the later two tectonic processes from the Middle Triassic to the Early Cretaceous.
6.2
Relationship between Gold Mineralization and Structure
The structural features and dynamic analysis are direct methods to determine the relationship between the gold mineralization and structures. In the unconformity, the brecciated ore and pyrite veins propose a tensional kinetics. And this tectonic kinetics is also verified by the finite strain parameters, including the vorticities and the inclined angles of the footwall, the hanging wall, and the orebodies. From a pure structural viewpoint, the tectonic transformation process related to gold mineralization should occur during the Indosinian orogeny (Middle to Late Triassic), or the Yanshanian intracontinental orogeny (Jurassic to Early Cretaceous) of the Youjiang Basin. But the lack of compressional structures in the orebodies increases the confidence level of ore-forming in Yanshanian intracontinental orogeny. And the new precise geochronology data of the Carlin-type gold deposits in the northern Youjiang Basin (Wang et al., 2021; Chen et al., 2019; Zheng et al., 2019) also prove that the gold mineralization at Getang may be generated owing to the tectonic transformation from compression to extension during the intracontinental orogeny (ca. 150–130 Ma). The locally thinned or thickened orebodies related to the irregularity distribution of tectonic stress might be resulted from the uneven paleokarst surface.
7.
CONCLUSIONS
According to the field geological investigations, structural analysis, and joints and finite strain measurement, the structural control on the gold mineralization in the Getang gold deposit are summarized as follows.
(1) Three episodes of structural evolution are identified at the Getang gold deposit: paleokarst generated by a crustal uplift at the end of the Middle Permian, the NW-trending structures formed under a NNE-SSW-trending compression during the Indosinian orogeny, and the NE-trending structures reactivated or formed under a NW-SE-trending compression during the Yanshanian intracontinental orogeny.
(2) Structural analyses and geochronology data prove that the Getang gold deposit was formed during the tectonic transition from compression to extension during the Yanshanian intracontinental orogeny (ca. 150–130 Ma).
(3) The unconformity in the Getang gold deposit recorded the two episodes of tectonic evolution in the NNE-SSW and NW-SE directions. The thickness of gold orebodies is constrained by the uneven paleokarst surface.
ACKNOWLEDGMENTS:
This study was financially supported by the National Natural Science Foundation of China (Nos. 42072091, 41972206), the Hubei Provincial Natural Science Foundation Joint Project (No. 2023AFD210), the China Geological Survey (Nos. 12120115036201, DD20190443). Fieldwork greatly benefited from the Geological Party 105, Guizhou Bureau of Geology and Mineral Exploration & Development. The support and constructive advice from Prof. Zonggui Zhou are also thanked. We are grateful to Prof. Liang Qiu and an anonymous reviewer, whose constructive comments are helpful in improving this paper. Sincere thanks to Prof. Ge Yao for his editorial handling on this paper. The final publication is available at Springer via https://doi.org/10.1007/s12583-021-1461-8.
Bell, R. M., Kolb, J., Waight, T. E., 2018. Assessment of Lithological, Geochemical and Structural Controls on Gold Distribution in the Nalunaq Gold Deposit, South Greenland Using Three-Dimensional Implicit Modelling. Geological Society, London, Special Publications, 453(1): 385–405. https://doi.org/10.1144/sp453.2
Berger, B. R., Tingley, J. V., Drew, L. J., 2003. Structural Localization and Origin of Compartmentalized FluidFlow, Comstock Lode, Virginia City, Nevada. Economic Geology, 98(2): 387–408. https://doi.org/10.2113/gsecongeo.98.2.387
Blenkinsop, T. G., 2004. Orebody Geometry in Lode Gold Deposits from Zimbabwe: Implications for Fluid Flow, Deformation and Mineralization. Journal of Structural Geology, 26(6/7): 1293–1301. https://doi.org/10.1016/j.jsg.2003.11.010
Bureau of Geology and Mineral Exploration and Development Guizhou Province (BGMG), 2014. Geological Map of the Getang Gold Deposit, Guiyang (in Chinese)
Cassinerio, M., Muntean, J., 2011. Patterns of Lithology, Structure, Alteration and Trace Elements around High-Grade Ore Zones at the Turquoise Ridge Gold Deposit, Getchell District, Nevada. In: Steininger, R., Pennell, W., eds., Great Basin Evolution and Metallogeny, Vol. I and II, DEStech Publ. Inc., Lancaster, 949–977
Chen, M. H., Bagas, L., Liao, X., et al., 2019. Hydrothermal Apatite SIMS THPB Dating: Constraints on the Timing of Low-Temperature Hydrothermal Au Deposits in Nibao, SW China. Lithos, 324/325: 418–428. https://doi.org/10.1016/j.lithos.2018.11.018
Chen, M. H., Huang, Q. W., Hu, Y., et al., 2009. Genetic Types of Phyllosilicate (Micas) and Its 39Ar-40Ar Dating in Lannigou Gold Deposit, Guizhou Province, China. Acta Mineralogica Sinica, 29(3): 353–362 (in Chinese with English Abstract)
Chen, M. H., Mao, J. W., Bierlein, F. P., et al., 2011. Structural Features and Metallogenesis of the Carlin-Type Jinfeng (Lannigou) Gold Deposit, Guizhou Province, China. Ore Geology Reviews, 43(1): 217–234. https://doi.org/10.1016/j.oregeorev.2011.06.009
Chen, M. H., Mao, J. W., Li, C., et al., 2015. Re-Os Isochron Ages for Arsenopyrite from Carlin-Like Gold Deposits in the Yunnan-Guizhou-Guangxi "Golden Triangle", Southwestern China. Ore Geology Reviews, 64: 316–327. https://doi.org/10.1016/j.oregeorev.2014.07.019
Chen, M. H., Mao, J. W., Uttley, P., et al., 2007. Structure Analysis and Structural Metallogenesis of Jinfeng (Lannigou) Gold Deposit in Guizhou Province. Mineral Deposits, 26(4): 380–396 (in Chinese with English Abstract)
Chen, M. H., Mao, J. W., Wu, L. L., et al., 2006. A Review on the Chronology of Micro-Disseminated Gold Deposits in Yunnan-Guizhou-Guangxi Triangle Area, Southwestern China. Journal of Guilin University of Technology, 26(3): 334–340 (in Chinese with English Abstract)
Cline, J. S., Hofstra, A. H., Muntean, J. L., et al., 2005. Carlin-Type Gold Deposits in Nevada: Critical Geologic Characteristics and Viable Models. Economic Geology, 100: 451–484. https://doi.org/10.5382/av100.1
Du, Y. S., Huang, H. W., Huang, Z. Q., et al., 2009. Basin Translation from Late Palaeozoic to Triassic of Youjiang Basin and Its Tectonic Significance. Geological Science and Technology Information, 28(6): 10–15 (in Chinese with English Abstract)
Du, Y. S., Huang, H., Yang, J. H., et al., 2013. The Basin Translation from Late Paleozoic to Triassic of the Youjiang Basin and Its Tectonic Signification. Geological Review, 59(1): 1–11 (in Chinese with English Abstract)
Fang, W. X., Hu, R. Z., Su, W. C., et al., 2006. Features of Metallogenic System of Compound Continental Dynamics in Yunnan-Guizhou-Guangxi-Hunan Provinces. Geotectonica et Metallogenia, 30(4): 470–480 (in Chinese with English Abstract)
Fu, Z. K., Qi, J., Zhang, J. Z., 2008. Thrust Faulted Nappe Structural Character and Its Exploration Significance of Nayang Ore Block of Shuiyindong Gold Field in Guizhou. Guizhou Geology, 25(3): 188–192 (in Chinese with English Abstract)
Groves, D. I., Goldfarb, R. J., Santosh, M., 2016. The Conjunction of Factors that Lead to Formation of Giant Gold Provinces and Deposits in Non-Arc Settings. Geoscience Frontiers, 7(3): 303–314 (in Chinese with English Abstract)
Guo, Z. C., Zhou, Z. F., 2006. Exploration Practice of Huijiabao-Anticline Gold Deposit, Southwest Guizhou and Establishment on Two-Story-Building Model. Guizhou Geology, 23(3): 176–181, 186 (in Chinese with English Abstract)
He, B., Xu, Y. G., Chung, S. L., et al., 2003. Sedimentary Evidence for a Rapid, Kilometer-Scale Crustal Doming Prior to the Eruption of the Emeishan Flood Basalts. Earth and Planetary Science Letters, 213(3/4): 391–405. https://doi.org/10.1016/s0012-821x(03)00323-6
Holcombe, R. J., 2009. Georient v9.4. 4, Stereographic Projections and Rose Diagram Software. Department of Earth Sciences, University of Queensland, Australia. http://www.holcombe.net.au/software/
Hu, R. Z., Chen, W. T., Xu, D. R., et al., 2017a. Reviews and New Metallogenic Models of Mineral Deposits in South China: An Introduction. Journal of Asian Earth Sciences, 137: 1–8. https://doi.org/10.1016/j.jseaes.2017.02.035
Hu, R. Z., Fu, S. L., Huang, Y., et al., 2017b. The Giant South China Mesozoic Low-Temperature Metallogenic Domain: Reviews and a New Geodynamic Model. Journal of Asian Earth Sciences, 137: 9–34. https://doi.org/10.1016/j.jseaes.2016.10.016
Hu, R. Z., Su, W. C., Bi, X. W., et al., 2002. Geology and Geochemistry of Carlin-Type Gold Deposits in China. Mineralium Deposita, 37(3/4): 378–392. https://doi.org/10.1007/s00126-001-0242-7
Hu, X. L., Gong, Y. J., Zeng, G. P., et al., 2018. Multistage Pyrite in the Getang Sediment-Hosted Disseminated Gold Deposit, Southwestern Guizhou Province, China: Insights from Textures and in situ Chemical and Sulfur Isotopic Analyses. Ore Geology Reviews, 99: 1–16. https://doi.org/10.1016/j.oregeorev.2018.05.020
Hu, X. L., Zeng, G. P., Zhang, Z. J., et al., 2018. Gold Mineralization Associated with Emeishan Basaltic Rocks: Mineralogical, Geochemical, and Isotopic Evidences from the Lianhuashan Ore Field, Southwestern Guizhou Province, China. Ore Geology Reviews, 95: 604–619. https://doi.org/10.1016/j.oregeorev.2018.03.016
Hu, Y. Z., Liu, W. H., Wang, J. J., et al., 2017. Basin-Scale Structure Control of Carlin-Style Gold Deposits in Central Southwestern Guizhou, China: Insights from Seismic Reflection Profiles and Gravity Data. Ore Geology Reviews, 91: 444–462. https://doi.org/10.1016/j.oregeorev.2017.09.011
Hu, Y. Z., Zhang, G. Q., Wang, J. J., et al., 2012. Seismic Evidence of Thrust-Fold in Carlin-Type Gold Deposit, Central Southwestern Guizhou and Its Significance. Earth Science Frontiers, 19(4): 63–71 (in Chinese with English Abstract)
Huang, Y., He, C., Chen, N. S., et al., 2019. Diabase Sills in the Outer Zone of the Emeishan Large Igneous Province, Southwest China: Petrogenesis and Tectonic Implications. Journal of Earth Science, 30(4): 739–753. https://doi.org/10.1007/s12583-019-1241-x
Jin, X. Y., 2017. Geology, Mineralization and Genesis of the Nibao, Shuiyindong and Yata Gold Deposits in SW Guizhou Province, China: [Dissertation]. China University of Geosciences, Wuhan (in Chinese with English Abstract)
Lai, C. K., Meffre, S., Crawford, A. J., et al., 2014. The Western Ailaoshan Volcanic Belts and Their SE Asia Connection: A New Tectonic Model for the Eastern Indochina Block. Gondwana Research, 26(1): 52–74. https://doi.org/10.1016/j.gr.2013.03.003
Large, S. J. E., Bakker, E. Y. N., Weis, P., et al., 2016. Trace Elements in Fluid Inclusions of Sediment-Hosted Gold Deposits Indicate a Magmatic-Hydrothermal Origin of the Carlin Ore Trend. Geology, 44(12): 1015–1018. https://doi.org/10.1130/g38351.1
Li, J. H., Zhao, G. C., Johnston, S. T., et al., 2017. Permo-Triassic Structural Evolution of the Shiwandashan and Youjiang Structural Belts, South China. Journal of Structural Geology, 100: 24–44. https://doi.org/10.1016/j.jsg.2017.05.004
Li, Z. Y., Zeng, Z. X., 2006. Finite Strain Measurement of Rocks by Using of Inertia Moment Ellipses. Geological Science and Technology Information, 25(6): 37–40 (in Chinese with English Abstract)
Liu, J. Z., Deng, Y. M., Liu, C. Q., et al., 2006. Metallogenic Conditions and Model of the Superlarge Shuiyindong Stratabound Gold Deposit in Zhenfeng County, Guizhou Province. Geology in China, 33(1): 169–177 (in Chinese with English Abstract)
Liu, J. Z., Xia, Y., Tao, Y., et al., 2014. The Relation between SBT and Gold-Antimony Deposit Metallogenesis and Prospecting in Southwest Guizhou. Guizhou Geology, 31(4): 267–272 (in Chinese with English Abstract)
Liu, J. Z., Xia, Y., Zhang, X. C., et al., 2008. Model of Strata Karlin-Type Gold Deposit: The Shuiyingdong Super-Scale Gold Deposit. Gold Science and Technology, 16(3): 1–5 (in Chinese with English Abstract)
Liu, J. Z., Yang, C. F., Xia, Y., et al., 2010. Sbt Study and Ideas in Patform Lithofaices Area in the Southwest Guizhou. Guizhou Geology, 27(3): 178–184 (in Chinese with English Abstract)
Liu, S., Su, W. C., Hu, R. Z., et al., 2010. Geochronological and Geochemical Constraints on the Petrogenesis of Alkaline Ultramafic Dykes from Southwest Guizhou Province, SW China. Lithos, 114(1/2): 253–264. https://doi.org/10.1016/j.lithos.2009.08.012
Liu, S., Zhang, P. X., Xiong, C. J., et al., 2013. A Study on the Geochemical Characteristics of SBT in Getang Gold Deposit. Journal of Guizhou University (Natural Sciences), 30(5): 43–48 (in Chinese with English Abstract)
Liu, Y., Hu, K., Han, S. C., et al., 2015. The Nature of Ore-Forming Fluids of the Carlin-Type Gold Deposit in Southwest China: A Case from the Zimudang Gold Deposit. Resource Geology, 65(2): 136–159. https://doi.org/10.1111/rge.12060
Luo, D. W., 2015. Metalllogenic System and Metalllogenic Prediction of the Carlin-Type Gold Deposit in Southwest Guizhou Province: [Dissertation]. China University of Geosciences, Wuhan (in Chinese with English Abstract)
Luo, D. W., Yao, S. Z., Wang, C. X., et al., 2016. Evaluation of Denudation Degree of Carlin-Type Gold Deposits in Southwest Guizhou Province. Earth Science, 41(2): 199–217 (in Chinese with English Abstract)
Luo, D. W., Zeng, G. P., 2018. Application and Effects of Singularity Analysis in Evaluating the Denudation Degree of Carlin-Type Gold Deposits in Southwest Guizhou, China. Ore Geology Reviews, 96: 164–180. https://doi.org/10.1016/j.oregeorev.2018.04.018
Luo, X. H., 1997. Analysis of Gold Mineralization in Southwestern Guizhou Based on Structural Styles. Guizhou Geology, 14(4): 312–320 (in Chinese with English Abstract)
Luo, X. H., 1997b. A Study on the Control of Geometrical and Kinetic Features of Fault Structures on the Location of Gold Deposits─The Example from Carlin-Type Gold Deposits of Southwestern Guizhou. Guizhou Geology, 14(1): 46–54 (in Chinese with English Abstract)
Mao, J. Q., Du, D. Q., Pan, N. X., et al., 1990. Analysis of Detachment and Gold Ore Deposit in Southwestern Guizhou. Journal of Guizhou University of Technology (Natural Science Edition), 19(3): 44–49 (in Chinese with English Abstract)
Means, W. D., Hobbs, B. E., Lister, G. S., et al., 1980. Vorticity and Non-Coaxiality in Progressive Deformations. Journal of Structural Geology, 2(3): 371–378. https://doi.org/10.1016/0191-8141(80)90024-3
Meng, L. X., Zhou, Y., Cai, Y. F., et al., 2020. Southwestern Boundary between the Yangtze and Cathaysia Blocks: Evidence from Detrital Zircon U-Pb Ages of Early Paleozoic Sedimentary Rocks from Qinzhou-Fangchenggang Area, Guangxi. Earth Science, 45(4): 1227–1242 (in Chinese with English Abstract)
Micklethwaite, S., 2009. Mechanisms of Faulting and Permeability Enhancement during Epithermal Mineralisation: Cracow Goldfield, Australia. Journal of Structural Geology, 31(3): 288–300. https://doi.org/10.1016/j.jsg.2008.11.016
Micklethwaite, S., 2011. Fault-Induced Damage Controlling the Formation of Carlin-Type Ore Deposits. In: Steininger, R., Pennell, W., eds., Great Basin Evolution and Metallogeny, Vols. Ⅰ and Ⅱ, DEStech Publ. Inc., Lancaster, 221–231
Páez, G. N., Ruiz, R., Guido, D. M., et al., 2011. Structurally Controlled Fluid Flow: High-Grade Silver Ore-Shoots at Martha Epithermal Mine, Deseado Massif, Argentina. Journal of Structural Geology, 33(5): 985–999. https://doi.org/10.1016/j.jsg.2011.02.007
Peters, S. G., Huang, J. Z., Li, Z. P., et al., 2007. Sedimentary Rock-Hosted Au Deposits of the Dian-Qian-Gui Area, Guizhou, and Yunnan Provinces, and Guangxi District, China. Ore Geology Reviews, 31(1/2/3/4): 170–204. https://doi.org/10.1016/j.oregeorev.2005.03.014
Pi, Q. H., Hu, R. Z., Xiong, B., et al., 2017. In situ SIMS U-Pb Dating of Hydrothermal Rutile: Reliable Age for the Zhesang Carlin-Type Gold Deposit in the Golden Triangle Region, SW China. Mineralium Deposita, 52(8): 1179–1190. https://doi.org/10.1007/s00126-017-0715-y
Price, N. J., Cosgrove, J. W., 1990. Analysis of Geological Structures, Chapter 5, Cambridge University Press, Cambridge
Qiu, H. N., Bai, X. J., 2019. Fluid Inclusion 40Ar/39Ar Dating Technique and Its Applications. Earth Science, 44(3): 685–697 (in Chinese with English Abstract)
Qiu, L. A., Yang, W. X., Yan, D. P., et al., 2019. Geochronology of Early Mesozoic Diabase Units in Southwestern China: Metallogenic and Tectonic Implications. Geological Magazine, 156(7): 1141–1156. https://doi.org/10.1017/s0016756818000493
Qiu, L., Yan, D. P., Tang, S. L., et al., 2016. Mesozoic Geology of Southwestern China: Indosinian Foreland Overthrusting and Subsequent Deformation. Journal of Asian Earth Sciences, 122: 91–105. https://doi.org/10.1016/j.jseaes.2016.03.006
Qiu, L., Yan, D. P., Yang, W. X., et al., 2017. Early to Middle Triassic Sedimentary Records in the Youjiang Basin, South China: Implications for Indosinian Orogenesis. Journal of Asian Earth Sciences, 141: 125–139. https://doi.org/10.1016/j.jseaes.2016.09.020
Ramsay, J. G., Huber, M. I., 1983. The Techniques of Modern Structural Geology, Vol. 1: Strain Analysis. Academic Press, New York
Ren, G. M., Pang, W. H., Wang, L. Q., et al., 2020. Detrital Zircons of 3.8 Ga in Southwestern Yangtze Block and Its Geological Implications. Earth Science, 45(8): 3040–3053 (in Chinese with English Abstract)
Sibson, R. H., 1996. Structural Permeability of Fluid-Driven Fault-Fracture Meshes. Journal of Structural Geology, 18(8): 1031–1042. https://doi.org/10.1016/0191-8141(96)00032-6
Su, W. C., Dong, W. D., Zhang, X. C., et al., 2018. Chapter 5 Carlin-Type Gold Deposits in the Dian-Qian-Gui "Golden Triangle" of Southwest China. Economic Geology, 20: 157–185
Su, W. C., Hu, R. Z., Xia, B., et al., 2009. Calcite Sm-Nd Isochron Age of the Shuiyindong Carlin-Type Gold Deposit, Guizhou, China. Chemical Geology, 258(3/4): 269–274. https://doi.org/10.1016/j.chemgeo.2008.10.030
Su, W. C., Zhang, H. T., Hu, R. Z., et al., 2012. Mineralogy and Geochemistry of Gold-Bearing Arsenian Pyrite from the Shuiyindong Carlin-Type Gold Deposit, Guizhou, China: Implications for Gold Depositional Processes. Mineralium Deposita, 47(6): 653–662. https://doi.org/10.1007/s00126-011-0328-9
Su, W., Heinrich, C. A., Pettke, T., et al., 2009. Sediment-Hosted Gold Deposits in Guizhou, China: Products of Wall-Rock Sulfidation by Deep Crustal Fluids. Economic Geology, 104(1): 73–93. https://doi.org/10.2113/gsecongeo.104.1.73
Tan, Q. P., Xia, Y., Wang, X. Q., et al., 2017. Tectonic Model and Tectonic-Geochemistry Characteristics of the Huijiabao Gold Orefield, SW Guizhou Province. Geotectonica et Metallogenia, 41: 291–304 (in Chinese with English Abstract)
Tan, Q. P., Xia, Y., Xie, Z. J., et al., 2015. Migration Paths and Precipitation Mechanisms of Ore-Forming Fluids at the Shuiyindong Carlin-Type Gold Deposit, Guizhou, China. Ore Geology Reviews, 69: 140–156. https://doi.org/10.1016/j.oregeorev.2015.02.006
Tan, Q. P., Xia, Y., Xie, Z J., et al., 2019. Two Hydrothermal Events at the Shuiyindong Carlin-Type Gold Deposit in Southwestern China: Insight from Sm-Nd Dating of Fluorite and Calcite. Minerals, 9(4): 230. https://doi.org/10.3390/min9040230
Tikoff, B., Fossen, H., 1995. The Limitations of Three-Dimensional Kinematic Vorticity Analysis. Journal of Structural Geology, 17(12): 1771–1784. https://doi.org/10.1016/0191-8141(95)00069-p
Tu, G. Z., 1990. The Sw Qinling and the Sw Guizhou Uranium and Gold Metallogenic Belts, and Their Similarites to the Carlin: Type Gold Deposits in Tiie Western States, Usa. Uranium Geology, 6(6): 321–325 (in Chinese with English Abstract)
Wang, L., Zhang, Y. W., Liu, S. G., 2009. The Application of Regional Gravity and Magnetic Data to Delineating Intrusive Bodies and Local Geological Structures in Guizhou Province. Geophysical and Geochemical Exploration, 33(3): 245–249 (in Chinese with English Abstract)
Wang, Y. G., 1992. Tectonic Frame and Features of Guizhou: Proceeding of the Conference of Regional Structure-Ore-Field in the Guizhou Province, Guizhou Scientific and Technology Publishing House, Guiyang (in Chinese)
Wang, Y. G., Sue, S. T., Zhang, M. F., 1994. Structure and Carlin-Type Gold Deposits in Southwestern Guizhou Province. Geological Publishing House, Guiyang (in Chinese)
Wang, Y. G., Wang, L. T., Zhang, M. F., et al., 1995. Texture of the Upper Crust and Pattern of the Disseminated Gold Deposits Distributed in Nanpanjiang Area. Guizhou Geology, 12(2): 91–183 (in Chinese with English Abstract)
Wang, Z. P., Tan, Q. P., Xia, Y., et al., 2021. Sm-Nd Isochron Age Constraints of Au and Sb Mineralization in Southwestern Guizhou Province, China. Minerals, 11(2): 100. https://doi.org/10.3390/min11020100
Wu, S. Y., Hou, L., Ding, J., et al., 2016. Ore-Controlling Structure Types and Characteristics of Ore-Forming Fluid of the Carlin-Type Gold Orefield in Southwestern Guizhou, China. Acta Petrologica Sinica, 32(8): 2407–2424 (in Chinese with English Abstract)
Yan, J., Hu, R. Z., Liu, S., et al., 2018. NanoSIMS Element Mapping and Sulfur Isotope Analysis of Au-Bearing Pyrite from Lannigou Carlin-Type Au Deposit in SW China: New Insights into the Origin and Evolution of Au-Bearing Fluids. Ore Geology Reviews, 92: 29–41. https://doi.org/10.1016/j.oregeorev.2017.10.015
Zaw, K., Meffre, S., Lai, C. K., et al., 2014. Tectonics and Metallogeny of Mainland Southeast Asia—A Review and Contribution. Gondwana Research, 26(1): 5–30. https://doi.org/10.1016/j.gr.2013.10.010
Zeng, G. P., Luo, D. W., Gong, Y. J., et al., 2018. Structures and Implications for Fluid Migration in the Jiadi Carlin-Type Gold Deposit, Guizhou Province, Southwest China. Resource Geology, 68(4): 373–394. https://doi.org/10.1111/rge.12175
Zeng, Z. G., Yang, E. L., Ji, G. S., et al., 2014. Characteristics and Metallogenic Mode of Gold Deposit in Haimagu Area of Guizhou. Guizhou Geology, 31(4): 261–266 (in Chinese with English Abstract)
Zhang, J. B., Ding, X. Z., Liu, Y. X., et al., 2020. Geochronology and Geochemistry of the 890 Ma I-Type Granites in the Southwestern Yangtze Block: Petrogenesis and Crustal Evolution. Journal of Earth Science, 31(6): 1216–1228. https://doi.org/10.1007/s12583-020-1339-1
Zhang, X. C., Spiro, B., Halls, C., et al., 2003. Sediment-Hosted Disseminated Gold Deposits in Southwest Guizhou, PRC: Their Geological Setting and Origin in Relation to Mineralogical, Fluid Inclusion, and Stable-Isotope Characteristics. International Geology Review, 45(5): 407–470. https://doi.org/10.2747/0020-6814.45.5.407
Zheng, L. L., Yang, R. D., Gao, J. B., et al., 2019. Quartz Rb-Sr Isochron Ages of Two Type Orebodies from the Nibao Carlin-Type Gold Deposit, Guizhou, China. Minerals, 9(7): 399. https://doi.org/10.3390/min9070399
Jingdan Xiao, Zhuojun Xie, Yong Xia, et al. Consistent crystal orientation of core and rim pyrites indicates an epitaxial growth of rim in Carlin-type gold deposits. Geoscience Frontiers, 2024. doi:10.1016/j.gsf.2024.101966
2.
Yuzuo Liu, Jiao Wang, Wanzhong Shi, et al. A novel method for evaluating shale gas preservation conditions in an area on a regional scale. Scientific Reports, 2024, 14(1) doi:10.1038/s41598-024-76290-4
3.
Xiaolong Wang, Shengtao Cao, Qinping Tan, et al. Exploration Vectors and Indicators Extracted by Factor Analysis and Association Rule Algorithms at the Lintan Carlin-Type Gold Deposit, Youjiang Basin, China. Minerals, 2024, 14(5): 492. doi:10.3390/min14050492
Figure 1. (a) Simplified tectonic map of Southwest China and North Vietnam showing the location of the Youjiang Basin (modified after Su et al., 2018); (b) Geological map of the Southwest Guizhou showing the geology, structure, and distribution of the representative Carlin-type gold deposits (modified after Luo and Zeng, 2018). ASRR. Ailaoshan-Red River shear zone; MSF. Mile-Shizong fault; ZYF. Ziyun-Yadu fault; NPF. Nanpanjiang fault; BF. Youjiang fault; GFF. Guangnan-Funing fault; PNF. Pingxiang-Nanning fault; NVB. North Vietnam Block. Gold deposits: SYD. Shuiyindong; ZMD. Zimudang; LNG. Lannigou; LWC. Laowanchang; JD. Jiadi; NB. Nibao; GT. Getang; XW. Xiongwu; YT. Yata; BQ. Banqi; BD. Baidi.
Figure 2. Simplified geological map of the Getang gold deposit (modified after BGMG, 2014).
Figure 3. (a) Photograph of stopes showing occurrences of the primary and oxidized ores in the unconformity; (b) geological section presenting the spatial relationship of the Maokou Formation, unconformity, and the Longtan Formation; (c), (d) geological sections illustrating the features of mineralization in the Getang gold deposit.
Figure 4. A–A' and B–B' geological sections of the Getang gold deposit. The A–A' geological section showing an anticline that trends to the northeast; the B–B' geological section presenting an anticline that trends to the southeast.
Figure 5. The Getang anticline trends to the southeast in the Erlongkou Block.
Figure 6. Structural features of the Haimagu fault. (a) Breccias in the Haimagu fault; (b) positive steps on the Haimagu fault plane; (c) limestone breccias enclosed by the early white calcite vein; (d) the late red calcite vein with steep attitudes.
Figure 7. NE-trending folds in the Getang gold deposit. (a) Photograph showing a NE-trending syncline in the Erlongkou Block; (b) photograph showing NE-trending folds in the Erlongkou Block; (c) photograph showing NE-trending folds in the Kehua Block; (d) photograph showing NE-trending folds in the Kehua Block.
Figure 8. Interlayer-gliding structures in the Getang gold deposit. (a) Photograph illustrating the interlayer-gliding structure in the Longtan Formation; (b) photograph illustrating the interlayer-gliding structure in the Longtan Formation; (c) photograph illustrating the interlayer-gliding structure close to the unconformity in the Kehua Block; (d) photograph illustrating the interlayer-gliding structure close to the unconformity in the Kehua Block.
Figure 9. Featured photos of the unconformity. (a) Disseminated pyrites in the argillite; (b) massive pyrite in the silicified carbonaceous shale; (c) breccias in the unconformity; (d) comb structure of the pyrite-quartz veins; (e) fluorite stockworks in the unconformity; (f) orpiment stockworks and realgar aggregate in the unconformity.
Figure 10. Stereograms of joints of the Getang gold deposit.
Figure 11. Stress trajectories showed by stereograms of joints on the geological map of the Getang gold deposit.
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