平邑盆地官庄群湖相碳酸盐岩的古地理意义

摘 要] 本文旨在以平邑盆地官庄群湖相碳酸盐岩为例,研究湖相碳酸盐岩的古地理指示意义。以沉积学理论为指导,依据野外露头剖面分析了平邑盆地古近纪官庄群的地层及其沉积特点,结合盆地的形成及演化,分析了古生物、古气候、物源、水介质物理化学条件等沉积环境条件,明确了官庄群湖相碳酸盐岩沉积时的古地理格局与特征。研究表明平邑盆地在古近纪官庄群沉积时为温暖的内陆淡水湖泊环境,构造活动相对静止,地形平坦,有利于湖泊相碳酸盐岩沉积,且碳酸盐岩集中发育在浅水、中等偏低能量、低陆源碎屑物质的环境。从而说明湖相碳酸盐岩地层形成的古地理背景为构造活动平静、地形平坦、浅水低能沉积环境。

Paleogeographic Significance of Guanzhuang Group Lacustrine Carbonate in the Pingyi Basin

Abstract:This paper,taking lacustrine carbonate rocks of Guanzhuang Group of Pingyi Basin for example,aims at studying the paleogeographic significance of lacustrine carbonate rocks. Taking the sedimentary theory as guiding theory and based on the outcrop section,we analyze the formation and sedimentary features of Guangzhuang Group. Combined with the formation and evolution of the basin,we also analyze the conditions of sedimentary environment,such as the paleontology,ancient climate,content sources,physical and chemical conditions of water medium,and so on,and clarify the paleogeographic patterns and characteristics when Guanzhuang Group was deposited. The study suggests that the basin was a warm inland environment when lacustrine carbonate rocks were deposited. And the tectonic movement was relatively static,paleotopography was relatively flat,which was favorable to the deposition of the lacustrine carbonate rocks,and carbonate concentration in the environment of shallow water,low and middle energy,little terrigenous fragmental materials. Thus it is demonstrated that the favorable paleogeographic setting for lacustrine carbonate strata was the sedimentary environment with relatively static tectonic movement,flat terrain,shallow water and low energy.