川东南兴文地区长兴期含煤和腕足动物地层及成煤环境初探

PRELIMINARY STUDY OF CHANGXINGIAN COAL-BEARING AND BRACHIOPOD-BEARING STRATA AND COAL-FORMING ENVIRONMENT IN XINGWEN AREA OF SOUTHEAST SICHUAN PROVINCE

本文系统描述了四川省兴文县川堰落水崖剖面长兴期地层，根据本区长兴期地层以灰岩、泥灰岩、钙质泥岩、粉砂岩为主，并夹有煤层及富含腕足动物化石等特点，作者认为本区长兴期地层称为汪家寨组比较全盘，其下界位于B4煤层顶，上界则以Leptochondria,Palaeoneilo，Pteria等的出现作为三叠系的开始，本区当是垢沉积环境则主要属陆表海障壁海岸体系，初期为泥炭坪成煤环境，后期过渡为障壁后沼泽成煤环境。

This paper describes systematically Changxingian strata of Chuanyan Luoshuiya Section in Xingwen Area of Southeast Sichuan Province. Based on the facts that Changxingian formation mainly contains limestone,marl,calcareous mudstone and siltstone which are intercalated with coal seams,and that a number of fossils of brachiopods are found. The author considers that it is better to name Changxingian strata as Wangjiazhai Formation,Its lower boundary is at the top of seam B_4,And appearance of Pteria,Leptochondria,Palaeoneilo can be roughly regarded as the beginning of the Triassic system. The sedimentary environment in this area was mainly an epicontinental barrier-coast system. The lower part of this formation represents the peat-flat coal-forming environment and the upper part shows the backbarrier coal-forming environment.