徐州贾汪地区中—上寒武统藻礁、风暴层与海平面变化

Middle-Upper Cambrian Algal Reefs, Tempesite and Sea Level Changes in Jiawang, Xuzhou

笔者详细研究了徐州贾汪地区中—上寒武统的二郎山等剖面,将张夏组—凤山组划分为3个各具特色的三级层序,根据各层序内副层序的堆叠形式进一步划分出海侵体系域(TST)、凝缩段(CS)及高位体系域(HST)。其中张夏层序的藻礁为中—晚寒武世期间发育的最大规模碳酸盐岩缓坡藻礁,崮山层序凝缩段代表中—晚寒武世最大海泛(海侵)期沉积,长山—凤山层序顶部白云岩代表中—晚寒武世最小海平面(海退)时期的沉积。

The Middle-Upper Cambrian in the Jiawang area is represented by the Erlangshan section. It is exposed more completely from the Zhangxia Formation to Fengshan Formation. The bottom boundary is an exposed surface at the top of red sandstone of the Xuzhuang Formation (SB2) and the top boundary is the Sanshanzi dolomite (s. s. ) of the Fengshan Formation (SB2). The section includes the following three different characteristic sequences; (1) the Zhangxia sequence (DSD , which corresponds with the Zhangxia Formation, characterised by ooid shoals and great algal built with various branched algae; (2) the Gushan sequence (DS2), which corresponds with the Gushan Formation, characterised by episodic deposits-debries flows, basin micrite and allochthonous oolitic limestone with cross beddings; (3) the Changshan-Fengshan sequence (DS3), which corresponds with the Changshan and Fengshan Formations, characterised by volute autochonous edgewise limestone, dolomized thick-bedded stromatolithic limestone and dolomite (Sanshanzi dolomite s. s. ). Of them, algal reefs in the Zhangxia sequence are the greatest carbonate ramp algal reef of the Middle-Upper Cambrian, the condensed section in the Gushan sequence is the maximum seaflood surface in the Middle-Upper Cambrian which respre-sents the highest sea level, dolomite on the top of the Changshan-Fengshan sequence respre-sents deposits in the period of the lowest sea level during the Middle-Upper Cambrian.