Sulfur and Lead Isotope Compositions of the Xiaohe Gold Deposit at Xunyang, Shaanxi Province, and Its Geological Significance

doi:10.19657/j.geoscience.1000-8527.2021.115

Abstract

Abstract:

The Xiaohe is a medium-sized gold deposit discovered in the central belt of the South Qinling Orogen in recent years. The ores are fine-disseminated, and the orebodies are controlled by both strata and structures. Based on field work, four metallogenic stages are divided according to mineral assemblages and crosscutting relationships: Ⅰ. Quartz veins with little sulfide in early-ore-stage; Ⅱ. Quartz veins with main-ore-stage pyrite and arsenopyrite in main mineralization stage; Ⅲ. Quartz veins with main-ore-stage polymetallic sulfides; Ⅳ. Late-ore-stage calcite and quartz veins. Stage Ⅱ and Ⅲ are the main gold mineralization stages. In situ sulfur isotope analysis show that the δ³⁴S value of stage Ⅰ pyrite=20.80‰-25.77‰ (avg.23.59‰), stage Ⅱ pyrite and arsenopyrite=15.46‰-19.12‰ (avg.17.5‰), stage Ⅲ galena and sphalerite=11.35‰-16.78‰ (avg.13.88‰). This indicates that the sulfur is mainly sedimentary-sourced, and there is continuous addition of low-δ³⁴S hydrothermal fluid during the ore-forming process. The sulfide Pb isotope analysis yielded ²⁰⁶Pb/²⁰⁴Pb=17.882,1-18.367,4, ²⁰⁷Pb/²⁰⁴Pb=15.614,0-15.674,1, and ²⁰⁸Pb/²⁰⁴Pb=38.016,3-38.934,2, indicating that the lead was derived mainly from the crust with certain mantle input. Based on the deposit geological and S and Pb isotope characteristics, we suggest that fluid mixing occurred in the Xiaohe gold mineralization.

Key words: Xiaohe gold deposit, metallogenic stage, sulfur isotope, lead isotope, south Qinling Orogen

CLC Number:

P618.51

MENG Wuyi, LIU Jiajun, WEI Liyong, ZHANG Zhen, WU Huanhuan, FAN Baocheng, PAN Yuan, LI Guoying, JIA Bin. Sulfur and Lead Isotope Compositions of the Xiaohe Gold Deposit at Xunyang, Shaanxi Province, and Its Geological Significance[J]. Geoscience, 2021, 35(06): 1587-1596.

Figures/Tables 11

References 32

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样品编号	矿石类型	成矿阶段	δ³⁴S/‰
y20-py1	黄铁矿	Ⅰ	25.77±0.14
y20-py2		Ⅰ	25.25±0.19
y20-py3		Ⅰ	23.42±0.19
y20-py4		Ⅰ	22.71±0.17
y20-py5		Ⅰ	20.80±0.35
y20-py6		Ⅱ	19.86±0.19
y20-py7		Ⅱ	19.38±0.18
y19-py1		Ⅱ	19.12±0.17
y19-py2		Ⅱ	17.94±0.17
y19-py3		Ⅱ	16.29±0.51
y19-apy1	毒砂	Ⅱ	15.50±0.45
y19-apy2		Ⅱ	15.46±0.46
y19-apy3		Ⅱ	16.43±0.47
y21-sp1	闪锌矿	Ⅲ	16.39±2.47
y21-sp2		Ⅲ	16.31±2.36
y22-sp3		Ⅲ	15.73±0.17
y22-sp4		Ⅲ	16.78±0.18
y22-gal1	方铅矿	Ⅲ	11.71±0.37
y21-gal2		Ⅲ	11.44±0.25
y22-gal3		Ⅲ	11.35±0.32
y21-gal4		Ⅲ	11.29±0.28

样品编号	矿石类型	成矿阶段	δ³⁴S/‰
y20-py1	黄铁矿	Ⅰ	25.77±0.14
y20-py2		Ⅰ	25.25±0.19
y20-py3		Ⅰ	23.42±0.19
y20-py4		Ⅰ	22.71±0.17
y20-py5		Ⅰ	20.80±0.35
y20-py6		Ⅱ	19.86±0.19
y20-py7		Ⅱ	19.38±0.18
y19-py1		Ⅱ	19.12±0.17
y19-py2		Ⅱ	17.94±0.17
y19-py3		Ⅱ	16.29±0.51
y19-apy1	毒砂	Ⅱ	15.50±0.45
y19-apy2		Ⅱ	15.46±0.46
y19-apy3		Ⅱ	16.43±0.47
y21-sp1	闪锌矿	Ⅲ	16.39±2.47
y21-sp2		Ⅲ	16.31±2.36
y22-sp3		Ⅲ	15.73±0.17
y22-sp4		Ⅲ	16.78±0.18
y22-gal1	方铅矿	Ⅲ	11.71±0.37
y21-gal2		Ⅲ	11.44±0.25
y22-gal3		Ⅲ	11.35±0.32
y21-gal4		Ⅲ	11.29±0.28

原始样号	样品名	矿石类型	²⁰⁶Pb/²⁰⁴Pb	²⁰⁷Pb/²⁰⁴Pb	²⁰⁸Pb/²⁰⁴Pb	μ	ω	Th/U	Δα	Δβ	Δγ
y01	石英脉矿石	毒砂	17.882 1	15.617 4	38.284 5	9.56	39.09	3.96	74.61	21.31	46.67
y02	粉砂质板岩	黄铁矿	18.128 2	15.631 7	38.468 2	9.56	38.54	3.90	76.15	21.30	44.53
y03	粉砂质板岩	黄铁矿	18.290 7	15.668 0	38.630 3	9.61	38.64	3.89	79.88	23.28	45.69
y04	石英方解石脉	黄铁矿	18.183 7	15.652 6	38.524 7	9.59	38.66	3.90	78.29	22.59	45.44
y05	粉砂质千枚岩	黄铁矿	18.302 5	15.674 1	38.627 6	9.62	38.62	3.89	80.50	23.68	45.57
y06	黄铁矿化石英脉	黄铁矿	18.276 2	15.661 1	38.464 6	9.60	37.95	3.83	79.19	22.84	41.29
y07	黄铁矿化石英脉	黄铁矿	17.957 0	15.614 0	38.016 3	9.55	37.42	3.79	74.36	20.73	36.80
y08	黄铁矿化石英脉	黄铁矿	18.278 4	15.661 4	38.458 8	9.60	37.92	3.82	79.24	22.86	41.09
y09	黄铁矿化石英脉	黄铁矿	18.274 3	15.661 1	38.463 2	9.60	37.96	3.83	79.24	22.85	41.34
y10	黄铁矿化石英脉	黄铁矿	18.258 4	15.655 9	38.438 6	9.59	37.90	3.82	78.71	22.54	40.90
y11	铅锌矿化石英脉	方铅矿	18.304 3	15.672 8	38.636 3	9.62	38.63	3.89	80.36	23.57	45.67
y12	铅锌矿化石英脉	方铅矿	18.341 5	15.672 3	38.603 3	9.61	38.27	3.85	80.37	23.40	43.57
y13	铅锌矿化石英脉	方铅矿	18.302 3	15.671 5	38.636 0	9.62	38.63	3.89	80.24	23.50	45.66
y14	铅锌矿化石英脉	方铅矿	18.308 3	15.671 6	38.629 0	9.62	38.56	3.88	80.27	23.48	45.30
y15	黄铁矿化砂岩	黄铁矿	18.304 8	15.663 8	38.934 2	9.60	39.79	4.01	79.50	22.93	53.24
y16	黄铁矿化砂岩	黄铁矿	18.367 4	15.662 6	38.624 7	9.59	38.12	3.85	79.48	22.63	42.81

原始样号	样品名	矿石类型	²⁰⁶Pb/²⁰⁴Pb	²⁰⁷Pb/²⁰⁴Pb	²⁰⁸Pb/²⁰⁴Pb	μ	ω	Th/U	Δα	Δβ	Δγ
y01	石英脉矿石	毒砂	17.882 1	15.617 4	38.284 5	9.56	39.09	3.96	74.61	21.31	46.67
y02	粉砂质板岩	黄铁矿	18.128 2	15.631 7	38.468 2	9.56	38.54	3.90	76.15	21.30	44.53
y03	粉砂质板岩	黄铁矿	18.290 7	15.668 0	38.630 3	9.61	38.64	3.89	79.88	23.28	45.69
y04	石英方解石脉	黄铁矿	18.183 7	15.652 6	38.524 7	9.59	38.66	3.90	78.29	22.59	45.44
y05	粉砂质千枚岩	黄铁矿	18.302 5	15.674 1	38.627 6	9.62	38.62	3.89	80.50	23.68	45.57
y06	黄铁矿化石英脉	黄铁矿	18.276 2	15.661 1	38.464 6	9.60	37.95	3.83	79.19	22.84	41.29
y07	黄铁矿化石英脉	黄铁矿	17.957 0	15.614 0	38.016 3	9.55	37.42	3.79	74.36	20.73	36.80
y08	黄铁矿化石英脉	黄铁矿	18.278 4	15.661 4	38.458 8	9.60	37.92	3.82	79.24	22.86	41.09
y09	黄铁矿化石英脉	黄铁矿	18.274 3	15.661 1	38.463 2	9.60	37.96	3.83	79.24	22.85	41.34
y10	黄铁矿化石英脉	黄铁矿	18.258 4	15.655 9	38.438 6	9.59	37.90	3.82	78.71	22.54	40.90
y11	铅锌矿化石英脉	方铅矿	18.304 3	15.672 8	38.636 3	9.62	38.63	3.89	80.36	23.57	45.67
y12	铅锌矿化石英脉	方铅矿	18.341 5	15.672 3	38.603 3	9.61	38.27	3.85	80.37	23.40	43.57
y13	铅锌矿化石英脉	方铅矿	18.302 3	15.671 5	38.636 0	9.62	38.63	3.89	80.24	23.50	45.66
y14	铅锌矿化石英脉	方铅矿	18.308 3	15.671 6	38.629 0	9.62	38.56	3.88	80.27	23.48	45.30
y15	黄铁矿化砂岩	黄铁矿	18.304 8	15.663 8	38.934 2	9.60	39.79	4.01	79.50	22.93	53.24
y16	黄铁矿化砂岩	黄铁矿	18.367 4	15.662 6	38.624 7	9.59	38.12	3.85	79.48	22.63	42.81