鲁西南地区官庄群沉积特征与沉积环境分析

摘要

鲁西南地区上白垩统一始新统主要发育官庄群,前人对该群的研究大多集中于地层归属年代的划分上,而对于沉积环境的分析涉及较少.本文主要运用岩石学、沉积地球化学方法对鲁西南地区平邑盆地广阜庄-挑沟剖面地层沉积特征及沉积环境演化进行了研究.结果表明:官庄群的固城组为陆相河湖碎屑岩沉积,卞桥组为浅湖碳酸盐岩和蒸发岩沉积,常路组以滨浅湖碳酸盐岩沉积为主,朱家沟组为一套山麓洪积扇沉积；卞桥组和常路组碳酸盐岩总体属于高盐度、强蒸发的陆相咸化湖泊环境沉积产物；官庄群沉积旋回的发育主要受蒙山断裂的多期次活动及古气候条件控制.%The Upper Cretaceous - Eocene Guanzhuang Group is well developed in southwestern Shandong. The previous studies were once concentrated mainly in stratigraphic division and correlation, and scarcely in sedimentary environmental analysis. The present paper focuses on the sedimentary characteristics and environments of the Guangfuzhuang-Tiaogou section in the Pingyi Basin on the basis of petrological and geochemical examination. In the Guanzhuang Group, there occur the continental fluviolacustrine clastic rocks in the Gucheng Formation; shallow lacustrine carbonate rocks and evaporates in the Bianqiao Formation; littoral-shallow lacustrine carbonate rocks in the Changlu Formation, and pediment fluvial fan deposits in the Zhujiagou Formation. The carbonate rocks in the Bianqiao and Changlu Formations were laid down in the highly saline and highly evaporative continental salinized lake environments. The depositional cycles in the Guanzhuang Group are generally controlled by the multiphase faulting of the Mengshan fault and palaeoclimatic changes.