滇东南丘北地区晚二叠世吴家坪早期岩相古地理特征

Characteristics of Lithofacies Paleogeography of Qiubei Area,Southeast of Yunnan Provence during Early Wujiaping Period

滇东南丘北地区上二叠统吴家坪阶主要为一套含铝土矿的碎屑岩系。根据区内实测剖面的沉积特征以及区域地质资料分析,认为研究区吴家坪早期为低能淤泥质海岸到局限浅海的沉积环境。在对54条剖面的岩性、厚度、沉积特征等资料定性、定量分析的基础上,采用单因素分析、多因素综合作图法编制了丘北地区吴家坪早期的岩相古地理图,分析了其沉积相分布和演化特征。吴家坪早期,丘北地区总体表现为潮坪-局限浅海的沉积环境,铝土矿主要发育在吴家坪阶下部的第一个三级层序中。通过对区内已知矿点与古地理关系的研究,认为铝土矿成矿的最有利沉积环境是潮下带-浅海上部。

The Wujiaping Stage in the Permian is mainly composed of clastic rocks with bauxite in Qiubei Area, southeast of Yunnan Provence, China. Based on the analysis of sedimentary characteristics of sections and the geological data of this area, the sedimentary environment of the area during early Wujiaping period was reported as mud coast to restricted shallow marine. According to the qualitative and quantitative analysis of the characteristics of 54 sections, lithofacies paleogeographic map of the first sequence of Wujiaping Stage was drawn, with single factor analysis and comprehensive mapping method. It is considered that the dominant sedimentary environment of the area in the early Wujiaping Age is tidal fiat to shallow marine, and the bauxite beds mainly developed in the first third-sequence of the lower Wujiapingian Stage. According to the analysis of the relation between distribution of known mineralization point and paleogeography, it can be obtained that the most conducive environment for the formation of bauxite is subtidal zone to upper shallow marine.