摘要
武山铜矿层状含铜黄铁矿矿体与花岗闪长斑岩具有完全不同的Sr同位素组成。层状矿体中胶黄铁矿、黄铁矿的87Sr／86Sr比值变化于0．7117－0．7241之间，而花岗闪长斑岩中长石和磷灰石的87Sr／87Sr在0．7072-0．7099之间。表明二者具有不同的物质来源，层状矿体物质主要来自上地壳和地层。而花岗间长班岩则主要来自上地幔和下地壳。铅同位素组成表明层状矿体中的铅来自古生代地层。层状矿体硫化物的Rb－Sr等时线年龄为328±21Ma，87Sr／86Sr的初始值为0．7138，表明民状矿体矿石形成于石炭纪，成矿物质自上地壳；而花岗闪长班岩的Rb－Sr等时线年龄为140Ma，为燕山早期的产物。根据研究结果，并结合矿体地质特征等，我们认为武山层状含铜黄铁矿矿体为与海西期海底火山活动有关的喷气（热水）沉积矿床。
The Sr-isotopic compositions of stratiform cupriferous pyrite orebodies and associated gra-nodioritic porphyry are apparently different. The values of 87Sr/86Sr of mcinikovite and pyritein strati form orebodies range from 0. 7117 to 0. 7241; these values of feldspar and apatite inthe granodioritic porphyry are between 0. 7072 and 0. 7099. The difference of the values of87Sr/86Sr shows that they have different origins of materials. The ore-forming materinls ofstratiform ore were from the upper crust, and the granodioritic magma derived from the uppermantle and lower crust. The Pb-isotopic compositions also exhibit that the lead in the strati-form ore carne from the Palaeozoic strata. The Rb-Sr isochronic age of sulfide in stratiform oreis 3281±21 Ma and the initial value of 87Sr/86Sr is 0. 7138, reflecting that the stratiforin sulfideore was formed during the Carboniferous Period and the ore-forming materials were from theupper crust. This age of granodioritic porphyry is about 140Ma, indicating it is the result ofearly Yanshan movement. The good fit of sulfide samples on the isochron shows that theyhave the same initial value of 87Sr/86Sr in the age of 328±21Ma and all deposited in that time.The research demonstrates that the stratiform cupriferous pyrite ore deposit in Wushan isthe submarine exhalative sedimentary deposit which is genetically related to submarine growthfaults and submarine volcanism in the Hercynian Period.The revival of these faults in the Yanshan Period resulted the intrusion of granodioriticporphyry. The intrusive rock not only cut through and reformed the stratiform ore-bodies, butalso gave rise thc skarn ore.
出处
《火山地质与矿产》
1995年第2期94-100,共7页
Volcanology & Mineral Resources
基金
国家自然科学基金!4902702104
国家攀登项目!30-12
关键词
铜矿床
锶同位素
地球化学
黄铁矿
含铜
Sr-isotopic geochemistry, stratiform cupriferous pyrite orebody, Wushan, Jiangxi
