华南下寒武统黑色岩系铂多金属矿中黄铁矿流体包裹体的He—Ar同位素体系

华南下寒武统黑色岩系铂多金属矿中黄铁矿流体包裹体的He—Ar同位素体系

孙晓明1 2, 王敏1, 薛婷1, 马名扬1, 李延河3

1. 中山大学地球科学系，广州 510275; 2.南京大学成矿作用研究国家重点实验室，南京 210093 ; 3. 中国地质科学院矿产资源研究所，北京 100037

收稿日期:2003-12-20 修回日期:2003-12-20 出版日期:2003-12-20 发布日期:2003-12-20

He-Ar Isotopic Systematics of Fluid Inclusions in Pyrites from PGE-Polymetallic Deposits in Lower Cambrian Black Rock Series，Southern China

SUN Xiao-ming1 2, WANG Min1, XUE Ting1, MA Ming-yang1, LI Yan-he3

1. Department of Earth Sciences, Sun Yat-sen University, Guangzhou 510275, China; 2. State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China; 3. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China

Received:2003-12-20 Revised:2003-12-20 Online:2003-12-20 Published:2003-12-20

摘要/Abstract

摘要： 利用惰性气体同位素质谱仪测定了华南下寒武统具代表性的黑色岩系铂多金属矿中黄铁矿流体包裹体的He-Ar同位素组成，发现其^3He／^4He均较低，为0．43×10^-8～26．39×10^-8，R／Rα为0．003～0．189，而^40Ar/^36Ar为258～287，接近大气饱和水。同位素地球化学示踪研究显示，该矿成矿流体主要由建造水(盆地热卤水)和大气饱和水(海水)组成，基本不含地幔流体或深源岩浆水。黑色岩系铂多金属矿的成矿可能与华南克拉通南缘加里东冒地槽的演化有关。在早寒武世，接受了巨厚沉积的加里东盆地中的建造水由于上覆沉积物的压力，顺层侧向迁移，并沿断裂上升与海水混合而成矿。

Abstract: He-Ar isotopic compositions of fluid inclusions trapped in pyrites from some representative PGE-polymetallic deposits in Lower Cambrian black rock series in Southern China were analysed by using an inert gas isotopic mass spectrometer．The results show that the ore-forming fluid possesses a low 3He/4He ratio，varying between 0.43×10-8 and 26.39× 10-8，with an R/Ra value of 0.003～0.189．The 40Ar/36Ar are 258～ 287, closing to that of air-saturated water (ASW)．He-At isotopic indicator studies show that the ore-forming fluid was mainly composed of formation water or basinal hot brine an d spa water，while the content of mantle fluid or deep-derived magmatic water might be neglected ．The PGE-polymetallic mineralization might be related to evolution of Caledonian miogeosynclines distributed along southern margin of the South China Craton．In the Early Cambrian Period，the formation water(basinal hot brine)trapped in the Caledonian basins where accumulated extremely thick sediments was expelled and migrated laterally along strata be cause of the pressure generated by overlying sediments．The basinal ho t brine ascended along faults，mixed with sea water and finally deposited ore minerals．

孙晓明 , 王敏, 薛婷, 马名扬, 李延河. 华南下寒武统黑色岩系铂多金属矿中黄铁矿流体包裹体的He—Ar同位素体系[J]. J4.

SUN Xiao-ming1 2, WANG Min1, XUE Ting1, MA Ming-yang1, LI Yan-he3. He-Ar Isotopic Systematics of Fluid Inclusions in Pyrites from PGE-Polymetallic Deposits in Lower Cambrian Black Rock Series，Southern China[J]. J4.