鄂尔多斯盆地南缘蓟县系冯家湾组微生物岩成储机制  

Reservoir formation mechanism of the microbialite in the Fengjiawan Formation of the Mesoproterozoic Jixian System,southern Ordos Basin

作　　者：张静[1] 张宝民[1] ZHANG Jing;ZHANG Baomin(Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《沉积与特提斯地质》2025年第1期102-111,共10页Sedimentary Geology and Tethyan Geology

基　　金：中国石油天然气集团有限公司基础性前瞻性重大科技专项“叠合盆地中下组合油气成藏与保持机制研究”(2023ZZ02);国家重点研发计划项目“超深层及中新元古界油气资源形成保持机制与分布预测”(2017YFC0603104)。

摘　　要：在鄂尔多斯盆地南缘中元古界蓟县系冯家湾组硅质叠层石和鲕粒岩中,存在白云石及其溶蚀形成的孔洞。分布特征与发育规模明显受富有机质组构控制的白云石和溶蚀孔洞是基质孔隙发育的关键。显微薄片、扫描电镜、阴极发光、大面积拼接成像及微量元素原位成像等分析显示,大量自形白云石晶体分布于叠层石的暗色纹层与鲕粒的暗色圈层中,且晶体周缘普见缝隙的存在。部分白云石发生了溶蚀,形成晶体铸模孔并成为暗色组构中孔洞的基本构成单元。白云石的形成与随后的溶蚀均发生在富有机质组构内部。组构内受微生物因素影响的成岩物质的富集,以及随之产生的环境酸碱度变化,共同促进了白云石的发育与溶解过程。上述现象和认识可以为前寒武系部分白云岩的成因和可能与微生物因素有关的成岩、成储研究提供一些参考借鉴。Dolomite crystals and related pores and vugs,evidently controlled by organic-rich fabrics,can be found in the siliceous stromatolites and oolites in the Fengjiawan Formation of the Mesoproterozoic Jixian System,located in the southern Ordos Basin.With the application of microscope,scanning electron microscope(SEM),cathodoluminescence,large-area SEM image acquisition,and in-situ trace element imaging,it can be observed that many euhedral dolomite crystals are concentrated within the dark laminae of the stromatolites and the dark spheres of the ooids,with gaps present on the crystal peripheries.A considerable number of these dolomite crystals have undergone dissolution,leading to the formation of moldic pores and vugs,which are the dominant matrix pores in the stromatolites and oolites in the study area.Dolomite formation and dissolution were confined to the organic-rich fabrics.The microenvironment within these fabrics was influenced by microbial factors,with the enrichment of necessary diagenetic substances and changes in pH.These phenomena and scientific understandings may have some referential value for the genesis of some Precambrian dolomites and microbial-related diagenesis,which are of great significance for petroleum geology.

关 键 词：鄂尔多斯盆地 冯家湾组 微生物岩 白云石 溶蚀 

分 类 号：P618.13[天文地球—矿床学]