地质学报2017，Vol.91Issue(1)：213-231,19.
华南地区泥盆系MVT铅锌矿床S、Pb同位素特征
The Sulfur-Lead Isotope Geochemistry of MVT Pb-Zn Deposits in Devonian System in South China
摘要
Abstract
The Mississippi-valley type (MVT) Pb-Zn deposits,south China,occur in the Devonian platformsandstone-carbonate rocks,are associated with the basin brine in Cretaceous.Two types were recognized,one is middle-low temperature hydrothermal type such as Fankou,and the other is low temperature typesuch as Siding and Beishan deposits.The studies on geologic setting,fluid inclusion microthermometry,and δ34S values indicate that sulfur mainly came from reduced fluid,minor reduced from ∑SO42 in oxidizedbrine,and a few from wall rocks in the deposits.In the middle-low temperature type hydrothermal deposits,δ4S ranges from 12％ to 22％,and thermochemical fractionation of sulfur isotope is the principal for metal precipitation,without obvious bacteria fractionation observed.In low temperature type deposits,δ34S value of the ore is lower and in a wide range,bacteria fractionation is the principal,the thermochemical fractionation only in the forming of the coarse-grain ore.The ore lead isotope composition of the deposits shows a linear array,indicating the mixing sources for lead.The old lead came from the eroded Paleozoic continent,young lead represents the common lead mainly from the Devonian sediments.The proportion of two sources of leads is related to the content of the debris in the Devonian sedimentary rocks.The lead directly precipitated from the oxidized basin brines,ultimately from the Devonian sediments (especially clastic rocks at the Transgression) that fluid flows through,further more ultimately from the Paleozoic continent and marine sediments.It is suggested that the mineralization mechanism is given as follows:The mixing of the two types of fluid leads to the precipitation of sulfide rapidly.The oxidized brines rich in metal-richbasin,and contains a small amount of sulfur of ∑SO42-,migrated along the red sandstone of Lower Devonian.The reduced fluid is rich in sulfur of ∑H2S.Fluid mixing function is limited to within the scope of a deposits or ore field,but not the regional.关键词
密西西比河谷型/铅锌矿/硫同位素/铅同位素/分馏机制/成矿机制/物质来源/华南Key words
Mississippi valley type (MVT)/Pb-Zn deposit/sulfur isotope/lead isotope/isotope fractionation/metallogenic mechanism/origin of the ore/south China引用本文复制引用
祝新友,甄世民,程细音,原桂强,杨汉壮,韩英,王艳丽..华南地区泥盆系MVT铅锌矿床S、Pb同位素特征[J].地质学报,2017,91(1):213-231,19.基金项目
本文为中国地质调查局Ⅱ级项目“内蒙古赤峰有色金属基地综合质调查”(DD20160072)、国家科技支撑课题“湖南锡田地区深部成矿岩体空间结构与成矿预测”(2011BAB04B08)、全国危机矿山接替资源找矿项目“湘南-粤北地区锡钨多金属矿床成矿规律总结研究”(20089927)联合资助. （DD20160072）
