摘要
鲕粒不仅是古环境的重要指示标志,由其构成的鲕粒石灰岩通常也是重要的油气储集层。但自鲕粒被发现一个多世纪以来,关于其无机成因还是有机成因就一直存在争议。分别系统归纳了典型鲕粒的物理化学成因及微生物成因、鲕粒的圈层结构类型及成因,结合前人研究成果建立了新的鲕粒成因模式,解释了常见鲕粒的形成过程。对鲕粒研究综述和实例分析认为,鲕粒新圈层的形成是微生物介导的,鲕粒圈层形态是受沉积水体能量控制的,光合微生物及硫酸盐还原细菌等建设性微生物群落均促进了鲕粒圈层的沉淀;鲕粒的圈层结构主要为径向生长的放射状、随机分布的杂乱状和切线状,在地质历史时期观察到的其他鲕粒结构均是受活跃的破坏性钻孔生物及不同程度成岩作用改造的结果;鲕粒最原始的结构是径向生长的放射状,是在低能静水环境中由非晶质钙碳酸盐(ACC)矿化形成的,随机分布结构及切线状结构是被水动力剪切改造形成的结构,鲕粒中明显的暗色同心薄层是鲕粒生长过程中间歇性出现的微生物群落建设性或破坏性定殖后生物矿化的产物,受水动力影响这三种结构既可以单独发育,也可以组合出现,构成了鲕粒形态的多样性;核心供给速率大小、沉积水体碳酸钙饱和度高低、沉积水体能量强弱及建设性微生物群落活跃程度共同控制了鲕粒粒径大小。
Oolitic limestone is a significant indicator of the paleoenvironment,and also provides an important hydrocarbon reservoir.However,ever since ooids were first recognized more than a century ago their origin,whether organic or inorganic,has been controversial.This study systematically summarizes the physicochemical and microbiological genesis of typical ooids and their structural types.A new formation mechanism for ooids is proposed,based on previous research reports.The research review and case analysis suggests that microorganisms mediate the formation of new oolitic circles.The distribution of carbonate minerals in the oolitic circles is influenced by the energy of the sedimentary water body,and constructive microbial communities(e.g.,photosynthetic microorganisms and sulfate reduction bacteria)promote the precipitation of the oolitic circles.The circular structure is mainly radial,randomly distributed and tangential.Other observed oolitic structures have all been modified by the action of destructive drilling organisms and different degrees of diagenesis.The most primitive structure of an ooid is radial growth formed by the mineralization of amorphous calcium carbonate(ACC)in a low-energy,static water environment.The random distribution and tangential structure are the result of hydrodynamic shearing.The obvious dark concentric thin layers observed in ooids are the product of biomineralization of the microbial community that appears intermittently during the growth of the ooid after constructive or destructive colonization.These three structures develop either individually or in combination depending on the hydrodynamics of their environment.The core supply rate,the calcium carbonate saturation and energy of the sedimentary water body,and the action of the constructive microbial community,all influence the size of the oolitic particle size.
作者
郭芪恒
金振奎
史书婷
刘元博
王金艺
GUO QiHeng;JIN ZhenKui;SHI ShuTing;LIU YuanBo;WANG JinYi(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi’an 710018,China;1st Oil Plant of Changqing Oil Field,PetroChina,Yan’an,Shaanxi 716000,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2023年第4期959-967,共9页
Acta Sedimentologica Sinica
基金
国家重点基础研究发展计划(973计划)项目(2006CB202300)。
