地质力学学报2026，Vol.32Issue(4)：958-979,22.DOI:10.12090/j.issn.1006-6616.2025031
鄂尔多斯盆地西缘复杂构造带奥陶系克里摩里组白云岩成因探讨
Genesis of Ordovician Kelimoli Formation dolomites in the complex tectonic zone along the western margin of the Ordos Basin
摘要
Abstract
[Objective]The dolomite in the Ordovician Kelimoli Formation of the complex tectonic zone along the western Ordos Basin margin is a high-quality reservoir for natural gas exploration.However,its genetic mechanism and the relationships among the sedimentary environment,multi-stage tectonic superimposition,and diagenetic alteration remain controversial,limiting effective guidance for oil and gas exploration.[Methods]To elucidate the genesis of this dolomite,a comprehensive analytical approach was applied,incorporating thin-section petrography,cathodoluminescence(CL),C-O isotopes,X-ray diffraction(XRD)ordering degrees,trace and rare earth element(REE)geochemistry,and Sr isotopes,integrated with regional tectonic evolution.[Results]Under CL,the dolomites generally exhibit weak dark-brown luminescence with distinct zonation,alongside authigenic quartz and saddle dolomite,indicating hydrothermal involvement and multi-stage recrystallization during deep burial.Carbon and oxygen isotopic signatures further support a burial origin.XRD data reveal a relatively low ordering degree in dolomites,which decreases with increasing temperature,suggesting rapid crystallization under elevated temperatures.REE patterns display positive Ce and Eu anomalies,indicating that dolomitization occurred in a relatively closed,high-temperature,and high-pressure diagenetic system via internal fluid readjustment and material redistribution.Overall,the dolomite shows a relatively low degree of order,and the order decreases with higher temperatures,suggesting that the dolomite formed in an environment with relatively high temperature and rapid crystallization rate.Geochemically,lower Sr contents correlate with higher Fe and Mn concentrations,reflecting multi-stage superimposed alteration under deep burial conditions.Furthermore,strontium isotope values of medium-to coarse-grained dolomite closely approach average crustal values,likely influenced by crustal Sr transported along coeval tectonic conduits.[Conclusions]This research attributes the dolomite formation primarily to deep burial and the coeval superimposition of tectonic fluid modification.The origin and evolution of the Ordovician Kelimoli Formation dolomite were strongly controlled by deep fault systems.During the co-deposition period,this fault system controlled the development of high-energy terraces.In the subsequent tectonic activity phase,the deep fault system became a fluid migration channel,facilitating the superimposed modification of dolomite bodies.[Significance]The research results provide fundamental support for the efficient exploration of oil and gas resources.关键词
白云岩/深埋藏成因/构造热液成因/克里摩里组/奥陶系/鄂尔多斯盆地西缘Key words
dolomite/deep-seated genesis/tectonic hydrothermal genesis/Kelimoli Formation/Ordovician/western margin of the Ordos Basin分类
天文与地球科学引用本文复制引用
马占荣,李振宏,刘建平,胡爱平,寇琳琳..鄂尔多斯盆地西缘复杂构造带奥陶系克里摩里组白云岩成因探讨[J].地质力学学报,2026,32(4):958-979,22.基金项目
国家自然科学基金项目(U2244220,41972119) （U2244220,41972119）
中国石油长庆油田分公司重大科技专项(2023DZZ02) （2023DZZ02）
中国石油长庆油田分公司科研生产项目(2024-5413) This research was financially supported by the National Natural Science Foundation of China(Grant Nos.U2244220 and 41972119),the Major Science and Technology Special Project of Changqing Oilfield Branch,PetroChina(Grant No.2023DZZ02),and the Scientific Research and Production Project of Changqing Oilfield Branch,PetroChina(Grant No.2024-5413). （2024-5413）
