库车坳陷中部新近系-第四系砾岩层的沉积特征及分布规律

为了解决库车坳陷新近系-第四系砾岩层引起的速度变化和工程决策问题，利用砾岩层野外露头和钻井岩屑等资料，对砾岩层的沉积特征及分布规律进行了系统研究。分别对野外砾岩层和钻井岩屑的厚度、岩性、结构构造及砾石成分进行统计分析，在区域上对各层系的砾岩层进行划分和对比。认为库车坳陷新近系-第四系砾岩层可以划分为四期，具有冲积扇、扇三角洲及冲积平原三种沉积成因，它们的规模、水动力条件及沉积构造等具有较大差异。以冲积扇砾岩层规模大，发育四大物源体系，各物源体系的砾石成分分区明显，砾石粒径随相带分异。库车坳陷砾岩层整体具有纵向上多期次连续发育、相带差异明显，横向上相变快、集中分布的特点，新生代构造演化、构造样式及南北向断裂是控制砾岩层发育、沉积特点及分布规律的主要因素。

Sedimentary Characteristics and Distribution of Neogene Quaternary Gravel Layers in the Middle of Kuqa Depression,Tarim Basin

 Based on the outcrop investigation and core borings identification, we systematically studied the cycle of development, the sedimentary and distribution characteristics of Neogene Quaternary gravel layers of Kuqa Depression in Tarim Basin, to solve the problems of velocity changes and engineering decision. We analysed the thicknes, lithology, structures, tectonic and gravel composition of different outcrops and rock debris, and we also correlate gravel layers of all period. We believe  that  there were four periods which developed thick gravel layers, and the sedimentary origins of gravel layers could be alluvial fan, fan delta and fluvial plain. All gravels had four provenance systems, in which there developed different gravel composition. The gravel layers of Kuqa depression continuously developed in different periods vertically, and had different facies which changed fast laterally. The tectonic evolution, tectonic style, and the north south faults were the main factors which influenced the sedimentary characteristics, distribution of the gravel layers.