城门山及武山铜矿床的硫同位素研究

地质概况江西城门山矿床和武山矿床是长江中下游铁铜成矿带大冶-九江成矿亚带东南部位的两个与斑岩有成因关系的铜矿床。在地质构造上,前者处于九江-瑞昌东西向拗陷带中的长山-城门湖背斜倾伏端的北翼,后者处在横立山-黄桥向斜东端的北翼。两矿区的地层分布相似,主要是志留系至三叠系地层。其中,泥盆系上统五通组砂岩及石炭系中统黄龙组灰岩与矿床关系密切。

SULFUR ISOTOPE STUDY OF THE COPPER ORE DEPOSIT OF CHENGMENSHAN AND WUSHAN

In this paper, we report the results of determination cf sulfur isotope ratios of 39 pyrites in the deposites. The results is shown as follows:1. The δS³⁴ values of pyrites in Chengmcnshau ore deposit range from - 1.3‰ to 3.6‰. The peak value of δS³⁴ in the sulfur isotopic distribution plot is 2.4‰. The δS³⁴ values of pyrites in Wushan ore deposit range from -1.1‰ to 3.6‰. The peak value of δS³⁴ in the sulfur isotopic distribution plot is 0.9‰. Their sulfur isotope coni-posiition are close to the meteorite value.2. The mean δS³⁴ value in porphyry ore is smaller than skarns one, and the mean δS³⁴ value in skarns ore is smaller than massive one. They are 2.1, 3.0 and 3.5‰, respectively, for Chengmenshan ore deposit. They are 0.6, 1.2 and 3.6‰, respectively, for Wushan ore deposit.3. The δS³⁴ values of pyrites in shallower position of porphyry body are greater than those in deeper position.4. The sulfur isotope compositions of massive ore in Wutong sandstone are occa-sionly extraordinary light. For example, the δS³⁴ value of W-7 sample is -12.8‰.During the formation of both ore deposits, there were no intensive variations of the physical and chemical conditions not strongly vary. The Raylight fraetiomation model of sulfur isotope of hydrothermal fluid can be used to interpret the variations in δS³⁴ values found within these porphyry bodies. It is attributed to the geological process contaminating sedimentary pyrites that the sulfur isotope composition of massive ore in Wutong sandstone are extraordinary light.