南秦岭柞水—山阳矿集区夏家店金矿床黄铁矿微量元素和氢、氧、硫同位素对矿床成因的制约

为了研究柞水—山阳矿集区夏家店金矿床成因,采用LA-ICP-MS和LA-MC-ICP-MS技术分析夏家店金矿床矿体及围岩样品中黄铁矿原位微量元素及氢、氧、硫同位素组成特征。结果表明,该矿床黄铁矿的Co/Ni 比值为0.11~0.76,说明其与沉积作用有关。矿石中黄铁矿的δ³⁴S值(-9.40‰~7.16‰)与围岩碳质板岩的δ³⁴S值(-8.84‰~10.64‰)接近,黄铁矿的δ³⁴S均值(2.47‰)基本落在岩浆硫的范围内,指示矿石硫可能由地层硫和岩浆硫混合而成。氢、氧同位素测试结果表明,夏家店矿床成矿流体可能主要来自岩浆水,成矿后期有大气降水的加入。综合矿床地质特征、成矿温度、金赋存状态等特征和黄铁矿微量元素、硫同位素组成可知,夏家店金矿床属于卡林型金矿,其成矿流体主要来自岩浆水,成矿后期有大气降水加入;其成矿物质是由深部岩浆与地层混合而成。

Pyrite Trace Element,Hydrogen, Oxygen,and Sulfur Isotope Geochemistry of the Xiajiadian Gold Deposit in Zhashui-Shanyang Orefield,South Qinling Orogen,and Its Metallogenic Constraints

To clarify the genesis of Xiajiadian gold deposit in the Zhashui-Shanyang orefield, in-situ trace element, hydrogen, oxygen and sulfur isotope compositions of the ore pyrite and wallrock samples were analyzed by LA-(MC)-ICP-MS techniques. The results show that the pyrite Co/Ni ratio ranges from 0.11 to 0.76, indicating that it is sedimentary pyrite. The pyrite δ³⁴S value (-9.40‰ to 7.16‰) is close to that of the carbonaceous slate wallrock (-8.84‰ to 10.64 ‰), whilst the average pyrite δ³⁴S value (2.47‰) falls within the magmatic sulfur range, suggesting that the ore sulfur may have sourced from the mixing of sedimentary sulfur with magmatic sulfur. The hydrogen-oxygen isotope data show that the ore-forming fluid was principally originated from magmatic water, with meteoric water input in the late-stage mineralization. Evidence from geological characteristics, ore-forming temperature, gold occurrence and pyrite trace elements and sulfur isotopes suggest that the deposit belongs to Carlin-type. The ore-forming fluid may have come mainly from magmatic water with late-stage meteoric water input, featuring a crust-mantle mixed source.