塔里木盆地西北缘震旦纪构造-沉积演化特征

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：ZSQ Ⅰ、ZSQ Ⅱ和ZSQ Ⅲ，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。

Tectono-sedimentary evolution of the Sinian in the Northwest Tarim Basin

Based on the field section survey and research of the Sinian in the Northwest Tarim Basin of China and the analysis of regional tectonic setting, it indicated that the Sugetbrak Formation of the Lower Sinian in Northwest Tarim Basin is main terrigenous clastic deposition, which composed of fluvial, lake, offshore and delta facies. And Chigebrak Formation of the Upper Sinian is a set of carbonates deposited on a restricted carbonate platform, which is dominated by tidal flat mudstones, beach grainstones and mixed tidal flat at the bottom. According to the characteristics of the assemblage of rocks and the carbon isotope evolution, the Sinian can be divided into three third-order sequences:ZSQ Ⅰ, ZSQ Ⅱ and ZSQ Ⅲ by the three unconformities. The three sequences reveal the depositional model and tectono-sedimentary evolution of the rift basin developed on the early plate margin. The early is the primary extensional stage, which is a group of coarse detrital rocks. Then the rapid extensional stage, which is composed of sandstone and mudstone of lake, offshore and delta accompanied by eruption of basalt. At the end, the steady subsidence stage with carbonate platform sediments developed.