四川大岩子铂-钯矿床(点)热液成矿的地球化学证据

Geochemical Evidence for Hydrothermal Mineralization of the Dayanzi Pt-Pd Deposit in Huili County, Sichuan Province

大岩子铂-钯矿区的岩石有白云岩、辉石岩脉、辉绿岩脉,矿体赋存在构造蚀变破碎带中,以外接触带的白云岩一侧为主,次为内接触带的辉石岩,矿石类型有矿化白云岩和矿化辉石岩两种类型。通过对含矿白云岩、含矿辉石岩、断层泥及辉绿岩的地球化学特征研究,认为大岩子矿床先后经历超基性岩浆的侵入,即形成辉石岩脉;基性岩浆的侵入,即形成辉绿岩脉;富含Pt、Pd的岩浆期后热液活动,即形成以Pt、Pd为主、富含As、Cu、Sb、Ag、Cd的热液矿床,其中Pt、Pd的富集成矿主要与热液活动有关。

The rocks in the Dayanzi Pt-Pd deposit are mainly dolomitite as well as pyroxenite and diabase veins. The orebodies occur in the tectonic ahered and shattered zone between the dolomitite and the pyroxenite vein, mostly on the dolomitite side of the exocontact zone and subordinately in Dyroxenite of the endocontact zone. As a result, there exist two types of ores： mineralized dolomitite and mineralized pyroxenite. According to gcochemical characteristics of mineralized dolomitite, mineralized pyroxenite, diabase and fault gouge,it is considered that the formation of the Dayanzi Pt-Pd deposit experienced uhra-mafic magmatic intrusion （forming pyroxenite）, marie magmatie intrusion （ forming diabase） and postmagmatic hydrothennal activity （ forming Pt-Pd hydrothermal deposit）, resulting in the formation of Pt-and Pd bearing ore minerals rich in As, Cu, Sb, Ag and Cd. Pt and Pd mineralization is related to the postmagnatic hydrothermal activity.