一种辫状河、曲流河复合沉积体层序特征及其成因

为了探讨辫状河、曲流河复合沉积体系的层序地层分析方法,以哈萨克斯坦南图尔盖盆地南部下白垩统沉积体为例,在确定河流成因类型和相构成的基础上,考虑沉积地质、测井和地震资料,对下白垩统沉积体进行层序地层划分.结果表明:研究区下白垩统层序1主要发育低位体系域和湖侵体系域,高位体系域发育局限.低位体系域主要为辫状河沉积,包括河床滞留沉积和心滩;湖侵体系域主要为曲流河沉积,包括曲流河河道和泛滥平原.辫状河与曲流河复合沉积层序主要受古气候、古构造和沉积物供给因素控制.该复合沉积层序的形成为认识和对比地下复杂河流相地层提供了较好的实例.

Characteristics of composite sedimentary sequence of braided and meandering river and their genetic interpretation

A composite stratigraphy of depositional system of braided and meandering river in South Turgai Basin in Kazakhstan is analyzed.The causes of river type and phase composition are determined,it includes the meandering river channel,flood plain,riverbed detention sediment and bar of braided river.According to sedimentary geology,logging and seismic data,the sedimentary sequence of Lower Cretaceous sedimentary body is divided.Low stand system tract and transgrasive system tract developed in sequence 1,and high stand system tract poorly developed.Braided river developed in LST and meandering river mostly developed in TST.The composite sedimentary sequence of braided river and meandering river is controlled by paleoclimate,palaeotectonic and sediment supply.This composite sedimentary sequence of braided and meandering river provides a good example of comparison for understanding the formation of underground strata of river.