Ore genesis of the Tieshajie Cu deposit: Implications for Cu mineralization in the Qin-Hang Metallogenic Belt, South China

The Tieshajie Cu deposit, located in the northeastern part of the Qin-Hang Metallogenic Belt (QHMB), South China


Introduction
The collision and amalgamation of the Yangtze Craton and Cathaysia Block during the Neoproterozoic in South China led to the formation of the Qin-Hang suture zone (Mao et al., 2011;Shu, 2012).Following the amalgamation, the Qin-Hang Metallogenic Belt (QHMB), a significant zone of porphyry-skarn Cu-polymetallic mineralization, was developed along the suture zone during the Mid-Late Jurassic.The QHMB includes numerous Cu-polymetallic deposits, e.g., the Dexing, Yinshan, Yongping, Yuanzhuding, Baoshan, and Qibaoshan deposits (Mao et al., 2013).Recently, there has been a consensus that Late Mesozoic deposits and associated magmatism in the QHMB link to the regional geodynamics, but there are divergent perspectives regarding the nature of the geodynamic controls.For instance, Mao et al. (2021) proposed that these Cu-polymetallic deposits were related to the mantle and lower-crustal melts from the subduction-metasomatized lithosphere, triggered by a low-angle subduction of the Paleo-Pacific plate beneath the South China during the Middle-Late Jurassic.In contrast, Zhou et al. (2017) suggested that these porphyry Cu deposits were associated with the partial melting of the lower crust induced by the continental crustal extension and thinning, and upwelling of the asthenospheric mantle.Moreover, there are several deposits in the northeastern part of the QHMB (e.g., Pingshui and Tieshajie) which have long been regarded to be Neoproterozoic volcanic-associated massive sulfide (VMS) deposits and have been interpreted as reflecting the existence of metal-rich juvenile crust in the Neoproterozic (Wang et al., 2018;Chen et al., 2014).It has been suggested, therefore, that the coeval formation of metal-rich juvenile crust with these Neoproterozoic VMS deposits, which was subsequently partially melted in the Mesozoic, could be a "vital step" for the formation of the regional Mesozoic extensive development of porphyry copper-gold mineralization (Ni and Wang, 2017).However, although previous investigations have primarily concentrated on deposit geology and metamorphic petrology in these VMS deposits, the mineralization has not been dated, and therefore, their genesis remains equivocal.
The Tieshajie Cu deposit (5.2 Mt ores with a mean Cu grade of 1.07 wt%; Wang et al., 2018), is a stratiform-like sulfide deposit hosted by strongly metamorphosed and deformed Meso-Neoproterozoic strata.It has long been proposed that the Tieshajie deposit exhibits characteristics typical of VMS deposits, such as lenticular and stratiform-like orebodies that are semiconformable hosted in the Meso-Neoproterozoic marine volcanic strata (Ye, 1987;He et al., 2008;Wang et al., 2018).These volcanic host rocks have been accurately dated using the LA-ICP-MS zircon U-Pb method, revealing ages ranging from 1172 to 980 Ma (He et al., 2008;Ni and Wang, 2017;Wang et al., 2018;Gao et al., 2013;Zhu, 2017).However, the lack of direct dating of the mineralization means the nature and genesis of the deposit remain ambiguous, and this extends to a more precise comprehension of the metal source.Here, we present a hydrothermal titanite LA-ICP-MS U-Pb age and constrain the timing of the Tieshajie Cu mineralization.We also present Re-Os isotope and in-situ S-Cu data of chalcopyrite to constrain the source of the metals and sulfur within the system.Our new results suggest that the Tieshajie deposit has a magmatic-hydrothermal origin, and belongs to the distal part of the Mid-Late Jurassic (170-150 Ma) porphyry-skarn Cu metallogenic event in the QHMB.
The assembly of the Cathaysia Block and Yangtze Craton during the Neoproterozoic era resulted in the development of the Qin-Hang suture zone in South China.(Fig. 1; Chen and Jahn, 1998).In the northeastern part of the Qin-Hang suture zone, the exposed strata primarily comprise Neoproterozoic Shuangqiaoshan Group, characterized by low-grade metamorphic sedimentary rocks and mafic volcanic formations.This unit was overlain or intruded by Middle Jurassic volcanic-subvolcanic rocks.In the late Mesozoic, Paleo-Pacific plate beneath the South China block subducted northwest resulted in the formation of Mid-Late Jurassic calc-alkaline granitoids with comparatively high ε Nd(t) values and younger model ages (T 2DM ) in South China (Gilder et al., 1996).Moreover, a sequence of Mid-Late Jurassic (170-150 Ma) magmatichydrothermal Cu-Au-Ag-Pb-Zn polymetallic deposits are dispersed along the Qin-Hang zone and its adjacent regions (referred to as the QHMB) (Mao et al., 2011) Zn-Ag and Dongxiang hydrothermal Cu deposits (Mao et al., 2013).

Deposit geology
The Tieshajie deposit is situated in the northeastern domain of the QHMB, northeastern Jiangxi Province (Fig. 1).The strata exposed in the mine area include the Meso-Neoproterozoic Tieshajie Group and Lower-Middle Jurassic Linshan Group (Fig. 2A, B).The Tieshajie Group occurs in the central part of the area.It is a marine 1081-m-thick extrusivesedimentary rock sequence, including phyllite, slate, silty sandstone, greywacke, basalts, spilite, quartz keratophyre, limestone, tuff, rhyolite, and marble rocks.The initial lithostratigraphic sequence of the Tieshajie Group has been disintegrated, with now the rhyolites, basalts, and marbles are intercalated (Cheng et al., 1991).Zircon U-Pb age constrains formation time of the Tieshajie Group, including a quartz keratophyre (1201-1091 Ma; He et al., 2008), basalts (1012 ± 4 Ma; Wang et al., 2018), rhyolite (1132-1172 Ma;Gao et al., 2013), spilite (1153-980 Ma;Luo, 2010) and tuff (1109 ± 3 Ma; Zhu, 2017).The Tieshajie Group is unconformably overlain by the Jurassic Linshan Group in the south of the area, which predominantly consists of conglomerate, sandstone, and siltstone.The intrusive rocks primarily consist of granite porphyry and quartz porphyry dikes, emplaced in the Meso-Neoproterozoic Tieshajie Fig. 2. A. Geologic map of the Tieshajie area (modified after Wang et al., 2018).B. Geological map of the Tieshajie deposit (modified after Zhu, 2017).Orebodies V, V 6 and V 9 are projected to the surface.C. Cross section of the Tieshajie Cu deposit (modified after Wang et al., 2018).
C. Jiang et al.
Group.The granite porphyry occurs in the central and northwestern parts of the mine area.The E-W striking quartz porphyry dikes are mostly exposed adjacent to the southern part of the mine area, and vary in width from 15 to 20 m and continue along strike for about 800 m, and have a whole rock K-Ar age of 158.1 Ma (Luo, 2010).The predominant structures in the area are E-W and NNE-SSW-striking faults which were formed along the weak zones of the Tieshajie Group (Wang et al., 2018), for example, the E-W-striking Caopinwu-Zhangjialong faults, which strike 180 to 200 • and dip 70 to 90 • .
In the mine area, there are twenty-six lenticular, and stratiform-like Cu orebodies that extend from 226 m (surface) to − 220 m in elevation.These orebodies are mostly contained inside the interlayered fracture zones and are parallel to each other, with a distance of generally 15-30 m between adjacent orebodies (Fig. 2C).The orebodies dip north at 80 to 85 • , range in average thickness from 3.5 to 5 m and have an average strike length of about 400 m.
Based on previous studies and field investigation, we have identified three-style of ores in the Tieshajie deposit: 1) massive ores (Fig. 3A, B), 2) disseminated ores (Fig. 3C, D), and 3) veinlet ores (Fig. 3E, F).Style 1 mineralization is primarily observed in the central part of the orebodies.The ore minerals consist of chalcopyrite, pyrite, and arsenopyrite with minor galena and sphalerite.The major gangue minerals are quartz, actinolite, K-feldspar, and sericite with minor calcite, and titanite.Chalcopyrite is the major ore mineral in the style 1 mineralization, coexisting with anhedral pyrite, euhedral fine-grained arsenopyrite, galena, and sphalerite.The sulfides are intergrown with subhedral quartz, actinolite, and K-feldspar, as well as fine-grained sericite, calcite, and titanite, forming massive ores (Fig. 4A).In addition, framboidal and gelatinous pyrite have been documented in previous publications in the massive ores (Xu, 1992;Wang et al., 2018;Ni and Wang, 2017).Style 2 mineralization predominantly occurs in the host volcanic rock.The ore minerals primarily consist of chalcopyrite, pyrite, and sphalerite, while gangue minerals are dominated by quartz, actinolite, calcite, sericite, and chlorite with minor K-feldspar.Chalcopyrite, pyrite, and sphalerite occur as subhedral to anhedral grains in disseminated ores, while quartz and actinolite occur as subhedral grains together with anhedral finegrained calcite, sericite, and chlorite forming aggregates (Fig. 4B-D).Style 3 mineralization is primarily developed in the margin of orebodies.Ore minerals primarily comprise of chalcopyrite, pyrite, arsenopyrite, and sphalerite, while the major gangue minerals contain quartz, sericite, calcite, and chlorite.Chalcopyrite, pyrite, arsenopyrite are subhedral to anhedral in quartz-calcite veinlets; sericite and chlorite occur as euhedral to subhedral grains in the veinlets of sulfide-quartz-calcite (Fig. 4E-I).
Ore-related hydrothermal alteration in the Tieshajie deposit includes silicification, actinolitization, potassic alteration, sericitization, and chloritization.Silicification is developed, and is represented as veins or disseminations in all the three-style of ores.Actinolitization mainly occurs as radial and needle-like actinolite in massive and disseminated ore (Fig. 4B).Potassic alteration is commonly associated with massive mineralization, and is in an assemblage with chalcopyrite (Fig. 3G-H).Sericite and chlorite predominantly occur as clusters in disseminated

Sampling and analytical methods
We took 10 representative samples from the V9 orebody (underground − 200 m).Field investigation, petrographic and mineragraphic studies have been conducted, and then we focused on samples from different ore types (see details below) suitable for geochronological and S-Cu isotope studies.The titanite samples were collected from disseminated ore (TSJ-05) and were used for trace elemental analyses and in-situ LA-ICP-MS U-Pb dating.Sample TSJ-05 consists of quartz (35 vol%), chlorite (30 vol%), chalcopyrite (25 vol%), pyrite (5 vol%), titanite (4 vol%), and arsenopyrite (1 vol%), with minor amounts of calcite.Carefully prepared polished thin sections were subjected to thorough examination using both transmitted and reflected light microscopy to discern and analyze the intricate mineral paragenetic relationships.In particular, detailed investigations were conducted utilizing backscattered electron (BSE) image to discern titanite morphology and internal structures.The findings demonstrate that the titanite grains are intergrown with Cu sulfides, exhibiting a size range primarily between 0.1 and 1.5 mm (euhedral to subhedral), lacking any oscillatory zoning (Fig. 5).Titanite grains were scrutinized utilizing photomicrographs and BSE images for imperfections such as fractures, inclusions, or alterations, and suitable targets were recorded in a series of high-definition images, which were subsequently utilized for trace-element and U-Pb dating analyses.
The analytical methods of Re-Os and in-situ S isotopes of chalcopyrite are presented in the Appendix.

Trace element of titanite
All the in-situ trace elements analysis of titanite were analyzed at the State Key Laboratory of Continental Dynamics, Northwest University, China.In-situ mineral trace element was performed on thin sections using an Agilent 7900 ICP-MS coupled with RESOlution M-50 193-nm ArF Excimer Laser Ablation system.Helium and argon gases were mixed using a T-connector prior to their introduction into the ICP.Laser ablation spot sizes were set to a width of 37 μm for trace element analysis of minerals.For multiple-standard calibration, standard materials including SRM610, BIR-1G, and BCR-2G were utilized.The internal calibration standard was 29 Si, and NIST 610 functioned as the external calibration standard.To achieve reliable trace element analysis, offline signal selection techniques were employed using the Excel-based tool ICPMSDataCal.These techniques involved synthesizing background and analyzed signals, correcting for temporal drift, and performing quantitative calibration (Liu et al., 2008).

In-situ LA-ICP-MS U-Pb titanite dating
In-situ U-Pb isotopes analyses of titanite from the sample disseminated ores were carried out at Yanduzhongshi Geological Analysis Laboratories in China, using an Analytikjena M90 quadrupole ICPMS equipped with a 193 nm NWR193 Ar-F excimer laser.The laser diameter of 20 μm was applied to each spot analysis, with a 7 Hz repetition rate.The dwell time for the isotopes was as follows: 10 ms for 29 Si, 43 Ca, 232 Th and 238 U, 15 ms for 204 Pb, 206 Pb and 208 Pb, and 30 ms for 207 Pb.
Each measurement involved a 20-second background acquisition, succeeded by a 60-second data acquisition from the sample.Subsequently, a 60-second period was designated for the purpose of purging the sample cell and plumbing lines.The matrix-matched BLR-1 titanite, with a known age of 1041.1 ± 0.4 Ma (Aleinikoff et al., 2007), was utilized as a calibration material to account for mass discrimination and U-Pb isotope fractionation.As a quality control material, the OLT-1 titanite (1015 ± 2 Ma; Kennedy et al., 2010) was approved for use in the method.The ICPMSDatCal 10.2 software was used for data reduction, which involved selective signal integration and converting integrated signals to element concentrations (Liu et al., 2010).

Fs-LA-MC-ICP-MS in-situ Cu isotope of chalcopyrite
In-situ Cu isotope analyses of chalcopyrite were done at the State Key Laboratory of Continental Dynamics, Northwest University, Xi'an, using a Neptune Plus™ MC-ICP-MS combined with an NWR Femto UC dualwave femtosecond laser ablation (ESI, USA) at SKLCD.The sophisticated line-scan mode was used for all measurements, which had parameters including a diameter of 20 μm, an 8 Hz laser repetition rate, a 1 μm s − 1 scan speed, and a 0.5 J cm − 2 laser energy density.Each individual measurement extended over a duration of 142.4 s, encompassing significant stages such as a meticulous 30-second background measurement, followed by a precise 52.4-second data acquisition phase.Subsequently, a thorough 60-second washout period was employed to ensure the removal of any residual effects.The experimental lines utilized for these analyses exhibited an approximate length of 52.4 μm, facilitating a comprehensive assessment of the sample.During the analysis, instrument drift and mass bias were corrected utilizing the standard-sample bracketing (SSB) method.Chalcopyrite was measured using the external standard TC1725 (Bao et al., 2021a, δ 65 Cu = − 0.06 ‰), and the accuracy of the measurement was assessed using an inhouse standard (CPY-1, chalcopyrite, δ 65 Cu = +0.06‰, Bao et al., 2021b) as a control-quality standard.Cu isotope data are represented as δ 65 Cu values relative to the NIST SRM 976 standard in delta notation: δ 65 Cu NIST976 = [( 65 Cu/ 63 Cu sample )/( 65 Cu/ 63 Cu) TC1725 − 1] × 1000 + δ 65 Cu NIST976(TC1725) .The detailed in-situ Cu isotope-analysis procedures are elaborated in Bao et al., (2021b) and Lv et al. (2022).

In-situ U-Pb age of titanite
Eighteen spots were examined on eighteen titanite grains from sample TSJ-5.The U-Pb isotope data acquired from these titanite samples are depicted on a Tera-Wasserburg diagram, exhibiting a welldefined linear array.This linear array yields a lower intercept age of 161.4 ± 6.0 Ma (MSWD = 1.6) (Fig. 6B; Appendix Table A2).The weighted average 206 Pb/ 238 U age after 207 Pb-correction is 160.1 ± 4.4 Ma (MSWD = 1.2) (Fig. 6B), consistent with the lower-intercept age within error.

Re-Os isotopes of chalcopyrite
Ten analyses of chalcopyrite at Tieshajie contain low total Re (0.2528 to 4.5999 ppb), low 187 Os (0.0026 to 0.0211 ppb) and common Os ranging between 0.0085 and 0.0565 ppb.The ranges of 187 Os to common Os vary from 0.19 to 0.47, showing significantly low ratios of radiogenic 187 Os.The 187 Re/ 188 Os and 187 Os/ 188 Os data exhibit scatter around a regression line (Fig. 9A), and yield a low-quality isochron age (253 ± 75 Ma, MSWD = 11644).However, five samples (20TSJ-03, 04, 09, 10, and 11) among the ten samples define a flat-slope isochron with a relatively high-quality age of 188 ± 30 Ma (MSWD = 183) (Fig. 9A).A model age for the system cannot be determined because of the particularly low radiogenic 187 Os and low 187 Re/ 188 Os ratios ranging from 46.1 to 614.0 (Table 2).

The timing of the Tieshajie Cu mineralization
Zircon U-Pb ages of the Tieshajie Group range from 1201 to 980 Ma (He et al., 2008;Wang et al., 2018;Gao et al., 2013;Luo, 2010;Zhu, 2017), representing the age of the host rock.It was hoped that the Re-Os study conducted here would directly date the mineralization.The Re-Os isotope data from chalcopyrite have extremely low Re concentrations (mostly < 1 ppb), low 187 Re/ 188 Os ratios (46.1-614.0),slightly radiogenic 187 Os/ 188 Os values (0.85-3.60), and yield a low-quality isochron age (253 ± 75 Ma, MSWD = 11644) (Table 2; Fig. 9A).This seems likely to be caused by Re loss, leading to low radiogenic 187 Os/ 188 Os values.Re loss would cause the isochron anticlockwise rotation (raising the slope) and drive samples to the lower left of the true isochron (e.g., Mathur et al., 1999;Kemppinen et al., 2018).If the samples with the lowest Re concentrations (0.181-0.847 ppb) are excluded from the calculation, the remaining five samples (20TSJ-03, 04, 09, 10, and 11) with higher Re concentrations (0.455-4.600 ppb) define a relatively flat-slope isochron (Fig. 9A), yielding a relatively high-quality age (188 ± 30 Ma, MSWD = 183).Given that Re loss would define the isochron age older than the true age, the true Re-Os isochron age ought to be younger than 188 Ma.
Hydrothermal titanite U-Pb dating has demonstrated its efficacy as a reliable approach for directly ascertaining the chronology of mineralization events (Jemielita et al., 1990;Frost et al., 2001;Li et al., 2010).Titanite coexisting with chalcopyrite (Fig. 5) is characterized by low concentrations of Th/U (0.15-0.45) and REE (121-3200 ppm, mean = 679 ppm), and displays left-leaning REE patterns with light REE depletion (Fig. 6A), demonstrating a hydrothermal genesis (Aleinikoff et al., 2002;Frost et al., 2001;Li et al., 2010).Moreover, the titanite U-Pb age of 160.1 ± 4.4 Ma is coeval with a K-Ar age of 158.1 Ma obtained for the quartz porphyry in the area (Luo, 2010).Therefore, our new titanite U-Pb age indicates that there is a ca.160 Ma magmatichydrothermal event at Tieshajie which resulted in Cu mineralization.

Ore-forming material sources
The absence of sulfate minerals in the Tieshajie deposit indicates that the sulfur isotope of H 2 S would mostly influence the δ 34 S values of sulfide, independent of pH and oxygen fugacity (fO 2 ) (Ohmoto and Rye, 1979).Therefore, it is reasonable to assume that H 2 S was the main sulfur species present in the ore-forming fluid, which means that the δ 34 S value  A4.The MORB, basalt, and granite data from Rollinson (1993). of sulfide represents the bulk sulfur isotopic composition in the fluid of the Tieshajie deposit.In combination with previous S isotope data of sulfide, the sulfide of Tieshajie has δ 34 S value ranging from +2.0 to +7.7 ‰ (Fig. 7; Appendix Table A3, A4; Luo, 2010;He et al., 2008;Zhu, 2017;Ye, 1987; this study), which is slightly higher than the characteristics of magma sulfur (0 ± 3 ‰; Ohmoto and Goldhaber, 1997).Furthermore, Zheng (2020) reported whole rock δ 34 S values (+3.2 to +7.2 ‰) for the Tieshajie Group in the region.Thus, the range of δ 34 S values at Tieshajie suggests a magmatic source with some input of sulfur from the Tieshajie Group.
The chalcopyrite has extremely low Re concentration (mostly <1 ppb), which is inconsistent with sulfides from typical VMS deposits (Fig. 9B).The Re-Os isotope characteristics have been commonly utilized to trace ore metal sources (Morelli et al., 2007;Li et al., 2018;Soares et al., 2021).If the Meso-Neoproterozoic age was utilized to determine the initial 187 Os/ 188 Os ratios of chalcopyrite, the ratios have both positive and negative values (− 6.84 to 1.04; Table 2), which cannot be explained by a geological scenario.By comparison, the initial 187 Os/ 188 Os ratios (0.74 to 2.00; Table 2) calculated at an age of 160 Ma imply a significant crustal derivation ( 187 Os/ 188 Os (mantle-derived magma) ≈ 0.12, 187 Os/ 188 Os (upper crust) = 1.69;Shirey and Walker, 1998;Esser and Turekian, 1993).In general, chalcopyrite from ancient VMS deposits   Housh and Çiftçi, 2008;Mason et al., 2005;Ikehata et al., 2011;Deng et al., 2019), and particularly the Δδ 65 Cu within a single ancient VMS deposit is commonly less than 1‰, which are distinct from the δ 65 Cu values (− 1.13 to +0.12 ‰) at Tieshajie.Furthermore, the negative δ 65 Cu trend from massive ore to veinlet ore at Tieshajie correlates to a hydrothermal alteration transformation from potassic to phyllic (Fig. 8B; Table 1), likely suggesting that negative Cu isotope fractionation is more readily induced under stronger acidic hydrothermal conditions (Maher et al., 2011;Gregory and Mathur, 2017).In summary, all the observations indicate the magmatic-hydrothermal origin of the Tieshajie Cu deposit, and the ore-forming material is primarily derived from magmatic-hydrothermal fluids, while there is a minor contribution from the host rock via fluid-rock interactions.

A genetic model for the Tieshajie Cu mineralization
The consistency of the quartz porphyry and hydrothermal titanite ages suggests a link between the granite intrusions and the mineralization.Therefore, we propose that the Tieshajie Cu deposit may belong to the distal part of a Late Jurassic porphyry system.The orebodies are hosted within the Neoproterozoic meta-sedimentary rock of the Tieshajie Group but the mineralization is genetically relevant to the intrusions with an age of ~160 Ma.Following this, at ca. 160 Ma, when the rising magmas were emplaced into the host rock, the fracture zone in the area reactivated and expanded.The magmatic-hydrothermal fluids emanating from intrusions interacted with the host rock to generate hydrothermal alteration and form the Cu orebodies in the fractures.The age of the Tieshajie Cu deposit is coeval with the Mid-Late Jurassic (170-150 Ma) magmatic-hydrothermal metallogenic event in the QHMB (Mao et al., 2011(Mao et al., , 2013) (Fig. 10; Appendix Table A7).This event is interpreted to be connected with the subduction of the Paleo-Pacific plate (Mao et al., 2021) Luo, 2010;Zhu, 2017) is similar to the Pacific subduction sediments and enriched mantle (Appendix Fig. A1), and is partially overlapping with the Dexing porphyry Cu-related rocks (Appendix Fig. A2).Therefore, we propose that the Tieshajie Cu mineralization is a Late Jurassic magmatic-hydrothermal mineral system, probably induced by the subduction of the Paleo-Pacific plate.As such, the scenario that the Neoproterozoic VMS deposits and the generation of the coeval metal-rich juvenile crust in the QHMB are the "vital step" in the development of the widespread Mesozoic porphyry copper-gold mineralization at a regional scale may need to be reassessed.Os (e λt − 1), where λ is the 187 Re decay constant (λ = 1.666 × 10 − 11 year − 1 ) (Smoliar et al., 1996).A7.
Fig.1.A. Schematic map of tectonic domains of China.B. Spatial distribution of the major mineral deposits in the Qin-Hang metallogenic belt in South China (modified after Ni et al., 2015; Mao et al., 2013).

Fig. 3 .
Fig. 3. Photographs of the ores at the Tieshajie deposit. A. Photograph of the massive sulfide ores.B. Photograph of the massive sulfide ore.C. Photograph of the massive and disseminated sulfide ores, and host rock.D. Photograph of the carbonatization, silicification and potassic alteration in the disseminated ore.E. Photograph of the veins of chalcopyrite-quartz in the metamorphic volcanic-sedimentary rocks.F. Photograph of the veinlet sulfide ore.G. Photograph of the potassic alteration and chloritization.H. Photograph of the intense potassic alteration.I. Photograph of the chloritization and sericitization in the rhyolite.Abbreviations: Cal = calcite, Ccp = chalcopyrite, Chl = chlorite, Kfs = K-feldspar, Qz = quartz, Ser = sericite.

Fig. 7 .
Fig. 7. A. Histograms of δ 34 S values of sulfides in the Tieshajie deposit.Data sources from Appendix Table A3.B. Diagram showing variation in δ 34 S values of sulfide in the Tieshajie deposit, compared to previous studies on sulfides from the Yanshanian deposits in the northeastern part of QHMB, including the Yongping skarn Cu deposit, the Dexing porphyry Cu deposit, the Longtougang skarn Cu-Pb-Zn deposit, the Yinshan epithermal Cu deposit, the Lengshuikeng Ag-Pb-Zn deposit, the Tongshan skarn Cu deposit, and the Pingshui Cu deposit.Data source from Appendix TableA4.The MORB, basalt, and granite data fromRollinson (1993).

Fig. 8 .
Fig. 8. A. Diagram showing variation in δ 65 Cu values of chalcopyrite in the Tieshajie deposit, compared to previous studies on copper-rich minerals from porphyry deposits, high-sulfidation epithermal deposits, skarn deposits, ancient VMS deposits, modern seafloor chimneys, sediment-hosted stratiform copper (SSC) deposits, vein-type deposits.Data source from Appendix Table A6.B. Diagram showing variation in δ 65 Cu values of different ores in the Tieshajie deposit.
new titanite U-Pb age of 160.1 ± 4.4 Ma and the chalcopyrite Re-Os dating indicate an epigenetic magmatic-hydrothermal origin instead of a Neoproterozoic VMS origin for the Tieshajie Cu mineralization.2. The Re-Os and in-situ S-Cu isotope compositions of sulfides indicate asignificant crustal contribution to the hydrothermal system.Oreforming material is mainly from magmatic-hydrothermal fluids with minor contributions from the host rocks via fluid-rock interaction.3. The Tieshajie Cu mineral system is a distal part of the Late Jurassic porphyry-skarn metallogenic event in the QHMB, South China,

Fig. 10 .
Fig. 10.Compilation of geochronological data for the Yanshanian deposits in the northeastern part of QHMB.Data source from Appendix TableA7.

Table 1
In-situ copper isotopic compositions of chalcopyrite from the Tieshajie deposit.