辽宁兴城地区大红峪组底界性质及地质意义

为进一步确定燕山裂陷槽中元古界大红峪组底界性质,笔者对位于燕山中元古代沉积盆地边缘的兴城地区进行调查研究。通过对研究区多个剖面上大红峪组底部砾岩的特征、类型及成因的初步分析,得出该组沉积之前地表经历了差异性侵蚀,造成古地形起伏较大。大红峪组底部与下伏地层的不整合包括单斜不整合和超覆不整合两种类型,其代表的"兴城运动"没有影响到更广阔的范围。根据大红峪组底界明显的沉积间断现象,笔者认为将标准剖面大红峪组底界置于"小白石英岩"之下更为合理。

Nature and geological significance of bottom boundary of Dahongyu Formation in Xingcheng area,Liaoning

In order to further determine the nature of the bottom boundary of Mesoproterozoic Dahongyu Formation in Yanshan aulacogen, the authors investigate the outcrops in Xingcheng area located at the edge of the Yanshan Mesoproterozoic sedimentary basin. Through the preliminary analysis of the features, types and genesis of the conglomerate at the bottom of Dahongyu Formation in several sections in the study area, it is shown that there had been differential erosion before the deposition of Dahongyu Formation, resulting in obvious fluctuations of palaeotopography. The unconformity includes two types, namely monoclinic unconformity and overlapping unconformity, and the influence of the "Xingcheng Movement" represented by it may not affect the broader scope. According to the obvious depositional hiatus at the bottom boundary of Dahongyu Formation, it is more reasonable to put the bottom boundary of Dahongyu Formation in the standard section under the "small white quartzite".