河北省怀来新元古代长龙山组沉积相研究

The Study on Sedimentary Facies of Changlongshan Formation of Neoproterozoic Era in Huailai, Hebei

河北省怀来新元古代长龙山组主要为一套富含Chuaria等宏观藻类化石的碎屑岩沉积组合。对剖面的岩相分析及地球化学的研究，确定了潮坪、浅水陆棚及海滩等三种沉积相。由此提出了长龙山组的沉积相模式。长龙山组表现为三种沉积相的周期性叠里，组成了两个碎屑岩沉积序列。长龙山组的下部序列由湖坪相到浅水陆棚相再返回到海滩相；上部序列由浅水陆棚相及海滩相组成。Chuaria等宏观藻类化石主要发育在浅水陆棚相的滨外页岩亚相之中。综合分析表明，长龙山组是有河流参与的潮汐及波浪影响的滨浅海沉积环境。

Changlongshan format ion of N aproteroziic Era in Huailai Hebei is consists of rnainly a sedimentary assoriation of clastic rock with rich macroalgal forssils (Churaia). Studying the sedimentary environment will have an important significane to the ecology of rnacrtalgal organisrns and paleogeography evolution. Three sedimentary facies are tidal flat, shallowshelf and beach facies, which are established through the analysis lithofaies and the study geochernistry in the section. Therefore the sedimentary medel is raised on the basis of sedimentary facies analysis. The Changlongshan formation shows the cyclical accumulation of the three sedimentary facies, and consisting of two sedimentary equences of clastic rock. The evolution feature in the lower of sedimentary Sequences is from the tidal flat facies to shallow shelf facies,then back to beach system. The upper directly develope into the shallow shelf facies, then tobeah facies. The Chudria formed mainly in the offehore shale subfacies of the shallow shelf facies. Cimprehensive analysis shows that sedimentary environrnent of Changlongshan formation is the littoral and neritic sea controled by the tidal, sea wave and river.