Genesis of the Shaquanzi Zn–Pb deposit in the Eastern Tianshan, NW China: Constraints from geology, fluid inclusion and isotope geochemistry
Genesis of the Shaquanzi Zn–Pb deposit in the Eastern Tianshan, NW China: Constraints from geology, fluid inclusion and isotope geochemistry
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DOI：
10.1016/j.oregeorev.2023.105820
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发表时间：
2023-12
影响因子：
3.3
通讯作者：
Wanjian Lu;Yu Zhang;Liandang Zhao;Hong-Jun Jiang;Jiangtao Huang
中科院分区：
文献类型：
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作者：
Wanjian Lu;Yu Zhang;Liandang Zhao;Hong-Jun Jiang;Jiangtao Huang
沙泉子铅锌存款矿床位于中天山地体，主要产于中元古界卡瓦布拉克群硅质板岩和碳质大理岩中，矿化/蚀变可划分为矽卡岩期（I：早期矽卡岩阶段，II：晚期矽卡岩阶段），石英-硫化物阶段（Ⅲ：早期硫化物阶段，Ⅳ：晚期硫化物阶段，Ⅴ：石英-方解石阶段）和表生期（Ⅵ：表生蚀变阶段）。在矽卡岩期和石英-硫化物期的石榴石、石英、方解石、方解石中发现了W型流体包裹体。详细的流体包裹体研究表明，流体的温度从阶段I（510-520 °C）降低到阶段III（481-507 °C）、阶段IV（248-417 °C，峰值在280-400 °C）到阶段V（148-260 °C，峰值在200-220 °C），盐度为20.8- 22.2wt%NaCl当量，19.8-29.1重量% NaCl当量，10.6-27.8重量% NaCl当量（峰值在20-23重量%）和21.6-29.9重量% NaCl当量。(peak 23- 27wt%），表明成矿流体为高-中盐度、富Na-Mg-Fe-Ca的流体体系，可能是从高-中温向中温演化的。H-O同位素组成从第三阶段（δ 18 OH 2 O = 7.7 ‰ ~ 9.0 ‰，δ DH 2 O = − 105 ‰ ~ − 91 ‰）至Ⅳ期（δ 18 OH 2 O = 2.6 ‰ ~ 4.3 ‰，δ DH 2 O = − 114 ‰ ~ − 111 ‰）至第Ⅴ期（δ 18 OH 2 O = − 4.2 ‰ ~ − 3.7 ‰，δ DH 2 O = − 119 ‰ ~ − 96 ‰），表明成矿流体来源可能由岩浆流体演化为大气降水。早期硫化物、晚期硫化物和石英-方解石阶段的δ 34 SH 2 O平均值分别为5.7 ‰、8.5 ‰和14.0 ‰，表明早期硫主要来源于岩浆热液硫，而晚期δ 34 SH 2 O值的增加可能来源于卡瓦布拉克群的水岩反应。因此，我们认为沙泉子可能是一个矽卡岩型锌铅存款矿床。
The Shaquanzi Zn–Pb deposit, located in the Central Tianshan Terrane, is mainly hosted by siliceous slates and carbonaceous marbles of the Mesoproterozoic Kawabulake Group, and its mineralization / alteration can be divided into skarn period (I: early skarn stage, II: late skarn stage), quartz-sulfide period (III: early sulfide stage, IV: late sulfide stage and V: quartz-calcite stage) and supergene period (VI: supergene alteration stage). The W-type fluid inclusions (FIs) were identified in the garnet, chlorite, quartz, and calcite in skarn and quartz-sulfide periods. Detailed fluid inclusion study shows temperature of fluids decreased from Stage I (510–520 °C) through, Stage III (481–507 °C), Stage IV (248–417 °C, peak at 280–400 °C) to Stage V (148–260 °C, peak at 200–220 °C), with salinities of 20.8–22.2 wt% NaCl eqv., 19.8–29.1 wt% NaCl eqv., 10.6–27.8 wt% NaCl eqv. (peaks at 20–23 wt%), and 21.6–29.9 wt% NaCl eqv. (peak at 23–27 wt%), respectively, indicating that the ore-forming fluids consisted of a high-medium salinity and Na-Mg-Fe-Ca-rich fluid system, and may have evolved from high-medium temperature to medium temperature. The H–O isotopic compositions varied from Stage III (δ18OH2O= 7.7 ‰–9.0 ‰ and δDH2O= − 105 ‰ to − 91 ‰) through Stage IV (δ18OH2O= 2.6 ‰ to 4.3 ‰ and δDH2O= − 114 ‰ to − 111 ‰) to Stage V (δ18OH2O= − 4.2 ‰ to − 3.7 ‰ and δDH2O= − 119 ‰ to − 96 ‰), suggesting that the ore-forming fluid sources may have evolved from magmatic fluids to meteoric water. The average δ34SH2Ovalues of the early sulfide, late sulfide, and quartz-calcite stages are 5.7 ‰, 8.5 ‰ and 14.0 ‰, respectively, indicating that the sulfur in the early stage was mainly derived from magmatic hydrothermal sulfur, while the increase of the δ34SH2Ovalues in the late stages is likely to be sourced from the Kawabulake Group through water–rock reaction. Above all, we propose that the Shaquanzi may have been a skarn-type Zn–Pb deposit.