塔西南缘铅锌矿硫同位素特征及硫的来源探讨

Sulfur Isotope Characteristics and the Source of Sulfur for Discussion in the Lead-Zinc Ore Belt of the Southwestern Margin of Tarim,Xinjiang

通过塔西南缘铅锌矿带金属硫化物(方铅矿、黄铁矿、黄铜矿、闪锌矿)的硫同位素测试研究,结果显示δ34S值范围在-38.3‰～24.0‰,具双峰式分布,推测两种或两种以上流体相混合是导致矿床硫同位素组成变化的主要原因,一类硫化物的δ34S值集中在-6‰～6‰,组成的矿石呈细粒、草莓状结构及浸染状构造;另一类硫化物的δ34S值集中在-32‰～-24‰,组成的矿石呈粗粒、脉状或角砾状构造。两种流体受构造应力和压实作用的影响,沿着断裂或岩石的裂隙运移并相混合,发生热化学硫酸盐还原反应,产生的HS-与Zn2+、Pb2+结合形成闪锌矿、方铅矿,在有利部位沉淀成矿。硫主要来源于海水硫酸盐。

The research of sulfur stable isotope of lead and zinc ore belt in southwestern margin of Tarim platform shows the values of δ34S distributed widely with a range of from-38.3 to 24.0 per mil and distributed as bimodal,which may resulted from the mixing of at least two fluid phases.The values of δ34S are divided into two markedly different types,one fluid＇s δ34S value concentrates between-6 and 6 per mil and the corresponding sulfide ores are fine granules with framboidal or disseminated textures;while the other＇s concentrates between-32 and-24 per mil and the corresponding sulfide ores are coarse granules with vein and brecciated structures.Driven by tectonic stress and compaction,these two types of fluids migrated along fault or rock fracture.They mixed and the thermochemical sulfate reduction reaction happened to produce HS-,which reacted with Zn2＋ and Pb2＋ to form sphalerite or galena.The metallogenic fluid precipitated at favored sites to be ore deposits.Therefore,the main material source of the ore sulfur is the seawater sulfate.