刚果(布)Boko Songho-Mindouli成矿带硫、铅同位素特征及其地质意义

Boko Songho-Mindouli成矿带是刚果(布)南部重要的铜多金属矿成矿远景区。以成矿带中Grande、Luangu、Mpassa和Moubiri 4个典型铜多金属矿床的矿石矿物黄铁矿、辉铜矿为研究对象,测定其硫、铅同位素组成,揭示该矿带成矿物质来源并探讨其成矿机制。结果表明:矿石矿物δ~(34)S值变化于-1.4‰~23.0‰,平均7.29‰,反映其兼有幔源岩浆成因和生物成因的特点;矿石矿物的~(206)Pb/~(204)Pb值的变化范围为17.810~18.046,~(207)Pb/~(204)Pb值的变化范围为15.592~15.651,~(208)Pb/~(204)Pb值的变化范围为37.719~38.066,其特征显示铅来源具有多源性,而以壳源为主,同时混有深源地幔铅。硫、铅的来源相同,具有相似的地质演化史,矿床属于沉积—热液改造型矿床,受地层和构造控制。

S,Pb isotopic characteristics of Boko Songho-Mindouli metallogenic beltin the Republic of Congo and their geological significance

The Boko Songho-Mindouli metallogenic belt is an important prospective area for copper polymetallic mineralization in the southern part of the Republic of Congo.The paper researched the rock minerals of pyrite and chalcocite from Grande,Luangu,Mpassa and Moubiri that are 4 typical copper polymetallic deposits,determined the composition of sulfur and lead isotopes,revealed the ore-forming sources of the metallogenic belt and explored its mechanism of mineralization.The results show that the δ34S value of the ore minerals ranges-1.4 ‰-23.0 ‰,averaging 7.29 ‰,indicating the mantle-derived magmatic and biogenic origins of the deposit;206Pb/204Pb value ranges 17.810-18.046,207Pb/204Pb 15.592-15.651 and 208Pb/204Pb 37.719-38.066,indicating multiple sources of lead that are dominated by crust sources and mixed with mantle derived lead.The sulfur and lead have the same sources and similar geological evolution history.The deposit belongs to a reformed sedimentary hydrothermal deposit controlled by strata and structure.