青海柴达木盆地北缘寒武纪和奥陶纪海相红层的分布与时代

参照青海省柴达木盆地北缘寒武纪和奥陶纪地层相关文献资料,通过野外地质调查和系统样品分析结果,在柴北缘寒武纪—奥陶纪地层中梳理和识别出了19层海相红层。其中,寒武纪地层中识别出了12层海相红层,奥陶纪地层中识别出了7层海相红层。除奥陶纪石灰沟组海相红层(QORB3,QORB4,QORB5及QORB6)为深水大洋红层外,其余15层海相红层均属浅水—半深水陆棚红层。依据海相红层及其上下层位所含化石,本文初步论述了各海相红层的大致时代,并与我国主要块体的同期海相红层进行对比。上述研究对进一步开展全国乃至全球寒武纪、奥陶纪海相红层分布及对比提供了基础数据和资料。此外,通过国内同期红层的对比,本文还讨论了河北唐山寒武纪海相红层的分布及中国南方中奥陶世大坪期—达瑞威尔期早期海相红层广布事件。

Distribution and ages of Cambrian and Ordovician marine red beds in the northern margin of Qiadam Basin, Qinghai Province

According to the field investigation in the northern margin of the Qiadam Basin, Qinghai Province, and previous results, the study discussed the Cambrian and Ordovician marine red beds in this area. Nineteen marine red beds have been recognized in the Cambrian and Ordovician strata in the northern margin of the Qiadam Basin. Among them twelve are Cambrian marine red beds and seven Ordovician marine red beds. Most of them belong to the Shelf Red Beds (SRBs), only four of them are of the Oceanic Red Beds (ORBs) (Shihuigou Formation marine Red Beds of Ordovician). Based on the fossils in marine red beds and the upper and lower layers of the red beds, this paper preliminarily discussed the general ages of the red beds and compared them with the coeval marine red beds in the main blocks of China. This results in this study provide basic data for further research in the distribution pattern and stratigraphic correlation of the Cambrian and Ordovician marine red beds in China and even the world. In addition, the distribution of the Cambrian marine red beds in Tangshan, Hebei Province, and the widespread events of Dapingian to early Darriwilian (Middle Ordovician) marine red beds in South China are discussed.