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时间:2020-06-01
《蒙古国早-中侏罗世含煤盆地分布及构造背景和地层.pdf》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、第42卷第3期煤田地质与勘探Vl01.42NO.32014年6月c0ALGBO【DGY&E)【()RrONJun.20l4文章编号:1001-1986(2014)03—0001-07蒙古国早一中侏罗世含煤盆地分布及构造背景和地层吴根耀(中国科学院地质与地球物理研究所,北京100029)摘要:蒙古国早一中侏罗世的主控构造是蒙古一鄂霍次克洋的消减闭合,其北地区发育弧后张裂盆地,其南的拼合大陆内的古缝合线被该消减造山运动激活而发生陆内造山。内蒙的3个陆内造山的磨拉石盆地均延入蒙古境内,故蒙古东部磨拉石盆地的发育与内蒙有相似的几何学和运动学特征。概述了各盆地的代表性地层,尽管其岩性和含煤性有明
2、显差别,但因受制于同一个造山作用,沉积记录都以砾岩开始,都为向上变细的序列,且煤层均赋存于地层柱的中部,据此可把盆地演化分为成煤前、成煤和成煤后3个阶段。成煤阶段大煤田的形成受构造(堆积空间)和气候(成煤物质供应1的双重控制。关键词:弧后张裂盆地;磨拉石盆地;含煤地层;盆地演化;早一中侏罗世;蒙古国中图分类号:P618.11文献标识码:ADOI:10.3969~.issn.1001—1986.2014.03.001Distribution,tectonicsettingsandstrataofEarly-MiddleJurassiccoal—bearingbasinsinMongoli
3、aWUGenyao(InstituteofGeologyandGeophysics,ChineseAcademyofSciences,Be~mg100029,China)Abstract:ThekeystructureduringEarly··MiddleJurassicinMongoliaissubductionandclosureoftheMongo--lia—Okhotskocean.Tothenorthoftheoceantheredevelopsagroupofback·arcextensionalbasins,whereastothesouthoftheoceanthere
4、existsanamalgamationcontinent,wherethefossilgeosuturesarerejuvenatedbythesub-ductionorogenyandinlandorogenyoccurs.InInnerMongoliaofChina,theredevelopthreemolassebasinsrelatedtotheinlandorogeny,allofthesebasinsstretchintoMongolia,SOthatthemolassebasinsineasternMongoliahavethesamegeometricandkinem
5、aticfeaturesasthatinInnerMongolia.Thetypicalstratigraphiccolumnsintheabove—mentionedfourbasinsarebrieflyillustrated.Althoughtherearedistinctlithologicandcoalycharacterscon-strainedbythesameorogeny,thesedimentaryrecordsshowsomesimilaritiesinallofthebasins,suchasthickconglomeratesinthebasalpart,au
6、pward-finingsuccession,andthecoalseamsinthemiddlepartofthecolumn,etc.Basedonthesimilarities,theevolutionofEarly—MiddleJurassicbasinscanbedividedintothreestages,namely,thepre-coal-formingstage,coal—formingstageandpostcoal—formingstage.Thecreationofeconomiccoalfieldsarecontrolledbythestructure(dep
7、ositingspace)andclimate(suppliesofmothersubstanceofcoa1)inthecoal—formingstage.Keywords:back-arcextensionalbasin;molassebasin;coal-bearingstrata;basinevolution;Early-MiddleJurassic;Mongolia蒙古是个内陆国家,尽管国土面积不算很大(略在着挤压和拉张两种截然不同的
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