论文部分内容阅读
宁夏一带的香山群,由于各种原因,其时代和地层的划分自建立以来一直处于争论不休的状态。产生这种问题的原因最终聚集在两个问题上的分歧:香山群的地层构造和化石产出部位的沉积构造环境分析上。根据野外的实际观察及前人资料的综合分析,香山群的构造并非成简单的单斜排列,各个单元的沉积也各具特征。其中第一和第三亚群(包括徐家圈组第四段)为秦—祁—贺裂陷槽裂陷初期的产物,分布于盆地的东缘,时代为中寒武—晚寒武世;第二亚群(不含徐家圈组第四段)和第四亚群为裂陷槽裂陷中晚期的产物,主要分布于盆地的西北缘,时代为奥陶纪。结合区域地层的综合分析,提出了早古生代贺兰裂陷盆地的沉积充填模式及地层格架。
The Xiangshan Group in Ningxia has been in a state of endless debate for a variety of reasons since its establishment and formation. The reasons for this kind of problem eventually converge on two issues: the structural formation of the Xiangshan Group and the tectonic environment of the fossil production site. According to the field observations and comprehensive analysis of previous data, Xiangshan Group structure is not a simple monoclinic arrangement, the deposition of each unit also has its own characteristics. The first and the third subgroups (including the fourth member of Xujiahe Formation) are the initial products of the Qin-Qi-He rift trough, distributed in the eastern margin of the basin, with the age of Middle Cambrian-Late Cambrian. The second sub-group (excluding the fourth member of the Xujiahe Formation) and the fourth sub-group are the products of the middle and late rift rifts. They are mainly distributed in the northwestern margin of the basin and are dated to Ordovician. Combined with the comprehensive analysis of regional strata, the sedimentary filling pattern and stratigraphic framework of the Helan rift basin in the Early Paleozoic are proposed.