鄂尔多斯盆地奥陶纪马家沟期岩相古地理演化与成钾意义  

Evolution of Lithofacies Paleogeography in the Ordos Basin and Its Implication of Potash Formation

作　　者：张永生[1] 邢恩袁[1] 王卓卓[1] 郑绵平[1] 施立志[1] 苏奎[1] 桂宝玲[1] 吴素娟[1] 蒋苏扬 朱常伟 

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部盐湖资源与环境重点实验室,北京100037

出　　处：《地质学报》2015年第11期1921-1935,共15页Acta Geologica Sinica

基　　金：国家重大基础研究计划973课题“鄂尔多斯奥陶纪古陆表海盆成钾条件、机理和后期演化”(编号:2011CB403001);中国地质调查局地调工作项目“陕北奥陶纪盐盆地钾盐资源调查评价”(编号:1212011085516)联合资助项目的成果

摘　　要：本次研究主要依据龙探1井、镇钾1井等8口基干井,通过岩心观察、测井解释、镜下薄片鉴定、沉积微相分析,结合区域构造资料并参考前人研究成果,对鄂尔多斯盆地奥陶系马家沟组沉积相进行了识别和划分,编制或修编了鄂尔多斯盆地马家沟一期至马家沟六期各时期的岩相古地理图。研究结果表明:鄂尔多斯盆地马家沟组主要发育碳酸盐岩台地相,包含开阔台地和局限蒸发台地两种亚相,与成盐成钾密切相关的局限蒸发台地可进一步划分为云坪、盐湖、膏湖、淡化泻湖等微相;平面上,马家沟组一段—六段主要发育陆(隆)、云坪、盐湖、膏湖、开阔台地及浅滩6个古地理单元,每个古地理单元在各段的分布情况有所不同。在半封闭的构造格局、华北古陆表海为主的预备卤水补给方式和奥陶纪极端干旱的古气候条件共同作用下,使有利成钾区最终定位在鄂尔多斯盆地东部盐坳绥德地区。This research is mainly on the basis of eight backbone wells including Longtan1 well and Zhenjia1 well.Through drill core observation,well logging interpretation,microscopic slice identification and sedimentary microfacies analysis,combined with regional tectonic information and reference to the predecessors＇ achievements,the sedimentary facies of ordovician Majiagou Formation in the northern Shaanxi salt basin has been recognized and classified.Also compilation and revision of lithofacies paleogeographic maps in each majiagou period from 1to 6has been completed.The results show that carbonate platform facies accouts for the most in majiagou formation of shaanxi salt basin,along with open platform and restricted evaporate platform subfacies development.The restricted evaporate platform closely related to potash formation is further divided into microfacies,such as dolomitic flat,salt lake,gypsum lake,desalination lagoon.Paleogeographic research shows that 6paleogeographic units including land,dolomitic flat,salt lake,gypsum lake,open platform and shallow lake has been developed during Majiagou Stage from 1 to 6.The distribution of paleogeographic unit in each member is different respectively.The key strata of potash-forming in the research area,in another word Om56 appears the paleogeographical pattern of＂two depressions and one lifting＂which is the core factor for the formation of secondary salt sag.Looking for favorable potash sag is the key to breakthrough in the northern Shaanxi salt basin.

关 键 词：奥陶纪 马家沟组 岩相古地理 成钾盐凹 马五段6亚段 

分 类 号：P619.211[天文地球—矿床学] P534.42[天文地球—地质学]