Ore genesis of the Fancha gold deposit, Xiaoqinling goldfield, southern margin of the North China Craton: Constraints from pyrite Re-Os geochronology and He-Ar, in-situ S-Pb isotopes

Journal Pre-proofs Ore genesis of the Fancha gold deposit, Xiaoqinling goldfield, southern margin of the North China Craton: Constraints from pyrite Re-Os geochronology and He-Ar, in-situ S-Pb isotopes Junchen Liu, Yitian Wang, Qiaoqing Hu, Ran Wei, Shikang Huang, Zhenghao Sun, Jiaolong Hao PII: DOI: Reference:

S0169-1368(19)30663-8 https://doi.org/10.1016/j.oregeorev.2020.103373 OREGEO 103373

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Ore Geology Reviews

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23 July 2019 8 January 2020 29 January 2020

Please cite this article as: J. Liu, Y. Wang, Q. Hu, R. Wei, S. Huang, Z. Sun, J. Hao, Ore genesis of the Fancha gold deposit, Xiaoqinling goldfield, southern margin of the North China Craton: Constraints from pyrite Re-Os geochronology and He-Ar, in-situ S-Pb isotopes, Ore Geology Reviews (2020), doi: https://doi.org/10.1016/ j.oregeorev.2020.103373

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Ore genesis of the Fancha gold deposit, Xiaoqinling goldfield,

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southern margin of the North China Craton: Constraints from

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pyrite Re-Os geochronology and He-Ar, in-situ S-Pb isotopes

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Junchen Liu

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Sun a, Jiaolong Hao c

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a

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Resources, Chinese Academy of Geological Sciences, Beijing, China

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b

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China.

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a,b,

Yitian Wang a,*, Qiaoqing Hu a, Ran Wei a, Shikang Huang a, Zhenghao

MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral

School of Earth Science and Resources, China University of Geosciences, Beijing,

c Lingbao

Jinyuan Mining Co. Ltd., Lingbao, Henan, China.

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*Corresponding to: Yitian Wang, MNR Key Laboratory of Metallogeny and Mineral

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Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences,

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Beijing 100037, China. Email address: [email protected]

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First author Email address: [email protected]

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Abstract

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The Fancha gold deposit is one of the representative “lode type” deposit in the

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Xiaoqinling goldfiled. Four-stage mineralization process were identified, namely, I) the

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barren quartz stage; II) the pyrite-dominated stage; III) the quartz-polymetallic sulfides

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stage; and Ⅳ) the quartz-carbonate stage. Correspondingly, pyrite crystal can be divided

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into three generations, i.e. Py1, Py2 and Py3 according to their different textures and

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paragenesis during the first three mineralization stages. In order to better understand the

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ore genesis, an integrated analysis on Re-Os-He-Ar-S-Pb multi-isotopes was carried out

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for each mineralization stage to delineate the timing of the mineralization and the origins

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of the ore-forming materials in detail. Gold-bearing pyrite yields a Re-Os isochron age of

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124.3 ± 2.6 Ma (MSWD = 1.9), overlapping with the previous hydrothermal mica

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40Ar/39Ar

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3He/4He

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and those of the Py3 are 0.20 to 0.33 and 647.67 to 8913.55, respectively, which reveal a

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significant contribution of mantle component in the ore-forming fluids, and the content of

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crust fluid is increasing in the later evolution. In-situ δ34S values of the sulfides in the

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auriferous quartz veins, including the pyrite (Py1, Py2 and Py3), chalcopyrite, sphalerite,

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galena, bismuthinite, and tetradymite, display a relatively narrow range (-4.9 to 3.6‰)

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consistent with magmatic sulfur, which are quite different from those of the pyrite in

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surrounding rock ( -7.8 to -9.3‰). In-situ Pb isotopic compositions of the galena and

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bismuthinite of stage III are homogeneous with values of

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206Pb/204Pb

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15.588-15.590, 18.283-18.288, respectively, indicating a mixed Pb sources with obvious

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proportions of mantle. Combined with previous data, we suggest that the ore-forming

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fluids and metals of the Fancha gold deposit stemmed directly from the regional

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mantle-derived magmatic hydrothermal system, which is coupled with the large-scale

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lithospheric extension and thinning in the eastern North China Craton during the Early

ages, suggesting that gold mineralization occurred in the Early Cretaceous. The

(R/Ra) and

40Ar/36Ar

values of the Py2 are 0.68 to 1.17 and 656.55 to 7384.2,

208Pb/204Pb, 207Pb/204Pb,

and

being 37.482-37.508, 15.392-15.523, 16.995-17.006, and 39.279-39.287,

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Cretaceous.

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Keywords: pyrite Re-Os dating; He-Ar isotopes; in-situ S-Pb isotopes; Fancha gold

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deposit; Xiaoqinling goldfield; North China Craton

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1. Introduction

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The Xiaoqinling goldfield is located along the southern margin of North China

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Craton (NCC), bounded by the Taiyao fault to the north and the Xiaohe fault to the south,

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respectively. As the second largest gold producing area in China, it contains more than

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1200 gold-bearing quartz veins and with a proven reserve of 800 tons of gold at least

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(Mao et al., 2002a; Yang et al, 2003; Jian et al., 2015). Numerous geologists have never

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stopped paying attention to the Xiaoqinling goldfield, not only because of the huge

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tonnage of gold resource, but also the controversial ore genesis and geodynamic setting.

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The debate mainly focused on two points of view: the orogenic gold deposits associated

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with the Early Mesozoic orogeny evolution between the Yangtze and NCC Craton (e.g.,

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Chen and Fu, 1992; Chen, 2006; Chen et al., 2009; Jiang et al., 2009), and the

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magmatism-related gold deposits coupled with the late Mesozoic lithospheric thinning by

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almost 100 Myr later (e.g., Yang et al., 2003; J.W. Li et al., 2012a, b; L. Li et al., 2015;

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Zhu et al., 2015).

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The Fancha gold deposit is characterized by its high gold grade (mean grade of

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11.45 g/t Au; Ren, 2012) and diverse ore minerals. The discovery of abundant Bi-bearing

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minerals in the deep tunnel provides a new entry point for research, and therefore, chosen

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the Fancha gold deposit as a valuable case-study of the Xiaoqinling goldfield in this

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study. Previous studies have unilaterally described on the Fancha gold deposit (Li et al.,

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2012a; Ren, 2012; Sheng, 2016), lacking a comprehensive and systematic geochemical

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isotopes research on ore-forming system, especially the application of in-situ technique.

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Previous sericite 40Ar/39Ar dating of Fancha gold deposit produced a broad span of ages

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between 134.3 and 122.6 Ma (Li et al., 2012a; Ren, 2012), and it is unclear whether the

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dates obtained represent the timing of gold deposition, or an overprint event later on,

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because of the low closure temperature of mica itself. Here, we employed Au-bearing

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pyrite Re-Os dating to directly constrain the timing of the gold mineralization, which is

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considered to be one of the most effective dating methods at present (e.g., Stein et al.,

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2000; Morelli et al., 2004). He-Ar isotopes of pyrite in major gold mineralization stages

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were measured for tracing the sources of ore-forming fluids. In-situ S and Pb isotopes

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analysis using by LA-MC-ICP-MS were employed for indicating the origin of

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ore-forming metals, which can precisely characterize the isotopic compositions of

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minerals in different mineralization stages, and provide a possible way to obtain the

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values for the extremely minute minerals (Yuan et al., 2015; Bao et al., 2017; Zhu et al.,

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2017), such as micron-sized Te-Bi minerals. The new isotopic data obtained in this study

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provide valuable information for the timing of gold mineralization and the source of

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ore-forming materials of the Fancha gold deposit, and combined with previously

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published geochronological and geochemical data, we further refine the genesis

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mechanism of the gold deposits in the Xiaoqinling goldfield.

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2. Regional geology

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The Xiaoqinling goldfield is located along the southern margin of the NCC, which

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belongs to the northernmost portion of Qinling-Dabie Orogen (insert of Fig. 1). The

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WNW-trending Qinling-Dabie orogen, interpreted as the central portion of the Central

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China Orogen (CCO), delimits the boundary between the NCC and Yangtze Cratons that

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evolved from the multistage collision between the two cratons since Paleozoic, and the

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final collision of which took place in the Triassic (Mao et al., 2008; Dong et al., 2011;

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Chen and Santosh, 2014).

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The conspicuous Taiyao Fault and Xiaohe Fault are nearly E-W-trending, restricting

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the boundary of the Xiaoqinling region in the north and the south, respectively (Fig. 1).

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The tectonic framework of the Xiaoqinling region is nearly E-W-trending, consisting of a

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compound anticline with a series of folds and faults. Several major folds lie across the

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Xiaoqinling region, which are, from north to south, the Wulicun anticline, the Qishuping

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syncline, the Laoyacha anticline, the Miaogou syncline and the Shangyangzhai anticline

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(Fig. 1). The structural studies reveal that the major structures experienced an early stage

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of ductile deformation and were overprinted by late brittle deformation, possibly related

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to the continental collision between the Yangtze Craton and NCC in the Early Triassic

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(Ames et al., 1993; Chavagnac and Jahn, 1996; Zhang et al., 2000; Dong et al., 2011).

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Auriferous quartz veins were constrained by the dominantly E-W-trending structures, and

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occur where the ductile shear zones developed along limbs of the major folds (Mao et al.,

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2002a), which naturally constitute three gold belts in Xiaoqinling goldfield, i.e., the

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north, the middle, and the south gold belt (Fig. 1).

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The Neoarchean amphibolite-facies metamorphic rocks of the Taihua Group is the

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dominant lithostratigraphic unit, and also the major strata host for gold-bearing quartz

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veins in the Xiaoqinling goldfield (Fig. 1). The Taihua Group consists of amphibolite,

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amphibolite plagiogneiss, migmatite, biotite gneiss, graphite schist, quartzite and marble

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(Cai and Su, 1985; Hacker et al., 1996), which probably formed in the Neoarchean and

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have been subjected to amphibolite-facies metamorphism in the Paleoproterozoic (Zhou

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et al., 1998; Ni et al., 2003; Li et al., 2007a; Xu et al., 2009). Secondly, part of the

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Paleoproterozoic metavolcanic rocks of the Xiong’ er Group, the Mesoproterozoic clastic

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rocks and carbonate of Guandaokou Group are outcropping to the south of the Xiaohe

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Fault (Fig. 1).

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Voluminous magmatic rocks were widely distributed in the Xiaoqinling region (Fig.

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1). Two suites of granitoid intrusions are divided based on their age: one is older, the

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other is younger (Wang et al., 2010b). The older plutons include the Paleoproterozoic

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Guijiayu biotite hornblende granite (1748 Ma, Li et al., 1996) and the Mesoproterozoic

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Xiaohe biotite granite (1463 Ma, Li et al., 1996), which were situated in the southern

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edge of the Xiaoqinling region. The younger granites were emplaced between 146 Ma

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and 129 Ma (Mao et al., 2010; Wang et al., 2010b; Li et al., 2012a; Zhao et al., 2012;

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Wen et al., 2019), successively named the Huashan, Wenyu and Niangniangshan biotite

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monzogranite plutons from west to east. Moreover, the Taihua Group metamorphic rocks

127

were intruded by a large number of granite pegmatites and mafic dikes. The granite

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pegmatites were considered as the assembly of the Columbia supercontinent in the period

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of 2.1-1.85 Ga (Zhao et al., 2009; Li et al., 2011b; Ni et al., 2012). The widespread

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mafic dikes, including diabase, gabbro and lamprophyre, were emplaced in episodes at

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ca. 1.85-1.80 Ga, 850-700 Ma, 220-200 Ma and 140-120 Ma, recording the regional

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history of tectonic evolution. (Wang et al., 2008; Zhao et al., 2010; Bi et al., 2011a; Li et

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al., 2012b; Ren, 2012).

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3. Deposit geology

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3.1. Geology of the Fancha gold deposit

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The Fancha lode gold deposit belongs to the south gold belt of the Xiaoqinling

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goldfield, which is located on the eastern plunging crown of the Laoyacha anticline (Fig.

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1). Deformation during the orogeny led to the formation of a series of approximately

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E-W- to NW- striking faults with localized shearing and folds (Fig. 2). The Laoyacha

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anticline is the major one in the mining area, with the gentle dip northern limb, and steep

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dip southern limb. Numerous subsidiary faults were developed in the both limbs of the

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anticline, which offered the favorable spatial context for gold accumulation. Auriferous

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quartz veins were hosted by biotite plagiogneiss, amphibole plagiogneiss, migmatite, and

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amphibolite of the Taihua Group (Fig. 2). Quantity of mafic dikes were scattered all over

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the mining area (Fig. 2), majority of which were formed much earlier than gold

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mineralization with strong alteration and deformation, and minor mafic dikes were

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emplaced in the Late Mesozoic (140-137 Ma; Ren, 2012).

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Mineralization occurs dominantly as auriferous quartz veins with subordinate altered

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wall rocks in the Fancha gold deposit. Dozens of veins have been discovered and the

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major auriferous quartz veins include Nos. S310, S301, S902 and eastern parts of S60

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(Fig. 2), with proven reserves of more than 12.66 t Au (mean grade of 11.45 g/t Au; Ren,

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2012). Lode S60 is an outstanding gold vein with more than resource of 22 t Au (Li et al.,

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2012b), extending from Yangzhaiyu in the west to Fancha gold deposit in the east. This

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vein is over 6 km long and 0.3 to 6 m thick, with a minimum vertical extent of 1,000 m.

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Other major gold-bearing veins are generally 500 to 1000 m long, with 0.3 to 3.8 m thick,

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and distributed in a roughly E-W and N-E direction, dipping to the south and northwest at

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moderate angles (Fig. 2). The current mining tunnels of the Fancha gold deposit control

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the deepest auriferous quartz vein to the depth of 297 m above sea level, and mass of

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bismuthinite and other Bi-bearing minerals were exposed in the auriferous quartz veins

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here (Liu et al., 2019). The ore vein with bismuthinite extends steadily to the end of

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tunnel with around 1 to 3 m thick (Fig. 3h). This discovery may imply that there are

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abundant Bi resources in the deep of the south ore belt, or even probably in the whole

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Xiaoqinling goldfield.

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3.2. Mineralogy assemblage and paragenetic sequence

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At the Fancha gold deposit, native gold occurs mainly as native gold with irregular

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grains or stringers filling fractures in sulfides and quartz (Fig. 5), and the pyrite is the

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predominant gold-bearing sulfide, followed by chalcopyrite, galena, and sphalerite (Figs.

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3-5). Secondly, gold particles are commonly recognized in complex Au(Ag)-Te-Bi

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assemblages (Fig. 5). Te-Bi minerals are ubiquitous in the auriferous quartz veins,

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including petzite, sylvanite, hessite, calaverite, rucklidgeite, altaite, volynskite,

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tellurobismuthite, tetradymite, buckhornite, krupkaite, bismuthinite, and native bismuth

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(Liu et al., 2019). Gangue minerals are mainly of quartz and calcite, with minor biotite,

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sericite, K-feldspar, monazite, rutile, apatite, and chlorite. The alteration halos are

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commonly 0.2-1 m in width from the ore veins, primarily including silicification,

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pyrite-sericite-quartz alteration, K-feldspathization, biotitization, chloritization, and

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carbonatization (Ren, 2012; Sheng, 2016; Liu et al., 2019).

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Based on macroscopic vein cross-cutting relationships and microscopic mineral

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morphology, four principle stages of mineralization process can be distinguished (Fig. 3),

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namely, I) the barren quartz stage; II) the pyrite-dominated stage; III) the

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quartz-polymetallic sulfides stage; and IV) the quartz-carbonate stage. Pyrite crystal only

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distributed in the first three stages, and can be classified to three generations, i.e., Py1,

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Py2 and Py3 correspondingly, according to their different textures and paragenesis during

183

the mineralization stages. In addition, disseminations of pyrite also present in the wall

184

rock far from the ore veins (Fig. 4d).

185

Stage I is primarily composed of milky barren quartz (Fig. 3a), with minor

186

coarse-grained euhedral to subhedral pyrite (Py 1, Figs. 3b, 4a), without Au signature. It

187

is the main part of quartz veins, containing wall rock breccias in places (Fig. 3a),

188

probably indicating a fault-valve behavior under brittle-ductile conditions. Stage II is

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defined by quartz-pyrite veins, which commonly crosscutting the stage I quartz vein (Fig.

190

3c). The dominant mineral is fine to medium grained subhedral to anhedral pyrite (Py 2,

191

Figs. 3d, 4b), ranging in size mostly from 0.02 to 1 mm. Most pyrite grains are porous

192

and fractured, which are usually filled with other sulfides, native gold, and Te-Bi

193

minerals (Fig. 4b). Stage III is represented by quartz-polymetallic sulfides veins, which

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contain abundant galena, chalcopyrite and sphalerite (Figs. 3e, f). The fine to medium

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grained subhedral to anhedral pyrite (Py 3, Fig. 4c) is commonly intergrown with these

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sulfide minerals, and accessory gold and Te-Bi minerals. Stage IV is characterized by

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millimeter to centimeter wide quartz-calcite veins and lack of ore minerals (Fig. 3g).

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Collectively, stage II and III are the main gold mineralization stages, however, not all the

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ore veins are entirely developed with four stages. The detailed paragenetic sequence for

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minerals in the Fancha gold deposit is summarized in Fig. 6.

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4. Samples and analytical methods

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All samples were collected from underground workings at different levels of the

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Fancha gold deposit. After making the polished thin sections, microscopic observation

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was carried out to preliminarily characterize the morphology, textures and paragenesis of

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ore-related minerals. Then, the representative samples were selected for the further tests

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(Table A1). A portion of the samples were crushed, and pyrites were hand‐picked under a

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binocular microscope. The purity of single mineral separation is over 99%, and all

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mineral separations were cleaned in an ultrasonic bath. The other portions were polished

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into thick thin sections for high precision in-situ LA-MC-ICP-MS sulfur and lead isotope

210

analysis.

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4.1. Re-Os isotope dating

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Six pyrite samples from stage II were selected for rhenium and osmium isotope

213

analysis. Re and Os isotopic ratios were measured with a Thermo Fisher Scientific

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Triton-plus at the National Research Center of Geoanalysis, Chinese Academy of

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Geological Sciences, Beijing. The sample preparation, chemical separation, and ICP-MS

216

measurement are performed in accordance with Re-Os isotope testing procedures and

217

standards (Du et al., 1994; Qu and Du, 2003; Du et al., 2009; Li et al., 2009; Li et al.,

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2010), which are described briefly as follows:

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Appropriate amounts samples were weighed and loaded into a Carius tube through a

220

thin neck long funnel. The mixed 190Os and 185Re spiked solution was accurately weighed

221

and carefully added to each sample tube, and then, 2 ml of concentrated HCl and 4 ml of

222

concentrated HNO3 were successively added, while the bottom part of the tube is frozen

223

at -50 to -80 ℃ in the mixture of liquid N2 and ethanol. The Carius tubes were sealed in a

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stainless-steel jacket and heated in an oven at 220 °C for 24 h. The Os is separated by the

225

method of direct distillation from Carius tube for 50 min, and trapped in 5 mL 1:1 HBr,

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and micro distillation was used for N-TIMS (Triton) determination of the Os isotope

227

ratios. The remaining Re-bearing solution was saved in 150 ml Teflon beaker and

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evaporated to dryness. In order to reduce the acidity, repeatedly add the water twice when

229

it is near-dryness. The residues were re-dissolved in 10 ml of 5 mol l−1 NaOH, followed

230

by 10 ml of acetone in Teflon separation funnel for Re extraction. After centrifugation,

231

the acetone phase transferred to a 100 ml beaker that contained 2 ml of water already.

232

The acetone was evaporated at 50 ℃ on the hot plate, and then the residual solution was

233

heated to 120 ℃ to dryness. Finally, Re isotope ratios were determined by N-TIMS from

234

2% HNO3 containing the product. The national standard material, GBW04477 (sulfides

235

from the Jinchuan Cu-Ni deposit in China) was used to monitor the accuracy of the

236

measurements (Yang et al., 2005).

237

4.2. He-Ar isotopes analysis

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Ten pyrite samples from stage II and stage III were analyzed for He and Ar isotopic

239

compositions using an all-metal extraction line coupled mass spectrometer (Helix SFT) at

240

the Stable Isotope Laboratory of the Institute of Mineral Resources, Chinese Academy of

241

Geological Sciences, Beijing. The sensitivities of the Helix SFT for He were >2×10-4

242

A/Torr at 800 μA, and for Ar >7×10-4 A/Torr at 200 μA, respectively. 4He was measured

243

by a Faraday cup with a resolution of >400 and 3He by an electronic multiplier with a

244

resolution of >700, which can completely separate 3He and HD+. The system blank was

245

measured according to the same procedure for the sample analysis but without crushing

246

the sample, and helium and argon blanks were below 2×10-11 cm3 STP and 1×10-10 cm3

247

STP respectively. The He and Ar results were measured by peak-height comparison with

248

0.1 ml standard air whose 3He/4He ratio is 1.4×10-6 and 40Ar/36Ar ratio is 295.5 (Stuart et

249

al., 1995). The details of these crushing and analytical methods are described below:

250

Gas extraction and processing were performed in a 316 stainless steel extraction

251

line. The pyrite chips were loaded into the crusher and baked into the turbo pump at ~150

252

℃ for at least 24 h to remove the gas adsorbed on the surface of the samples and the inner

253

wall of the crusher. The samples were crushed by a hydraulic press, and the released

254

gases were first purified for 10 min by a “U” shaped cold finger at -70 ℃ which was

255

controlled by a mixture of dry-ice and alcohol to remove most of water. The other active

256

gases were adsorbed by four Zr-Al getter pumps (two at room temperature, the other two

257

at 450 ℃) for 20 min in total. Argon was frozen into a cold finger with charcoal at -193

258

℃, and then neon was adsorbed by charcoal at 30 K which was achieved by a cryogenic

259

trap. After purification, helium was admitted to the mass spectrometer and analyzed, and

260

the residual gas was pumped. After He analysis, the parameters for the Ar analysis were

261

loaded, waiting for 30 min in order to stabilize magnet field. The cold finger was heated

262

to150 ℃ for 48 h release the argon and inlet it to mass spectrometer.

263

4.3. In-situ S isotope analysis

264

Representative pyrite crystals from stage I to stage III and wall rock (i.e., amphibole

265

plagiogneiss) were selected for in-situ LA-MC-ICP-MS sulfur isotope analysis by using a

266

Resonetics-S155 excimer ArF laser ablation system with Nu Plasma II multicollector

267

ICP-MS at the State Key Laboratory of Geological Processes and Mineral Resources,

268

China University of Geosciences, Wuhan. Detailed test methods follow Zhu et al. (2016,

269

2017). The energy fluence of the laser is approximately 3 J/cm2. For single spot analysis,

270

the diameter is 33 μm with a laser repletion rate of 8 Hz. The true sulfur isotope ratio was

271

calculated by correction for instrumental mass bias by linear interpolation between the

272

biases calculated from two neighboring standard analyses. Isotope data are reported in

273

delta notation (‰) in comparison with Vienna Cañon Diablo Troilite (V-CDT):

274

δ34SV-CDT = [((34S/ 32S)sample/ (34S/32S)V-CDT) -1] × 103

275

Where (34S/32S)sample is the measured

276

defined as 0.044163 (Ding et al., 2001). The precision of

277

0.00003 (1δ). An in-house pyrite standard named WS-1 was used to calibrate the mass

278

bias for S isotopes (Zhu et al., 2016). This consists of a natural pyrite crystal from the

279

Wenshan polymetallic skarn deposit, Yunnan Province, China. The 34SV-CDT value (0.3 ±

280

0.1%) for WS-1 natural pyrite was determined using the CF-IRMS method on a MAT

281

253 isotope ratio mass spectrometer (Thermo Finnigan, Bremen, Germany) at the

282

Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing.

283

Standards were measured before, and after every four spot analyses. We also use the

284

pyrite standard to get data of chalcopyrite, galena, sphalerite, bismuthinite and

285

tetradymite, and these data should be considered as roughly results due to no proper

286

standard.

34S/32S

ratio in the sample and (34S/32S)V-CDT is 34S/32S

analysis is less than

287

4.4. In-situ Pb isotope analysis

288

Eleven analysis spots, including galena and bismuthinite from stage III, were

289

selected for in-situ LA-MC-ICP-MS lead isotope analysis. The analysis were conducted

290

by a 193nm laser ablation system (RESOlution M-50, ASI) connected to a Nu Plasma II

291

multicollector ICP-MS (Wrexham, UK) at the State Key Laboratory of Continental

292

Dynamics, Department of Geology, Northwest University, Xi’an. Homogeneous

293

nano-particulate pressed sulfide powder tablets (PSPTs) as reference materials was used

294

to monitor the accuracy of the measurements. The NIST610 standard (Pb=426 μg g-1)

295

was used to optimize instrument parameters, in order to obtain maximum analytical

296

sensitivity, stable signals, as well as optimum peak shape and alignment. Analytical

297

signals could be deducted through the Time Resolved Analysis (TRA) mode, with an

298

integration time of 0.2 s. Each spot included a background measurement for 30 s,

299

followed by an additional 50 s of ablation for signal collection and 120 s of wash time to

300

reduce memory effects. The laser frequency for galena was 2 Hz, with 9 μm of spot size,

301

for bismuthinite was 6 Hz, with 30 μm of spot size, respectively. The

302

204Hg+204Pb, 205Tl, 206Pb, 207Pb,

303

Faraday cups. The

304

and determine the interference from the

305

Analytical procedures, reference material PSPTs, and data processing has been

306

previously described in detail by Yuan et al. (2015), and Bao et al. (2017).

204Hg/202Hg

and

208Pb

202Hg, 203Tl,

ion beams were collected by corresponding

natural abundance ratio (0.229883) was used to calculate 204Hg

species on the

204Pb

intensity obtained.

307

5. Results

308

5.1 Re-Os age of pyrite

309

The Re and Os data for six pyrite samples from the Fancha gold deposit are

310

presented in Table 1 and shown in Fig. 7. The total Re and Os abundances in Py2 range

311

from 0.1214 to 0.4030 ppb and 0.0005 to 0.0374 ppb, respectively, with low

312

ratios ranging from 52.03 to 4692 and

313

samples from the Fancha gold deposit are distinct from low-level and highly radiogenic

314

sulfides (LLHR) as defined by Stein et al. (2000). Therefore, we use the conventional

315

isochron plots of

316

and isochron regressions used Isoplot 3.0 with model 3 (Ludwig, 2003).

317

187Re/188Os

versus

187Os/188Os

187Os/188Os

187Re/188Os

from 1.352 to 11.136. These pyrite

ratios in the regression analysis (Fig. 7),

Regression of all pyrite samples Re-Os isotopic data yields an isochron age of 126.0 187Os/188Os

318

± 11.0 Ma with a large degree of scatter (MSWD = 395), and initial

ratio of

319

1.36 ± 0.36 (Fig. 7a). Regression of five pyrite samples, excepting for sample FC1206-3,

320

yields an identical isochron age of 124.7 ± 9.6 Ma (MSWD = 119), with an initial

321

187Os/188Os

322

Re-Os isotopic data yields an age of 122.3 ± 9.6 Ma (MSWD = 35), and initial

323

187Os/188Os

324

define a more precise isochron age of 124.3 ± 2.6 (MSWD = 1.9), and initial 187Os/188Os

325

ratio of 1.48 ± 0.49 (Fig. 7d).

326

5.2. He-Ar isotopic compositions

ratio of 1.46 ± 0.35 (Fig. 7b). Regression of four of the six pyrite samples

ratio of 1.36 ± 0.36 (Fig. 7c). Finally, regression of only three pyrite samples

327

The analytical results of He and Ar isotopic compositions of fluid inclusions in

328

pyrites from the Fancha gold deposit are listed in Table 2 and shown in Fig. 8 and 9. The

329

concentrations of 4He range from 74.64×10-8 to 457.50×10-8 cm3 STP/g (mean 215.19

330

×10-8 cm3 STP/g), and 3He/4He ratios are between 2.80×10-7 and 16.39×10-7 (mean 7.80

331

×10-7), i.e., 0.20-1.17 Ra, with an average of 0.56 Ra, where Ra (1.4×10-6) represents the

332

atmospheric 3He/4He ratio (Stuart et al., 1995). The values of

333

from 60.66×10-8 to 247.90×10-8 cm3 STP/g (mean 144.64×10-8 cm3 STP/g).

334

Correspondingly, the

335

which is greater than the atmospheric standard value of 295.5. The 40Ar*/4He ratios range

336

from 0.24 to 0.97 (mean 0.64), using the formula

337

According to crust-mantle binary mixing model (Xu et al., 1996), Hemantle (%) =

338

[(3He/4He)sample - (3He/4He)crust] / [(3He/4He)mantle - (3He/4He)crust]×100, adopting 0.01 Ra

339

as crust He, and 6 Ra as mantle fluids, the ratio of mantle-derived He is 3.17-19.38 %

340

(mean 9.14%). In detail, the He and Ar isotopic compositions for the Py2 and Py3 are

341

slightly different. The 3He/4He ratios for Py2 are in the range of 0.68-1.17 Ra, with a

342

mean value of 0.86 Ra. For Py3, the 3He/4He ratios are 0.20-0.33 Ra, with a mean value

343

of 0.25 Ra. The Hemantle (%) for the Py2 and Py3 are 11.22-19.38%, 3.17-5.30%, with the

344

mean values of 14.21% and 4.07%, respectively.

345

5.3. S isotopic compositions

346

40Ar/36Ar

40Ar

in all samples range

ratios range from 656.55 to 8913.55 (mean 3399.29),

40Ar*/4He

= (40Ar-295.5 ×36Ar)/4He.

A total of 60 spots were performed for in-situ sulfur isotope, and the δ34S values of

347

sulfides are listed in Table 3 and shown in Fig. 10. Sulfide analyses included Py1 (n=6),

348

Py2 (n=10), Py3 (n=9), chalcopyrite (n=6), sphalerite (n=5), galena (n=5), bismuthinite

349

(n=6), tetradymite (n=7), and pyrite from amphibolite plagiogneiss (n=6).

350

The measured δ34S data of three generations pyrite vary from -4.9 to 3.6‰

351

(averaging -1.0‰), without systematic difference. The analyses of Py1, Py2 and Py3 are

352

similar to each other, tightly ranging from -1.8 to 2.8‰, -4.9 to 0.2‰, and -4.0 to 3.6‰,

353

with the average at 0.3‰, -2.5‰ and -0.2‰, respectively. In contrast, the pyrite grains in

354

the wall rock (i.e., amphibole plagiogneiss) show the significant difference for δ34S

355

values, ranging from -9.3 to -7.8‰ with an average of -8.8‰. In addition, the δ34S values

356

of chalcopyrite (1.7 to 3.4‰), sphalerite (1.7 to 2.7‰), galena (-4.9 to -4.5‰),

357

bismuthinite (2.4 to 2.6‰), and tetradymite (1.7 to 3.1‰) in stage III are relatively close

358

to each other, and consistent with the δ34S values of pyrite in the ore veins.

359

5.4. Pb isotopic compositions

360

Considering LA-MC-ICP-MS analytical method is not applicable for those minerals

361

containing low Pb concentrations (< 10 ppm), e.g., pyrite, chalcopyrite and sphalerite in

362

the Fancha gold deposit, we finally chose galena and bismuthinite with high Pb contents

363

from the stage III for in-situ lead isotope analyses in this study. The results are presented

364

in Table 4 and shown in Fig. 11.

365 366

Six spots of galena have in-situ

208Pb/204Pb

ratios of 37.482 to 37.508,

207Pb/204Pb

ratios of 15.392 to 15.523, and 206Pb/204Pb ratios of 16.995 to 17.006. In-situ Pb isotopic

208Pb/204Pb,

367

ratios of bismuthinite (n=5) are 39.279 to 39.287 for

368

207Pb/204Pb,

369

bismuthinite are homogeneous, respectively, whereas the

370

206Pb/204Pb

371

6. Discussion

372

6.1 Timing of the gold mineralization

15.588 to 15.590 for

and 18.283 to 18.288 for 206Pb/204Pb. Both the Pb isotope data of galena and 208Pb/204Pb,

207Pb/204Pb,

rations of galena are slightly lower than the ratios of bismuthinite.

373

The Re-Os isochron diagram demonstrates that all the six pyrite samples separate

374

analyses yields an isochron age of 126.0 ± 11.0 Ma with a pretty large mean square

375

weighted deviation (MSWD = 395) (Fig. 7). This an imprecise isochron age caused by

376

the relative deviation of sample FC1206-3 in the regression, implying open system

377

behavior of Re-Os isotopes by the process of Re gain or Os loss (Fig. 7a). Previous

378

studies concluded that Re-Os isotopic system can be perturbed by a variety of processes

379

such as hydrothermal or supergene alteration, deformation, and metamorphism (Lambert

380

et al., 1998; Ruiz and Mathur, 1999; Xiong and Wood, 1999, 2001; Morelli et al., 2004;

381

Tristá-Aguilera et al., 2006; Xiong et al., 2006). All the samples in this study were taken

382

from the ore veins without supergene altered. Microscopic observations show that most

383

pyrite grains from sample FC1206-3 are characterized by well development of

384

microfractures and filled with chalcopyrite, galena and Te-Bi minerals. Therefore, we

385

suspect that the deformation and hydrothermal alteration later on may be the major

386

factors altering the Re-Os isotope systematics.

387

Except for sample FC1206-3, the regression of five pyrite samples Re-Os isotopic

388

data yields an isochron age of 124.7 ± 9.6 Ma with a MSWD value of 119 (Fig. 7b). The

389

isochron age still has a large MSWD and uncertainty value, which we assign to a

390

contribution of analytical error associated with a low Os content of pyrite grains from the

391

Fancha gold deposit. This is a common phenomenon for Re-Os isochron age for pyrite

392

and has been confirmed elsewhere (e.g., Chen et al., 2007; Jiang et al., 2017). If the

393

analysis spots are excluded further, as described below, the MSWD value will be

394

significantly lowered. Regression of four of the six pyrite samples (FCSM1-1, FCSM1-2,

395

FCSM1-3 and FC1206-4) Re-Os isotopic data yields an age of 122.3 ± 9.6 Ma with the

396

MSWD value of 35 (Fig. 7c), and three samples (FCSM1-1, FCSM1-3 and FC1206-4)

397

constrain a more precise isochron age of 124.3 ± 2.6 with the MSWD value of 1.9 (Fig.

398

7d). Although the pyrite samples are gradually deleted, these Re-Os isochron ages are

399

consistent within error range, indicating a unique timing of the mineralization event.

400

Thus, the Re-Os isochron age of 124.3 ± 2.6 Ma (MSWD = 1.9) can be used to represent

401

the timing of pyrite formation in the Fancha gold deposit. Petrographic studies show that

402

the pyrite is the predominant sulfide minerals and commonly associated with gold in the

403

quartz veins. Gold occurs as inclusion within the pyrite or as veins infilling in

404

microfractures of pyrite (Fig. 5). LA-ICP-MS data shows that the Py2 contains abundant

405

Au contents, which is closely related to gold precipitation (Liu et al., 2019), indicating

406

that pyrite (Py2) was formed almost simultaneously with gold, or slightly earlier than

407

gold. Therefore, the pyrite Re-Os isochron age of 124.3 ± 2.6 Ma approximately

408

represents the timing of gold mineralization. The new Re-Os pyrite isochron age is

409

consistent with the previous 40Ar-39Ar sericite ages of the Fancha gold deposit (Li et al.,

410

2012a; Ren, 2012), indicating that the gold mineralization occurred in the Early

411

Cretaceous.

412

Accurate constraint for mineralization age is one the most important factors for

413

understanding the ore genesis. The different dates have resulted in different geodynamic

414

settings being postulated to account for the gold mineralization. In recent years, with the

415

advancement of testing technology, a dozens of age data of gold mineralization in the

416

Xiaoqinling goldfield were obtained (Xu et al., 1998; Q.Z. Li et al., 2002; Wang et al.,

417

2002, 2010a; H.M. Li et al., 2007b; N. Li et al, 2008, 2011a; J.W. Li et al., 2012a,b; Ren,

418

2012; Qiang et al., 2013; Jian et al., 2015; H.X. Zhao et al., 2015; S.R. Zhao et al., 2019).

419

As shown in the Table 5, previous geochronology produced two major date clusters, i.e.,

420

the Late Triassic and the Early Cretaceous. These dating methods are mainly via Re-Os

421

of molybdenite and 40Ar-39Ar of sericite or biotite. Re-Os geochronology of molybdenite

422

itself is one of the most robust methods for dating at present, however, the intergrowth

423

relationship between molybdenite and gold needs to be further demonstrated. Similarly,

424

the association between gold and mica is ambiguous, and because of low closure

425

temperatures of mica itself, it is vulnerable to be interfered by hydrothermal later on.

426

Therefore, whether these results can represent the timing of gold mineralization should be

427

interpreted in caution. The Re-Os of pyrite isochron age obtained this study, as a direct

428

test method, provides a new robust data for the timing of gold mineralization in the

429

Xiaoqinling goldfield.

430

6.2. Sources of the ore-forming fluids

431

The noble gases have distinct isotopic compositions in different reservoirs, and their

432

isotopic ratios can quantify the presence of crust and mantle components during the

433

ore-forming processes (Kendrick and Burnard, 2013). Therefore, noble gases can be used

434

as an ideal tracer for the crust and mantle contributions to ore-forming fluids (Stuart et

435

al., 1995; Turner et al., 1993). All the pyrite samples selected in this study were obtained

436

from underground tunnels, so cosmogenic He as a source of high 3He/4He can be ruled

437

out. As suitable noble gas carrier, He and Ar diffusion coefficients of fluid inclusions in

438

pyrite are very low (Hu et al., 1998; Burnard et al., 1999). Therefore, He and Ar diffusive

439

loss from fluid inclusions for He-Ar isotopic compositions is negligible. In addition, the

440

radiogenic 3He can also be ignored considering the lack of Li-bearing minerals in study

441

area (Stuart et al., 1995; Ballentine and Burnard, 2002). Consequently, the analytical data

442

can represent the initial values of the ore-forming fluids.

443

In general, the inclusion-trapped He-Ar isotopes originate from three potential

444

ultimate sources: 1) air-saturated water (ASW, i.e., meteoric or marine water), with

445

3He/4He

446

with high 3He and low

447

crust-derived fluids, with 3He/4He ratios of 0.01-0.05 Ra and 40Ar/36Ar > 45,000 (Burnard

448

et al., 1999). The amount of helium in the atmosphere is extremely low that it has limited

ratio of 1.4×10-6 (1 Ra) and 36Ar

40Ar/36Ar

ratio of 295.5; 2) mantle-derived fluids,

content, 3He/4He = 6-9 Ra and

40Ar/36Ar

> 40,000; and 3)

449

influence on the He abundances and isotopic compositions of most crustal fluids (Stuart

450

et al., 1994). Thus, the Helium in the ore‐forming fluids of the Fancha gold deposit could

451

have only two possible sources of mantle and/or crust.

452

The 3He/4He ratios of fluid inclusions in pyrite (Py2 and Py3) range from 0.20 to

453

1.17 Ra, with an average of 0.56 Ra, which is 1-2 orders of magnitude higher than the

454

crustal values (0.01-0.05 Ra) but lower than the mantle values (6-9 Ra), revealing a

455

mixing between crustal and mantle-derived components in the ore-forming fluids. In the

456

4He

457

helium isotopic composition, and distributed in two regions (Fig. 8). Obviously, the data

458

points of Py2 are closer to the mantle curves, while Py3 is relatively deviated. The

459

proportion of mantle He shows that the mantle-derived components of Py2 (11.22-

460

19.38%) are more than those of Py3 (3.17-5.30%). The Hemantle(%) values tend to

461

decrease gradually from early to late stages indicating the increasing influence of crust

462

component during the evolution of the ore‐forming fluid.

463

vs. 3He plot, data points are located in the transition zone of the mantle and crust

Similarly, the measured

40Ar/36Ar

values (656.55 to 8913.55) are significantly

464

higher than the air-saturated water value (295.5), and the higher 40Ar/36Ar values indicate

465

a significantly higher concentration of 40Ar* (radiogenic 40Ar). All the 40Ar*/4He values

466

are between 0.24 and 0.97, higher than the crustal production ratio (0.2; Stuart et al.,

467

1995). The data points in 40Ar/36Ar vs. R/Ra diagram (Fig. 9a) and

468

diagram (Fig. 9b) present the same distribution characteristics, that is, all the analytical

469

data fall between the fields for crustal and mantle fluids, and the data points of Py3 are

40Ar*/4He

vs. R/Ra

470

closer to the crust fluid than Py2. The Ar isotopes also imply dominant mantle-derived

471

fluid and evolution from early to late stages. In summary, the He-Ar noble gas isotope

472

data of the Fancha gold deposit reveal a significant contribution of mantle component in

473

the ore-forming fluid, and more crust fluids were mixed in the stage III compared with

474

the stage II, which is consistent with previous studies of other gold deposits in the

475

Xiaoqinling goldfield (Y.T. Wang et al., 2005; Li et al., 2012a; L. Wang et al., 2018).

476

The compositions of ore fluids in the Fancha gold deposit, i.e., medium-salinity and

477

H2O-CO2-CH4-NaCl (Ren, 2012), is similar to those of other representative gold deposits

478

in the Xiaoqinling, such as Dahu (Jian et al, 2015), Yangzhaiyu (Li et al., 2012b),

479

Qiangma, and Wenyu gold deposit (Zhou et al., 2014, 2015). Although the characteristics

480

of CO2-rich fluids are similar to those of orogenic gold deposits, the latest research on ore

481

fluids of Dahu gold deposit by UV-fs-LA-ICP-MS technique suggests that the ore fluids

482

clearly differ from metamorphic fluids, but evolved from a magmatic system (Jian et al.,

483

2018). Thus, combined with He-Ar isotope data, the original ore-forming fluids of the

484

Fancha gold deposit show an affinity to mantle-derived magmatic fluids.

485

6.3. Sources of the ore-forming metals

486

The sulfur isotopic composition can be used to trace the sulfur source and constrain

487

the genesis of the ore deposit (Ohmoto, 1972). More importantly, Au is most commonly

488

transported as bisulfide complexes in gold deposits (Benning and Seward, 1996;

489

Pal'yanova, 2008), and therefore, delimiting the sulfur source is critical in defining the

490

gold source. The application of in-situ S isotope using the LA-MC-ICP-MS technique

491

allowed us to more precisely constrain the sulfur sources. Particularly, we chose the

492

position of the minerals in contact with gold in order to more accurately characterize the

493

origin source without excessive interference (Fig. 5). Because the absence of sulfate

494

minerals in the auriferous quartz veins, and the similar δ34S values of sulfides with

495

approximate relative order, i.e., δ34Spyrite > δ34Schalcopyrite > δ34Ssphalerite > δ34Sgalena,

496

indicating an equilibrium crystallization between the sulfides (Ohmoto, 1972). Thus, the

497

measured δ34S values of sulfides can nearly represent the total sulfur isotopic

498

composition of the hydrothermal system (Ohmoto and Rye, 1979; Ohmoto and

499

Goldhaber, 1997).

500

The δ34S values of gold-related sulfide minerals from the Fancha gold deposit are

501

relatively narrow, ranging from -4.9 to 3.6‰ with an average of -0.1‰ (Table 3,

502

Fig.10a). Compared with previous conventional bulk S isotope data of major gold

503

deposits in the south ore belt of Xiaoqinling goldfield (Nie et al., 2001; Zhao, 2011; Li et

504

al., 2012a,b; Liu et al., unpublished data), in-situ LA-MC-ICP-MS method defined a

505

more narrow and accurate range of the δ34S values in this study (Fig. 10d). Analyses of

506

Py1, Py2 and Py3 have similar values to each other, tightly ranging from -1.8 to 2.8‰,

507

-4.9 to 0.2‰, and -4.0 to 3.6‰, respectively, with the average at 0.3‰, -2.5‰ and -0.2‰

508

(Fig. 10b). Data of Py2 and Py3 have more negative and positive values than Py1, likely

509

resulting from local variations of redox conditions, temperature, and/or fractionation of

510

the ore fluids (Ohmoto, 1972). Similarly, the δ34S values of chalcopyrite (1.7 to 3.4‰),

511

sphalerite (1.7 to 2.7‰) and galena (-4.9 to -4.5‰) in the stage III are consistent with

512

pyrite in veins (Fig. 10c). Meanwhile, the δ34S values of tellurides and Bi-sulfosalts

513

associated with gold were obtained for the first time in the Xiaoqinling goldfield.

514

Bismuthinite and tetradymite analysis data show relatively concentrated values, ranging

515

from 2.4 to 2.6‰ and 1.7 to 3.1‰, respectively (Fig. 10c). The near-zero δ34S values is

516

considered as the indicative of magmatic sulfur source (Ohmoto, 1972; Hoefs, 2009), and

517

the data mentioned above all show the characteristics of magmatic sulfur. Among them,

518

the δ34S values of tetradymite here are approximately the same as the tetradymite (-0.5 to

519

2.1‰) of Dashuigou deposit, which is the unique tellurium-dominated deposit over the

520

world and is considered to be magmatic genesis (Mao et al., 1995, 2002b).

521

In contrast, the pyrite grains in the amphibole plagiogneiss show significantly

522

different δ34S values, ranging from -9.3 to -7.8‰ with an average of -8.8‰ (Fig. 10a).

523

The amphibole plagiogneiss sample, representative of Taihua Group, was collected far

524

away from the gold-bearing quartz veins. Pyrite was disseminated distributed, occurring

525

as medium to fine grained, euhedral to subhedral (Fig. 4d). Therefore, we interpret that

526

the δ34S values of pyrite in the wall rock is the result of regional metamorphism, which

527

should be earlier than gold mineralization and has no effect on the sulfides in the

528

auriferous quartz veins. Accordingly, we believe that the relatively uniform δ34S values

529

of the minerals in the auriferous quartz veins suggest a consistent sulfur source, and the

530

near-zero δ34S values indicate the magmatic derivation.

531

The lead isotope, as a common tracer, can reflect important information about the

532

sources of ore metals and the geotectonic environment related to the ore formation

533

(Zhang, 1992). Both galena and bismuthinite from the stage III show a high degree of

534

uniformity in data (Table 4), and the Pb isotopic compositions of bismuthinite are slightly

535

higher than those of galena. In the Pb isotope compositional diagram (Zartman and Doe,

536

1981), the spots of galena and bismuthinite almost fall on the mantle curves and the

537

orogenic belt curves, respectively (Fig. 11a), or within the field of the lower crust and

538

mantle (Fig. 11b), which probably indicates a mixed Pb sources with certain proportions

539

of mantle. Furthermore, the previous bulk Pb isotope data of Taihua Group and Late

540

Mesozoic granitoids in the Xiaoqinling region are also plotted into the diagram (Fan et

541

al., 1994; S.M. Li et al., 1996; Nie et al., 2001; Chen et al., 2009; H.Y. Li et al., 2011; Ni

542

et al., 2012; Wang et al., 2015), and the respective field represent different sources of Pb.

543

As shown in Fig. 11, Pb isotopic compositions of the Taihua Group cover a large scale

544

field, showing the complexity of Pb sources. The Mesozoic granitoids, including Wenyu,

545

Laoniushan, Huashan, and Jinduicheng granitic plutons, are narrowly scattered with most

546

plotting near mantle and orogenic belt curves. Comparatively, the Pb isotopes of galena

547

and bismuthinite overlap more closely with the field of Mesozoic granitoids. On the other

548

hand, the Taihua Group has low content of Te and Bi so that it is unlikely to provide

549

sufficient metal source for such abundant Te-Bi minerals in the gold veins (Liu et al.,

550

2019). In other words, it implies that the source of Te and Bi must be external to the

551

Taihua Group, and as mentioned above, the δ34S value of bismuthinite and tetradymite

552

suggest the magmatic origin. In conclusion, the Pb isotopic compositions indicate the

553

mantle component, and the Pb and other metals in the Fancha gold deposit are mainly

554

derived from magmatism. Additionally, initial

555

provide unique insight into the ore-forming process to some extent (e.g., Arne et al.,

556

2001; Morelli et al., 2005, 2007, 2010). The initial

557

pyrite from the Fancha gold deposit is between the value of mantle (0.129; Meisel et al.,

558

2001) and upper crustal (1.9256; Esser and Turekian, 1993), suggesting the contribution

559

of mantle component.

560

6.4. Ore genesis and geodynamic setting

187Os/188Os

ratios of the sulfides can

187Os/188Os

ratio (1.48 ± 0.49) of

561

The geotectonic location of the Xiaoqinling region is extremely special, which has

562

been involved into the process of the Qinling orogeny and also has experienced the

563

destruction of the NCC (e.g., Mao et al., 2008; Dong et al., 2011; Zhu et al., 2011).

564

Complex geodynamic evolution has resulted in the different geodynamic settings being

565

postulated to account for gold mineralization. Although the gold deposits show

566

similarities with the classical ‘‘orogenic gold deposits’’ to some extent, i.e., occurrence in

567

Precambrian metamorphic terranes, lode gold systems controlled by structures, and

568

CO2-rich ore-forming fluid (e.g., Groves et al. 1998; Goldfarb et al. 2005), the difference

569

is more significant. Foremost is that the timing of gold mineralization in the Xiaoqinling

570

region is confirmed to be the Early Cretaceous, which is almost 2 Ga later than the

571

Paleoproterozoic peak metamorphism and 100 Ma later than the Triassic orogeny process

572

between the NCC and Yangtze Craton. Hence, the orogenic model is not applicable.

573

Last decade, a mass of geochronological data indicate that a large-scale gold

574

mineralization event occurred in the eastern of NCC during the Early Cretaceous. The

575

Xiong’ershan goldfield, also located in the southern margin of the North China Craton,

576

was formed between 136 and 115 Ma (Wang et al., 2001; Han et al., 2007; Yao et al.,

577

2009; Tang et al., 2013). The same is true for the Jiaodong peninsula, the largest

578

goldfield of China located in the eastern margin of the NCC, where gold mineralization

579

took place during 130-108 Ma (Li et al., 2003, 2006; Yang et al., 2014, 2016a; Zhu et al.,

580

2015 and reference therein). Not only that, abundant previous studies reveal that these

581

gold deposits are highly consistent in terms of tectonic location, geological

582

characteristics, mineralization types, ore-forming fluids, and material compositions (e.g.,

583

Deng et al., 2015; Li et al., 2015; Zhu et al., 2015; Yang et al., 2016b; Deng and Wang,

584

2016). Accordingly, some researchers classified these deposits as “Jiaodong-type” gold

585

deposits, named after the largest goldfield (e.g., L. Li et al., 2015; Deng and Wang, 2016;

586

Li and Santosh, 2017), which are also distributed in regions including Liaodong-Ji’nan,

587

central Taihangshan, Jibei-Jidong, and Chifeng-Chaoyang. The large-scale gold

588

mineralization in the eastern NCC requires huge amount of ore-forming materials,

589

continuous heat and fluid supply, which is controlled by a unified tectonic event.

590

Geophysical and geological study demonstrated that more than half of the thickness of

591

the lithosphere in the eastern NCC has been lost in the Late Mesozoic (e.g., Yang et al.,

592

2008; Zhu et al., 2011), which is coincident with the gold deposition in time, indicating

593

that the ultimate control of the gold mineralization is the lithospheric extension setting of

594

the NCC during the Late Mesozoic (Yang et al., 2003; Zhu et al., 2015, 2017; Deng and

595

Wang, 2016). It is believe that the lithospheric extension and thinning of the NCC were

596

triggered by the westward subduction of the Paleo-Pacific plate (Li et al., 2012a; Zhu et

597

al., 2011, 2015; Deng and Wang, 2016).

598

The large-scale lithospheric thinning is inevitably accompanied by asthenospheric

599

upwelling,

crust-mantle

interaction

and

intensive

tectonic-magmatic

activities.

600

Voluminous felsic igneous rocks and mafic dikes were recorded in the southern margin

601

of the NCC (e.g. Wang et al., 2008; Ye et al., 2008; Mao et al., 2010; Bi et al., 2011a; Li

602

et al., 2012b; Ren, 2012; Zhao et al., 2018), many of which are spatially closely related

603

with the gold deposits. This explains why the isotopic composition of the Fancha gold

604

deposit shows the affinity of mantle-derived magma. The Wenyu pluton, the typical Late

605

Mesozoic magmatic intrusion in the Xiaoqinling goldfield, was proved to be involved in

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deep-sourced material in the late stage of evolution and provided better metallogenic

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environment for gold mineralization around it (Wen et al., 2019; Zhi et al., 2019).

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Contemporaneous mafic dikes were reported in the Wenyu (130-125 Ma) and

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Huanglongpu (129 Ma) deposit (Wang et al., 2008; Mao et al., 2010; Li et al., 2012b).

610

Recently, the Qiyugou (Qi189) gold deposit, located in the Xiong’ershan goldfield, was

611

confirmed to formed in the period of 129-127 Ma and coincides with the crystallization

612

age of the ore-hosting porphyritic granite (Qi et al., 2019), which is a direct evidence of

613

genetic link between the gold mineralization and magmatism. Thus, we believe that the

614

ore-forming fluids and metals of the Fancha gold deposit stemmed directly from the

615

mantle-derived magmatic system, which could have provided materials, sufficient heat

616

energy, volatiles, and components for the gold mineralization. In addition, the major and

617

secondary faults related to the extension evolution either served as channels or sites for

618

auriferous fluids.

619

7. Conclusion

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The Fancha lode gold deposit is a typical representative of the Xiaoqinling goldfield,

621

which is controlled by fault structures and hosted in the Neoarchean Taihua Group

622

metamorphic rocks. The gold-bearing pyrite of stage II yield a Re-Os isochron age of

623

124.3 ± 2.6 Ma (MSWD = 1.9), indicating the gold mineralization took place in the Early

624

Cretaceous. Data of stable isotopes and noble gas isotopes show consistent signatures that

625

the ore-forming fluids and metals are genetic to the mantle-derived magma. In view of

626

the geochronology and isotopes analysis, and combined with previous data, we believe

627

that the gold mineralization formed in the Early Cretaceous, coupled with the large-scale

628

lithospheric extension and thinning in the eastern NCC. The asthenospheric upwelling

629

and crust-mantle interaction generated intensive magmatism, which could have provided

630

materials, sufficient heat energy, volatiles, and components to form the regional

631

mantle-derived magmatic hydrothermal mineralization system.

632 633 634

635

Acknowledgement

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This research was financially supported by the Ministry of Science and Technology

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of China (grant no. 2016YFC0600106). We would like to thank engineers of Xiangwei

638

Zhang, Anwang Ye, Yuwei Zhang, and Chong Zhang and other staffs from the Lingbao

639

Jinyuan Mining Co., Ltd. for the field investigation. Sincere thanks go to the Di Zhang

640

and Yuancan Ying at the State Key Laboratory of Geological Processes and Mineral

641

Resources, China University of Geosciences, Wuhan for assistance of in-situ S analysis.

642

My appreciation is extended to Zhian Bao at the State Key Laboratory of Continental

643

Dynamics, Department of Geology, Northwest University, Xi’an for his support during

644

the experiment. We acknowledge Dr. Chao Li for his meaningful suggestions on pyrite

645

Re-Os data processing.

646 647 648 649 650 651 652 653 654

655

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Xiong, Y., Wood, S.A., 2001. Hydrothermal transport and deposition of rhenium under subcritical conditions (up to 200 °C) in light of experimental studies. Economic Geology. 96, 1429-1444. Xiong, Y., Wood, S.A., Kruszewski, J., 2006. Hydrothermal transport and deposition of rhenium under subcritical conditions revisited. Economic Geology. 101, 471-478. Xu, Q.D., Zhong, Z.Q., Zhou, H.W., Yang, F.C., Tang, X.C., 1998. 40Ar-39Ar dating of the Xiaoqingling gold area in Henan Province. Geological Review. 44, 323-327 (in Chinese with English abstract). Xu, X.S., Griffin, W.L., Ma, X., O'Reilly, S.Y., He, Z.Y., Zhang, C.L., 2009. The Taihua group on the southern margin of the North China craton: further insights from U-Pb ages and Hf isotope compositions of zircons. Mineralogy and Petrology. 97, 43-59. Xu, Y.C., Ping, S., Tao, M.X., Liu, W.H., 1996. Geochemistry of mantle-derived volatiles in natural gases from eastern China oil/gas provinces (I). A novel helium resourcecommercial accumulation of mantle-derived helium in the sedmentary crust. Science in China. 26, 1-8 (in Chinese). Xue, L.W., Chai, S.G., Zhu, J.W., Li, M.L., 2004. Study on accompanying tellurium resources in Xiaoqinling gold deposit. Conservation and Utilization of Mineral Resources. 42-45 (in Chinese with English abstract). Yang, G., Du, A.D., Lu, J.R., Qu, W.J., Chen, J.F., 2005. Re-Os (ICP-MS) dating of themassive sulfide ores from the Jinchuuan Ni-Cu-PGE deposit. Science in China Ser. D Earth Sciences. 48, 1672-1677. Yang, J.H., Wu, Y.B., and Wilde, S.A., 2003. A review of the geodynamic setting of large-scale Late Mesozoic gold mineralization in the North China Craton: an association with lithospheric thinning. Ore Geology Reviews. 23, 125-152. Yang, J.H., Wu, F.Y., Wilde, S.A., Belousova, E., Griffin, W.L., 2008. Mesozoic decratonization of the North China block. Geology. 36, 467-470. Yang, L.Q., Deng, J., Goldfarb, R.J., Zhang, J., Gao, B.F., Wang, Z.L., 2014. 40Ar/39Ar geochronological constraints on the formation of the Dayingezhuang gold deposit: new implications for timing and duration of hydrothermal activity in the Jiaodong gold province, China. Gondwana Research. 25, 1469-1483. Yang, L.Q., Deng, J., Wang, Z.L., Zhang, L., Goldfarb, R.J., Yuan,W.M.,Weinberg, R.F., Zhang, R.Z., 2016a. Thermochronologic constraints on evolution of the Linglong Metamorphic Core Complex and implications for gold mineralization: a case study from the Xiadian gold deposit, Jiaodong Peninsula, eastern China. Ore Geology Reviews. 72, 165-178. Yang, L.Q., Deng, J., Guo, L.N.,Wang, Z.L., Li, X.Z., Li, J.L., 2016b. Origin and evolution of ore fluid, and gold-deposition processes at the giant Taishang gold deposit, Jiaodong Peninsula, eastern China. Ore Geology Reviews. 72, 585-602. Yao, J.M., Zhao, T.P., Li, J., Sun, Y.L., Yuan, Z.L., Chen, W., Han, J., 2009. Molybdenite Re-Os age and zircon U-Pb age and Hf isotope geochemistry of the Qiyugou gold system, Henan Province. Acta Petrologica Sinica. 25, 374-384 (in Chinese with

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English abstract). Ye, H.S., Mao, J.W., Xu, L.G., Gao, J.J., Xie, G.Q., Li, X.Q., He, C.F., 2008. SHRIMP zircon U-Pb dating and geochemistry of the Taishanmiao aluminous A-type granite in western Henan Province. Geological Review. 54, 699-711 (in Chinese with English abstract). Yuan, H.L., Yin, C., Chen, K.Y., Bao, Z.A., Zong, C., Dai, M.N., Lai, S.C., Wang, R., Jiang, S.Y., 2015. High precision in-situ Pb isotopic analysis of sulfide minerals by femtosecond laser ablation multicollector inductively coupled plasma mass spectrometry. Science China Earth Sciences. 58, 1713-1721. Zartman, R.E., Doe, B.R., 1981. Plumbotectonics-the model. Tectonophysics. 75, 135-142. Zhang, J.J., Zheng, Y.D., Liu, S.W., 2000. Application of general shear theory to the study of formation mechanism for the metamorphic core complex: A case of Xiaoqinling in central China. Acta Geologica Sinica-English Edition. 74, 19-28. Zhang, L.G., 1992. Present status and aspects of lead isotope geology. Geology and Prospecting. 28, 21-29 (in Chinese with English abstract). Zhao, G.C., He, Y.H., Sun, M., 2009. The Xiong'er volcanic belt at the southernmargin of the North China Craton: Petrographic and geochemical evidence for its outboard position in the Paleo-Mesoproterozoic Columbia Supercontinent. Gondwana Research. 16, 170-181. Zhao, H.J., Mao, J.W., Ye, H.S., Xie, G.Q., Yang, Z.X., 2010. Geochronology and geochemistry of the alkaline granite porphyry and diabase dikes in Huanglongpu area of Shanxi Province: Petrogenesis and implications for tectonic environment. Geology In China. 37, 12-27. Zhao, H.X., 2011. Geochemistry of ore-forming processes of the Xiaoqinling gold district, Henan Province. Doctoral dissertation. Nanjing University, China (114 pp (in Chinese with English abstract). Zhao, H.X., Jiang, S.Y., Feimmel, H.E., Dai, B.Z., Ma, L., 2012. Geochemistry, chronology and Sr-Nd-Hf isotopes of two Mesozoic granitoids in the Xiaoqinling gold district: Implication for large-scale lithospheric thinning in the North China Craton. Chemical Geology. 294-295, 173-189. Zhao, H.X., Dai, B.Z., Li, B., Zhu, Z.Y., 2015. Genesis of the Checangyu molybdenum deposit in the Xiaoqinling district: Constraints from the Re-Os dating of molybdenite and in situ trace element analysis of pyrite. Acta Petrologica Sinica. 37, 784-790 (in Chinese with English abstract). Zhao, S.R., Li, J.W., Lentz, D., Bi, S.J., Zhao, X.F., Tang, K.F., 2019. Discrete mineralization events at the Hongtuling Au-(Mo) vein deposit in the Xiaoqinling district, southern North China Craton: Evidence from monazite U-Pb and molybdenite Re-Os dating. Ore Geology Reviews. 109, 413-425. Zhao, T.P., Meng, L., Gao, X.Y., Jin, C., Wu, Q., Bao, Z.W., 2018. Late Mesozoic felsic magmatism and Mo-Au-Pb-Zn mineralization in the southern margin of the North

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1099

Figure captions

1100

Fig. 1. Geologic map of the Xiaoqinling gold field (modified after Jian et al., 2014). The

1101

insert shows location of Xiaoqinling terrane, which belongs to the northernmost portion

1102

of Qinling-Dabie Orogen. The rectangular area marked by dashed lines shows the

1103

location of the Fancha gold deposit and is detailed in Fig. 2.

1104

Fig. 2. Geologic map of the Fancha gold deposit (modified after Ren, 2012; Sheng,

1105

2016).

1106

Fig. 3. Photographs showing mineral assemblages and mineralization stages in the

1107

Fancha gold deposit. (a) Barren quartz vein (stage I) containing wall rock breccias. (b)

1108

Quartz vein containing aggregates of coarse grained pyrite. (c) Qtz-Py veins (stage II)

1109

cutting through the barren quartz vein (stage I). (d) Dense disseminated fine to medium

1110

grained Py2 in quartz. (e) The Qtz-Py-Gn (stage III) overprinting earlier mineralization

1111

stages. (f) Pyrite co-existing with galena, chalcopyrite and sphalerite. (g) Qtz-Cal veins

1112

(stage IV) cutting through earlier veins. (h) Bismuthinite occurs as massive and

1113

veinlet-disseminated co-existing with pyrite in quartz vein (stage III). Abbreviations:

1114

Qtz=quartz; Py=pyrite; Ccp=chalcopyrite; Gn=galena; Sp=sphalerite; Cal=calcite;

1115

Bmt=bismuthinite.

1116

Fig. 4. Representative reflected-light photomicrographs showing the typical morphology

1117

and textures of pyrite. (a) Coarse grained, cubic or pyritohedral pyrite (Py1), with

1118

inclusion-free. (b) Medium to fine grained, subhedral to anhedral pyrite (Py2) displaying

1119

porosities and microfractures, with abundant inclusions. (c) Medium to fine grained,

1120

subhedral pyrite (Py3) intergrown with chalcopyrite, galena, and sphalerite. (d) Medium

1121

to fine grained, euhedral to subhedral pyrite in wall rock far from ore vein.

1122

Abbreviations: Qtz=quartz; Py=pyrite; Ccp=chalcopyrite; Gn=galena; Sp=sphalerite;

1123

Au=gold; Clv=calaverite; Rt=rutile.

1124

Fig. 5. Representative reflected-light photomicrographs showing the common occurrence

1125

and associations of gold. (a) Gold as inclusions in pyrite. (b) gold veins filling in quartz

1126

microfractures. (c) Co-precipitation of gold, galena, altaite and chalcopyrite, filling

1127

fractures in pyrite. (d) Gold coexisting with galena and chalcopyrite in quartz. (e) Gold

1128

coexisting with chalcopyrite and sphalerite, filling fractures in pyrite. (f) Large patches

1129

bismuthinite containing gold and tetradymite. (g) Aggregate of tellurobismuthite, gold

1130

and sphalerite, along the boundary of pyrite. (h) Intergrowth of tellurobismuthite, petzite,

1131

gold, chalcopyrite, calaverite, tetradymite, and altaite in quartz. Abbreviations: Au=gold;

1132

Py=pyrite; Qtz=quartz; Gn=galena; Alt=altaite; Ccp=chalcopyrite; Bmt=bismuthinite;

1133

Ttd=tetradymite; Sp=sphalerite; Ptz=petzite; Tlb=tellurobismuthite.

1134

Fig. 6. Paragenetic sequence for the Fancha gold deposit. The widths of the solid lines

1135

denote relative abundance of minerals.

1136

Fig. 7. Re and Os isochron ages of pyrite from the Fancha gold deposit. (a) All six

1137

analyses showing the behavior of Re-Os decoupling; (b) The regression is based on five

1138

points, excluding samples FC1206-3; (c) Using four points without samples FC1206-3

1139

and FC1206-5 yielding an isochron age; (d) Three points from samples FC1206-4,

1140

FCSM1-1 and FCSM1-3 yielding an isochron age.

1141

Fig. 8. He isotopic composition of fluid inclusions in pyrite from the Fancha gold deposit

1142

(modified after Mamyrin et al., 1984). Data are collected from Y.T. Wang et al. (2005),

1143

Li et al. (2012a) and L. Wang et al. (2018).

1144

Fig. 9. (a) R/Ra-40Ar/36Ar diagram for the Fancha gold deposit; (b) R/Ra-40*Ar/4He

1145

diagram for the Fancha gold deposit. Fields of mantle and crust fields are from Hu et al.

1146

(2009). Data are collected from Y.T. Wang et al. (2005), Li et al. (2012a) and L. Wang et

1147

al. (2018).

1148

Fig. 10. (a) Histogram of total in-situ S isotopic composition of sulfides from the Fancha

1149

gold deposit; (b) Histogram of in-situ sulfur isotopic composition of pyrite grains from

1150

stage I, 2, and 3; (c) Histogram of in-situ sulfur isotopic composition of chalcopyrite,

1151

sphalerite, galena, bismuthinite, and tetradymite from stage III; (d) Histogram of bulk S

1152

isotope data from the representative deposits in south belt of Xiaoqinling gold field

1153

through the conventional analytical method. Data are collected from Nie et al. (2001),

1154

Zhao (2011), Li et al. (2012a,b), and Liu et al. (unpublished data). Abbreviations:

1155

Py1=pyrite from stage I; Py2=pyrite from stage II; Py3=pyrite from stage III; Gn=galena;

1156

Ccp=chalcopyrite; Sp=sphalerite; Bmt=bismuthinite; Ttd=tetradymite; QM=Qiangma

1157

gold

1158

DC=Dongchuang gold deposit; FC=Fancha gold deposit; YZY=Yangzhaiyu gold deposit.

1159

Fig. 11. In-situ Pb isotope compositional diagram for galena and bismuthinite from the

1160

Fancha gold deposit. The bulk Pb isotopes data for the Taihua Group and Mesozoic

deposit;

DTY=Dongtongyu

gold

deposit;

WY=Wenyu

gold

deposit;

1161

granitoids (i.e., Wenyu, Laoniushan, Huashan and Jinduicheng) are from Fan et al.

1162

(1994), S.M. Li et al. (1996), Nie et al. (2001), Chen et al. (2009), H.Y. Li et al. (2011),

1163

Ni et al. (2012), and Wang et al. (2015). The Pb evolution curves of Upper Crust,

1164

Orogenic Belt, Mantle and Lower Crust are from Zartman and Doe (1981).

1165 1166

1167

Table captions

1168

Table 1 Re and Os abundance and isotopic data for pyrite from the Fancha gold deposit

1169

Table 2 He and Ar isotopic compositions of inclusion‐trapped fluid in pyrite from

1170

Fancha gold deposit and integration of previous data of Xiaoqinling goldfield

1171

Note:“-” = below detection, m.g. = main gold stage; R/Ra = (3He/4He)sample/(3He/4He)air, where air 3He/4He

1172

= 1.4×10-6; 40Ar*/4He = (40Ar-295.5×36Ar)/ 4He; The proportion of mantle 4He in the fluid is calculated as

1173

4He

1174

6-9 Ra.

1175

Table 3 In-situ S isotopic composition of sulfide samples from the Fancha gold deposit

1176

Table 4 In-situ Pb isotopic composition of sulfide samples from the Fancha gold deposit

1177

Table 5 Compiled geochronology data of the Xiaoqinling goldfield

1178

mantle

= (R-Rc)/(Rm-Rc)×100%, where crustal 3He/4He (Rc) = 0.01-0.05 Ra and mantle 3He/4He (Rm) =

1179

Appendix

1180

Table A1 Information on samples presented in this paper

1181

No.

Sample

Elevation (m) Mineralization stage

Description

1

MNG-1

1530

III

Massive quartz-polymetallic sulfides gold ore with abundant chalcopyrite and galena

2

MNG-2

1530

II

Massive quartz-pyrite gold ore with fine to medium grainedpyrite

3

MNG-3

1530

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

4

FC1447-3

1447

wallrock

5 FC1340-19

1340

III

Massive quartz-polymetallic sulfides gold ore with abundant galena, chalcopyrite and sphalerite

6 FC1340-41

1340

III

Massive quartz-polymetallic sulfides gold ore with abundant galena, chalcopyrite and sphalerite

7

FC1206-3

1206

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

8

FC1206-4

1206

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

9

FC1206-5

1206

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

10 FC1060-9

1060

III

Massive quartz-polymetallic sulfides gold ore with abundant chalcopyrite

11 FC1026-3

1026

I

Milky barren quartz with minor coarse-grained euhedral to subhedral pyrite

12 FC1026-7

1026

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

13

FC540-8

540

III

Massive quartz-polymetallic sulfides gold ore with abundant galena, chalcopyrite and sphalerite

14 FCSM1-1

456

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

15 FCSM1-2

456

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

16 FCSM1-3

456

II

Massive quartz-pyrite gold ore with fine to medium grained pyrite

17

FCS17-2

456

III

Massive quartz-polymetallic sulfides gold ore with abundant chalcopyrite, galena, and sphalerite

18

FC296-7

296

III

Massive quartz-bismuthinite ore with pyrite co-existing abundant Bi-bearing minerals

Amphibole plagiogneiss with disseminated fine-grained pyrite

1182

Conflict of interest statement

1183

We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence

1184

our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be

1185

construed as influencing the position presented in, or the review of, the manuscript entitled, “Ore genesis of the Fancha gold deposit,

1186

Xiaoqinling goldfield, southern margin of the North China Craton: Constraints from pyrite Re-Os geochronology and He-Ar, in-situ

1187

S-Pb isotopes”.

1188

1189 1190 1191 1192 1193 1194 1195

1196

Highlights: 1. A comprehensive and systematic study on the deposit geology, mineralization characteristics and sources of ore-forming materials on Fancha gold deposit. The He-Ar, S, and Pb isotopes were employed to delineate the different mineralization stages. 2. The Fancha gold deposit was formed in the early Cretaceous (124.3 ± 2.6 Ma), which was directly determine by the gold-stage pyrite Re-Os dating. This is the first published pyrite Re-Os isochron age in the Xiaoqinling region. 3. The ore-forming fluids in the Fancha gold deposit were derived from a magmatic with a significant contribution of mantle

1197 1198 1199

component. 4. In-situ technique precisely acquire S-Pb isotopic compositions, especially small scale Te- and Bi-bearing minerals. The ore-forming metals in the Fancha gold deposit are mantle-derived magmatic in origin.

1200

5. Base on the study of geochronology and isotopes, we believe that the ore-forming fluids and metals of the Fancha gold deposit

1201

directly stem from a mantle-derived magmatic system, coupling with the destruction of the North China Craton in the Early

1202

Cretaceous.

1203

1204

1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216

Fig. 1

1217 1218 1219 1220

Fig. 2

1222 1223 1224

1225

Fig. 3

1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239

Fig. 4

1240 1241 1242 1243 1244 1245 1246 1247

1249 1250

Fig. 5

1251

1252 1253 1254 1255

Fig. 6

1256

1257 1258

1259

Fig. 7

1260 1261 1262 1263 1264 1265 1266 1267

Fig. 8

1268 1269 1270 1271 1272 1273

1274 1275 1276 1277

Fig. 9

1278 1279 1280 1281 1282

Fig. 10

1283 1284 1285 1286 1287 1288 1289

1290 1291 1292

Fig. 11

1293 1294

Table 1

1295

187

187

187

Samp

Wei

Re

±

Os

±

±

Re/

±

Os/

±

Os le

ght/g

(ppb)

(2σ)

(ppb)

(2σ)

(2σ)

188

(2σ)

188

(2σ)

(ppb) Os FCS M1-1 FCS

0.6 505 0.6

0.2 126 0.1

0.0 016 0.0

0.0 005 0.0

0.0 000 0.0

0.0 004 0.0

0.0 000 0.0

Os

19 87.0

34. 0

5.6 64

76

3.2

0 .083 0

8.1 M1-2 FCS M1-3

502 0.6 505

646 0.6 512

012 0.0 054

010 0.0 007

000 0.0 000

004 0.0 010

000 0.0 000

5.8

35

46 92.0

76. 0

11. 136

.013 0 .127

FC12

0.6

0.1

0.0

0.0

0.0

0.0

0.0

55

2.2

0

6.3 06-3

510 FC12

0.6

214 0.1

009 0.0

011 0.0

000 0.0

003 0.0

000

2.5

0.0

04

58

2.6

.011 0

6.8 06-4

501 FC12

0.6

465 0.4

011 0.0

012 0.0

000 0.0

004 0.0

000

6.6

0.0

94

52.

1.3

.033 0

0.9 06-5 1296 1297 1298 1299 1300 1301 1302 1303

508

030

030

374

006

066

001

0

52

.013

1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317

1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330

Table 2

Sta Sample

4He×10-8

3He/4He×10-

R/

40Ar×10-8

Pyrite

7

Ra

（cm3STP/g）

11.97

II

5

101.98

9.55 140.80

%

0

0.67

14.10

7384.2 137.06

8

0.93 0

0.6 Pyrite

He

4157.9

0.6 Pyrite

Ar

II 141.70

FC1026-7

HeMantle Reference

（cm3STP/g）

0.8

FCSM1-2

40Ar*/4

Mineral ge

FCSM1-1

40Ar/36

11.22

5080.8

II

This study 0.71

159.15

9.69

9

120.34

6

11.39

0.9 MNG-2

MNG-3

Pyrite

Pyrite

II

II

0.90 96.34

12.68

74.64

16.39

1 1.1

147.11

716.81

132.01

656.55

14.96 0.97

19.38

7 0.3 FCS17-2

Pyrite

8913.5

III

0.92 237.01

4.58

3

FC1340-1

225.06 0.2

Pyrite

0.36 336.77

3.31

4

134.93 0.2

Pyrite

3

0.26 3.59

6

FC1340-4

60.66 0.2

2

4.11

1211.1

III

1

3.78

2014.7

III 198.28

Pyrite

5.30

3209.5

III

9

FC1060-9

5

0.41 457.50

2.80

0

247.90

1

139.32

647.67

3.17

0.2 MNG-1

Pyrite

III 309.66

3.47

0.24

5

3.97 1.7

516HY4

Pyrite

II

668.00

24.00

Y.T. Wang et al., 58.40

1

980.00

0.06

28.38 2005

0.9 522GZ1

Pyrite

II

396.00

13.00

20.00

588.00

0.03

15.36

9.50

611.00

0.07

22.54

46.60

602.00

0.23

30.88

137.7

877.00

1.74

4.67

30.9

724.00

0.07

5.84

0.19

4.67

-

-

3 1.3 614YL1

Pyrite

II

71.00

19.00 6 1.8

512XY22

Pyrite

II

104.00

26.00 6 0.2

512XY22

Quartz

II

52.00

4.00 9 0.3

517HY6

Pyrite

III

275.00

5.00 6 0.2

517HY6

Chalcopyrite

III

35.00

4.00

1670.0 8.00

9 517HY6

Galena

III

-

-

0 -

3.40

465.00

519MJ1

Galena

III

-

-

-

4.60

345.00

-

-

111.60

371.00

0.02

7.01

0.29

29.05

0.4 519MJ1

Pyrite

III

1108.00

6.00 3

m. 13LZG-19

Pyrite

1.7 189.00

24.50

g.

66.80 5

m. 13LZG-69

Pyrite

110.00

30.00

2897.3 41.60

4 m.

Pyrite

94.00

0.34

7.80

2018

11.60

m.

35.56

1127.6

5

Pyrite

L. Wang et al.,

6 0.5

g.

QM7

9 2.1

g.

13LZG-77

1537.3

0.09

9.02

-

6.45

9 0.4

20.37

5.60

g.

-

-

0 Li et al., 2012a m.

QM18

Pyrite

0.9 5.66

g.

13.44

6

-

-

15.88

m. QM20

Pyrite

1.2 17.97

17.92

g.

Pyrite

11.03

12.32

Pyrite

16.85

13.44

Pyrite

48.25

15.96

14.54

17

403.00

0.35

15.89

21

636.00

0.31

18.80

12

504.00

0.25

10.83

-

-

-

25.23

10

380.00

0.29

17.19

4 m.

Pyrite

0.6 25.85

9.24

g.

6 m.

Pyrite

1.5 4.18

21.28

g. Pyrite

0.51

1.1

g.

DT2

608.00

6 m.

CE77

8

0.9

g.

CE30

21.28

8 m.

CE29

0.39

0.8

g.

CE48

442.00

8 m.

QM26

16

2 m.

9.49

14.56

1.0

g.

4 m.

DT32

Pyrite

1.1 15.74

15.54

g.

Pyrite

15.76

16.1

Pyrite

10.87

12.04

Pyrite

13.3

g.

19.05

16

419.00

0.58

14.20

-

-

-

15.70

-

-

-

10.70

-

-

-

7.96

5 m.

Pyrite

0.6 15.28

9.1

g.

5 m.

0.4 177.38

g.

0.46

0.9 278.98

Pyrite

663.00

6 m.

QN40

10

0.8

g.

QN32

18.36

5 m.

QN31

0.53

1.1

g.

DT77

445.00

1 m.

DT44

19

6.86 9

m. QSZ23

Pyrite

0.3 3.70

4.2

g.

Pyrite

-

4.92

-

-

-

3.57

0.2 1.53

g.

-

0 m.

QSZ24

-

3.08 2

Table 3

1331

Sample/N

S

δ34S

Sample/

Mineral o.

tage

Stage (‰)

(‰) FC1060-

I

Pyrite

0.5

1

Mineral

No.

FC1026-3/

Chalcopyr III

9/6 FC1026-3/

1.7 ite

FC1060I

Pyrite

0.3

2

III

Sphalerite

2.7

III

Sphalerite

1.7

III

Sphalerite

2.5

III

Sphalerite

2.6

9/1 FC1026-3/

FC1060I

Pyrite

0.0

3

9/2 FC1026-3/

FC1060I

Pyrite

-0.1

4

9/3 FC1026-3/

FC1060I

5

δ34S

Pyrite

2.8 9/4

FC1026-3/

FC1060I

Pyrite

-1.8

6

III

Sphalerite

2.3

III

Galena

-4.3

III

Galena

-4.7

III

Galena

-4.5

III

Galena

-4.9

III

Galena

-4.5

III

Bismuthin

2.3

9/5 FCSM1-1/

FC540-8 II

Pyrite

-1.8

1

/1 FCSM1-1/

FC540-8 II

Pyrite

-1.6

2

/2 FCSM1-1/

FC540-8 II

Pyrite

-2.5

3

/3 FCSM1-1/

FC540-8 II

Pyrite

-3.6

4

/4 FCSM1-1/

FC540-8 II

Pyrite

-1.7

5

/5 FCSM1-1/

II

Pyrite

-1.5

FC296-7

6

/1 FCSM1-1/

FC296-7 II

Pyrite

-4.5

7

Bismuthin III

/2 FCSM1-1/ II

Pyrite

-4.9

Bismuthin III

/3 FCSM1-1/ Pyrite

0.2

9

Bismuthin III

/4 FCSM1-1/ Pyrite

-3.1

10

Bismuthin III

/5 FC1060-9/

II

1

-2.7

I FC1060-9/

Bismuthin III

/6 II -4.0

2.6 ite

FC296-7 Pyrite

I

2.6 ite

FC296-7 Pyrite

2.4 ite

FC296-7 II

2.6 ite

FC296-7 II

2.3 ite

FC296-7

8

2

ite

Tetradymi III

/1

3.1 te

FC1060-9/

II

FC296-7 Pyrite

3

0.7

I

III /2

II FC17-2/1

Pyrite

-0.1

Tetradymi III

/3 II

FC17-2/2

-1.5

I

Tetradymi III

/4 II

FC17-2/3

1.7

I

Tetradymi III

/5 II

FC17-2/4

1.6

I

Tetradymi III

/6 II

FC17-2/5

Pyrite

-1.2

Tetradymi III

/7 II

Pyrite

3.6

2.5 te

FC296-7

I

2.3 te

FC296-7 Pyrite

2.3 te

FC296-7 Pyrite

1.7 te

FC296-7 Pyrite

2.5 te

FC296-7

I

FC17-2/6

Tetradymi

2.5 te

FC1447-

Wall

Pyrite

-9.0

I FC1060-9/

3/1 II

Chalcopyr

rock FC1447-

Wall

3.3 1

I FC1060-9/

ite II

3/2

Chalcopyr

I

FC1447-

FC1060-9/

ite II

3/3

Chalcopyr

I FC1060-9/

II

3/4

Chalcopyr

I FC1060-9/

II

3/5

Chalcopyr

1332 1333

I

ite

-8.3

Pyrite

-7.8

rock FC1447-

3/6

Pyrite

Wall

Wall

1.8 5

-9.1

rock FC1447-

ite

Pyrite

Wall

2.4 4

-9.3

rock FC1447-

ite

Pyrite

Wall

3.3 3

-9.1

rock

3.4 2

Pyrite

rock

1334 1335 1336 1337 1338 1339 1340 1341 1342 1343

Table 4 Sample/N o. FC540-8/1

Sta Mineral

208Pb/204Pb

207Pb/204Pb

206Pb/204Pb

Galena

37.483 ± 0.005

15.393 ± 0.002

16.996 ± 0.002

ge III

FC540-8/2

III

Galena

37.482 ± 0.006

15.392 ± 0.002

16.995 ± 0.002

FC540-8/3

III

Galena

37.506 ± 0.008

15.401 ± 0.003

17.003 ± 0.003

FC540-8/4

III

Galena

37.498 ± 0.006

15.398 ± 0.002

17.002 ± 0.002

FC540-8/5

III

Galena

37.493 ± 0.006

15.397 ± 0.002

16.999 ± 0.002

FC540-8/6

III

Galena

37.508 ± 0.006

15.405 ± 0.002

17.006 ± 0.002

39.279 ± 0.003

15.589 ± 0.001

18.283 ± 0.001

39.285 ± 0.003

15.589 ± 0.001

18.285 ± 0.001

39.286 ± 0.003

15.590 ± 0.001

18.287 ± 0.001

39.287 ± 0.003

15.588 ± 0.001

18.288 ± 0.001

Bismuthinit FC296-7/1

III e Bismuthinit

FC296-7/2

III e Bismuthinit

FC296-7/3

III e Bismuthinit

FC296-7/4

III e

Bismuthinit FC296-7/5

III

39.280 ± 0.003

15.590 ± 0.001

18.283 ± 0.001

e 1344 1345 1346 1347

Table 5

1348 No.

Deposit

Dating method

Measured mineral

Age (Ma)

Reference

1

Baishuiling

Re-Os

Molybdenite

134.5 ± 0.5

J.W. Li et al., 2012a

2

Baishuiling

Re-Os

Molybdenite

131.0 ± 0.6

J.W. Li et al., 2012a

3

Checangyu

Re-Os

Molybdenite

132.7 ± 2.2

H.X. Zhao et al., 2015

4

Checangyu

Re-Os

Molybdenite

133.8 ± 4.3

H.X. Zhao et al., 2015

5

Quanjiayu

Re-Os

Molybdenite

129.1 ± 1.6

H.M. Li et al., 2007a

6

Quanjiayu

Re-Os

Molybdenite

130.8 ± 1.5

H.M. Li et al., 2007a

7

Simuyu

Re-Os

Molybdenite

131.1 ± 0.5

J.W. Li et al., 2012a

8

Simuyu

Re-Os

Molybdenite

131.3 ± 0.5

J.W. Li et al., 2012a

9

Majiawa

Re-Os

Molybdenite

232.0 ± 11.0

Wang et al., 2010a

10

Dahu

Re-Os

Molybdenite

232.9 ± 2.7

H.M. Li et al., 2007a

11

Dahu

Re-Os

Molybdenite

223.0 ± 2.8

H.M. Li et al., 2007a

12

Dahu

Re-Os

Molybdenite

218.0 ± 41.0

N. Li et al., 2008

13

Dahu

Re-Os

Molybdenite

206.4 ± 3.9

Jian et al., 2015

14

Hongtuling

Re-Os

Molybdenite

204.0 ± 4.6

S.R Zhao et al., 2019

15

Chen’ er

40Ar-39Ar

Sericite

126.7 ± 1.2

J.W. Li et al., 2012a

16

Chen’ er

40Ar-40Ar

Sericite

126.5 ± 1.2

J.W. Li et al., 2012a

17

Chen’ er

40Ar-41Ar

Sericite

128.9 ± 0.8

J.W. Li et al., 2012a

18

Chen’ er

40Ar-42Ar

Sericite

130.4 ± 0.8

J.W. Li et al., 2012a

19

Chen’ er

40Ar-43Ar

Sericite

130.4 ± 1.0

J.W. Li et al., 2012a

20

Chen’ er

40Ar-44Ar

Sericite

130.9 ± 2.0

J.W. Li et al., 2012a

21

Chen’ er

40Ar-39Ar

Biotite

129.8 ± 1.3

J.W. Li et al., 2012a

22

Dongchuang

40Ar-39Ar

Sericite

132.2 ± 2.6

Xu et al., 1998

23

Dongchuang

40Ar-39Ar

Sericite

132.6 ± 2.6

Q.Z. Li et al., 2002

24

Dongchuang

40Ar-39Ar

Sericite

130.7 ± 1.7

J.W. Li et al., 2012a

25

Dongtongyu

40Ar-39Ar

Sericite

143.5 ± 1.4

J.W. Li et al., 2012a

26

Dongtongyu

40Ar-39Ar

Sericite

118.9 ± 1.2

J.W. Li et al., 2012a

27

Dongtongyu

40Ar-39Ar

Sericite

125.1 ± 1.0

J.W. Li et al., 2012a

28

Fancha

40Ar-39Ar

Sericite

130.5 ± 1.3

Ren, 2012

29

Fancha

40Ar-39Ar

Sericite

120.2 ± 2.2

Ren, 2012

30

Fancha

40Ar-39Ar

Sericite

130.5 ± 1.5

J.W. Li et al., 2012a

Fancha

40Ar-39Ar

Sericite

122.6 ± 1.0

J.W. Li et al., 2012a

32

Fancha

40Ar-39Ar

Sericite

134.3 ± 0.6

J.W. Li et al., 2012a

33

Fancha

40Ar-39Ar

Sericite

131.1 ± 0.9

J.W. Li et al., 2012a

34

Qiangma

40Ar-39Ar

Sericite

125.4 ± 0.7

J.W. Li et al., 2012a

35

Qiangma

40Ar-39Ar

Sericite

124.1 ± 1.3

J.W. Li et al., 2012a

36

Qiangma

40Ar-39Ar

Sericite

120.3 ± 0.6

J.W. Li et al., 2012a

31

37

Shancheyu

40Ar-39Ar

Sericite

129.8 ± 1.7

J.W. Li et al., 2012a

38

Shancheyu

40Ar-39Ar

Sericite

127.0 ± 1.3

J.W. Li et al., 2012a

39

Wenyu

40Ar-39Ar

Sericite

129.5 ± 1.5

J.W. Li et al., 2012a

40

Yangzhaiyu

40Ar-39Ar

Sericite

132.3 ± 0.5

J.W. Li et al., 2012b

41

Yangzhaiyu

40Ar-39Ar

Sericite

124.3 ± 1.4

J.W. Li et al., 2012b

Hongtuling

40Ar-39Ar

Biotite

126.7 ± 0.2

Wang et al., 2002

43

Hongtuling

40Ar-39Ar

Biotite

128.5 ± 0.2

Wang et al., 2002

44

Yangzhaiyu

40Ar-39Ar

Biotite

134.5 ± 0.7

J.W. Li et al., 2012b

45

Yangzhaiyu

40Ar-39Ar

Biotite

123.7 ± 0.5

J.W. Li et al., 2012b

46

Dahu

U-Th-Pb

Monazite

216 ± 5 ~125

N. Li et al., 2011a

47

Qinnan

U-Pb

Monazite

120.9 ± 0.9

Qiang et al., 2013

48

Qinnan

Th-Pb

Monazite

122.6 ± 1.9

Qiang et al., 2013

49

Hongtuling

U-Pb

Monazite

130.4 ± 5.3

S.R. Zhao et al., 2019

50

Hongtuling

U-Pb

Monazite

203.5 ± 8.1

S.R. Zhao et al., 2019

42

1349 1350 1351 1352