摘要
川滇黔铅锌矿集区位于扬子地块西南缘,发育有400多个矿床(点),铅锌矿石储量超2亿t,Pb平均品位(质量分数)达5%,Zn平均品位达10%。矿体主要呈似层状、脉状赋存于震旦系—二叠系碳酸盐岩地层中,为碳酸盐岩容矿后生铅锌矿床。文中通过综合分析川滇黔矿集区21个典型矿床的S-Pb多元同位素数据,示踪成矿元素主要来源,并为进一步找矿提供指导。研究区大部分铅锌矿床硫化物的δ34S值介于9.0‰~28.6‰之间,与震旦系—二叠系地层中海水硫酸盐δ34S值(+8.0‰到+38.7‰)相似,暗示研究区铅锌矿床硫化物中的S主要来源于赋矿地层中海水硫酸盐,TSR作用是还原硫的主要生成机制。部分矿床中,含硫有机质热解可能是还原硫的另外一种生成机制。该区硫化物Pb同位素组成显示4种不同的成矿物质来源模式:(1)唐家等矿床Pb主要来源于基底岩石;(2)金沙厂、乐马厂、乐红等矿床Pb主要来源于基底富放射性成因Pb的岩层及盖层沉积岩中富有机质地层;(3)会泽、天宝山、茂租、银厂沟、大梁子、云炉河、毛坪、富乐、杉树林、天桥等矿床Pb主要来源于基底岩石和沉积盖层中多源流体的混合,峨眉山玄武岩可能提供少量成矿物质;(4)青山、赤普、银厂坡、筲箕湾、板板桥等矿床Pb主要来源于沉积盖层,基底岩石提供了部分成矿物质。典型矿床的S-Pb同位素组成特征表明成矿物质具有混合来源的特征。
The SichuanYunanGuizhou （ChuanDianQian） PbZn metallogenic province, located along the western margin of the Yangtze block, comprises more than 400 ore deposits or prospects. The average Pb and Zn grades of its 200 Mt ore reserve are 5 and 10 wt%, respectively. The PbZn ore bodies mainly distributed as stratoid or veintype within the Sinian to Permian carbonate rocks, suggesting a typical epigenetic PbZn mineralization. In this study, isotope data of S and Pb sulfides from 21 deposits were compiled to reveal the source of oreforming materials, and provide guidance for further prospecting. The δ34S values of most sulfide minerals range from ＋9.0‰ to ＋28.6‰, similar to the SiniantoPermian seawater sulfate （＋8.0‰ to ＋38.7‰）. It suggests that S in sulfides mainly came from thermochemical sulfate reduction （TSR） of the hoststrata seawater sulfate. In addition, thermal decomposition of sulfurbearing organic matter could provide part of reduced sulfur in mineralization in some PbZn deposits. The Pb isotopic compositions of sulfides in the research area indicate four possible Pb sources： （1） Pb of the Tangjia deposit originated mainly from the basement rocks; （2） Pb in the Jinshachang, Lemachang and Lehong deposits mainly came from basement rocks containing radiogenic Pb isotopes and cap rock organicrich sediments; （3） Pb of the Huize, Tianbaoshan, Maozu, Yinchanggou, Daliangzi, Yunluhe, Maoping, Fule, Shanshulin and Tianqiao deposits originated primarily from basement rocks and oreforming fluid of multiple metalbearing brine mixing in the cap stratum, and partly from Permian Emeishan basalt; （4） Pb of the Qingshan, Chipu, Yinchangpo, Shaojiwan and Banbanqiao deposits mainly came from sedimentary rocks, and partly from basement rocks. The multiple SPb isotope composition in typical PbZn deposits is indicative of mixed origin for oreforming materials in the metallogenic province.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2018年第1期125-137,共13页
Earth Science Frontiers
基金
国家重点基础研究发展计划"973"项目(2014CB440903)
国家重点研发计划项目(2017YFC0602502)
国家自然科学基金项目(41402063
41672093)
长江大学青年人才基金项目(2015cqr15)
关键词
川滇黔
铅锌矿
成矿物质来源
S同位素
PB同位素
Sichuan-Yunnan-Guizhou
Pb Zn deposit
ore-forming material
S isotopic composition
Pb isotopic composition
