河北唐山地区中奥陶统马家沟组碳酸盐岩微相分析  

Carbonate Microfacies Analysis of Middle Ordovician Majiagou Formation in Tangshan Area,Hebei Province

作　　者：李娜[1] 张宁[2] 董元[1] 

机构地区：[1]中国地质大学研究生院,武汉430074 [2]中国地质大学地球科学学院

出　　处：《地质科技情报》2008年第4期20-26,38,共8页Geological Science and Technology Information

基　　金：国家自然科学基金项目(40576025)

摘　　要：介绍了河北唐山地区中奥陶统马家沟组碳酸盐岩的主要颗粒组成及特征,同时采用微相分析的方法,对该组碳酸盐岩的生物组合、颗粒成分、基质类型及其结构等微相特征进行了研究,将唐山地区的马家沟组沉积归纳为8种微相类型,即:纹层状灰泥岩、砾屑灰岩、含生物碎屑灰泥岩、生物碎屑粒泥灰岩、生物碎屑泥粒灰岩、生物碎屑漂砾岩、生物碎屑-球粒钙质粉屑岩、次生晶粒结构微相。将微相分析与宏观沉积构造分析相结合,识别出了河北唐山马家沟组为碳酸盐岩缓坡沉积,其垂向序列展示出2个演化旋回,每个旋回下部从内缓坡潮坪相开始,向上依次演化为内缓坡局限海-开阔海相、中缓坡相和外缓坡相,然后经过一次海退而转化为另一个旋回。但是,另一个旋回的起点通常不会重复退回原点,可能继续更高级旋回的海侵或海退过程退回相关的相位。The Middle Ordovician Majiagou Formation in Tangshan area, Hebei Province, is mainly composed of carbonate rocks, identified by eighty thin sections. This paper first introduces the main grain composition and characteristics of carbonate rocks, and then analyses microfacies, the microfacies characters of the carbonate rocks, such as the biotic assemblage, grain composition and the type and texture of the matrix. Majiagou Formation carbonate rock of the studied area can be mainly divided into eight microfacies types： laminated mudstone, rudstone, bioclastic mudstone, bioclastic wackstone, bioclastic packstone, bioclastic floatstone, bioclastic-pelletd calcisiltite and secondary crystalline granular textural microfacies. The macro-field observation reveals that Majiagou Formation is mainly deposited in the carbonate ramp environment, and its vertical sequence shows two evolution cycles. The lower part of each cycle starts from the tidal flat of the iner ramp facies, and gradually evolved upwards to the restricted-open marine facies, the middle ramp facies and the outer ramp facies. After a regression, the first circle transisted to be second circle. However, unlike the first one the second circle usually as starts its depositional facies from more senior transgression or regression, and then to the related facies.

关 键 词：碳酸盐岩微相 马家沟组 中奥陶统 唐山地区 

分 类 号：P534.42[天文地球—古生物学与地层学]