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本文在对塔里木盆地西北缘震旦系开展野外地质剖面实测工作及室内研究基础上,结合区域构造背景分析认为,塔里木盆地西北缘下震旦统苏盖特布拉克组发育河流相、湖泊相、滨海相及三角洲相碎屑岩沉积,上震旦统奇格布拉克组发育局限台地潮坪亚相、台内滩亚相碳酸盐岩沉积,底部发育混积潮坪相沉积。根据震旦系地层岩石组合特征及C同位素演化趋势,将震旦系划分为3个Ⅲ级层序:ZSQⅠ、ZSQⅡ和ZSQⅢ,每个层序顶部分别对应一个不整合面。在此基础上建立塔里木盆地西北缘震旦纪拉张性裂谷沉积模式,并划分为3个构造沉积演化阶段:初始拉张阶段,对应于早震旦世早期,沉积一套粗碎屑岩堆积;快速拉张阶段,对应于早震旦世晚期,沉积一套湖相、滨海相、三角洲相砂岩,泥岩沉积,同时伴随玄武岩喷发;稳定沉降阶段,对应于晚震旦世,形成碳酸盐岩台地沉积。
Based on the field survey and field studies of the Sinian formation in the northwestern margin of the Tarim Basin, combining with the tectonic setting analysis, it is concluded that the Lower Sinian Suguobulak Formation in the northwestern margin of Tarim Basin develops the facies of the rivers and lakes, Marine facies and deltaic clastic sediments. In the Upper Sinian conglomerate, the Qiabuluk Formation is characterized by the deposition of tidal flat subfacies, intraplate neotectonian carbonate rocks and the accumulation of tidal flat sediments at the bottom. According to the characteristics of the lithosphere assemblages and C isotopic evolution in the Sinian stratigraphic system, the Sinian system is divided into three Ⅲ-order sequences: ZSQⅠ, ZSQⅡ and ZSQⅢ, and the top of each sequence corresponds to an unconformity. On this basis, the Sinian extensional rift sedimentary model in the northwestern margin of the Tarim Basin was established and divided into three structural depositional evolution stages: the initial extensional stage corresponding to the early Early Sinian deposition of a set of coarse clastic rocks The rapid pull-out phase corresponds to the late Early Sinian deposition of a suite of lacustrine facies, coastal facies, delta facies sandstone and mudstone deposition accompanied by basaltic eruptions, and stable settling stages corresponding to Late Sinian formation of carbonate Salt rock platform deposition.