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1、全球板块构造演化全球板块构造演化pptpptLatePrecambrianSupercontinentandIceHouseWorldThismapillustratesthebreak-upofthesupercontinent,Rodinia,whichformed1100millionyearsago.TheLatePrecambrianwasanIceHouseWorld,muchlikethepresent-day.Cambrian:thebeginningofthePaleozoicEra.Animalswithhard-shellsappearedingreatnumbersfo
2、rthefirsttimeduringtheCambrian.Thecontinentswerefloodedbyshallowseas.ThesupercontinentofGondwanahadjustformedandwaslocatedneartheSouthPole.AncientOceansSeparatetheContinentsDuringtheOrdovicianancientoceansseparatedthebarrencontinentsofLaurentia,Baltica,SiberiaandGondwana.TheendoftheOrdovicianwasoneo
3、fthecoldesttimesinEarthhistory.IcecoveredmuchofthesouthernregionofGondwana.ContinentsBegintoCollideasPaleozoicOceansCloseLaurentiacollideswithBalticaclosingthenorthenbranchoftheIapetusOceanandformingtheOldRedSandstonecontinent.Coralreefsexpandandlandplantsbegintocolonizethebarrencontinents.TheDevoni
4、anWastheAgeofFish!BytheDevoniantheearlyPaleozoicoceanswereclosing,formingapre-Pangea.FreshwaterfishwereabletomigratefromthesouthernhemispherecontinentstoNorthAmericaandEurope.ForestsgrewforthefirsttimeintheequatorialregionsofArticCanada.DuringtheEarlyCarboniferousPangeaBeginstoForm.DuringtheEarlyCar
5、boniferousthePaleozoicoceansbetweenEuramericaandGondwanabegantoclose,formingtheAppalachianandVariscanmountains.AnicecapgrewattheSouthPoleasfour-leggedvertebratesevolvedinthecoalswampsneartheEquator.TheLateCarboniferousaTimeofGreatCoalSwampsBytheLateCarboniferousthecontinentsthatmakeupmodernNorthAmer
6、icaandEuropehadcollidedwiththesoutherncontinentsofGondwanatoformthewesternhalfofPangea.Icecoveredmuchofthesouthernhemisphereandvastcoalswampsformedalongtheequator.AttheendofthePermianwasGreatestExtinctionofAllTimeVastdesertscoveredwesternPangeaduringthePermianasreptilesspreadacrossthefaceofthesuperc
7、ontinent.99%ofalllifeperishedduringtheextinctioneventthatmarkedtheendofthePaleozoicEra.AttheendoftheTriassic,Pangeabegantoriftapart.ThesupercontinentofPangea,mostlyassembledbytheTriassic,allowedlandanimalstomigratefromtheSouthPoletotheNorthPole.LifebegantorediversifyafterthegreatPermo-Triassicextinc
8、tionandwarm-waterfaunasspreadacrossTethys.EarlyJurassic,theDinosaursspreadacrossPangeaBytheEarlyJurassic,south-centralAsiahadassembled.AwideTethysoceanseparatedthenortherncontinentsfromGondwana.ThoughPangeawasintact,thefirstrumblingsofcontinentalbreakupcouldbeheard.PangeaBeginstoRiftApartThesupercon
9、tinentofPangeabegantobreakapartintheMiddleJurassic.IntheLateJurassictheCentralAtlanticOceanwasanarrowoceanseparatingAfricafromeasternNorthAmerica.EasternGondwanahadbeguntoseparateformWesternGondwana.NewOceansBegintoOpenDuringtheCretaceoustheSouthAtlanticOceanopened.IndiaseparatedfromMadagascarandrac
10、ednorthwardonacollisioncoursewithEurasia.NoticethatNorthAmericawasconnectedtoEurope,andthatAustraliawasstilljoinedtoAntarctica.TheEndoftheDinosaursThebullseyemarksthelocationoftheChicxulubimpactsite.Theimpactofa10milewidecometcausedglobalclimatechangesthatkilledthedinosaursandmanyotherformsoflife.By
11、theLateCretaceoustheoceanshadwidened,andIndiaapproachedthesouthernmarginofAsia.DuringtheEarlyCenozoicIndiabegantoCollidewithAsia.50-55millionyearsagoIndiabegantocollidewithAsiaformingtheTibetanplateauandHimalayas.Australia,whichwasattachedtoAntarctica,begantomoverapidlynorthward.TheWorldAssumesaMode
12、rnConfiguration20millionyearsago,Antarcticawascoverdbyiceandthenortherncontinentswerecoolingrapidly.Theworldhastakenonamodernlook,butnoticethatFloridaandpartsofAsiawerefloodedbythesea.TheEarthhasbeeninanIceHouseClimateforthelast30millionyearsWhentheEarthisinitsIceHouseclimatemode,thereisiceatthepole
13、s.ThepolaricesheetexpandsandcontactsbecauseofvariationsintheEarthsorbit(Milankovitchcycles).Thelastexpansionofthepolaricesheetstookplaceabout18,000yearsago.ThePresent-dayworldhaswelldefinedclimaticzones.WeareenteringanewphaseofcontinentalcollisionthatwillultimatelyresultintheformationofanewPangeasup
14、ercontinentinthefuture.GlobalclimateiswarmingbecauseweareleavinganIceAgeandbecauseweareaddinggreenhousegasestotheatmosphere.ThisisthewaytheWorldmaylooklike50millionyearsfromnow!Ifwecontinuepresent-dayplatemotionstheAtlanticwillwiden,AfricawillcollidewithEuropeclosingtheMediterranean,Australiawillcol
15、lidewithS.E.Asia,andCaliforniawillslidenorthwardupthecoasttoAlaska.TheAtlanticOceanbeginstoCloseNewsubductionzonesalongtheeasterncoastsofNorthAmericaandSouthAmericawillbegintoconsumetheoceanfloorseparatingNorthAmericafromAfrica.About100millionyearsfromnowthepresent-dayMid-AtlanticRidgewillbesubductedandthecontinentswillcomeclosertogether.PangeaUltimawillform250millionyearsintheFutureThenextPangea,PangeaUltimawillformasaresultofthesubductionoftheoceanflooroftheNorthandSouthAtlanticbeneatheasternNorthAmericaandSouthAmerica.Thissupercontinentwillhaveasmalloceanbasintrappedatitscenter.结束结束