【摘要】 三江地区兰坪盆地中-新生代砂岩和板岩中赋存有脉状铜矿床,其成因一直存在争议。本文选取金满矿床作为实例进行了详细的铜和硫同位素研究。解析了该矿床成矿物质来源及其富集机理。研究表明金满矿床具有多期性、成矿物质多来源性。硫同位素数据显示,大部分分布在-5.0‰⁺3.4‰之间,个别富集硫的轻同位素,δ³⁴S值达-10.1‰、-11.4‰、-11.6‰,认为硫主要来源于盆地蒸发岩硫酸盐,通过有机质热分解作用还原成H₂S,同时有少量生物成因硫及深部来源硫。铜同位素研究表明,成矿早阶段铜同位素δ⁶⁵Cu值在零附近,铜主要来源于深部地壳或上地幔,晚阶段硫化物富集铜的轻同位素,δ⁶⁵Cu值达-1.10‰、-1.02‰,铜主要来自盆地内成矿流体流经的地层。结合研究区成矿物质来源、流体性质及地质背景,认为不同性质流体混合发生氧化还原作用促使金属硫化物沉淀是金满矿床主要形成机制。另外,成矿流体沿断裂上涌,外界条件突变,压力下降,气体逸出等过程对硫化物沉淀也起到一定作用。更多还原

【Abstract】 The vein-type copper deposit hosted in the sandstone and slate in the Lanping Basin,Sanjiang area is controversy about ore genesis. In this study,we report a detail S and Cu isotopic investigation on the typical Jinman deposit. We discuss the material sources and its deposition mechanism. The Jinman deposit is characterized by different ore-forming stages and materials from multiple sources. This deposit has major sulfur isotopic variation of sulfides from- 5. 0‰ to + 3. 4‰ and minor with δ³⁴S value of- 10. 1‰,- 11. 4‰ and- 11. 6‰. We suggest that S is mainly derived from sulfate of evaporite in the Lanping Basin,reacting with organic material and generating H₂ S,and some S from biogenic sulfur and deep magmatic source. The copper isotope indicates that the copper isotope value at the early stage sulfides are close to zero,suggesting that the copper mainly derived from the lower crust or upper mantle,whereas with δ⁶⁵Cu value at the late stage sulfides are- 1. 10‰ and- 1. 02‰,showing the copper from stratum leached by ore-forming fluid. Based on the sources of ore-forming materials,nature of ore-forming fluid and geological setting,the deposition mechanism mainly resulted from oxidation-reduction by the mixture different ore-forming fluids. Copper mineralization is also related to the condition changes of ore-forming fluid when it rose along the faults,including the reduction of pressure and gas evolution.更多还原