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1、第26卷第1期OIL&GASGEOLOGY2005年2月文章编号:0253-9985(2005)01-0086-06准噶尔盆地西北缘构造演化与扇体形成和分布12111雷振宇,鲁兵,蔚远江,张立平,石昕(1.中国石油勘探开发研究院,北京100083;2.中国石油勘探开发公司,北京100034)摘要:准噶尔盆地西北缘经历了多次(期)不同性质的构造演化。在新生代以后,表现出(类)前陆盆地性质,伴随区域构造运动发生强烈的碰撞挤压、冲断作用。断裂活动具有明显的推覆性质,产生了与断裂带平行的褶皱构造。西北缘逆掩断裂普遍具有同
2、生活动性质,对扇体的形成有明显的控制作用。主要表现为冲断作用持续发生,上、下盘地形相差悬殊,自冲断席上剥蚀下来的碎屑物堆积于断崖根部而形成各类扇体(冲积扇、扇三角洲和水下扇等),阶梯式逆冲断裂则形成多级扇体。研究表明,从二叠纪到侏罗纪构造活动逐渐减弱,扇体规模逐渐变小;在平面上由于构造活动的位移,导致了扇体的迁移。总体来看,百口泉-夏子街地区活动性最强,延续时间最长,形成的扇体规模较大、叠置程度高、迁移明显;车拐-克拉玛依地区活动性较弱,形成的扇体规模小、叠置程度差、迁移小。关键词:准噶尔西北缘;构造演化;断裂活动;扇体迁移
3、中图分类号:TE112.322文献标识码:ATectonicevolutionanddevelopmentanddistributionoffansonnorthwesternedgeofJunggarBasinLeiZhenyu,LuBing,WeiYuanjiang,ZhangLiping,ShiXin(1.PetroleumExplorationandDevelopmentResearchInstitute,PetroChina,Beijing;2.PetroleumExplorationandDevelopme
4、ntCompany,PetroChina,Beijing)Abstract:ThenorthwesternedgeofJunggarBasinexperiencedmultiphasetectonicmovementsofdifferentnatures,anditappearedasaforelandbasinsinceCenozoic.Extensivecollision,compressionandthrustingoccurredalongwithregionaltectonicmovement,andfaultin
5、gapparentlyhadthenatureofoverthrusting,resultinginfoldstructurestobeinparallelwiththefracturezone.Theoverthrustfaultswerecommonlysyngeneticandcontrolledobviouslythedevelopmentoffans.Thrustingoccurredcontinuously,sotopographiesonthehangingwallsweregreatlydifferentf
6、romthoseonthefootwalls.Clasticsdenudedfromthethrustsheetsaccumulatedonthefootoffaultscarps,leadingtotheformationofvariousfans(alluvialfan,fandeltaandsubmarinefan,etc.).Stepthrustfaultsledtotheformationofmultistagefans.TectonicactivitiesattenuatedgraduallyfromPermia
7、ntoJurassicandthesizesoffansdecreasedgradually.Lateraldisplacementoftectonicactivitiesresultedinthemigrationoffans.Asawhole,thestrongestandlongesttectonicactivitiesoccurredinBaikouquanXiazijiearea,hencethefansinthatareawouldberelativelylarge,highlysuperimposedand
8、largelymigrated;whilethoseinCheguaiKaramayareawererelativelyweak,sothefanswouldbesmall,poorlysuperimposedandshortlymigrated.Keywords:northwester
