川东邻水-渝北地区石炭系黄龙组白云岩成因  

Dolostone genesis of Huanglong Formation of Carboniferous in Linshui of eastern Sichuan—northern Chongqing area.

作　　者：胡忠贵[1] 郑荣才[1] 文华国[1] 蔡家兰[2] 陈守春[2] 胡九珍[1] 李瑰丽[2] 

机构地区：[1]成都理工大学“油气藏地质及开发工程”国家重点实验室,成都610059 [2]中国石油西南油气田分公司重庆气矿,重庆400021

出　　处：《岩石学报》2008年第6期1369-1378,共10页Acta Petrologica Sinica

基　　金：中石油西南油气田分公司2006年重点项目《邻水-渝北地区石炭系~三叠系沉积相研究》(项目编号k06-5)部分研究成果

摘　　要：以岩石结构分析为基础,结合 Sr 同位素和 Sr 含量等资料,对川东邻水—渝北地区石炭系黄龙组广泛发育的白云岩成因进行了研究,从中识别出准同生期白云岩、成岩期埋藏白云岩、表生期淡水白云石和晚成岩期热液白云石等成因类型,其中具备储集意义的仅为成岩期交代成因的埋藏白云岩,其岩性主要为颗粒白云岩和晶粒白云岩。综合不同成因类型的白云岩 Sr 同位素和 Sr 含量地球化学特征,将白云石化过程划分为准同生期,早成岩期、中成岩期,古表生期和再埋藏晚成岩期五个成岩阶段。各阶段的白云岩(或白云石)在结构上有不同特征,其 Sr 同位素和 Sr 含量地球化学特征亦有显著差别,反映研究区白云化流体不仅来自同时期囚禁的海源地层水,而且受到古表生期岩溶过程中的淡水和再埋藏晚期热液的影响。根据岩石学特征和各种地化指标,结合研究区古地理背景,建立了黄龙组准同生、埋藏、淡水、热液白云岩(或白云石)化模式。On the basis of analysing the rock structure and combined with the analysis of strontium isotopes and strontium concentration, the origin of dolomite reservoir in the Upper Carboniferous Huanglong Formation in Linshui of eastern Sichuan -- northern Chongqing area is discussed and four kinds of origin types： the penecontemporaneous dolostone, the burial diagenetic dolostone, the fresh water dolomite of epidiagenesis and hydrothermal dolomite of late diagenetic stage have been recognized. The burial diagenetic dolostone with diagenetic metasomatic geneses only are of reservoir significance, including two main rock types of grain dolostone and crystalline dolostone. Intigrativly analyzing the geochemical charaeheristics of strontium isotope and strontium concentration of different dolostones, the authors have divided the diagenesis process into five diagenetic stages, including the penecontemporaneous diagenesis, early diagenesis, middle diagenesis, paleo-epidiagenesis and reburial late diagenesis. In every diagenetic stage, the texture of reservoir dolostones is notable different and the geochemical characteristics of strontium isotopes and strontium concentration are of conspicuous variance. This shows that the dolomitizing fluids not only came from homochronous bounded sea source formation water, but enormously affected by fresh water during paleokarst in paleo-epidiagenetic stage and might be affected by underlying hydrothermal fluid in reburial stage. Based on the lithological and all kinds of geochemical characters of dolostones, and combined with the palaeogeographieal setting of the study area, the four models of dolomization of Huanglong Formation have been set up： the peneeontemporaneous dolomization, the burial dolomization, the fresh water dolomization and hydrothermal dolomization.

关 键 词：川东邻水-渝北 石炭系黄龙组 白云石化作用 SR同位素 Sr含量 地球化学 

分 类 号：P588.245[天文地球—岩石学]