扬子板块北缘下志留统龙马溪组重晶石结核特征及其成因机制分析
发布时间：2018-08-19 09:31
【摘要】：在扬子板块北缘城口明中剖面及巫溪徐家坝剖面下志留统龙马溪组底部的硅质岩、泥岩中发现椭球状重晶石结核。其矿物组成主要为重晶石颗粒与作为"基质"的黄铁矿、粘土矿物和石英。通过重晶石岩石学、矿物学及锶同位素分析表明,重晶石结核形成于早期成岩阶段松软沉积物的孔隙水中。上升洋流带来丰富的营养及富钡物质,表层海水的高初始生产力促使生物繁盛,海水中的钡通过生物作用富集形成生物钡,生物钡(bio-barite)在埋藏过程中的硫酸盐耗竭区(sulfate depleted zones)通过硫酸盐细菌作用(BSR)溶解被激活提供了钡的来源。围岩岩性(黑色泥岩和硅质泥岩)表明重晶石结核形成于缺氧的环境中。上述研究对深入理解早志留世时期扬子板块北缘古海洋环境有一定的启示作用。
[Abstract]:The ellipsoid barite nodules were found in the siliceous rocks at the bottom of the Longmaxi formation in the lower Silurian in the Chengkou and Xujiaba sections of the northern margin of the Yangtze plate. Its mineral composition is mainly barite particles and pyrite, clay minerals and quartz as "matrix". Barite petrology mineralogy and strontium isotope analysis indicate that barite nodules were formed in the pore water of soft sediments in early diagenetic stage. The rising ocean currents bring abundant nutrients and barium rich materials. The high initial productivity of the surface seawater promotes the biological prosperity, and the barium in the sea water is enriched by biological action to form biological barium. The (sulfate depleted zones) in the sulfate depletion zone during the burial of biological barium (bio-barite) provides a source of barium through the activation of (BSR) solution by sulfate bacteria. The lithology of surrounding rock (black mudstone and siliceous mudstone) indicates that barite nodules were formed in anoxic environment. These studies are helpful to understand the paleo-marine environment in the northern margin of the Yangtze plate during the early Silurian period.
【作者单位】： 油气藏地质及开发工程国家重点实验室成都理工大学;成都理工大学能源学院;成都理工大学地球科学学院;
【基金】：中国地质调查项目(121220115003801-04)~~
【分类号】：P578.71
[Abstract]:The ellipsoid barite nodules were found in the siliceous rocks at the bottom of the Longmaxi formation in the lower Silurian in the Chengkou and Xujiaba sections of the northern margin of the Yangtze plate. Its mineral composition is mainly barite particles and pyrite, clay minerals and quartz as "matrix". Barite petrology mineralogy and strontium isotope analysis indicate that barite nodules were formed in the pore water of soft sediments in early diagenetic stage. The rising ocean currents bring abundant nutrients and barium rich materials. The high initial productivity of the surface seawater promotes the biological prosperity, and the barium in the sea water is enriched by biological action to form biological barium. The (sulfate depleted zones) in the sulfate depletion zone during the burial of biological barium (bio-barite) provides a source of barium through the activation of (BSR) solution by sulfate bacteria. The lithology of surrounding rock (black mudstone and siliceous mudstone) indicates that barite nodules were formed in anoxic environment. These studies are helpful to understand the paleo-marine environment in the northern margin of the Yangtze plate during the early Silurian period.
【作者单位】： 油气藏地质及开发工程国家重点实验室成都理工大学;成都理工大学能源学院;成都理工大学地球科学学院;
【基金】：中国地质调查项目(121220115003801-04)~~
【分类号】：P578.71
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