甘肃陇东新庄井田延安组沉积环境分析——对鄂尔多斯盆地中侏罗世早期古地理演化的启示  

Sedimentary Environment Analysis of the Yan’an Formation in the Xinzhuang Well Field,Longdong,Gansu Province:Implications for paleogeographic evolution of the early Middle Jurassic in Ordos Basin

作　　者：王仲学 丁仲昭 樊鑫 戴霜 马欢欢 WANG ZhongXue;DING ZhongZhao;FAN Xin;DAI Shuang;MA HuanHuan(Comprehensive Survey Team of Gansu Coalfield Gelolgical Bureau,Tianshui,Gansu 741000,China;Key Laboratory of Western China’s Environmental Systems,Ministry of Education and School of Earth Sciences,Lanzhou University,Lanzhou 730000,China;Key Laboratory of Strategic Mineral Resources of the Upper Yellow River,Key Laboratory of Mineral Resources in Western China(Gansu Province),Lanzhou 730000,China)

机构地区：[1]甘肃煤田地质局综合普查队,甘肃天水741000 [2]兰州大学地质科学与矿产资源学院,甘肃省矿山环境和城市地质工程研究中心,兰州730000 [3]自然资源部黄河上游战略性矿产资源重点实验室,甘肃省西部矿产资源重点实验室,兰州730000

出　　处：《沉积学报》2023年第2期545-558,共14页Acta Sedimentologica Sinica

基　　金：第二次青藏高原综合科学考察研究(2019QZKK0704);国家自然科学基金项目(41972213);中央高校基本科研业务费专项资金项目(lzujbky-2019-44,lzujbky-2021-it07);中国国际地球科学计划项目(652)。

摘　　要：研究陇东地区延安组沉积环境精细变化,对认识我国西北地区成煤环境及气候环境演变具有重要意义。通过对陇东新庄井田钻孔岩性和测井资料分析,发现延安组沉积环境总体为三角洲环境,包括河道间、沼泽、天然堤和分流河道四种微相,煤层主要形成于河道间沼泽环境;沉积微相变化反映自下而上水体由浅变深再变浅,水动力由弱变强再减弱的过程。结合区域气候构造资料,显示延安组沉积期盆地内整体气候温暖湿润,构造比较稳定,成煤阶段主要受季节性气候差异的影响。综合分析盆地内延安组一、二段岩性和沉积微相变化,该时期鄂尔多斯盆地古地理环境分为四个阶段:延安组一段早期为气候稳定的沼泽阶段;延安组一段晚期气候相对干燥,以河道间环境为主,盆地局部出现抬升高地;延安组二段早期气候炎热干燥,以分流河道环境为主;延安组二段晚期盆地气候温暖湿润,以河道间沉积环境为主。Studying the evolution of sedimentary environments of the Yan’an Formation in the Longdong area is of great significance for understanding the evolution of coal forming and climate environments in Northwest China.Based on the analysis of borehole lithology and logging data in the Xinzhuang well field in the southwest Ningzheng mining area of Longdong,the sedimentary environment in this area is shown to be a meandering river delta environ⁃ment,further divided into four microfacies types:interchannel,marsh,natural dike,and distributary channel.The coal seam is primarily formed in an interchannel marsh environment.Bottom-up reflects the process of water body changing from deep to shallow and hydrodynamics changing from weak to strong and then to weak.Combined with the regional climatic and tectonic data,the overall climate in the basin during the sedimentary period of the Yan’an For⁃mation was warm and humid,the tectonic setting was relatively stable,and the coal forming stage was primarily af⁃fected by seasonal climate differences.Based on the comprehensive analysis of lithology and sedimentary microfacies changes of the First and Second members of the Yan’an Formation,the paleogeographic environment of the Ordos Ba⁃sin can be divided into four stages:the early stage of the First member of the Yan’an Formation was a marsh stage with a stable climate;in the late stage of the First member of Yan’an Formation,the climate was relatively dry,and the interchannel environment was dominant.The early stage of the Second member of the Yan’an Formation was char⁃acterized by a hot and dry climate and distributary channel environment.The basin of the late stage of the Second member of the Yan’an Formation was characterized by a warm and humid climate and interchannel sedimentary envi⁃ronment.

关 键 词：沉积微相 古地理演化 延安组 新庄井田 鄂尔多斯盆地 

分 类 号：P512.2[天文地球—地质学]