拉分盆地课件

Pull-ApartBasinsMajor:Marinegeology2013.01.02GeneraldescriptionMaincharactersUniquekeypointsExamplesGeneraldescriptionconcept

Apull-apartbasin(strike-slipbasin,rhombochasm)istypeofstructuralbasinwhichisdevelopedbetweentwooffsetsegmentsorataflexureinastrike-slipfaultoratransformfault.

Apull-apartbasindevelopswherethesenseofoffsetleadstoextension,eitherataright-steppingoffsetonadextralsensefaultoraleft-steppingoffsetonasinistralfault.Thisgeometrymeansthatfaultdisplacementwillliterallypullasectionofcrustapartandcausetheextension.GeneraldescriptionsettingsTheDeadSeaandtheSaltonSeadepressionsarepullapartbasins(Kearey,PhilipandFrederickJ.Vine,1996).TheCaymanTroughinthenorthernCaribbeanisanexampleofanelongatedpullapartbasinwhichhasdevelopedaspreadingridgeinthecenter(Einsele,Gerhard,2000).Alongstrike-slipboundaryzones(transformfaults)betweenrigid,continentalplates.Inzonesofobliquesubductionalongvolcanicarcs.Inzonesof“continentalescape”inresponsetocollision.T.h.Nilson;R.J.McLaughlin,1985Nilson和McLaughlin(1985)根据LittleSulphurCreek盆地、Ridge盆地和Hornelen盆地的研究成果，系统总结了拉分盆地地层和沉积充填特征。MaincharactersMaincharactersOriginatefromstrike-slipmotions.Occuronbothcontinentalandoceaniccrust.Typicallynarrow(<50kmwide)andofvariablelength.Theflooroflongbasinstendstosubsidedeeperthanthatofshortbasins.Longbasinsmaydevelopoceanicspreadingtroughswiththeintrusionofbasalticmagama.Rapidstrike-slipcausesextremelyfastsubsidenceandthusoftenanearly,shortphaseofbasindeepening.Latersubsidenceisdrivenmainlybytheincreasingsedimentload.GerhardEinsele,2000UniquekeypointsanddifferencesfromotherbasinsSedimentaryfacieschangerapidly.Strike-slipfaultdevelopedwithinthebasin.LiXiaoqing,WangZecheng,2003Example—GulfofCalifornia加利福尼亚及其邻近地区的断层系统和盆地（Lachenbruch和Sass,1980)Afteraninitialshallow-marine“proto-gulf”riftstage,thepresentGulfofCaliforniaformedalongthetransformboundarybetweentheNorthAmericanandthePacificplates.Thedextral,somewhattranstensionalplatemotionsoperatedatanaveragerateofseveralcm/a.Asaresult,aseriesofpull-apartbasinswasgeneratedwhichnowlie2000-3000mbelowsealevel,seperatedbythegrowingpull-apartbasins,newoceaniccrustwasaccreted(stageofearlydrifting).Incontrasttomid-oceanicspreadingridgesofmatureoceans,thespreadingcentersofthesepull-apartbasinsarelocatedinthemorphologicalbasindeeps,thusformingspreadingtroughs.Althoughthesetroughscollectlargeamountsofhemipelagicsediments,turbidites,andmassflowsfromnearbyslopesandmarinedeltas,theyremainopenduetothecontinuingrapidgrowthofthebasins.Example—GulfofCalifornia加利福尼亚边界区走滑构造格架图（据Moore,1969;Junger,1976)Example—GulfofCalifornia图片据T.h.Nilson;R.J.McLaughlin,1985

里奇盆地。该盆地在圣安德烈斯弯曲处形成，故认为是断弯盆地的典型代表。它是位于圣安德烈斯断裂和圣加布里尔断层间的豆英断块。块体北部处于释压弯曲处，属张扭性环境，形成拉分盆地，而在其西南部处于处于压扭环境，形成隆起，向盆地供应沉积物。References

1.Kearey,PhilipandFrederickJ.Vine,GlobalTectonics,BlackwellScience,2nded.,

1996,pp.131-133

2.Einsele,Gerhard,SedimentaryBasins:Evolution,Facies,andSedimentBudget,

Springer,2nded.,2000,p.630

3.H.NilsenandRobertJ.McLaughlin，Comparisonoftectonicframeworkand

depositionalpatternsofHornelenstrike-slipbasininNorwayandRidgeandLittle

SulphurCreekstrike-slipbasinsofCalifornia，AAPGBulletin(April1984),68(4):513

4.AHLachenbruch,JHSass,HeatflowandenergeticsoftheSanAndreas