太行山中南段长城系赵家庄组沉积特征

Depositional Characteristics of the Zhaojiazhuang Formation,Changcheng System,in the Middle-Southern Areas of the Taihang Mountains

前寒武纪沉积地层多因地质时代久远而受到过变质作用的强烈改造,因而沉积作用过程研究难度较大且较为薄弱。以详细的野外地质剖面测制工作为基础,结合区域地质背景资料分析,通过野外岩石类型鉴定、沉积构造鉴别及室内岩相古地理综合分析等,发现太行山中南段长城系赵家庄组发育陆相→海相的沉积岩相组合,主要形成环境为冲积扇相→潮坪相,地层顶底界线清晰,易于识别。赵家庄组完整的地层层序可划分为4段,包括粗碎屑岩层、砂岩页岩互层、页岩层和叠层石藻礁层,岩石类型丰富,地层沉积特征明显,具有明显的沉积环境指示作用,可以作为地质工作者进一步研究前寒武纪沉积环境及早期古生物的一个窗口。

As Precambrian sedimentary strata have likely been rigorously transformed due to metamorphism over a long period of geological time,studies on this sedimentary process are often challenging and yield unconvincing results.Employing a detailed field geological profile analysis,combined with an analysis of the regional geological background,we identified rock types and sedimentary structures,and conducted a comprehensive analysis of lithofacies and palaeogeography.Our results showed that the terrestrial!marine sedimentary facies in the Zhaojiazhuang Formation,Changcheng system of the mid-southern areas in the Taihang Mountains were formed mainly by alluvial fan facies!tidal flat facies.The boundary between the top and bottom layers was clearly visible and identifiable.The complete stratigraphic sequence of the Zhaojiazhuang Formation can be divided into four sections:coarse clastic rock,sandstones/shale interbed,shale,and layered limestone reef.The rock types are abundant,and the stratigraphic sedimentary characteristics are prominent.These features are significant indicators of the sedimentary environment and can be used by geologists to study the Precambrian sedimentary environment and early paleontology.