物探与化探2025，Vol.49Issue(4)：790-801,12.DOI:10.11720/wtyht.2025.1346
鄂西黄陵背斜周缘震旦系灯影组白云岩成因分析
Genetic analysis of dolomites in the Sinian Dengying Formation on the periphery of the Huangling anticline,western Hubei Province
摘要
Abstract
A suite of dolomite-dominated carbonate reservoirs is developed in the Sinian Dengying Formation in the Huangling anticline in the eastern part of the intracratonic rift,western Hubei Province.Investigating the formation environment and genetic mechanism of dolomites is crucial for determining the developmental mechanism of carbonate reservoirs and facilitating conventional oil and gas explo-ration in the study area.This study employed various analytical techniques,including cast thin sections,cathodoluminescence thin sec-tions,field emission scanning electron microscopy,carbon and oxygen isotope analyses of carbonate rocks,major and trace element an-alyses,whole-rock mineral analyses,and determination of the degree of order of dolomite.Using these techniques,this study analyzed the chemical composition and mineralogical characteristics of dolomites from the Dengying Formation on the periphery of the Huangling anticline.Furthermore,this study explored the formation environment,developmental mechanism,and modification process of dolo-mites.The results indicate that the dolomites from the Dengying Formation contained the same proportions of CaO and MgO molecules and low Sr content,aligning with the characteristics of penecontemporaneous dolomites.The analytical results of trace elements and carbon and oxygen isotopes confirm that the dolomites formed in a marine environment with low Fe and Mn contents.The average pale-oseawater salinity(Z)of 128.41,average temperature of 21.32℃,and average diagenetic temperature of 49.36℃created the favor-able environmental conditions for forming penecontemporaneous dolomites.Additionally,the dolomite from the Dengying Formation ex-hibited significantly lower δ18 O compared to the Dengyingian seawater,degrees of order ranging from 0.61 to 0.99,and a peak fre-quency distribution between 0.8 and 0.9,indicating that the dolomite experienced a progressively deepening burial modification process.The whole-rock mineral analyses reveal that the content of dolomite was positively correlated with its degree of order,sugges-ting that a high degree of dolomitization corresponded to a higher degree of order during burial modification.Therefore,this study holds that dolomites in the Dengying Formation were originally formed by penecontemporaneous dolomite.Through prolonged burial modifica-tion,micritic dolomite with a low degree of order experienced recrystallization,gradually transitioning into very finely crystalline/finely crystalline dolomite,accompanied by an elevated degree of order.Ultimately,dolomites of a penecontemporaneous-burial modification origin formed in the study area.关键词
黄陵背斜/灯影组/白云石成因/白云石有序度/成岩环境Key words
Huangling anticline/Dengying Formation/dolomite origin/degree of order of dolomite/diagenetic environment分类
天文与地球科学引用本文复制引用
李浩涵,张聪,李文正,张春贺,张远,王梓,陈维堃,方镕慧..鄂西黄陵背斜周缘震旦系灯影组白云岩成因分析[J].物探与化探,2025,49(4):790-801,12.基金项目
国家自然科学基金青年基金项目(42302177) （42302177）
国家自然科学基金项目(U2244208) （U2244208）
中国地质调查局地质调查项目(DD20240050) （DD20240050）
