Forming mechanism analysisof the abnormally high δ34S baryte deposits: A case study from theZhenning–Ziyun largeDevonian baryte deposits,Guizhou Province,China
Forming mechanism analysisof the abnormally high δ34S baryte deposits: A case study from theZhenning–Ziyun largeDevonian baryte deposits,Guizhou Province,China
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异常高δ34S重晶石矿床形成机制分析——以贵州镇宁—紫云大型泥盆系重晶石矿床为例
DOI：
10.1080/01490451.2015.1137657
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发表时间：
2017
影响因子：
2.3
通讯作者：
Zhu Mingjin
中科院分区：
文献类型：
--
作者：
Gao Junbo;Yang Ruidong;Zheng Lulin;Cheng Wei;Chen Jun;Zhu Mingjin
层状重晶石矿床广泛分布于我国及世界寒武系、泥盆系地层中。本文研究了扬子地台西南缘贵州省镇宁-紫云县上泥盆统硅质岩中层状重晶石矿床的硫同位素特征及其形成机制。本文介绍了镇宁县乐集剖面18个重晶石矿样品的硫同位素数据，其值范围为C41.9%~ C68.4%（AVGDC59.9%）。紫云县莫浩剖面重晶石矿石的d34 S值稳定，在C41.3%~ C47.0%（AVGDC44.0%）范围内。紫云县罗城剖面重晶石矿石的d34 S值为C27.6%~ C36.4%（AVGD为C32.7%）。所有样品的d34 S值均高于同期海水硫酸盐的d34 S值（C25%）。扫描电子显微镜分析表明，在重晶石颗粒和粒间表面，观察到球形、哑铃形、棒状的细菌和类细菌化石，以及不规则片状和框形的铁氧化物。铁氧化物呈不规则片状和框架状。这些结果表明，在封闭的盆地中，细菌硫酸盐还原作用与海水硫酸盐有关。此外，重晶石矿石d34 S值从乐集至莫浩、罗城剖面呈逐渐降低的趋势，表明乐集地区处于局限裂谷盆地的深水区，处于较封闭的沉积环境中。
Stratiform baryte deposits are widespread in Cambrian and Devonian strata in China and around the world. In this article, the authors studied the sulfur isotopic features and forming mechanism of the stratiform baryte deposits occurring within the Upper Devonian cherts of the Zhenning-Ziyun county, Guizhou province, located in the Southwestern margin of the Yangtze Platform. The sulfur isotopic data from 18 baryte ore samples of the Leji section of Zhenning county are presented herein with values that range from C41.9% to C68.4% (AVG D C59.9%). The d34S values of the baryte ore from the Mohao section of Ziyun county are stable and show a narrow range from C41.3% to C47.0% (AVG D C44.0%). In the Luocheng section of Ziyun county, the d34S values of the baryte ore vary from C27.6% to C36.4% (AVGD C32.7%). The d34S values of all samples are higher than those of the coeval seawater sulfates (C25%). The scanning electron microscope analysis indicates that spherical, dumbbell-shaped, clavate bacterial and bacteria-like.fossils were observed, as well as the irregular schistose and framboid forms of Fe oxides that occur around the surfaces of baryte grains and inter-grains. Fe oxides take irregular schistose and framboid forms. These findings imply the significant concentration of heavy sulfur related to the seawater sulfates with the action of bacterial sulfate reduction in a closed basin. In addition, the trend of the d34S value of baryte ores is gradually decreasing from the Leji to Mohao and Luocheng sections, which suggests that Leji area is located in the deepwater area of the restricted rift basin, and in a more closed depositional environment.