库车坳陷早三叠世三角洲相及伴生沉积

EARLY PERMIAN DELTAIC FACIES AND ITS ASSOCIATED SEDIMENTS IN KUQA DEPRESSION

库车坳陷下三叠统为三角洲、湖泊沉积。北缘发育的扇三角洲和辫状河三角洲是本区主要的沉积相类型。扇三角洲沉积以突发的灾变事件产生的重力流与牵引流沉积共存为特点。前者以碎屑流成因的块状砾岩为主占主导地位，后者为扇面河道砂体，多呈透镜状分布于重力流沉积物中；辫状河三角洲沉积以正常牵引流尤以河道沉积为主，砂体呈层状，侧积交错层发育。二者自成体系却又相互联系，构成两个密切相关的演化阶段，受控于坳陆边缘断裂活动的强度和延续时间。

Kuqa Depression is a 'dustpan' shape depression with steep slope in the north side andgentle slope in the south side.Fan-deltas and braid river deltas are developed on its northmargin while shore deposit, shallow lake deposit and meandering river deltas are developedon the south margin. The fan-deltas are characterized by gravity flow deposit associated withtractive current deposit' Both of the deposits were resulted by sudden catastrophic event. Theformer is primarily massive conglomerate; the later is mainly lenticular channel sand bodiesdistributed within the gravity flow deposit' The normal tractive current deposit of the braidriver deltas is primarily bedded channel sand bodies in which lateral aggradation and crossbedding are well developed' The fan deltas and braid river deltas are independant but closelyconnected to each other,their evolution is controlled by the intensity and range of faulting activity in depression margins.