摘要
中奥陶世克拉道克阶（Ｃａｒａｄｏｃｉａｎ）在全球范围内为海侵期，体现在全球范围广泛的黑色页岩沉积及笔石动物的大规模繁盛，湘黔地区这一时期地层发育完全，从碳酸盐台地－斜坡－外陆架盆地均有不同程度的响应。在台地区表现为碳酸盐台地的淹没，斜坡区表现为碳酸盐重力流及黑色页岩、粉砂岩沉积，形成碳酸盐与陆源碎屑的混合沉积，而在外陆架盆地区表现为黑色岩系大规模发育及笔石的大量繁盛。
Middle Ordovician Caradocian was transgressive stage in global scale. In this stage, the black shale was distributed in large scale and graptolite was massively propagated. It is obvious that sedimentation responsed to sea level rising during Middle Ordovician in the Guizhou and Hunan regions. From carbonate platform to outershelf basin the sedimentary characters are different. This differentiation is reflected in rocks and fossils. In carbonate platform it is indicated that sedimentary differentiation during Early Ordovician is not present and carbonate platform is drowned. Deep sea argillaceous micritic limestone was deposited in large area. Brachiopoda and trilobite disappear and noktonic nautilus flourish. In the transition area between inner and outer shelf,sedimentary rocks consist of black carbonaceous shale, siliceous shale and clay shale.Carbonate gravity flow is common and calcareous dolomite and manganiferous limestone are well developed. The fossil is mainly graptolite and nektonic trilobite. In the outer shelf basin, black shale is well developed and anoxic envionmental characters are obvious. Black siliceous slate and shale and pyritic crastals are well developed. Organism is only graptolite.
出处
《地质科学》
CAS
CSCD
北大核心
1998年第1期93-101,共9页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金
中科院院长基金
关键词
中奥陶世
海平面上升
黑色岩系
沉积响应
iddle Ordovician, Sea level rising, Black shale, Carbonate gravity flow, Guizhou and Hunan regions.
