【摘要】 <正> 川西松潘-甘孜印支地槽形成于三迭纪最早期,结束于三叠纪末。地层单位可分下三迭统和中、上三叠统二部分。主要沉积为一套巨厚陆源碎屑岩系。其下部称菠茨沟组,上部称西康群。在西康群的碎屑岩系中,广泛分布复理石沉积,如小金、道孚雅江和理县等地。本文主要对上述地区复理石沉积进行岩石和构造分析。更多还原

【Abstract】 Terrigenous flysch formations are developed in many places in Songpan-Garzegeosyncline, western Sichuan. On the basis of the results gained through work inthe Xiaojin area, the flysch rhythem may be divided into three units: (Ⅰ) arena-ceous, (Ⅱ)silty, and(Ⅲ) pelitic. Each unit may be subdivided into rhythemic layers; thus seven small rhythemic layers are distinguished, i. e. Ⅰa, Ⅰb, Ⅰc; Ⅱa, Ⅱb; Ⅲa and Ⅲb.These divisions are more practical than the fivefold divisions (i. e. A, B, C, D andE divisions) of the Bouma sequence, so can best reveal genetic features. These small rhythemic layers were formed in different environments. In additionto the turbidity-current processes, there might be the effect of marine currents. Thepelitic portion might be transported and deposited in the colloidal state. the Songpan-Garze geosyncline was formed on the basis of the disintegrationof continental crust in the late Permian. Therefore, the great majority of the flyschseries was deposited on the substrate of oceanic crust. At that time, many hugedeltas came into being at the northern margin of the oceanic basin, and afterwardsthe thrbidity currents formed by slumping transported clastic materials to thecentral part of the basin. In the ancient oceanic basin were distributed some ancientisland-arcs, which controlled sedimentation and eruption.更多还原