地质学报2011，Vol.85Issue(12)：2060-2069,10.DOI:11-1951/P.20111206.1222.003
塔中地区奥陶系白云岩岩石地球化学特征及成因机理分析
Geochemical Characteristics and Genetic Mechanism of the Ordovician Dolostone in the Tazhong Area, Tarim Basin
摘要
Abstract
The Ordovician dolomite in the Tazhong area is widely distributed, being one of the most important reservoirs in the Tarim basin due to its huge thickness. Based on the size of the crystal structure of dolostone and the original sedimentary features, six types of dolostone have been identified: micritic dolostone, algal-laminated micritic dolostone, granular dolostone, coarse and fine grained dolostone, medium-coarse crystalline dolostone, and mottled dolostone. The first two dolomites preserve the original sedimentary features. They are geochemcially characterized by high C and O isotopic compositions, slightly higher salinity than common seawater, high Sr and Nr, low Fe, roughly same REE pattern, which can be explained as the result of penecontemporaneous dolomitization. Granular dolostone and crystalline dolostone are of relative large crystals, distinct replacement structure, such as zonation structure. Geochemcial features display that C and O isotopic values shift to negative as diagenesis increasing, salinity index decreases gradually, and low Sr and Na, high Mn, varied total REE amount, the same REE distribution pattern as Ce and Eu anomalies, which can be explained by that they are the product of dolomitization during the burial stage and may be affected by structure hydrothermal superimposition during the process of dolomitization. Based on the study of origin of the dolostone, a dolomitation model applied to any type of dolostone in the study area is established.关键词
白云岩成因/碳氧同位素/元素地球化学/奥陶系/塔中地区Key words
dolostone genesis/ C and O isotope/ geochemistry/ Ordovician/ Tazhong area, Tarim basin引用本文复制引用
胡明毅,胡忠贵,李思田,王延奇..塔中地区奥陶系白云岩岩石地球化学特征及成因机理分析[J].地质学报,2011,85(12):2060-2069,10.基金项目
本文为国家重大专项"中国大型气田形成条件、富集规律及目标预测"下设课题(编号2008ZX05007-02)和中石化海相前瞻项目"塔里木盆地及周缘的动态演化与含油气前景"项目(编号YPH08114)资助成果. （编号2008ZX05007-02）
