华北地台寒武系张夏组盘车沟段岩石地层与古地理特征

LITHOSTRATIGRAPHIC AND PALAEOGEOGRAPHIC FEATURES OF THE PANCHEGOU MEMBER OF THE CHANGHIA FORMATION IN NORTH CHINA PLATFORM

华北地台东部寒武系张夏组地层岩性变化较大,盘车沟段是其中部一套碎屑岩发育的岩石地层单位。本文通过对鲁西东部地区13处盘车沟段发育的13条剖面进行研究,确定了其起始的精确生物地层位置,揭示了盘车沟段地层南厚北薄、顶底界面从南到北逐渐变新的变化规律,判断其发育受华北地台南升北降的构造运动的控制。同时,结合盘车沟段的古生物特征,判断盘车沟段代表了华北这一时期少见的台地边缘-陆棚环境,较准确地恢复了华北地台这一时期的古地理面貌。

Lithostratigraphic and palaeogeographic features of the Panchegou Member of the Changhia Formation vary across the eastern North China Plate. The Panchegou Member of the Changhia Formation was characterized mainly by classic deposits in comparison with other regions of the Changhia Formation, which was dominated by oolitic limstone, algal lumpy limestone and algal limestone. Thirteen sections from the middle and southern Shandong Province are studied here. Biostratigraphy of the lower and top boundaries of the Panchegou Member of the Changhia Formation was investigated in detail for the first time. It can be concluded that the Panchegou Member is gradually decreasing in thickness from the South to the North in the study area, and the lower and upper boundaries of the Panchegou Member are getting younger. It may be controlled by tectonic movement owing to uplifting of the southern part of the North China Plate and sinking of the northern part of the Plate. Additionally, comprehensive analysis of lithostratigraphy and palaegeography reveals that the platform margin-outshelf was well developed in North China Plate during the deposited time of the Panchegou Member.