豫西地区早二叠世碳酸盐岩台地沉积环境及地球化学特征

焦作-禹州地区下二叠统太原组沉积相可划分为5类：开阔台地相、局限台地相、障壁岛相、泻湖-沼泽相和潮坪相，海相碳酸盐岩地层中风暴沉积事件普遍发育。开阔台地主要发育生物碎屑灰岩，生物碎屑含量高且较为破碎，以LREE明显富集，∑REE、(LREE/HREE)N值与Fe含量正相关为特点，反映古水体开阔、动荡且富含生物碎屑和胶体。局限台地主要沉积泥晶灰岩，古水体环境表现为受限、相对安静的特点。研究区太原组下部灰岩段的底部灰岩形成于海侵体系域(TST)，生物碎屑含量、∑REE相对较高且轻重稀土无显著分异，Sr/Ba比值小而Ba丰度高；顶部灰岩形成于高水位体系域(HST)，显示台地水体逐渐受到限制，陆源控制作用减弱，演化为更加安静低能环境。不同体系域中局限台地灰岩的对比分析，可为恢复南华北二叠纪陆表海盆地古地理特征及演化提供重要资料。

Sedimentary Environments and Geochemical Characteristics of Early Permian Carbonate Platform in the Western Henan ProvinceYAO Xu

This paper presents the study of the sedimentary facies of Taiyuan Formation in typical sections from Jiaozuo area to Yuzhou area, mainly focusing on the platform sedimentary characteristics and evolution of epicontinental sea. Sedimentary facies of Taiyuan Formation, which is mainly featured by limestones along with interlayered siltstones, mud shales and coal seams, can be divided into five facies including open carbonate platform, limited carbonate platform, barrier island, lagoon swamp and tidal flat facies. The storm depositional events widely developed in the carbonate platform, which can be divided into several sedimentary cycles. Open carbonate platform (mainly in Yuzhou area) mainly contain amount of bioclastic, featured by substantial broken fossils, high content of trace elements and rare earth elements, much higher content of LREE than that of HREE, the respectively positive correlations between the value of ∑REE and the content of Fe as well as between that of LREE/HREE and Fe. Compared with open carbonate platform, restricted carbonate platform (mainly in Jiaozuo area) is featured by the widespread micrite, which infer that the ancient ocean in the restricted carbonate platform contained less fossils and colloids, and became much more restricted and quieter than that of open carbonate platform. The bottom limestones of the Lower Limestone Section of Taiyuan Formation, which is formed in transgressive systems tract(TST) during the early phase of first transgression, are featured by high content of biodetritus, Sc, Ba and ∑REE, low value of Sr/Ba, low differentiation between LREE and HREE. The top limestones of the Lower Limestone Section formed in highstand systems tract (HST), which reflected the sedimentary environment of the limited carbonate platform in the research area evolving from the previous turbulent water into confined and quite surroundings with biodetritus and collides diminishing and evaporation strengthening. It aims to put implications on the research of the characteristics and evolution by comparing with the sedimentary characteristics of Taiyuan Formation limestones in different stage of the system tracts in restricted carbonate platform.