遵义黄家湾镍钼铂族元素矿床地质、地球化学和Re-Os同位素年龄测定——兼论华南寒武系底部黑色页岩多金属成矿作用  

Geology, Geochemistry, and Re-Os Isotopic Dating of the Huangjiawan Ni-Mo-PGE Deposit, Zunyi, Guizhou Province ——with a Discussion of the Polymetallic Mineralization of Basal Cambrian Black Shales in South China

作　　者：毛景文[1] 张光弟[1] 杜安道[2] 王义天[1] 曾明果 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质科学院岩矿测试技术研究所,北京100037 [3]贵州省地质勘探开发局地质研究所,贵阳550002

出　　处：《地质学报》2001年第2期234-243,共10页Acta Geologica Sinica

基　　金：国家重点基础研究项目(编号G1999043211);国家地质调查项目(编号KD41)的成果

摘　　要：黄家湾矿是近几年在贵州遵义地区寒武系底部新发现的黑色页岩镍钼铂族元素矿床,本文介绍了矿床的基本特征和含矿地层,以及在矿层中鉴别出喷流间歇期形成的水云母黄铁矿层。利用负离子热表面电离质谱对矿石进行了Re-Os同位素年龄精测,获得541.3±16Ma(2σ)的等时线年龄。黄家湾矿是华南寒武纪黑色页岩多金属成矿带的一个组成部分。基于矿石的PGE和REE测试,结合前人的工作成果,分析区域构造演化历史和W-Sn-Mo-Sb地球化学富集区,认为区域黑色页岩由正常沉积作用形成;提出了镍钼铂族元素矿的成矿模式,认为这套矿床的形成是由海底喷流系统从海底镁铁质—超镁铁质岩中萃取物质与下伏富Mo-Re-(Cu)岩浆房提供成矿能源和部分物源共同作用的结果。Located tectonically at the southern margin of the' Yangtze craton, the Huangjiawan Ni-Mo-PGE deposit was recently discovered in black shale at the base of the Cambrian in the Zunyi area, Guizhou Province. The reserves of Ni + Mo metals are preliminarily estimated at more than 100,000 tons with 5. 5% Mo, 3. 5% Ni and 0. 20% Cu. U, Re, Os, Pt and Pd metals in the ores can be recovered as by-products. Orebodies occur as layers at the base of the Cambrian. They show many syngenetic characteristics, such as laminated, podiform and nodular textures. Their thickness generally ranges from 20 to 50 cm and may reach a maximum of 2 m. Moreover, a 2~5 cm thick non-mineralized hydromica-pyrite layer formed in the intermittency of hydrothermal emanations has been recognized from the ore layers. Ten ore samples were chosen to perform PGE, Au and REE analyses. Except for iridium, Ru and Au are similar to their primitive equivalents, and Os, Rh, Pt and Pd are abnormally high. The hydromica - pyrite layer exhibits a distinguishing primitive mantle-normalized pattern, showing low abundances of Os, Ir and Rb and high abundances of Au, Pd, Pt and Ru. Rare earth elements show moderate La/Yb ratios and Eu depletion with a slightly right-inclined chondrite-normalized pattern. The obvious Ce depletion of hydromica-pyrite layer indicates that seawater was involved in its formation process. Precise Re-Os dating of ores was performed by negative thermal ionization mass spectrometry, and yields an isochron age of 541. 3 ± 16 Ma (2σ), similar to the boundary age of 544 Ma between Cambrian and Precambri-an strata. Based on the new data obtained in the Huangjiawan Ni-Mo-PGE mine, combined with the results of previous work in the Ni-Mo-PGE belt and analyses of the Mo-W-Sn-Sb-Hg geochemical anomaly and granite-related W-Mo, W-Sn-Mo-Bi and Cu-Mo mineralization and the geological history of South China, the authors propose a genetic model for the Ni-Mo-PGE ore deposit. They suggest that the mixed hydrothermal fluids derived from both submarine e

关 键 词：黑色页岩 镍钼铂族元素矿床 铼-饿Re-Os同位素测年 寒武纪 扬子克拉通 地球化学 矿床地质 成矿作用 

分 类 号：P618.6[天文地球—矿床学] P618.53[天文地球—地质学]