川西理塘地区雅江残余盆地西康群两河口组沉积地质特征及物源分析

Sedimentary Geological Characteristics and Provenance Analysis of Lianghekou Formation, Xikang Group, Yajiang Residual Basin, Litang Area, Western Sichuan

川西理塘地区雅江残余盆地西康群两河口组地层位于甘孜理塘蛇绿混杂岩带东侧,是研究西南三江造山带沟弧体系的重要地区,为了解研究区两河口组沉积地质特征及物源性质,丰富三江造山带沟弧体系中的沉积地层,利用沉积学及岩石地球化学特征方法,对研究区两河口组地层进行沉积地质特征和物源分析,取得以下进展:两河口组发育递变层理、平行层理、斜层理、包卷层理,可见4种基本层序类型。沉积相分析可知,两河口组为盆地–斜坡沉积环境形成。岩石地球化学特征及判别图解表扬,物源主要形成于被动大陆边缘,但明显有大陆岛弧的物质加入。

The Lianghekou Formation of the Xikang Group in the Yajiang Residual Basin in the Litang Area of Western Sichuan is located on the east side of the Litang ophiolitic melange belt in Garzi, and it is an important window to study the gully arc system of the Sanjiang orogenic belt in the southwest. Source properties, enrich the sedimentary strata in the trench-arc system of the Sanjiang orogenic belt, and use the methods of sedimentology and petro-geochemical characteristics to analyze the sedimentary geological characteristics and provenance of the Lianghekou formation in the study area. The following progress has been made: the development of the Lianghekou Formation Variation bedding, parallel bedding, oblique bedding, and wrapping bedding can be seen in four basic sequence types. Sedimentary facies analysis shows that the Lianghekou Formation was formed in a basin-slope depositional environment. The petrochemical characteristics and identification diagrams show that the provenance of the Lianghekou Formation is mainly formed in the passive continental margin tectonic environment, but there are obvious additions from the continental island arc.