太行山南段长城系大河组石英岩状砂岩的同沉积构造

Synsedimentary structures in quartz rock sandstone of Dahe formation of great wall system in southern Taihang mountains

为获得中元古代大河组的沉积过程与形成机制,对太行山南段迴龙隧道和小灵山两个剖面开展地质调查。调查发现,两剖面中大河组沉积物中发育大量的同沉积构造,主要表现为成层出现的软沉积变形构造、脆性破裂的同沉积断层、滑塌构造三种类型。解析结果表明,大河组上发育的同沉积构造的触发条件可能是地震以及由地震触发的海啸事件作用,且这些震积事件多发生于潮上带环境下。大河组石英岩状砂岩中同沉积构造的发现,为中元古代大河组形成的沉积环境与沉积过程研究提供了科学依据。

This paper aims to uncover the sedimentary process and formation mechanism underlying the Mesoproterozoic Dahe formation by performing geological survey of the Dahe formation in the Huilong Tunnel and Xiaolingshan profiles in the Xiyagou area of the southern Taihang Mountains.The survey finds that the occurrence of a large number of synsedimentary structures in the sediments of the Dahe formation is characterized mainly by the three types:the soft sedimentary deformation structure with stratification,the synsedimentary fault with brittle fracture,and the slump structure.The results reveal that the triggering conditions of synsedimentary structures developed on the Dahe formation may be the result of earthquakes and earthquakes-induced tsunami,and above all,the occurrence of most of these events in the supratidal environment.The discovery of synsedimentary structures in quartzite sandstones of the Dahe formation could serve as a scientific basis for the study of sedimentary environment and sedimentary process behind the formation of the Mesoproterozoic Dahe formation.