剪切带中流体地球化学特征及其找矿意义

GEOCHEMICAL CHARACTERISTICS OF FLUIDS IN SHEAR ZONES AND THEIR SIGNIFICANCE FOR MINERAL RXPLORATION

太古代绿岩带剪切带中金矿成矿流体成分主要为Ｈ２Ｏ，ＣＯ２，Ｋ，Ｎａ，Ｃａ，Ｍｇ，Ｃｌ，ＳｉＯ２，ＣＨ４，Ｈ２Ｓ及Ｎ２。成矿流体是沿着剪切带及其控制的次一级构造上升。成矿流体的相分离是剪切带中造成矿物沉淀的普遍特征。剪切带金矿流体来源包括变质热液；岩浆热液；地幔去气与下地壳麻粒岩化热液；深部循环的地下水４种。当前除应用Ｃ，Ｈ，Ｏ及Ｓ同位素对流体来源进行探讨外，还运用亲石元素及Ｓ／Ｓｅ比值可作为流体来源示踪剂之一。研究剪切带所处的地质背景、流体来源和蚀变标志，寻找与鉴别剪切带的扩张空间，确定剪切带类型及其矿化类型、矿体产状，对指导找矿勘探有重要意义。

Ore-forming fluids of sheat zone-controlled gold deposits in Archean grcenstone belts consist of H2O, SiO2, CO2, K, Na, Ca, Mg, Cl as well as CH4, H2S and N2 etc. Fluid phase separation appears to be a common phenomenon during mineralization. Possible sources of the ore-forming fluids include metamorphic, magmatic, mantle degassing-granulitization fluids and deep circulating ground waters. In addition to stable isotopes of carbon,hydrogen, oxygen and sulfur, lithophile elements and S/Se ratio have been used as tracers of the ore-forming fluids. An understanding of the geologic setting. alteration features,shear zone types and associated dilatancy is important for exploration.