深水异地鲕粒灰岩的特征及成因探讨——以宁夏中宁地区香山群徐家圈组为例  

Characteristics and Genesis of Allochthonous Ordovician Limestone: A case for Middle Ordovician Xujiajuan Deepwater Oolitic Limestone in Zhongning Area, Ningxia

作　　者：王宁[1] 何幼斌[1] 李向东[2] 苑伯超[1] 罗进雄[1] 

机构地区：[1]长江大学地球科学学院 [2]中国地质科学院地质研究所

出　　处：《海相油气地质》2012年第3期72-78,共7页Marine Origin Petroleum Geology

基　　金：国家自然科学基金项目"鄂尔多斯盆地西缘中奥陶统深水牵引流沉积研究"(41072086)资助

摘　　要：深水异地鲕粒灰岩可从宏观特征、微观特征、粒度特征及沉积构造等方面进行识别。通过宁夏中宁县狼嘴子地区香山群徐家圈组中部发育的鲕粒灰岩的野外露头剖面和室内薄片观察,对鲕粒灰岩的宏观及微观特征进行了研究。对颗粒粒径的统计和对比分析表明,鲕粒与假鲕、正常鲕与表皮鲕分别来自不同环境,粒度分析结果显示其具有重力流搬运的特征。结合沉积背景认为,此种鲕粒灰岩应为深水异地沉积成因,鲕粒可能来自同时期的鄂尔多斯地块西缘碳酸盐台地,由重力流搬运至深水。Deepwater allogene oolitic limestone can be identified by macroscopic and microscopic features,grain size characteristics and sedimentary structures.Macroscopical and microscopical observation and analysis have done to the outcrop sections and rock thin sections form Middle Ordovician Xujiajuan oolitic limestone in Zhongning Area,Ningxia.The result of statistical analysis and contrast of rock grain sizes has shown that oolites and pseudoolites,normal oolites and epidermis oolites formed in different environments.The granularity is characterized by gravity flow transportation.Combined with the sedimentary background,it is believed that this kind of oolitc limestone is deepwater allogene deposits in origin and the oolites are likely to come from the contemporaneous carbonate platform in the west margin of Ordos Block to this deep water area by gravity flow transportation.

关 键 词：香山群 中奥陶统 鲕粒灰岩 深水沉积 沉积特征 岩石成因 

分 类 号：TE112.23[石油与天然气工程—油气勘探]