Sequence stratigraphy and lithofacies paleogeography of the Middle–Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area, SW China

• 作者: DENG Shenghui FAN Ru JIA Peng LI Wei LI Xin LU Yuanzheng ZHANG Zhijie
• 来源期刊: 石油勘探与开发:英文版
• 学科: 工学
• 关键词: Sichuan Basin Middle–Upper Cambrian Xixiangchi Group SEQUENCE STRATIGRAPHY THIRD-ORDER SEQUENCE carbon isotope composition lithofacies PALEOGEOGRAPHY sedimentary environment evolution
• 年，卷（期）: 2019,（2）
• 页码范围: 238-252
• 页数: 15页
• 分类号: TP274.2

摘要

Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sql-Sq5), of which sequences Ⅰ to Ⅲ(Sql-Sq3) are relatively complete, sequences Ⅳ and Ⅴ are denuded in the Late Cambrian because of the Dian-Chuan paleo-uplifts.Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence Ⅰdevelops high stand systems tract and transgressive systems tract. The other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts last shortly in time and are limited in area. The basic features of evaporative-restricted platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group, its sedimentary environment of "high in west and low in east" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence Ⅰ and sequence Ⅱ, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence Ⅱ and sequence Ⅲ. It indicates that there are two platform margin zones in the study area,a relatively stable, large-scale platform marginal zone in NE Guizhou-Western Hunan and Hubei, and a moving and small-scale platform marginal zone in North Chongqing-Western Hubei.