塔里木西南缘南华系下部沉积作用及其构造意义

塔里木西南缘的南华系下部地层呈北西向带状分布于莎车、叶城、皮山一线 ,可分为四个具有不同沉积大地构造意义的构造层序单元 :下部为河湖沉积 ,中部为湖盆沉积 ,上部为闭塞滨海相沉积 ,三者代表断陷盆地演化阶段 ;顶部为正常的 (滨 )浅海相沉积 ,代表拗陷盆地演化阶段。结合研究区内广泛发育的岩墙群、双峰式火山岩、大规模的混合岩化及其派生的碱性花岗岩等构造岩浆事件和同位素年代学研究成果综合分析 ,研究区的南华系下部层位形成于大陆裂谷背景。完整的层序和清晰的演化阶段不仅有利于研究区地层对比 ,也有助于建立 Rodinia超大陆裂解事件在研究区的表现形式

DEPOSITIONAL TYPES OF THE LOWER PART OF NANHUAN SYSTEM ON THE NORTHERN MARGIN OF SOUTHWEST TARIM AND THEIR TECTONIC SIGNIFICANCE

The lower part of Nanhuan System on the southwestern margin of Tarim Basin is distributed northwestwards along a belt from Shache through Yecheng to Pishan Coutries, and may be divided into four tectonic sequence units with different depositional geotectonic significance, namely, the fluviolacustrine lower part, the lacustrine-basin middle part, the restricted littoral upper part, the three parts representing the evolutional stages of the fault basin, and the normal shallow-water top part, representing the evolutional stage of the down-warped basin. Based on the result of the studies of widely developed dike swarm, bimodal volcanic rocks, and the large-scale migmatized and induced alkaline granites and other tectonomagmatic events as well as the isotopic chronological reseach, the strata in the lower part of the Nanhua System in the study area were formed under the continental rift condition. Complete sequences and clear evolution stages are helpful not only in the stratigraphic correlation in the study area, and also in the establishment of the patterns of the Rodinia supercontinental splitting event in the study area.