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沙河街组二段是本区的重要含油层系。其中腹足类化石丰富。用其生活环境恢复当时的古地理景观较为有效。文中主要叙述了沙河街组二段腹足类的组合特征及其分布,着重描述了优势属——Tulotomoides的发生、发展和生活环境,在剖面上阐明了沙河街组二段的古地理变迁。主要表现为湖盆由东向西退缩,致使这一时期的东营湖最终被冲积平原的侵占而消失。
The second section of Shahejie Formation is an important oil-bearing formation in this area. Gastropods fossil rich. With its living environment to restore the ancient landscape at the time more effective. The article mainly describes the combination characteristics and distribution of gastropods in the second member of Shahejie Formation, and emphatically describes the occurrence, development and living environment of the dominant species, Tulotomoides, and elucidates the palaeogeographic change in the second member of Shahejie Formation. Mainly showed that the lake basin retreated from east to west, resulting in Dongying Lake being disappeared in the alluvial plain at this period.