SEARCH

SEARCH BY CITATION

Keywords:

  • Yindonggou Ag–Au(–Pb–Zn) deposit;
  • isotope geochemistry;
  • ore genesis;
  • orogenic-type deposit;
  • Qinling Orogen;
  • central China

ABSTRACT

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

The Yindonggou Ag–Au(–Pb–Zn) deposit is hosted by metamorphosed volcanic rocks of the ca. 740–760 Ma Wudangshan Group in the Proterozoic Wudang Block of the southern part of the Qinling Orogen, central China. The deposit consists of a series of mineralized quartz veins located in the Yindongyan Anticline. Based on the mineral assemblages and cross-cutting relationships of quartz veins, the deposit can be divided into: (1) early fine-grained quartz–sphalerite–galena veins; (2) fine-grained quartz–silver–gold veins containing minor amounts of pyrite; (3) coarse-grained quartz veins with minor amounts of galena, sphalerite, and chalcopyrite; and (4) late ankerite–quartz veins. Most of the Pb–Zn mineralization formed during the early (Stage 1) veins followed by the deposition of Ag–Au mineralization in the Stage 2 veins. The δ18O value for the ore-forming fluids decreases from 6.6–9.4‰ in the Stage 1 veins through 3.6–4.9‰ in the Stage 2 veins to −1.2‰ to 0.4‰ in the Stage 3 veins (the δ18O values could not be determined for the Stage 4 veins). Furthermore, the δD values are −74‰ for the Stage 1 veins, −95‰ to −56 ‰ for the Stage 2 veins, and −48‰ to −73‰ for the Stage 3 veins. The δ13C values for ankerite in the Stage 4 veins are between −2.9‰ and −1.1‰. The δD vs. δ18OH2O plot for these values indicates that there was a shift from metamorphic fluids during the formation of the early veins to meteoric fluids during the formation of the later veins at the deposit. The H–O–C isotope systematics also indicate that the ore fluids forming the deposit were probably initially sourced from metamorphic dehydration of volcanic-carbonate rocks in the ca. 740–760 Ma Wudangshan Group and with time gradually mixed with meteoric water by Stage 4. The δ34S values for sulphides from the deposit range from −0.9‰ to 7.1‰ in the Stage 1 veins, 3.8‰ to 5.0‰ in the Stage 2 veins, and 2.4‰ to 11.3‰ in the wallrocks. Sulphides from the mineralized Stage 1 veins yield 206Pb/204Pb ratios of 16.44–16.6, 207Pb/204Pb ratios of 15.25–15.5, and 208Pb/204Pb ratios of 36.4–36.98. Five pyrite samples from the Stage 2 veins yield 206Pb/204Pb ratios of 16.475–16.529, 207Pb/204Pb ratios of 15.346–15.395, and 208Pb/204Pb ratios of 36.49–36.616. Both the S and Pb isotope ratios are between the ratios for units in the Wudangshan Group and mantle but differ from other lithological units in the Wudang Block, which suggest that the mineralized fluids interacted with both the Wudangshan Group and deep-seated sources. Thus, we suggest that the original ore-forming fluids are metamorphic in origin, and the metal deposition resulted from fluid mixing. From the characteristics observed, the Yindonggou Ag–Au(–Pb–Zn) deposit can be classified as an orogenic-type deposit generated during the Triassic Qinling Orogeny resulting from northward oceanic plate subduction along the Mian-Lue Suture. Copyright © 2014 John Wiley & Sons, Ltd.

1 INTRODUCTION

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

The Qinling Orogen is an orogenic belt located south of the North China Craton (NCC) that has experienced continental breakup, ocean opening, oceanic crust subduction, continental collision, and intracontinental deformation (Chen and Fu, 1992; Zhang et al., 1996; Chen, 2010). Based on the evolving understanding of orogenic-lode deposits in general (e.g. Groves et al., 1998; Goldfarb et al., 2001, 2005; Pirajno, 2009; Chen, 2013), different types of mineralization systems have been identified in the Qinling Orogen (Mao et al., 2002; Zhou et al., 2002; Chen et al., 2005; Chen and Santosh, 2014). These include orogenic-type deposits such as the Shanggong Au deposit (Chen, 2006; Chen et al., 2008), Wenyu Au deposit (Zhou et al., 2014a), Huachanggou Au deposit (Zhou et al., 2014b), Tieluping Ag deposit (Chen et al., 2004), Weishancheng Ag–Au belt (Zhang et al., 2011, 2013), Lengshuibeigou Pb–Zn deposit (Qi et al., 2007), Wangpingxigou Pb–Zn deposit (Yao et al., 2008), Dahu Au–Mo deposit (Li et al., 2011; Ni et al., 2012, 2014), and Zhifang Mo deposit (Deng et al., 2014). Other types of mineral deposits present in the orogen include: porphyry, skarn, and breccia pipe-hosted magmatic hydrothermal Mo–Au deposits (Chen et al., 2007a, 2009a, b; Li et al., 2012, 2013; Yang et al., 2012; Yang et al., 2013; Y.F. Yang et al., 2013; Deng et al., 2013a, b, c); Carlin-type gold deposit (Zhang et al., 2009; Mao et al., 2014; Zeng et al., 2014); Mississippi Valley-type Zn–Pb and epizonogenic hydrothermal Hg–Sb deposits (Y. Zhang et al., 2014).

Orogenic deposits identified in the Central Asian Orogen (CAO) to the north of the NCC include the Sawayaerdun Au deposit (Chen et al., 2012a, b), Sarekuobu Au deposit (L. Zhang et al., 2014), Tiemurt Pb–Zn deposit (Zhang et al., 2012; Zheng et al., 2013), Wulasigou Cu deposit (Zheng et al., 2012), and the Qiaxia Cu deposit (Zheng et al., 2014). However, orogenic Ag–polymetal deposits have only been reported in the Qinling Orogen, and especially in the Xiong'er Terrane and Tongbai region (Chen et al., 2004; Zhang et al., 2011). Recently, a number of Ag–polymetal deposits have been discovered in the Proterozoic Wudang Block in the southern part of the Qinling Orogen, such as the Yindonggou, Xujiapo, and Yindongping deposits. The ca. 740–760 Ma Wudangshan Group, which hosts most of the deposits, has been metamorphosed at the lower amphibolite to greenschist facies, similar to other districts hosting orogenic deposits (Zhou et al., 1998; Zhang et al., 1999a, b; Ling et al., 2007). All these indicate that the Wudang Block has a significant potential for the orogenic Ag–polymetal deposit.

The Yindonggou Ag–Au(–Pb–Zn) deposit, located in the northwestern part of the Wudang Block in Hubei Province, central China, is the largest Ag–Au deposit in the southern part of the Qinling Orogen (Fig. 1C). The deposit has been mined since the 1970s with a reserve of 2000 t Ag at 178 g/t Ag and 20 t Au at 1.79 g/t (including the mined ore). The deposit is located in an anticline, and its spatial distribution and ore genesis have attracted the interest of many geologists in recent years (Cai et al., 1999; Li et al., 2008, 2010). However, the sources of the metals and ore-forming fluids at the mine remain unclear.

image

Figure 1. Location and regional geology of the Wudang Block: (A) tectonic map of China showing the location of the Qinling Orogen, between the North China Craton (NCC) and Yangtze Craton (YC); (B) tectonic subdivision of the Qinling Orogen showing the location of the Wudang Block; (C) regional geology and location of Ag–polymetallic deposits in the Wudang block (modified after Li et al., 2011; Zhang et al., 1999a, b). This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

We report new data in this contribution obtained from field investigations and comprehensive laboratory studies on petrography, mineralogy, and C–H–O–S––Pb isotope geochemistry. The aim of this work is to clarify the ore genesis of the Yindonggou deposit and establish a regional metallogenic model as an aid for future mineral exploration in the region.

2 REGIONAL GEOLOGY

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

The Qinling Orogen is located in the central portion of the east-trending Central China Orogenic Belt (CCOB) and developed during the Mesozoic collision between the North China and Yangtze cratons (Fig. 1A; Chen et al., 2009b; Dong et al., 2011; Li et al., 2014). The San-Bao Fault is the northern limit of the orogen and the Longmenshan–Dabashan Fault is the southern limit. The orogen is subdivided into: (1) the Huaxiong Block to the north representing the tectonic southern margin of the NCC; (2) the northern Qinling accretionary belt; (3) the southern Qinling orogenic belt; and (4) the tectonic northern margin of the Yangtze Craton to the south. The Luanchuan Fault separates the Huaxiong Block and the northern Qinling accretionary belt, the Shang-Dan Fault separates the northern Qinling accretionary and southern Qinling orogenic belts, and the Mian-Lue Faults separates the southern Qinling orogenic belt from the Yangtze Craton to the south (Fig. 1B).

The Yindonggou Ag–Au(–Pb–Zn) deposit is a fault-controlled lode deposit located in the northwestern part of the Wudang Block (Liu, 1984, 1987, 1989; Lei and Tang, 1996; Lei et al., 1998). The Wudang Block is in the southern part of the Qinling Orogen (Zhang et al., 1995) and bound to the south by the Qingfeng Fault, which links with the foreland fold–thrust belt of the Yangtze Craton (Zhang et al., 2001).

The Wudang Block comprises the Neoproterozoic Wudangshan Group that is unconformably overlain by the early Neoproterozoic Yaolinghe Group, late Neoproterozoic to early Palaeozoic Doushantuo and Dengying formations, and Palaeozoic sedimentary rocks (Ling et al., 2002). The Wudangshan Group is intruded by Neoproterozoic mafic dykes (Fig. 1C).

The Wudangshan Group is a suite of greenschist facies metamorphosed volcanic-sedimentary rocks, consisting of mafic and felsic volcanic rocks interbedded with sedimentary rocks (Wang et al., 1991; Ling et al., 2002; Zhang et al., 2002). The group hosts many hydrothermal polymetallic deposits, including Yindonggou, Xujiapo, and Yingdongping (Fig. 1C). Protoliths for the metamorphosed mafic rocks in the group include basaltic andesite lava, pyroclastic rocks, and dacitic–rhyolitic and crystal lithic tuff. The U–Pb LA-ICP-MS zircon age of the pyroclastic rocks is 755 ± 3 Ma (Ling et al., 2007). Protoliths of the metamorphosed sedimentary rocks include feldspar–quartz sandstone and minor amounts of silty mudstone and muddy siltstone. A tuffaceous unit within the sedimentary succession has a U–Pb LA-ICP-MS zircon age of 744 ± 36 Ma (Cai et al., 2006).

The Yaolinghe Group contains greenschist facies metamorphosed quartz–keratophyre tuff and pebbly tuff (Wang et al., 1991; Zhang et al., 2002). The U–Pb LA-ICP-MS zircon age for the Yaolinghe volcanic rocks in the group is 685 ± 5 Ma (Ling et al., 2007).

The Palaeozoic Doushantuo and Dengying formations consist of limestone, dolomitic limestone, sericite schist, and phyllite, which host many Au deposits (Fig. 1C). In addition, minor outcrops of Mesozoic and Cenozoic strata are present around the Wudang Block.

The Wudang Block has been affected by multi-stage deformation events (Hu et al., 2002). These deformation events are characterized by NE- and subsequent NNW-trending folds and faults. The faults are the main structure observed in the region and include the Yunxian-Yunxi Fault in the north, the Shiyan-Baihe and Fangxian-Zhushan faults in the centre of the terrane, and the Qingfeng Fault in the south (Fig. 1C).

Intrusive rocks in the Wudang Block are mainly greenschist facies dolerite and gabbro dykes, which generally trend east and southeast as groups of dykes (Zhou et al., 1998; Ling et al., 2007). The dykes are commonly several kilometres long and hundreds of metres wide.

3 DEPOSIT GEOLOGY

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

The Wudangshan and Yaolinghe groups are the main units outcropping around the Yindonggou Ag–Au(–Pb–Zn) deposit where the Wudangshan Group includes metamorphosed volcaniclastic and sedimentary rocks (Fig. 2). The overlying Yaolinghe Group consists of metamorphosed quartz–keratophyre tuff and pebbly tuff, which are similar to those found in the lower part of the Wudangshan Group. The deposit is hosted by the lower part of the Wudangshan Group consisting of metamorphosed quartz–keratophyre tuff, potassium quartz–keratophyre, and pebbly tuff (Figs. 2 and 3). Metamorphosed dolerite is also present in the mining area (Fig. 2).

image

Figure 2. Geological sketch map of the Yindonggou Ag–Au(–Pb–Zn) deposit (modified after Li et al., 2008). This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

image

Figure 3. Geological profile for prospecting line no. 23 at the Yindonggou Ag–Au(–Pb–Zn) deposit (modified after Yue, 2013). This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

The main structures in the Yindonggou mining area include the east-trending Yingdongyan Anticline that plunges 10–30° west and two major east-trending faults on either side of the anticline (Fig. 2). A ductile-brittle shear zone is also present along the anticline's axial plane (Li et al., 2008), which dips 68° to the south. The fault on the northern side of the anticline (Fa) is a normal fault dipping north at 76°, and the one to the south (Fb) is a reverse fault dipping 78° south. The mineralization is located between these faults (Figs. 2 and 3).

3.1 Characteristics of the orebodies

The Yindonggou Ag–Au(–Pb–Zn) deposit is over 2 km long and between 150–300 m wide (Fig. 2). To date, 27 orebodies have been recognized in the mining area, which are commonly sheet-like vein arrays having slightly lenticular shapes (Fig. 4). The orebodies strike 166–175° and dip 70–80° northward at deeper levels and 50–65° north at shallow levels. The main orebody dips 75° towards 175° over a length of 1000 m and has an average thickness of 2.4 m. There are significant variations in both orebody thicknesses and ore composition along their length. The Ag–Au ores with the highest grade are present at shallow depths where they are associated with the lowest Pb–Zn grades (Fig. 3).

image

Figure 4. Photos of ore zones at the Yindonggou Ag–Au(–Pb–Zn) deposit: (A) quartz–sphalerite–galena Stage 1 vein; (B) quartz–sphalerite–galena Stage 1 vein cut by a Stage 2 quartz–Ag–Au vein, which are both cut by a massive Stage 4 ankerite–quartz vein; (C) Stage 2 Ag–Au–quartz vein cut a Stage 3 quartz vein; (D) Stage 2 Ag–Au–quartz vein; (E) Stage 2 Ag–Au–quartz vein cut by a massive Stage 4 ankerite–quartz vein; (F) deformed Stage 2 Ag–Au–quartz vein cross-cut by a Stage 4 ankerite–quartz vein. Abbreviations: Ank—ankerite; Cpy—chalcopyrite; Gl—galena; Q—quartz; Sph—sphalerite. This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

3.2 Ore types and mineral assemblages

The mineralization at Yindonggou includes quartz veins with sulphides and minor disseminated sulphides in the altered wallrocks. The main metallic minerals are jalpaite, native silver, acanthite, sphalerite, galena, pyrite, chalcopyrite, and a small amount of pyrargyrite, electrum, miedziankite, sandbergerite, and polybasite (Fig. 5). Quartz is the primary gangue mineral with subordinate amounts of sericite, ankerite, and chlorite. Lead and zinc mineralization typically forms quartz–sphalerite–galena veins with varying amounts of chalcopyrite replacing pyrite (Fig. 5A, B). Polybasite coexists with galena and chalcopyrite in the fine-grained quartz–silver–gold veins (Fig. 5C). Jalpaite, native silver, and acanthite are commonly associated with quartz with a local metasomatic and rimmed textures (Fig. 5D–F), which indicates replacement of sphalerite and galena by silver-minerals present in the fine-grained quartz–silver–gold veins. Argentite coexists with galena with a eutectic texture, and electrum coexists with jalpaite in the fine-grained quartz–silver–gold veins (Fig. 5G, H). Coarse-grained quartz veins are commonly poorly mineralized, although they locally host minor amounts of galena, sphalerite, and chalcopyrite (Fig. 6).

image

Figure 5. Photomicrographs showing the Yindonggou ore petrography: (A) exsolution texture between Stage 1 chalcopyrite and sphalerite; (B) Stage 1 sphalerite and galena replacing pyrite illustrating a metasomatized relict texture; (C) Stage 2 polybasite coexisting with galena and chalcopyrite; (D) Stage 2 jalpaite; (E) Stage 2 native silver coexisting with jalpaite in fine granular quartz veins; (F) Stage 1 sphalerite replaced by Stage 2 silver forming a metasomatic reaction rim (silver SEM content of the reaction rim is up to 12% ); (G) Stage 2 argentite coexisting with galena; (H) Stage 2 electrum coexisting with jalpaite; and (I) Stage 2 silica and sericite alteration. Abbreviations: Arn—Argentite; Ank—Ankerite; Cpy—Chalcopyrite; El—Electrum; Gl—galena; Jal—jalpaite; Pol—polybasite; Py—pyrite; Q—quartz; Ser—sericite; Slv—native silver; Sph—sphalerite. This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

image

Figure 6. Paragenetic relationship between mineral phases in the Yindonggou Ag–Au(–Pb–Zn) deposit.

Download figure to PowerPoint

3.3 Mineralization stages and wallrock alteration

The mineralized quartz veins can be subdivided into four types or stages based on their mineral assemblages and cross-cutting relationships (Fig. 4; Fig. 6). The earliest (Stage 1) are fine-grained quartz–sphalerite–galena veins with selvedges also mineralized in sphalerite and galena (Fig. 4A). The Stage 2 set is characterized by the fine-grained quartz–silver–gold(–pyrite) veins with grades >1000 g/t Ag that cross-cut the Stage 1 set (Fig. 4B–D). The Stage 3 set is characterized by the coarse-grained quartz veins with minor amounts of disseminated galena–sphalerite–chalcopyrite, which cross-cut the Stage 2 set of veins (Fig. 4C). The Stage 4 set comprises ankerite–quartz veins that cross-cut the Stage 2 and 3 sets (Fig. 4B, E). The Pb–Zn ore is hosted by the Stage 1 set of veins, and the majority of the Ag–Au ore is hosted by the Stage 2 set.

Silicification is the predominant alteration and is widespread at Yindonggou. Other alteration minerals include sericite, ankerite, and chlorite. Sericite and chlorite are commonly present in the ore-bearing quartz veins where they are associated with sulphides (Fig. 5I).

4 SAMPLE AND ANALYTICAL METHODS

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

Most of the samples collected for this study are from the four stages of veins from various levels underground at the Yindonggou mine. The samples were selected for microscopy studies to confirm the stage of veins they represent. Sulphides and quartz in these samples were crushed to a minus 10 mesh (420 micron) and then handpicked under a binocular microscope. The selected minerals were disaggregated, and fragments with no impurities were reserved.

Samples for H–O isotope analyses were collected from the different quartz vein stages. Of these, one was a quartz sample from the Stage 1, four were from the Stage 2, and two from the Stage 3. In order to eliminate other interlocking minerals (such as sulphides), quartz separates were soaked in a HNO3− solution at 60–80 ° C for 12 h and rinsed in deionized water. The separates were then treated six times using a supersonic centrifugal clarifier and rinsed with deionized water for a week. The samples were dried in an oven before analysis. The hydrogen and oxygen isotopes were analysed using a Finnigan MAT253 mass spectrometer in the Stable Isotope Laboratory at the Institute of Mineral Resources, Chinese Academy of Geological Science, Beijing, following the method outlined by Ding (1988). Oxygen gas was produced by quantitatively reacting the samples with pure BrF5 in externally heated nickel reaction vessels. Hydrogen was determined by quantitatively reacting the H2O with zinc at 550 °C. The results were normalized against V-SMOW standards with a precision of ±0.2‰ for δ18O and ±2‰ for δD.

Samples were collected from quartz veins containing polymetallic sulphides for lead isotope studies. These included five samples from the Stage 1 veins, five pyrite samples from Stage 2 veins, and five wallrock samples from the Wudangshan Group. Of these, approximately 10–50 mg of sample powders was first leached in acetone to remove surface contamination and then washed using distilled water and dried at 60 °C in an oven. The washed samples were then dissolved in a HF + HNO3 + HClO4 solution, and the Pb fraction was separated using strong alkali anion exchange resin with HBr and HCl as eluents. The lead isotopes were measured on a MAT-261 thermal ionization mass spectrometer using the standard NBS 981 in the Analytical Laboratory at the Beijing Research Institute of Uranium Geology, China. Measurements of the common-lead standard NBS 981 gave average values of 208Pb/206Pb = 2.1681 ± 0.0008, 207Pb/206Pb = 0.91464 ± 0.00033, and 204Pb/206Pb = 0.059042 ± 0.000037 with uncertainties of <0.1% at the 95% confidence level.

5 ISOTOPE RESULTS

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

5.1 Hydrogen and oxygen isotopes of quartz and fluids

The δ18O and δD values for the Yindonggou Ag–Au(–Pb–Zn) deposit are listed in Table 1. The δ18O values range from 11.1‰ to 13.9‰ for the Stage 1 veins, 11.2‰ to 12.5‰ for the Stage 2 veins, and 10.5‰ to 15.3‰ for the Stage 3 veins and are 10.7‰ for the Stage 4 veins (Table 1). Based on the detailed paragenesis study and using the temperatures acquired from the fluid inclusion study by Yue et al. (2013; Table 1), the δ18Owater values were calculated using equations for quartz–water by Clayton et al. (1972) and ankerite–water by Matthews and Katz (1977). The calculated δ18O values for the fluid hosted by Stage 1 quartz veins vary from 6.6‰ to 9.4‰; Stage 2 quartz veins are between 3.6‰ and 4.9‰; Stage 3 quartz veins range from −1.2‰ to 3.6‰; and the Stage 4 quartz veins is −3.2‰ (Table 1). As can be seen, these values generally decrease with each generation of quartz veins. Conversely, the measured δD values for fluids decrease as the quartz vein stages decrease in relative age with Stage 1 veins ranging between −74‰ and −69‰, Stage 2 veins ranging from −96‰ to −56‰, and Stage 3 veins ranging from −77‰ to −48‰; and the value for the Stage 4 quartz veins is −42‰ (Table 1).

Table 1. Oxygen, hydrogen, and carbon stable isotopic compositions of quartz and ankerite from the Yindonggou deposit
SampleStageMineralδ18Omineral (‰)δ18Owater (‰)δDwater (‰)δ13Cmineral (‰)δ13Cco2 (‰)T (°C)aReferences
  1. Notation:

  2. The temperatures are from Yue et al. (2013). The δ18Owater values were calculated using equations for quartz–water and ankerite–water provided by Clayton et al. (1972) and Matthews and Katz (1977), respectively. The δ13C in CO2 equilibrated with calcite was calculated using the equation of Deines et al. (1974).

  3. a

    The peak of homogenization temperatures (the range of homogenization temperatures).

Stage 1 (quartz–sphalerite–galena veins)
YDG-24-2Stage 1Quartz11.16.6 (5.8–7.3)−74  380 (350–410)Yue, et al., 2013
T3-148AStage 1Quartz12.37.8 (7.0–8.5)   380 (350–410)Wu et al., 1988
T3-224Stage 1Quartz13.48.9 (8.1–9.6)   380 (350–410)Wu et al., 1988
Q5Stage 1Quartz13.99.4 (8.6–10.1)−71  380 (350–410)Liu, 1984
Q6Stage 1Quartz13.69.1 (8.3–9.8)−73  380 (350–410)Liu, 1984
Q7Stage 1Quartz12.98.4 (7.6–9.1)−69  380 (350–410)Liu, 1984
Average  12.88.4−72    
Stage 2 (quartz–silver–gold veins)
YDG-11Stage 2Quartz12.14.5 (1.6–5.9)−75  280 (220–320)Yue, et al., 2013
YDG-27-2Stage 2Quartz11.74.1 (1.2–5.5)−87  280 (220–320)Yue, et al., 2013
YDG-59-1Stage 2Quartz11.64.0 (1.1–5.4)−95  280 (220–320)Yue, et al., 2013
YDG-60Stage 2Quartz11.84.2 (1.3–5.6)−93  280 (220–320)Yue, et al., 2013
Q1Stage 2Quartz12.54.9 (2.0–6.3)−78  280 (220–320)Liu, 1984
Q2Stage 2Quartz12.24.6 (1.7–6.0)−65  280 (220–320)Liu, 1984
Q3Stage 2Quartz12.44.8 (1.9–6.2)−75  280 (220–320)Liu, 1984
D84Stage 2Quartz11.23.6 (0.7–5.0)−63  280 (220–320)Wu et al., 1988
D85Stage 2Quartz12.04.4 (4.4–5.8)−56  280 (220–320)Wu et al., 1988
Average  11.94.3−76    
Stage 3 (quartz veins)
YDG-46-3Stage 3Quartz10.5−1.2 (−5.0 to 0.0)−48  200 (150–220)Yue, et al., 2013
YDG-58-2Stage 3Quartz12.10.4 (−3.4 to 1.6)−73  200 (150–220)Yue, et al., 2013
D-49-1Stage 3Quartz12.40.7 (−3.1 to 1.9)−77  200 (150–220)Wu et al., 1988
D-83Stage 3Quartz15.33.6 (−0.1 to 4.8)−63  200 (150–220)Wu et al., 1988
T3-9-10AStage 3Quartz11.90.2 (−3.6 to 1.4)−67  200 (150–220)Wu et al., 1988
T3-28-26Stage 3Quartz12.81.1 (−2.7 to 2.3)−67  200 (150–220)Wu et al., 1988
T3-78-81AStage 3Quartz12.81.1 (−2.7 to 2.3)−72  200 (150–220)Wu et al., 1988
T3-148BStage 3Quartz13.21.5 (−2.3 to 2.7)−69  200 (150–220)Wu et al., 1988
Average  12.60.9−67    
Stage 4 (ankerite–quartz veins)
D86Stage 4Ankerite11.0−1.4 (−2.9 to 0.0)−42−2.5−3.8 (−4.6 to −3.1)170 (150–190)Wu et al., 1988
D87Stage 4Ankerite10.7−1.7 (−3.2 to −0.3)−40−2.9−4.2 (−5 to −3.5)170 (150–190)Wu et al., 1988
D49-2Stage 4Ankerite11.3−1.1 (−2.6 to 0.3)−45−2.3−3.6 (−4.4 to −2.9)170 (150–190)Wu et al., 1988
C2Stage 4Ankerite13.10.7 (−0.8 to 2.1) 1.1−0.2 (−1.0 to 0.5)170 (150–190)Liu, 1984
C3Stage 4Ankerite13.00.6 (−0.9 to 2.0) −1.4−2.7 (−3.5 to −2.0)170 (150–190)Liu, 1984
C4Stage 4Ankerite13.41.0 (−0.5 to 2.4) −1.2−2.5 (−3.3 to −1.8)170 (150–190)Liu, 1984
YD024Stage 4Ankerite11.6−0.8 (−2.3 to 0.6) −1.8−3.1 (−3.9 to −2.4)170 (150–190)Wang, 1993a
YD044Stage 4Ankerite11.5−0.9 (−2.4 to 0.5) −2.2−3.5 (−4.3 to −2.8)170 (150–190)Wang, 1993a
Average  12.0−0.5−42−1.7−3.0  
D54Stage 4Quartz10.7−3.2 (−4.8 to −1.7)−42  170 (150–190)Wu et al., 1988
Q8Quartz from metamorphosed segregationQuartz13.48.1–11.1−39  350–500Liu, 1984
Q9Quartz10.55.2–8.2−10  350–500Liu, 1984
Q10Quartz12.26.9–9.9−18  350–500Liu, 1984
W1Silicified rhyolitic subvolcanicWhole rock12.3     Liu, 1984
WWhole rock11.9     Liu, 1984
W8Silicified clastic sedimentaryWhole rock12.6     Liu, 1984
W23Metamorphosed potassium quartz–keratophyreWhole rock14.4     Liu, 1984
W13Whole rock13.5     Liu, 1984
C1Dolomitic marbleWhole rock15.0  3.1   

5.2 Lead isotopes of sulphides and wall rocks

The Pb isotopic analyses completed for this study and previous data are listed in Table 2. Some of the data with U, Th, and Pb values were used to estimate the Pb isotope ratios assuming an age of 230 Ma, which is the 40Ar/39Ar date determined on muscovite from the Yindonggou deposit (Yue, 2013). These Pb isotopic ratios are presented as (208Pb/204Pb)i, (207Pb/204Pb)i, and (206Pb/204Pb)i.

Table 2. Lead isotope compositions of sulphides and rocks from the Yindonggou deposit
Sample no.SamplesPbThU208Pb/204Pb207Pb/204Pb206Pb/204Pb(208Pb/204Pb)i#(207Pb/204Pb)i#(206Pb/204Pb)i#Reference
Stage 1 (quartz–sphalerite–galena veins)
875-37-1-2Galena   36.52815.37716.484   This study
YDG-54-1Galena   36.55215.38216.512   This study
FL-2-5Galena   36.52715.37316.505   This study
FL-2-6Galena   36.55515.38216.511   This study
915-25-1Galena   36.66315.41516.535   This study
Pb-1Galena   36.43015.33016.440   Liu, 1984
Pb-2Galena   36.64015.41016.550   Liu, 1984
Pb-3Galena   36.50015.36016.490   Liu, 1984
Pb-4Galena   36.43015.34016.480   Liu, 1984
Pb-5Galena   36.42015.25016.480   Liu, 1984
Pb-6Galena   36.52015.37016.500   Liu, 1984
Pb-7Galena   36.52015.36016.510   Liu, 1984
Pb-8Galena   36.48015.40016.530   Liu, 1984
Pb-11Galena   36.48015.34016.520   Liu, 1984
Pb-12Galena   36.47015.34016.500   Liu, 1984
Pb-13Galena   36.49015.37016.530   Liu, 1984
Pb-14Galena   36.47015.33016.500   Liu, 1984
Pb-15Galena   36.49015.37016.540   Liu, 1984
Pb-16Galena   36.69015.35016.600   Liu, 1984
Pb-17Galena   36.57015.36016.520   Liu, 1984
Pb-18Galena   36.98015.50016.600   Liu, 1984
Pb-9Pyrite   36.40015.33016.470   Liu, 1984
Pb-10Pyrite   36.50015.38016.530   Liu, 1984
Average    36.53515.36616.515    
Stage 2 (quartz–silver–gold veins)
960-27-1Pyrite9750.0290.01536.58615.38516.51236.58615.38516.512This study
1060-27-1Pyrite19090.0130.05236.60015.38816.52936.60015.38816.529This study
YDG-46-1Pyrite27760.0430.05636.55915.36516.52036.55915.36516.520This study
YDG-40Pyrite22100.0650.03836.49015.34616.47536.49015.34616.475This study
YDG-61Pyrite50000.0490.03336.61615.39516.52936.61615.39516.529This study
Average    36.57015.37616.51336.57015.37616.513 
Wudangshan Group
830/875Wudangshan5.1516.05.8741.67815.55820.07439.18115.41517.260This study
1010-17-1Wudangshan8.8311.10.56743.07915.42217.06242.09115.41416.907This study
1010-17-3Wudangshan20.54.511.2437.00315.31116.78536.84515.30416.651This study
FL-2-1Wudangshan32.816.73.4837.44115.46217.26937.06915.45017.031This study
FL-2-3Wudangshan7.112.740.59637.34115.41417.07437.06115.40416.887This study
Pb-19Wudangshan   37.68015.41017.280   Liu, 1984
Pb-20Wudangshan   37.68015.44017.310   Liu, 1984
Pb-21Wudangshan   37.94015.50017.710   Liu, 1984
 Wudangshan   36.69815.43316.701   Liu, 1984
 Wudangshan   37.06915.40517.109   Liu, 1984
 Wudangshan   36.70115.36816.715   Liu, 1984
 Wudangshan   36.52015.36416.569   Liu, 1984
 Wudangshan   37.31315.50417.626   Liu, 1984
 Wudangshan   36.83915.37816.713   Liu, 1984
 Wudangshan   38.02915.47817.957   Liu, 1984
 Wudangshan   37.38615.43617.614   Liu, 1984
 Wudangshan   38.52515.40117.927   Liu, 1984
 Wudangshan   37.54315.48617.400   Liu, 1984
 Wudangshan   37.84915.42617.660   Liu, 1984
 Wudangshan   38.02915.52217.914   Liu, 1984
Average    37.91715.43617.42338.44915.39816.947 
Metadolerite
1Metadolerite   38.26715.56918.006   Zhang et al., 1999a
2Metadolerite   37.45115.44417.323   Zhang et al., 1999a
3Metadolerite   38.68215.56518.369   Zhang et al., 1999a
4Metadolerite   37.79815.51817.744   Zhang et al., 1999a
5Metadolerite   39.24016.24518.059   Zhang et al., 1999a
6Metadolerite   37.85615.51317.935   Zhang et al., 1999a
7Metadolerite   37.67915.50218.048   Zhang et al., 1999a
8Metadolerite   38.81315.58618.050   Zhang et al., 1999a
9Metadolerite   39.01115.59218.567   Zhang et al., 1999a
Average    38.31115.61518.011    

Sulphides from quartz–sphalerite–galena veins have 206Pb/204Pb values between 16.44 and 16.6, 207Pb/204Pb values between 15.25 and 15.5, and 208Pb/204Pb values of 36.4–36.98. Five pyrite crystals from the quartz–silver–gold veins have 206Pb/204Pb ratios of 16.475–16.529, 207Pb/204Pb ratios of 15.346–15.395, and 208Pb/204Pb ratios of 36.49–36.616 (Table 2). As the calculated (206Pb/204Pb)i, (207Pb/204Pb)i, and (208Pb/204Pb)i values are the same as the measured values due to their very low U and Th contents, the analytical data can be reliably used to trace the source of the metals and mineralizing fluids.

The rocks of the Wudangshan Group have 206Pb/204Pb ratios of 16.569–20.074, 207Pb/204Pb ratios of 15.311–15.558, and 208Pb/204Pb ratios of 36.52–43.079 (Table 2). The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios for the metadolerite are presented in Table 2. As can be seen, the Wudangshan Group and metadolerite display wider ranges of Pb isotopic values and more radiogenic compositions compared to the ore sulphides (Table 2).

6 DISCUSSION

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

6.1 Sources of metals and ore-forming fluids

6.1.1 Oxygen and hydrogen isotopes

Oxygen and hydrogen isotopes can be used to trace the source of the hydrothermal mineralization fluids (e.g. Hoefs, 1997; Pirajno, 2009). However, there is an overlap in δD vs δ18O values between metamorphic and magmatic fluids, resulting in difficulties in understanding the ore genesis (Kerrich et al., 2000). This is exemplified in the example of the Yindonggou deposit where the mineralizing fluid has been interpreted as being (1) magmatic (Cai et al., 1999); (2) meteoric (Zhang, 1985); (3) a metamorphic and magmatic mixture (Wang, 1993a); and (4) a magmatic and meteoric mixture (Liu, 1987, 1989). Thus, the δD and δ18O values for the deposit need to be investigated further.

The δ18O results for the Stage 1 veins range between 6.6‰ and 9.4‰ (Table 1). Combined with the δD values of −74‰ to −69‰, the δD vs δ18O values plot in the magmatic fluid field bordering on to the metamorphic fluid field (Fig. 7). This suggests that the H–O isotope composition of the mineralization fluid has a predominantly magmatic source with a contribution from a metamorphic source (Fig. 7).

image

Figure 7. δD–δ18O plots for ore-bearing fluids at the Yindonggou Ag–Au(–Pb–Zn) deposit; base map after Taylor (1974). Range of the Xiaoqinling and Jiaodong orogenic deposits after Jiang et al. (2009); Juneau gold belt, Mother Lode, and Chugach terrace orogenic Au deposits after Goldfarb et al. (2005). This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

Assuming that magmatic fluids are generated above the lowest eutectic point at temperatures above 573 °C (cf. Zhang et al., 2013), continuous cooling and water–rock reactions result in the reduction of δ18Owater values for magmatic water along with the deposition of hydrothermal minerals such as quartz and alkali feldspar. If the ore-forming fluid is magmatic, it will reach a δ18Owater value of 10.1‰ when the fluid's temperature decrease to 380 °C, which is the average homogenization temperature of the Stage 1 veins (Table 1). This means that the initial δ18Owater value must have been significantly higher than 10.1‰. However, there are no reported data on the original nature of mineralizing fluid at Yindonggou, so this conclusion cannot be reached.

The Indosinian (Late Triassic to Early Jurassic) plutons in the southern Qinling region are interpreted as I-type granites (Jiang et al., 2010; Li et al., 2014), with δ18O values rarely exceeding 10.1‰. Thus, the higher δ18O values for the early stage fluids at Yindonggou are suggestive of a metamorphic origin. This is supported by the following evidence: (1) the Yindonggou area is metamorphosed at greenschist facies (Wang, 1993a); (2) the δ18O values for quartz resulting from metamorphic segregation range between 10.5‰ and 13.4‰ (Liu, 1987), suggesting that the calculated δ18Owater values of 5.2–11.1‰ (using the temperature range of 350–500 °C) are consistent with the δ18Owater values for the Stage 1 fluid; (3) the Yindonggou mineralization was formed at ca. 230 Ma (Yue, 2013), but no Indosinian magmatism is known to exist with this age in the region (Wang et al., 1991; Lei et al., 1998); and (4) the ore-forming fluid for the Stage 1 veins is characterized by low salinity and is CO2-rich (Yue et al., 2013), which are consistent with metamorphosed fluids and differ significantly from those expected for magmatic fluids (Chen et al., 2007b).

As mentioned earlier, the δ18Owater value for the Stage 1 veins varies between 6.6‰ and 9.4‰, suggestive of metamorphic fluids. The δ18Owater values for the Stage 2 quartz veins vary from 3.6‰ to 4.9‰, which are between Stages 1 and 3 in value, suggesting a possible mixture between metamorphic and meteoric fluids (Fig. 7). The fluids in the late-stage mineral assemblages (Stages 3 and 4) have a composition that is close to that of meteoric fluid (Fig. 7). In detail, the δ18Owater values for the Stage 3 veins are between −1.2‰ and 3.6‰, (with δD values between −77‰ and −48‰), and the δ18Owater values for the Stage 4 ankerite–quartz veins range from −3.2‰ to 1.0‰ (with δD values between −45‰ and −40‰). These data suggest that the four stages of quartz veins were deposited from fluids that evolved from metamorphic to meteoric origins.

The δD values for the ore-forming fluids in the Stage 2 veins range from −95‰ to −56‰, which are generally lower than the values of −74‰ to −69‰ for the Stage 1. This indicates that there was H-isotope depletion from Stage 1 to Stage 2, which is a feature that is interpreted to be the result of the reaction between deep-sourced metamorphic and δD-depleted organic material in the host rocks (cf. Goldfarb et al., 1989; Peters et al., 1990; Jia et al., 2001). In fact, this phenomenon is prevalent in many hydrothermal vein deposits and has been interpreted to be related to H+ or HS ions being replaced by metallic ions and released into fluids during sulphide precipitation (Chen and Zhang, 2008).

The δ18O and δD values for the ore-forming fluids at Yindonggou (Table 3) plot in the lode-gold deposit field (Fig. 7; Goldfarb et al., 2005). The δ18O values for quartz collected from lode-gold deposits throughout the Earth are higher than 10‰, and the δ18Owater values for their ore-forming fluids are 5–25‰ (cf. Goldfarb et al., 2005). The δ18Owater values of the Jiaodong gold deposits on the Jiaodong Peninsula of eastern China ranges from 4.9‰ to 10.9‰, with δD values of −78‰ to −101‰ (Fig. 7; Jiang et al., 2009; Goldfarb and Santosh, 2014). In contrast, the Xiaoqinling gold deposits along the southern margin of the NCC have slightly lower δ18O and higher δD compositions than those of the Jiaodong gold deposits (Jiang et al., 2009; Fig. 7). Jiang et al. (2009) suggest that the Xiaoqinling deposits formed from metamorphic fluids with a small input of meteoric fluid. Similarly, Figure 7 indicates that the Stage 1 quartz veins, containing higher δ18O and δD values, were derived from a metamorphic-related fluid. In contrast, ore-forming fluids hosted by quartz from the quartz–silver–gold (Stage 2) veins are similar to those of other lode-gold deposits, and the fluids in the Stage 4 ankerite–quartz veins have a composition close to that of meteoric fluid.

Table 3. Sulphur isotopic ratios of sulphides and rocks from the Yindonggou deposit.
SampleStageOre typeδ34SV-CDTReference
GlCpySphPoPy
  1. Abbreviations: Cpy, Chalcopyrite; Gl, Galena; Po, Pyrrhotite; Py, Pyrite; Sph, Sphalerite

Quartz–sphalerite–galena veins
S-153Stage 1Pb–Zn2.3 3.5  Liu, 1984
S-161Stage 1Pb–Zn3.3 3.8  Liu, 1984
S-154Stage 1Pb–Zn2.8    Liu, 1984
S-197Stage 1Pb–Zn0.9 4.0  Liu, 1984
S-73Stage 1Pb–Zn1.74.63.7  Liu, 1984
S-262Stage 1Pb–Zn2.27.13.9  Liu, 1984
S-202Stage 1Pb–Zn  3.5  Liu, 1984
S-70Stage 1Pb–Zn  4.0  Liu, 1984
S-76Stage 1Pb–Zn2.6    Liu, 1984
W5-1Stage 1 2.1 3.5  Wu et al., 1988
T3189Stage 1 1.3 2.9  Wu et al., 1988
T3268Stage 1 2.5 1.1  Wu et al., 1988
T3270Stage 1 1.9 2.8  Wu et al., 1988
T3234Stage 1 2.0 2.5  Wu et al., 1988
T3227Stage 1 1.8 2.8  Wu et al., 1988
T3166Stage 1 2.2 2.8  Wu et al., 1988
T3247Stage 1 2.9 3.6  Wu et al., 1988
Average  2.25.93.2   
Quartz–silver–gold veins
S-224Stage 2Ag–Au4.2    Liu, 1984
S-315Stage 2Ag–Au3.8   4.8Liu, 1984
S-306Stage 2Ag–Au3.6    Liu, 1984
ZK159Stage 2     4.7Wu et al., 1988
S-2Stage 2     4.4Wu et al., 1988
S-3Stage 2     5.0Wu et al., 1988
S-5Stage 2     4.2Wu et al., 1988
S-10Stage 2     4.2Wu et al., 1988
J-1Stage 2     5.0Wu et al., 1988
Average  3.9   4.6 
Wudangshan Group
S-230Pyroclastic rocks   2.4 Liu, 1984
S-231Sedimentary clastic rock    11.3Liu, 1984
P5Pyroclastic rocks    9.1Wang, 1993a
X008Pyroclastic rocks    5.9Wang, 1993a
Average    2.48.8 
6.1.2 Carbon isotopes

Eight samples of the Stage 4 ankerite–quartz veins from Yindonggou have δ18O values between 10.7‰ to 13.4‰ and δ13C values between −2.9‰ to 1.1‰ (Table 1). A sample of dolomitic marble from the wallrock has a δ18O value of 15‰ and a δ13C value of 3.1‰ (Table 1). Fluid inclusions in three ankerite samples yield δD values of −45‰ to −40‰, similar to that of the Stage 4 quartz (−42‰; Table 1). Using the estimated temperature of 170 °C determined by Yue et al. (2013) and the dolomite–CO2 equilibrium equation of Sheppard and Schwarcz (1970), the calculated δ13CCO2 values for the ankerite are between −4.2‰ and −0.2‰ (Table 1). Using the dolomite–H2O equilibrium equation of Matthews and Katz (1977), the calculated δ18Owater values for the Stage 4 ankerite are between −1.7‰ and 1.0‰.

The δ13CCO2 values (from −4.2‰ to −0.2‰) for ore-forming fluids in the Stage 4 veins are significantly higher than those for organic matter that average −27‰ (Schidlowski, 1998), atmospheric CO2 ranging from −11‰ to −7‰ (Schidlowski, 1998), freshwater carbonate ranging from −20‰ to −9‰ (Hoefs, 1997), igneous rocks ranging from −30‰ to −3‰ (Hoefs, 1997), the continental crust value of −7‰ (Faure, 1986), and the mantle value of −7‰ to −5‰ (Hoefs, 1997). This indicates that the δ13CCO2 values for the Stage 4 fluid cannot have been a simple mixture of the above-mentioned possible sources (Fig. 8). In contrast, the δ13CΣC values for ore-forming fluids are similar to those of marine carbonates (−3‰ to 2‰; Hoefs, 1997). This suggests that the CO2 in the ore-forming fluids at Yindonggou was probably sourced from carbonate units during metamorphic decarbonization. However, the δ13C values generated by carbonate decarbonization are usually higher than the original values of carbonate (Schidlowski, 1998). Given that the dolomitic marble δ13C value is 3.1‰ in the mining area, the δ13CΣC of the ore-forming fluids value (≤ −1.9‰) is obviously lower, which indicates that there were other sources with lower δ13C values present when the mineralization was being formed. Meteoric water, which has lower δ13C and δ18O values, may have mixed with the ore-forming system at the deposit, which is consistent with the H–O isotope results documented above.

image

Figure 8. Chart showing ranges for C isotopic signatures for various rock types and for the Yindonggou Ag–Au(–Pb–Zn) deposit. Data sources: greenschist facies carbonate rocks (Guerrera et al., 1997); reduced C in sedimentary and metamorphic rocks (Ohmoto and Goldhaber, 1997); carbonates in most lode Au deposits (Chen et al., 2012b). This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

6.1.3 Lead isotopes

In the diagram of the plumbotectonic model for Pb isotopic systematics (cf. Zartman and Haines, 1988), the sulphide samples from the Yindonggou deposit define a trend crossing the mantle, orogen, and lower crust fields, showing the complexity of lead sources for the deposit (Fig. 9). Furthermore, these sulphides have lower 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios than those of the Wudangshan Group (Table 2; Fig. 9). However, considering that the ore sulphides were the result of fluid–rock interactions, the Wudangshan Group wallrock is possibly a major source for lead and other metals in the deposit.

image

Figure 9. Plumbotectonic model for the Yindonggou Ag–Au(–Pb–Zn) deposit. The base map is from Zartman and Doe (1981). This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

During the hydrothermal processes or fluid–rock interactions, radiogenic Pb isotopes (208Pb, 207Pb, and 206Pb) can be preferentially leached out of rocks and incorporated into mineralizing fluids, analogous to the commonly observed stepwise leaching effect in Pb isotope analysis (cf. Frei et al., 1998; Peng et al., 2006). Thus, if the ore-forming lead at Yindonggou is derived exclusively from the wallrocks, the Pb isotopic ratios of sulphides should be higher than those of the wallrocks. It is clear that the Pb isotope ratios of the Wudangshan Group at 230 Ma are higher and more variable than those of the ore sulphides, implying that the Pb isotope ratios of the ore-forming fluids must have been lower than the lowest Pb isotope ratios of the sulphides (Fig. 9).

In addition to the wallrock, the possible sources of lead in the Yindonggou deposit include the Indosinian granites, metadolerite, lower crust, and mantle. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios for the Indosinian granites located in the southern part of the Qinling Orogen have ranges of 17.5–17.872, 15.508–15.549, and 37.67–38.001, respectively (Qin, 2010), which are more radiogenic than the ore at Yindonggou. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values for the metadolerite are 17.323–18.527, 15.444–16.245, and 37.451–39.24, respectively (Table 2; Fig. 9), which are much higher than lead from the Yindonggou ore, which rules out the possibility of the metadolerite being a source. Taking into account that the lower crust and mantle have lower U and Th contents and lead isotopic ratios (Zartman and Doe, 1981), the ore-forming fluids at the deposit were likely sourced from the mantle or a source with an equivalent composition.

Previous studies have argued that the Mian-Lue oceanic crust in south Qinling was subducted northward beneath the South Qinling Belt during the Triassic (Chen, 2010; Chen and Santosh, 2014; Li et al., 2014). During this time, ca. 220 Ma, garnet-bearing granite-porphyry dykes, interpreted to have been generated by partial melting of accretionary sediment prisms in the fore-arc basin, were emplaced in the Yangshan gold belt (Zhang et al., 2009). At a similar time, the ca. 218 Ma Dahu Au–Mo deposit was formed in the Xiaoqinling area in the Qinling Orogen, which Ni et al. (2012) associate with fluids sourced from the metamorphic devolatilization of a refractory and subducted oceanic slab. Thus, we suggest that the Pb with low radiogenic isotopic values at Yindonggou deposit could have been sourced from the Mian-Lue oceanic crust.

6.1.4 Sulphur isotopes

Published δ34S isotopic values for sulphides and lithologies in the region around the Yindonggou Ag–Au(–Pb–Zn) deposit are listed in Table 3. The Stage 1 sulphides from the deposit have a very narrow range of the δ34S values of 0.9–3.3‰ for galena, 4.6–7.1‰ for chalcopyrite, and 1.1–4‰ for sphalerite (Table 3; Figs. 10 and 11). The Stage 2 sulphides have relatively higher δ34S values of 3.6–4.2‰ for galena and 4.2–5.0‰ for pyrite. In comparison, pyrrhotite from pyroclastic rocks assigned to the Wudangshan Group has a δ34S value of 2.4‰, which is similar to that of hydrothermal sulphides (Table 3).

image

Figure 10. Histogram of S-isotopes from the Yindonggou Ag–Au(–Pb–Zn) deposit.

Download figure to PowerPoint

image

Figure 11. δ34S values for hydrothermal sulphides from the Yindonggou Ag–Au(–Pb–Zn) deposit. References for the ranges of major sulphur reservoirs and other deposits are given in the text. This figure is available in colour online at wileyonlinelibrary.com/journal/gj

Download figure to PowerPoint

The relative order of δ34S enrichment at Yindonggou is δ34Schalcopyrite > δ34Ssphalerite > δ34Sgalena (Table 3), suggesting that sulphur isotope systems between coexisting sulphides were not equilibrated in the Stage 1 quartz–sphalerite–galena veins (Ohmoto, 1972). Given estimated or calculated values for fO2 and temperatures during mineral precipitation, the total δ34S values of the fluids can be estimated from the δ34S values of sulphides (Ohmoto and Rye, 1979; Ohmoto and Goldhaber, 1997). The Pb–Zn mineralization (Stage 1) at the Yindonggou deposit is relatively reduced (Yue et al., 2013), which is supported by the occurrence of CH4 and H2S in fluid inclusions studied from these veins (Liu, 1984; Yue et al., 2013). Given the low oxygen buffer and high temperature (350–410 °C), the sulphur isotopic fractionation between sulphides and fluids is usually small (i.e. <2‰; cf. Ohmoto and Goldhaber, 1997), which means that the measured δ34S values for sulphides are nearly equal to those of the fluids.

The relative order of δ34S enrichment at Yindonggou is δ34Spyrite > δ34Sgalena (Table 3), suggesting that there was sulphur isotope equilibrium between the coexisting pyrite and galena in the quartz–silver–gold (Stage 2) veins (cf. Ohmoto, 1972). Thus, the total δ34S values for the Stage 2 fluid are nearly equal to those for pyrite (Table 3).

Hydrothermal sulphides at Yindonggou have a δ34S range of 0.9–7.1‰. These values are similar to those of basaltic, granitic, metamorphic, and sedimentary rocks (Table 3; Fig. 11). However, these δ34S values are also similar to most lode-gold deposits on Earth that are associated with metamorphic fluids (Goldfarb et al., 2005), such as Juneau (Goldfarb et al., 1989), Kumtor (Ivanove, 2000) and Bendigo (Jia et al., 2001) (Fig. 11).

Although near-zero δ34S values indicate a possible magmatic source for many magmatic hydrothermal deposits (Hoefs, 1997), a combination of the high 7.1‰ value observed at the Yindonggou deposit, the geological background, and other isotope compositions preclude a magmatic origin. Moreover, the lack of known Triassic igneous rocks in the Wudang Block that might be coeval with mineralization of that age also supports this interpretation. Furthermore, Yue et al. (2013) suggest that the initial fluid forming the deposit was carbonic with low salinities, which Chen et al. (2007b) attribute to a metamorphogenic hydrothermal system.

In addition, the δ34S values of 2.4–11.3‰ for sulphides from wallrocks at the Yindonggou deposit are higher than those for the ore-forming fluids, which indicate that the sulphur source cannot be the wallrocks alone (Figs. 10 and 11). However, the relatively oxidized ore-forming fluids may lead to much lower δ34S values for sulphides in orogenic deposits, and ore-forming fluids can become oxidized during fluid boiling (cf. Fan et al., 1994; Hodkiewicz et al., 2009), which Yue et al. (2013) suggest happened at Yindonggou. Oxidation results in relatively 34S-depleted H2S in the residual ore fluid and precipitation of sulphide minerals with more negative δ34S values (Ohmoto and Rye, 1979; Shu et al., 2013). We thus suggest that the initial ore-forming fluid at the Yindonggou deposit was possibly sourced from the country rocks.

6.2 Ore-forming evolutions

6.2.1 Early quartz–sphalerite–galena stage

At present, many researchers suggest that the closure of the north part of the Palaeo-Tethys ocean took place from east to west during the Triassic (Meng and Zhang, 2000; Li et al., 2014). The Mian-Lue Ocean was not completely closed during the Triassic, and the northward oceanic plate was still not completely subducted at the Mian-Lue Suture (Ni et al., 2012; Li et al., 2014). During this period, the underthrust slab, as well as the volcanic-sedimentary and carbonate rocks around Yindonggou, was strongly structurally deformed and metamorphosed, which generated significant amounts of metamorphic fluids (Chen and Fu, 1992; Kerrich, 1999; Pirajno, 2009). Subsequently, these fluids, being rich in δ18O and δ13C (Fig. 7), migrated along brittle-ductile shear zones precipitating Stage 1 quartz–sphalerite–galena from a high-temperature (350–410 °C), low-salinity, and CO2-rich fluid (Yue et al., 2013).

6.2.2 Middle quartz–silver–gold stage

With continuous crustal uplift and erosion, the deeply buried Stage 1 quartz–sphalerite–galena veins and the structures around Yindonggou were elevated, resulting in decompression and a drop in temperatures to 220–320 °C (Yue et al., 2013). Fluid inclusion study indicates that extensive fluid mixing and local boiling happened during this stage (Yue et al., 2013). Fluid mixing caused by the inflow of meteoric fluids can effectively lead to the precipitation of native silver and electrum from fluids containing [Ag(HS)2] and [Au(HS)2] (Liu, 1987), according to the reaction: 2HCO−3+ [Ag(HS)2] + Fe3+ = Ag + FeS2 + 2H2O + 2CO2 and 2HCO−3 + [Au(HS)2] + Fe3+ = Au + FeS2 + 2H2O + 2CO2 (Chen et al., 2012b). Boiling associated with the escape of CO2gas and consumption of H+ in solution can also result in the precipitation of native silver and electrum from a solution containing [Ag(HS)2]. It is envisaged here that meteoric fluids originating from volcanic-sedimentary rocks with radiogenic Pb and a higher 34S value (Figs. 9 and 10), were introduced and mixed with the ore-forming fluids circulating in the faults and shears at the Yindonggou deposit. Similar silver and gold mineralization have been documented in many orogenic deposits formed during the compression–extension transition resulting in mixing and boiling of fluids (cf. Chen et al., 2004; Chen, 2006).

6.2.3 Late barren stages

The regional heat source and associated hydrothermal fluid circulation quickly dissipated following the mineralization of silver, gold, and other metals at Yindonggou. This was followed by the emplacement of coarse-grained quartz veins with minor amounts of galena–sphalerite–chalcopyrite mineralization forming the Stage 3, and finally the non-mineralized ankerite–quartz (Stage 4) veins. These late-stage veins developed from fluids at temperatures below 220 °C (Yue et al., 2013), and their stable isotope compositions suggest that the fluids were meteoric in origin (Fig. 7).

6.3 Ore genetic type

Current controversies on the genesis of the Yindonggou Ag–Au(–Pb–Zn) deposit include: (1) a magmatic hydrothermal source associated with Indosinian magmatism (Cai et al., 1999), (2) a subvolcanic hydrothermal source related to a Neoproterozoic volcanic hydrothermal event (Liu, 1984, 1989), (3) a mixed volcanic and sedimentary source (Wang et al., 1997), and (4) a metamorphic hydrothermal source (Wang et al., 1991; Wang, 1993a, b).

Muscovite separates from the Stage 2 quartz–silver–gold veins yielded a well-defined 40Ar/39Ar isotopic plateau age of 231 ± 2 Ma (Yue, 2013), which suggests that the mineralization took place during the Indosinian Orogeny (Liu, 1987); therefore, it is too young to be related to a Neoproterozoic volcanic hydrothermal event associated with the ca. 740–760 Ma Wudangshan Group. Furthermore, the lack of Triassic granites in the region precludes the deposit being related to Indosinian magmatism (Li et al., 2014).

The C, H, and O stable isotopes indicate that the ore-forming fluids were predominantly metamorphosed in origin contaminated with the meteoric fluid during Ag–Au mineralization at Stage 2. Subsequent fluids were then dominated by meteoric fluids. In addition, the S and Pb isotopes indicate that the Wudangshan Group and mantle or rocks with an equivalent composition are the source for the ore-forming material. Therefore, we propose that the Yindonggou deposit is an orogenic-type deposit. This hypothesis is supported by the following six lines of evidence:

  1. The deposit was formed in the southern Qinling Orogen during a Triassic subduction-related accretionary orogeny (Li et al., 2014; Han et al., 2014). This was followed by a Jurassic continental collision between the North China and the Yangtze cratons (Chen et al., 2004; Chen, 2010).
  2. The Wudangshan Group wallrocks at Yindonggou are regionally metamorphosed at greenschist facies.
  3. The ore bodies consist of mineralized quartz veins controlled by structures in the Yindongyan Anticline (Fig. 3).
  4. The initial fluid associated with the mineralizing events had a low salinity (5.1–10.2 wt.% NaCl equiv.) and a high CO2 content (Yue et al., 2013), suggesting that it was part of a metamorphogenic hydrothermal system (Chen et al., 2007b).
  5. The deposition of silver–gold took place at temperatures between 220 and 375 °C and pressures between 180 and 363 MPa. This suggests that the mineralization took place at a depth of between ~7 and 14 km, assuming lithostatic pressures, which is consistent with metamorphic hydrothermal conditions (Groves et al., 1998).
  6. There are no Triassic plutons in the area (Figs. 1 and 2; Li et al., 2014), ruling out the possibility of a magmatic origin.

Hence, the geology and isotopic geochemistry characteristics indicate that the Yindonggou deposit is an orogenic Ag–Au deposit.

7 CONCLUSIONS

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

The hydrothermal ore-forming process at the Yindonggou Ag–Au(–Pb–Zn) deposit includes the deposition of an early set of fine-grained quartz–sphalerite–galena veins (Stage 1). This was followed by the development of fine-grained dark grey or black quartz–silver–gold veins containing minor amounts of pyrite (Stage 2), coarse-grained quartz veins with minor amounts of galena, sphalerite, and chalcopyrite (Stage 3), and finally predominantly barren ankerite–quartz veins (Stage 4).

H–O–C isotopic systematics indicates that the ore-forming fluids in the earliest stage (Stage 1) originated mainly from the metamorphic dehydration of volcanic-carbonate rocks in the Wudangshan Group, and the last stage (Stage 4) from meteoric fluid. The two stages represent the mixture between metamorphic and meteoric fluids in different proportions. The S–Pb isotopic analysis suggests that the ore was sourced from the Wudangshan Group and mantle, or rocks with a similar composition.

It is therefore suggested that the Yindonggou Ag–Au(–Pb–Zn) deposit is an orogenic-type deposit formed during the metamorphism dehydration of subducted crustal material during the Triassic.

ACKNOWLEDGEMENTS

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES

This research was financially supported jointly by the 973-Program (nos. 2014CB440803 and 2012CB416602), the National Natural Science Foundation (nos. 41202050, 41372085, 41373043, and 41072061), China Postdoctoral Science Foundation (2012 M510261), and the National Crisis Mine Prospecting Foundation (20089934). We are grateful to Wenping Zhu for help during isotope analyses and thank the Hubei Silver Corporation for their help in field investigations. This contribution is partly from the ARC Centre of Excellence for Core to Crust Fluid Systems (http://www.ccfs.mq.edu.au), which one of us (L. Bagas) is associated with. Profs. Yanjing Chen, Huayong Chen, and two anonymous reviewers are thanked for their careful reviews and constructive suggestions, which have greatly improved this manuscript.

REFERENCES

  1. Top of page
  2. ABSTRACT
  3. 1 INTRODUCTION
  4. 2 REGIONAL GEOLOGY
  5. 3 DEPOSIT GEOLOGY
  6. 4 SAMPLE AND ANALYTICAL METHODS
  7. 5 ISOTOPE RESULTS
  8. 6 DISCUSSION
  9. 7 CONCLUSIONS
  10. ACKNOWLEDGEMENTS
  11. REFERENCES
  • Cai, J.H., Zhang, Y.M., Fu, J.M., Chen, S.F. 1999. The genesis of the Yindonggou Ag–polymetal deposit in the north-west Hubei. Acta Geoscientia Sinica 20, 316320 (in Chinese with English abstract).
  • Cai, Z.Y., Luo, H., Xiong, X.L., Wu, D.K., Wu, X.L., Sun, S.C., Yang, J. 2006. A discussion on the age of the meta-sedimentary rocks in the upper part of the Wudang Group: constrained by the grain-zircon U–Pb dating. Journal of Stratigraphy 30, 6063 (in Chinese with English abstract).
  • Chen, H.Y., Chen, Y.J., Baker, M.J. 2012a. Evolution of ore-forming fluids in the Sawayaerdun gold deposit in the Southwestern Chinese Tianshan metallogenic belt, Northwest China. Journal of Asian Earth Sciences 49, 131144.
  • Chen, H.Y., Chen, Y.J., Baker, M.J. 2012b. Isotopic geochemistry of the Sawayaerdun orogenic-type gold deposit, Tianshan, northwest China: implications for ore genesis and mineral exploration. Chemical Geology 310–311, 111.
  • Chen, Y.J. 2006. Orogenic-type deposits and their metallogenic model and exploration potential. Geology in China 33, 11811196 (in Chinese with English abstract).
  • Chen, Y.J. 2010. Indosinian tectonic setting, magmatism and metallogenesis in Qinling Orogen, central China. Geology in China 37, 854865 (in Chinese with English abstract).
  • Chen, Y.J. 2013. The development of continental collision metallogeny and its application. Acta Petrologica Sinica 29, 117 (in Chinese with English abstract).
  • Chen, Y.J., Chen, H.Y., Zaw, K., Pirajno, F., Zhang, Z.J. 2007a. Geodynamic settings and tectonic model of skarn gold deposits in China: an overview. Ore Geology Reviews 31, 139169.
  • Chen, Y.J., Fu, S.G. 1992. Gold Mineralization in West Henan, China. Seismological Press: Beijing; 1234 (in Chinese with English abstract).
  • Chen, Y.J., Ni, P., Fan, H.R., Pirajno, F., Lai, Y., Su, W.C., Zhang, H. 2007b. Diagnostic fluid inclusions of different types hydrothermal gold deposits. Acta Petrologica Sinica 23, 20852108 (in Chinese with English abstract).
  • Chen, Y.J., Pirajno, F., Li, N., Guo, D.S., Lai, Y. 2009a. Isotope systematics and fluid inclusion studies of the Qiyugou breccia pipe-hosted gold deposit, Qinling Orogen, Henan Province, China: implications for ore genesis. Ore Geology Reviews 35, 245261.
  • Chen, Y.J., Pirajno, F., Qi, J.P. 2005. Origin of gold metallogeny and sources of ore-forming fluids, in the Jiaodong Province, Eastern China. International Geology Review 47, 530549.
  • Chen, Y.J., Pirajno, F., Qi, J.P. 2008. The Shanggong gold deposit, Eastern Qinling Orogen, China: isotope geochemistry and implications for ore genesis. Journal of Asian Earth Sciences 33, 252266.
  • Chen, Y.J., Pirajno, F., Sui, Y.H. 2004. Isotope geochemistry of the Tieluping silver–lead deposit, Henan, China: a case study of orogenic silver-dominated deposits and related tectonic setting. Mineralium Deposita 39, 560575.
  • Chen, Y.J., Santosh, M. 2014. Triassic tectonics and mineral systems in Qinling Orogen, China. Geological Journal 49(4–5), 338358. DOI: 10.1002/gj.2618.
  • Chen, Y.J., Zhai, M.G., Jiang, S.Y. 2009b. Significant achievements and open issues in study of orogenesis and metallogenesis surrounding the North China continent. Acta Petrologica Sinica 25, 26952726 (in Chinese with English abstract).
  • Chen, Y.J., Zhang, L. 2008. Middle-stage δD-depletion in ore fluids of sulfide-bearing lode deposits: examples and origin. Geochimica 37, 353360 (in Chinese with English abstract).
  • Clayton, R.N., O'Neil, J.R., Mayeda, T.K. 1972. Oxygen isotope exchange between quartz and water. Journal of Geophysical Research 77, 30573067.
  • Deines, P., Langmuir, D., Harmon, R.S. 1974. Stable carbon isotope ratios and the existence of a gas phase in the evolution of carbonate ground waters. Geochimica et Cosmochimica Acta 38, 11471164.
  • Deng, X.H., Chen, Y.J., Santosh, M., Yao, J.M. 2013a. Genesis of the 1.76 Ga Zhaiwa Mo–Cu and its link with the Xiong'er volcanics in the North China Craton: implications for accretionary growth along the margin of the Columbia supercontinent. Precambrian Research 227, 337348.
  • Deng, X.H., Chen, Y.J., Santosh, M., Yao, J.M. 2013b. Re–Os geochronology, fluid inclusions and genesis of the 0.85 Ga tumen molybdenite–fluorite deposit in Eastern Qinling, China: implications for pre-Mesozoic Mo-enrichment and tectonic setting. Geological Journal 48, 484497.
  • Deng, X.H., Chen, Y.J., Santosh, M., Zhao, G.C., Yao, J.M. 2013c. Metallogeny during continental outgrowth in the Columbia supercontinent: isotopic characterization of the Zhaiwa Mo–Cu system in the North China Craton. Ore Geology Reviews 51, 4356.
  • Deng, X.H., Yao, J.M., Santosh, M., Chen, Y.J. 2014. Geology, fluid inclusions and sulphur isotopes of the Zhifang Mo deposit in Qinling Orogen, central China: a case study of orogenic-type Mo deposits. Geological Journal 49(4–5), 515533. DOI: 10.1002/gj.2559.
  • Ding, T.P. 1988. Stable Isotope Studies on Several Typical Deposits in China. Beijing Science and Technology Publishing House: Beijing; 171 (in Chinese).
  • Dong, Y.P., Zhang, G.W., Neubauer, F., Liu, X.M., Genser, J., Hauzenberger, C. 2011. Tectonic evolution of the Qinling orogen, China: review and synthesis. Journal of Asian Earth Sciences 41, 213237.
  • Fan, H.R., Xie, Y.H., Zhao, R., Wang, Y.L. 1994. Stable isotope geochemistry of rocks and gold deposits in the Xiong'ershan area, Western Henan Province. Collections of Geology and Exploration 9, 5464 (in Chinese with English abstract).
  • Faure, G. 1986. Principles of Isotope Geology (2nd edition). John Wiley & Sons: New York; 1589.
  • Frei, R., Nagler, T.F., Schonberg, R., Kramers, J.D. 1998. Re–Os, Sm–Nd, U–Pb, and stepwise lead leaching isotope systematics in shear-zone hosted gold mineralization: genetic tracing and age constraints of crustal hydrothermal activity. Geochimica Et Cosmochimica Acta 62, 19251936.
  • Goldfarb, R.J., Baker, T., Dube, B., Groves, D.I., Hart, C.J.R., Gosselin, P. 2005. Distribution, character and genesis of gold deposits in metamorphic terranes. Economic Geology 100th Anniversary Volume, 407450.
  • Goldfarb, R.J., Groves, D.I., Gardoll, S. 2001. Orogenic gold and geologic time: a global synthesis. Ore Geology Reviews 18, 175.
  • Goldfarb, R.J., Leach, D.L., Rose, S.C., Landis, G.P. 1989. Fluid inclusion geochemistry of gold-bearing quartz veins of the Juneau gold belt, southeastern Alaska: implications for ore genesis. Economic Geology Monograph 6, 363375.
  • Goldfarb, R.J., Santosh, M. 2014. The dilemma of the Jiaodong gold deposits: are they unique? Geoscience Frontiers 5, 139153.
  • Groves, D.I., Goldfarb, R.J., Gebre-Mariam, M., Hagemann, S.G., Robert, F. 1998. Orogenic gold deposits: a proposed classification in the context of their crustal distribution and relationship to other gold deposit types. Ore Geology Reviews 13, 727.
  • Guerrera, A., Peacock, S.M., Knauth, L.P. 1997. Large 18O and 13C depletions in greenschist facies carbonate rocks, western Arizona. Geology 25, 943946.
  • Han, J.S., Yao, J.M., Chen, Y.J. 2014. Geochronology and geochemistry of the Dashui adakitic granitoids in the western Qinling Orogen, central China: implications for Triassic tectonic setting. Geological Journal 49(4–5), 383401. DOI: 10.1002/gj.2541.
  • Hodkiewicz, P.F., Groves, D.I., Davidson, G.J., Weinberg, R.F., Hagemann, S.G. 2009. Influence of structural setting on sulphur isotopes in Archean orogenic gold deposits, Eastern Goldfields Province, Yilgarn, Western Australia. Mineralium Deposita 44, 129150.
  • Hoefs, J. 1997. Stable Isotope Geochemistry (4th edition). Springer-Verlag: Berlin; 1214.
  • Hu, J.M., Meng, Q.R., Bai, W.M., Zhao, G.C. 2002. Mid-Late Palaeozoic extension of the Wudang block in the South Qinling tectonic belt, China. Geological Bulletin of China 21, 471477 (in Chinese with English abstract).
  • Ivanove, S. 2000. Constrains on the fluid evolution at Kumtor deposit. GSA 2000 presentation. http://homepage.usask.ca/~smi454/project/articles/GSA2000.htm.
  • Jia, Y., Li, X., Kerrich, R. 2001. Stable isotope (O, H, S, C, and N) systematics of quartz vein systems in the turbidite-hosted Central and North Deborah gold deposits of the Bendigo gold field, central Victoria, Australia: constraints on the origin of ore-forming fluids. Economic Geology 96, 705721.
  • Jiang, S.Y., Dai, B.Z., Jiang, Y.H., Zhao, H.X., Hou, M.L. 2009. Jiaodong and Xiaoqinling: two orogenic gold provinces formed in different tectonic settings. Acta Petrologica Sinica 25, 27272738 (in Chinese with English abstract).
  • Jiang, Y.H., Jin, G.D., Liao, S.Y., Zhou, Q., Zhao, P. 2010. Geochemical and Sr–Nd–Hf isotopic constraints on the origin of Late Triassic granitoids from the Qinling orogen, central China: implications for a continental arc to continent–continent collision. Lithos 117, 183197.
  • Kerrich, R. 1999. Nature's gold factory. Science 284, 21012102.
  • Kerrich, R., Goldfarb, R., Groves, D., Garwin, S., Jia, Y. 2000. The characteristics, origins, and geodynamic settings of supergiant gold metallogenic provinces. Science in China Series D: Earth Sciences 43, 168.
  • Lei, S.H., Tang, G.Y. 1996. The structural model and genetic mechanics of the Wudang Nappe on the north margin of the Yangtze platform. Journal of Hebei College of Geology 19, 2532 (in Chinese with English abstract).
  • Lei, S.H., Tang, G.Y., Qin, Z.Y., Liu, B., Zhang, Z.C. 1998. Geology and mineralization genesis of the Yindonggou Ag–Au deposit, NW Hubei. Geology and Prospecting 34, 1321 (in Chinese with English abstract).
  • Li, N., Chen, Y.J., Ian, R.F., Zeng, Q.T. 2011. Triassic mineralization with Cretaceous overprint in the Dahu Au–Mo deposit, Xiaoqinling gold province: constraints from SHRIMP monazite U–Th–Pb geochronology. Gondwana Research 20, 543552.
  • Li, N., Chen, Y.J., Pirajno, F., Ni, Z.Y., Sun, Y.L. 2013. Timing of the Yuchiling giant porphyry Mo system, eastern Qinling, central China, and implications for ore genesis. Mineralium Deposita 48, 505524.
  • Li, N., Chen, Y.J., Santosh, M., Pirajno, F. 2014. Compositional polarity of Triassic granitoids in the Qinling Orogen, China: implication for termination of the northernmost Paleo-Tethys. Gondwana Research, DOI: 10.1016/j.gr.2013.09.017.
  • Li, N., Ulrich, T., Chen, Y.J., Thompson, T.B., Peace, V., Pirajno, F. 2012. Fluid evolution of the Yuchiling porphyry Mo deposit, East Qinling, China. Ore Geology Reviews 48, 442459.
  • Li, W.B., Zhou, W.D., Chen, S.C., Li, Y.P., Deng, X.H., Zhong, R.C. 2010. Geological characteristics of the Yindonggou silver deposit in Hubei Province and its implication for ore genesis. Earth Science Frontiers 17, 177185 (in Chinese with English abstract).
  • Li, Y.P., Wei, X.Y., Gao, F., Yu, J.T., Zhang, H.W. 2008. Geological characteristics and ore-forming mechanism for the gently dipping ore bodies in Yindonggou Ag–Au deposits, Hubei Province. Geological Survey and Research 31, 613 (in Chinese with English abstract).
  • Ling, W.L., Chen, J.P., Wang, X.H., Zhou, H.W. 2002. Geochemical features of the Neoproterozoic igneous rocks from the Wudang region and their implications for the reconstruction of the Jinning tectonic evolution along the south Qinling orogenic belt. Acta Petrologica Sinica 18, 2536 (in Chinese with English abstract).
  • Ling, W.L., Ren, B.F., Duan, R.C., Liu, X.M., Mao, X.W., Peng, L.H., Liu, Z.X., Chen, J.P., Yang, H.M. 2007. Timing of the Wudangshan, Yaolinghe volcanic sequences and mafic sills in South Qinling: U–Pb zircon geochronology and tectonic implication. Chinese Science Bulletin 52, 14451456 (in Chinese).
  • Liu, C.Q. 1984. Geochemistry and metallogenic mechanism study of Pb–Zn–Ag deposit in the Northwest of Hubei Province. Master Thesis, Institute of Geochemistry, Chinese Academy of Sciences; 1–164 (in Chinese with English abstract).
  • Liu, C.Q. 1987. Geochemistry and genesis of the Yindonggou lead-zinc-silver deposit. Mineral Deposits 6, 5361 (in Chinese with English abstract).
  • Liu, C.Q. 1989. A fluid inclusion study of Yindonggou Pb–Zn–Ag deposit in the northwest of Hubei Province. Geochimica 18, 139149 (in Chinese with English abstract).
  • Mao, J.W., Qiu, Y.M., Richard, J., Goldfarb, J.R., Zhang, Z.C., Garwin, S., Ren, F.S. 2002. Geology, distribution, and classification of gold deposits in the western Qinling belt, central China. Mineralium Deposita 37, 352377.
  • Mao, S.D., Chen, Y.J., Zhou, Z.J., Lu, Y.H., Guo, J.H., Qin, Y., Yu, J.Y. 2014. Zircon geochronology and Hf isotope geochemistry of the granitoids in the Yangshan gold field, western Qinling, China: implications for petrogenesis, ore genesis and tectonic setting. Geological Journal 49(4–5), 359382. DOI: 10.1002/gj.2589.
  • Matthews, A., Katz, A. 1977. Oxygen isotope fractionation during the dolomitisation of calcium carbonate. Geochimica et Cosmochimica Acta 41, 14311438.
  • Meng, Q.R., Zhang, G.W. 2000. Geologic framework and tectonic evolution of the Qinling orogen, central China. Tectonophysics 323, 183196.
  • Ni, Z.Y., Chen, Y.J., Li, N., Zhang, H. 2012. Pb–Sr–Nd isotope constraints on the fluid source of the Dahu Au–Mo deposit in Qinling Orogen, central China, and implication for Triassic tectonic setting. Ore Geology Reviews 46, 6067.
  • Ni, Z.Y., Li, N., Zhang, H. 2014. Hydrothermal mineralization at the Dahu Au-Mo deposit in the Xiaoqinling gold field, Qinling Orogen, central China. Geological Journal 49(4–5), 501514. DOI: 10.1002/gj.2564
  • Ohmoto H. 1972. Systematics of sulphides and carbon isotopes in hydrothermal ore deposits. Economic Geology 67, 551578.
  • Ohmoto, H., Goldhaber, M.B. 1997. Sulphides and carbon isotopes. Geochemistry of Hydrothermal Ore Deposits 3, 517612.
  • Ohmoto, H., Rye, R.O. 1979. Isotopes of sulphides and carbon. In: Geochemistry of Hydrothermal Ore Deposits, Barnes H.L. (ed.). Wiley Interscience, New York; 509567.
  • Peng, B., Frei, R., Tu, X.L. 2006. Nd–Sr–Pb isotopic geochemistry of scheelite from the Woxi W–Sb–Au deposit, western Hunan: implications for sources and evolution of ore-forming fluids. Acta Geologica Sinica 80, 561570 (in Chinese with English abstract).
  • Peters, S.G., Golding, S.D., Dowling, K. 1990. Melange and sediment-hosted gold-bearing quartz veins, Hodgkinson gold field, Queensland, Australia. Economic Geology 85, 312327.
  • Pirajno, F. 2009. Hydrothermal Processes and Mineral Systems. Springer: Berlin; 11250.
  • Qi, J.P., Chen, Y.J., Ni, P., Lai, Y., Ding, J.Y., Song, Y.W., Tang, G.J. 2007. Fluid inclusion constraints on the origin of the Lengshuibeigou Pb–Zn–Ag deposit, Henan Province. Acta Petrologica Sinica 23, 21192130 (in Chinese with English abstract).
  • Qin, J.F. 2010. Petrogenesis and geodynamic implications of the Late-Triassic Granitoids from the Qinling Orogenic Belt. PhD Thesis, Northwest University; 1–282 (in Chinese with English abstract).
  • Schidlowski, M. 1998. Beginning of terrestrial life: problems of the early record and implications for extraterrestrial scenarios. International Symposium on Optical Science, Engineering, and Instrumentation. International Society for Optics and Photonics, 3441, 149157.
  • Sheppard, S.M.F., Schwarcz, H.P. 1970. Fractionation of carbon and oxygen isotopes and magnesium between coexisting metamorphic calcite and dolomite. Contributions to Mineralogy and Petrology 26, 161198.
  • Shu, Q.H., Lai, Y., Sun, Y., Wang, C., Meng, S. 2013. Ore genesis and hydrothermal evolution of the Baiyinnuo'er zinc–lead skarn deposit, northeast China: evidence from isotopes (S, Pb) and fluid inclusions. Economic Geology 108, 835860.
  • Taylor, H.P., 1974. The application of oxygen and hydrogen isotope studies to problems of hydrothermal alteration and ore deposition. Economic Geology 69, 843883.
  • Wang, D.B. 1993a. Studies on stable isotope geochemistry and ore-forming physico-chemical condition of Yindonggou Au–Ag–Pb–Zn deposit, Zhushan County, Hubei Province. Mining Geology 14, 155164 (in Chinese with English abstract).
  • Wang, D.B. 1993b. The geochemical study on alteration of wall rocks of Yingonggou Au–Ag–Pb–Zn deposit, Zhushan County, Hubei Province. Contributions to Geology and Mineral Resources Research 8, 1626 (in Chinese with English abstract).
  • Wang, D.B., Zhang, B.R., Ma, Z.D., Huang, D.K., Lin, Y.W. 1991. Geological–geochemical investigation of the Yindonggou Xujiapo Au–Ag–multi-metal metallogenic belt. Geology and Prospecting 27, 4450 (in Chinese with English abstract).
  • Wang, P.A., Chen, Y.C., Pei, R.F. 1997. Qinling Orogenic Belt: Regional Metallogenic Series, Structure, Mineralization Cycles and Evolution. Geological Publishing House: Beijing; 1161 (in Chinese).
  • Wu, X.K., Zhou, J.H., Wang, S.Q. 1988. Yindonggou Ag–Au deposit, Zhushan County Hubei Province. Northwest Hubei Province Hubei Geological Minerals Investigation Bureau (in Chinese).
  • Yang, Y., Chen, Y.J., Zhang, J., Zhang, C. 2013. Ore geology, fluid inclusions and four-stage hydrothermal mineralization of the Shangfanggou giant Mo–Fe deposit in Eastern Qinling, central China. Ore Geology Reviews 55, 146161.
  • Yang, Y.F., Chen, Y.J., Li, N., Mi, M., Xu, Y.L., Li, F.L., Wan, S.Q. 2013. Fluid inclusion and isotope geochemistry of the Qian'echong giant porphyry Mo deposit, Dabie Shan, China: a case of NaCl-poor, CO2-rich fluid systems. Journal of Geochemical Exploration 124, 113.
  • Yang, Y.F., Li, N., Chen, Y.J. 2012. Fluid inclusion study of the Nannihu giant porphyry Mo–W deposit, Henan Province, China: implications for the nature of porphyry ore-fluid systems formed in a continental collision setting. Ore Geology Reviews 46, 8394.
  • Yao, J.M., Zhao, T.P., Wei, Q.G., Yuan, Z.L. 2008. Fluid inclusion features and genetic type of the Wangpingxigou Pb–Zn deposit, Henan Province. Acta Petrologica Sinica 24, 21132123 (in Chinese with English abstract).
  • Yue, S.W. 2013. Genesis and comparative study of the Jianchaling gold deposit in Mianlueyang and Yindonggou silver–gold deposit in northwest Hubei. PhD Thesis, Graduate University of Chinese Academy of Sciences; 1−195 (in Chinese with English abstract).
  • Yue, S.W., Zhai, Y.Y., Deng, X.H., Yu, J.T., Yang, L. 2013. Fluid inclusion and H–O isotope geochemistry and ore genesis of the Yindonggou deposit, Zhushan County, Hubei, China. Acta Petrologica Sinica 29, 2745 (in Chinese with English abstract).
  • Zartman, R., Doe, B. 1981. Plumbotectonics—the model. Tectonophysics 75, 135162.
  • Zartman, R.E., Haines, S.M. 1988. The plumbotectonic model for Pb isotopic systematics among major terrestrial reservoirs—a case for bi-directional transport. Geochimica et Cosmochimica Acta 52, 13271339.
  • Zeng, Q.T., McCuaig, T.C., Tohver, E., Bagas, L., Lu, Y.J. 2014. Episodic Triassic magmatism in the western South Qinling Orogen, central China and its implications. Geological Journal 49(4–5), 402423. DOI: 10.1002/gj.2571.
  • Zhang, C.L., Zhou, D.W., Jin, H.L., Han, S., Liu, Y.Y. 1999a. Study on the Sr, Nd, Pb and O isotopes of basic dyke swarms in the Wudang block and basic volcanic of the Yaolinghe Group. Acta Petrologica Sinica 15, 430437 (in Chinese with English abstract).
  • Zhang, C.L., Zhou, D.W., Liu, Y.Y. 1999b. Geochemistry of basic dykes in Wudangshan block and their tectonic significance. Geochimica 28, 126135 (in Chinese with English abstract).
  • Zhang, G.W., Meng, Q.R., Yu, Z.P., Sun, Y., Zhou, D.W., Guo, A.L. 1996. Orogenesis and dynamics of the Qinling orogen. Science in China Series D: Earth Sciences 26, 225234
  • Zhang, G.W., Zhang, B.R., Yuan, J.C., Xiao, Q.H. 2001. Qinling Orogenic Belt and Continental Dynamics. Science Press: Beijing; 1855 (in Chinese).
  • Zhang, G.W., Zhang, Z.Q., Dong, Y.P. 1995. Nature of main tectono-lithostratigraphic units of the Qinling Orogen: implications for the tectonic evolution. Acta Petrologica Sinica 11, 101114 (in Chinese with English abstract).
  • Zhang, J., Chen, Y.J., Pirajno, F., Deng, J., Chen, H.Y., Wang, C.M. 2013. Geology, C–H–O–S–Pb isotope systematics and geochronology of the Yindongpo gold deposit, Tongbai Mountains, central China: implication for ore genesis. Ore Geology Reviews 53, 343356.
  • Zhang, J., Chen, Y.J., Yang, Y., Deng, J. 2011. Lead isotope systematics of the Weishancheng Au–Ag belt, Tongbai Mountains, Central China: implication for ore genesis. International Geology Review 53, 656676.
  • Zhang, L., Chen, H.Y., Zheng, Y., Li, D.F. 2014. Geology, fluid inclusion and age constraints on genesis of the Sarekuobu gold deposit in Altay, NW China. Geological Journal 49(6), 653648. DOI: 10.1002/gj.2573.
  • Zhang, L., Yang, R.S., Mao, S.D., Lu, Y.H., Qi, Y., Liu, H.J. 2009. Sr and Pb isotopic feature and ore-forming material source of the Yangshan gold deposit. Acta Petrologica Sinica 25, 28112822 (in Chinese with English abstract).
  • Zhang, L., Zheng, Y., Chen, Y.J. 2012. Ore geology and fluid inclusion geochemistry of the Tiemurt Pb–Zn–Cu deposit, Altay, Xinjiang, China: a case study of orogenic-type Pb–Zn systems. Journal of Asian Earth Sciences 49, 6979.
  • Zhang, L.G. 1985. Geological Applicance for the Stable Isotope: The Hydrothermal Mineralization of Metal Activation and It's Prospecting. Shaanxi Science and Technology Publishing House: Xi'an; 1267 (in Chinese).
  • Zhang, Y., Tang, H.S., Chen, Y.J., Leng, C.B., Zhao, C.H. 2014. Ore geology, fluid inclusion and isotope geochemistry of the Xunyang Hg–Sb orefield, Qinling Orogen, central China. Geological Journal 49(6), 617634. DOI: 10.1002/gj2560.
  • Zhang, Z.Q., Zhang, G.W., Tang, S.H., Wang, J.H. 2002. The age of metamorphic rocks of the Wudang Group. Geology in China 29, 117125 (in Chinese with English abstract).
  • Zheng, Y., Zhang, L., Chen, H.Y., Li, D.F., Wang, C.M., Fang, J. 2014. CO2-rich fluid from metamorphic devolatilization of Triassic Orogeny: an example from the Qiaxia copper deposit in Altay, NW China. Geological Journal 49(4–5), 515533. DOI: 10.1002/gj.2536.
  • Zheng, Y., Zhang, L., Chen, Y.J., Qin, Y.J., Liu, C.F. 2012. Geology, fluid inclusion geochemistry, and 40Ar/39Ar geochronology of the Wulasigou Cu deposit, and their implications for ore genesis, Altay, Xinjiang, China. Ore Geology Reviews 49, 128140.
  • Zheng, Y., Zhang, L., Guo, Z.L. 2013. Zircon LA-ICP-MS U–Pb and biotite 40Ar/39Ar geochronology of the Tiemurt Pb–Zn–Cu deposit, Xinjiang: implications for genesis. Acta Petrologica Sinica 29, 191204 (in Chinese with English abstract).
  • Zhou, D.W., Zhang, C.L., Liu, L., Wang, J.L., Liu, Y.Y., Zhang, Z.Q. 1998. Sm–Nd dating of basic dykes from Wudang block and a discussion of related questions. Acta Geoscientia Sinica 19, 2530 (in Chinese with English abstract).
  • Zhou, T.H., Goldfarb, R.J., Phillips, G.N. 2002. Tectonics and distribution of gold deposits in China: an overview. Mineralium Deposita 37, 249282.
  • Zhou, Z.J., Chen, Y.J., Jiang, S.Y., Zhao, H.X., Qin, Y., Hu, C.J. 2014a. Geology, geochemistry and ore genesis of the Wenyu gold deposit, Xiaoqinling gold field, southern margin of North China Craton. Ore Geology Reviews 59, 120.
  • Zhou, Z.J., Lin, Z.W., Qin, Y. 2014b. Geology, geochemistry and genesis of the Huachanggou gold deposit, western Qinling Orogen, central China. Geological Journal 49(4–5), 424441. DOI: 10.1002/gj2561.