五台山南缘中元古界的层序地层特征及其古地理意义:以山西五台陈家庄剖面为例

中元古代时期的五台山南缘是华北克拉通北部的燕辽裂隙槽与南部的晋豫陕裂隙槽之间的交接地带。在该地区中元古界由常州沟组潮坪沉积体系碎屑岩地层和高于庄组潮坪沉积体系碳酸盐岩地层组成,常州沟组与下伏的早元古界滹沱群为角度不整合接触,高于庄组与上覆的寒武系之间为地层间断时间超过1000 Ma的平行不连续面;残留不全的元古界不但成为前寒武纪层序地层学划分的典型代表,而且成为窥视早期来自南部裂陷槽向北海侵以及晚期来自燕辽裂陷槽向南海侵的宝贵的物质记录,并且成为重新审视晋豫陕裂陷槽与燕辽裂陷槽的争议较大的地层对比的关键地层记录。对山西五台沉积状剖面中元古界沉积序列及其所表征的层序地层学特征的观察和描述,为今后的进一步研究提供了有用的线索,因而具有重要意义。

Sequence-Stratigraphic Features and Their Paleogeographical Implications for the Mesoproterozoic of the Southern Margin of Wutai Mountain: A Case Study of the Chenjiazhuang Section in Wutai County of Shanxi Province, North China

The study area,i.e.the southern margin region of the Wutai Mountain,is a conjoining region between the Jin-Yu-Shan in the southern part and the Yanliao Rift Troughs in the northern part of the Mesoproterozoic in the North-China Craton.A set of clastic rocks of the tidal-flat deposition system makes up the Changzhougou Formation,and a set of tidal-flat carbonate rocks does the Gaoyuzhuang Formation,both of which constitute the Mesoproterozoic of the study area.Its bottom boundary is an angular unconformity covering the Paleoproterozoic Hutuo Group,and top boundary is a leurodiscontinuity with a stratigraphic hiatus more than 1,000 Ma underlying the Cambrian system.Thus,the incomplete strata of the Mesoproterozoic become a true example for the study of sequence stratigraphy in the Precambrian,which is the key to peek the trangressive process from the Jin-Yu-Shan in the southern part in the early period and that from the Yanliao Rift Troughs in the northern part during the Mesoproterozoic in the study area,and provides a valuable stratigraphic record to correlate strata that remain uncertain.Further,the research and introduction on sequence-sequence features that are marked by depositional successions for the Mesoproterozoic at the Chenjiazhuang section in Wutai County of Shanxi Province will provide a useful clue for further study on the Precambrian sequence stratigraphy in the North-China Craton.