黔东北地区早奥陶世宁国中期地层相变位置的新认识  

A Re-examination of the Location of Sedimentary Facies Shiftduring the mid-Ningguo Period of Early Ordovicianin the Northeastern Guizhou

作　　者：李宗发 

机构地区：[1]贵州地勘局103地质大队

出　　处：《贵州地质》1998年第1期32-36,共5页Guizhou Geology

摘　　要：通过近几年1：5万区域地质调查资料综合整理后认为：早奥陶世宁国中期，黔东北地区具有西高东低的古地理格局，沉积相分带明显，以官舟—白沙一线为界，西侧为湄潭组以笔石页岩为主的内陆棚相沉积，东部则为大访组的介壳灰岩和笔石页岩混合的斜坡相沉积。这一划分，使该期相交线位置在前人基础上至少西移32km。The author found that the modified location of sedimentary factes contact of the mid - Ningguo petted of early Ordovician in the northeastern Guizhou ought to be moved westward at least 32 km away from its earlier determination after re - examination of information gained in 1 (50, 000 regional geological survey of recent years. The new line of fades change, the Gongzhou - Baisha - line, is distinctively identified by the graptolite shales of the Meitan formation indicating inner shelf depositional environment on the west side of this line, which changes eastward into the shell limestones mixed with grapolite shales of the Dawan formation, reflecting a deposition on slope - that displace an ancient appearance with relatively higher relief than the east.

关 键 词：宁国中期 地层 相变位置 黔东北 早奥陶世 

分 类 号：P534.42[天文地球—古生物学与地层学]