河北迁安常州沟组底砾岩特征及成因分析

Characteristics of basal conglomerate of the Changzhougou formation and its genesis analysis in Qianan,Hebei province

通过对迁安常州沟组底砾岩岩石学特征和剖面沉积特征分析,阐述了砾岩层的性质、形成的水动力条件及古水流方向,并结合砾岩沉积时的盆地构造背景和地貌特征综合探讨底砾岩的成因。对底砾岩的岩石学研究,粒度分析,沉积韵律特征及古水流综合分析的结果表明,常州沟组底砾岩为干旱氧化环境下山间河流沉积产物,具有多次搬运、近源快速沉积的特点,水动力条件强而稳定,古流向总体为南东—北西向,物源可能来自盆地东南部的山海关古隆起。

Based on the analysis of the petrologic characteristics and sedimentary characteristics of basal conglomerate of the Changzhougou formation in Qianan,combined with the study of tectonic setting and geomorphological characteristics of the basin,this paper deals with the hydrodynamic conditions,paleocurrent direction,characteristics and origins of the conglomerate layers.The study reveals that the basal conglomerate layers of the Changzhougou Formation are intermontane fluvial sediment,which indicates an arid and oxidizing environment.The gravels underwent repeated transportation and quickly deposited near source.Hydrodynamic conditions were strong and stable.The paleocurrent direction was SE-NW,the main source rocks of the basal conglomerate are Shanhaiguan Palaeo-uplift in the southeastern.