石油与天然气地质 ›› 1993, Vol. 14 ›› Issue (2): 153-160.doi: 10.11743/ogg19930209

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湖南石门中上寒武统白云岩成因

胡明毅   

  1. 江汉石油学院 湖北 沙市434102
  • 收稿日期:1992-02-26 修回日期:1992-10-06 出版日期:1993-06-25 发布日期:2012-01-16

ORIGIN OF MIDDLE-UPPER CAMBRIAN DOLOMITES IN SHIMEN,HUNAN

Hu Mingyi   

  1. Jianghan Institute of Petroleum, Shashi
  • Received:1992-02-26 Revised:1992-10-06 Online:1993-06-25 Published:2012-01-16

PDF (PC)

818

被引次数

19

摘要：

湖南石门中上寒武统白云岩极其发育,类型多样,不同类型的白云岩其成因机理和白云石化模式各不相同。泥晶白云岩和藻屑白云岩主要由泥晶白云石组成,白云石晶形差,有序度低,平均为0.71,富含碳、氧同位素值,微量元素 Sr2+含量高,为准同生期超咸水白云石化的产物。浅滩相的颗粒白云岩,其白云石晶体有序度高,平均为0.87,碳、氧同位素值低,盐度低,为浅滩混合水白云石化的产物。细晶白云岩由细晶白云石组成,白云石晶体具雾心结构和环带构造,部分见交代残余结构,其有序度低,碳、氧同位素值低,阴极发光显微镜下白云石晶体中心呈暗红色,边缘呈亮红色,为深埋藏白云石化的产物。

关键词: 白云石化作用, 有序度, 同位素, 阴极发光, 中上寒武统, 湖南

Abstract:

Middle-Upper Cambrian dolomites in Shimen,Hunan Province,are mainly composed of anhedral micritic dolomite,euhedral and subhedral granular dolomites,grain dolomite.Different kinds of dolomites formed in different environments may have different models of dolomitization.The anhedral micritic dolomite shows a lower ordering degree (average 0.71),a higher CaCO3 mole content (average 50.83%),higher δ13C and δ18O values (average+0.26‰ and-6.95‰PDB),a higher Sr2+ content and non luminescence.Grain dolomitehas a higher ordering degree (average 0.87),a lower CaCO3 mole content (average49.4%),lower δ13C and δ18O values (average-0.87‰ and-9.5‰ PDB),and a lower Sr2+ content.The euhedral and subhedral granular dolomites,who's ordering degrees,δ18O and δ13C values,Sr2+ content are samilar to grain dolomite,has a dark red to red in lumi-nescence.All evidences show that there were three origins of the dolomites in the study area.Anhedral micritic dolomite formed in high-magnesium water in tidal flat;grain dolomite formed in shoal mixing water;euhedral and subhedral granular dolomites were the products of dolomitization in deep burial mixing water.