Geologicalstructure
Thechemicalcompositionoftheupperlayerismainlyoxygen,silicon,andaluminum.Theaveragechemicalcompositionissimilartothatofgranite.Itiscalledgranitelayer,whichisalsocalled"silica-aluminumlayer".Thislayerisverythinatthebottomoftheocean,especiallyinthebottomoftheoceanbasin,andevenmissinginthemiddleofthePacificOcean.Itisadiscontinuouslayer.
Thelowerlayerisrichinsiliconandmagnesium,anditsaveragechemicalcompositionissimilartothatofbasalt.Itiscalledabasaltlayer,sosomepeoplecallita"silicon-magnesiumlayer"(inotherwords,theentirecrustisasilicon-aluminumlayer.Becausethealuminumcontentinthelowercruststillexceedsmagnesium;andtherockpartoftheuppermantlecontainsextremelyhighmagnesium,itiscalledthesilicon-magnesiumlayer);itisdistributedinthecontinentsandoceansandisacontinuouslayer.ThetwofloorsareseparatedbyaConraddiscontinuity.
Crustthickness
Thecrustistheoutermostlayeroftheearth'ssolidsurfacestructure.Theaveragethicknessoftheentirecrustisabout17kilometers,ofwhichthecontinentalcrustisthicker,about39-41onaverage.km.Thecrustinhighmountainsandplateauareasisthicker,upto70kilometers;thecrustinplainsandbasinsisrelativelythin.Oceaniccrustismuchthinnerthancontinentalcrust,onlyafewkilometersthick.
TheQinghai-TibetPlateauisthethickestplaceontheearth,withathicknessofmorethan70kilometers;thecrustinthesubmarinevalleyneartheequatorisonly1.6kilometersthick;thedeeptrenchintheeasternMarianaIslandsinthePacificOceanThethinnestcrustisthethinnestplaceontheearth.
InnerElements
Thereare112elementsintheperiodictableofchemicalelements,ofwhich92elementsandmorethan300isotopesexistintheshell.
Themostchemicalelementintheearth'scrustisoxygen,whichaccountsfor48.6%ofthetotalweight;followedbysilicon,whichaccountsfor26.3%;thefollowingarealuminum,iron,calcium,sodium,potassium,andmagnesium.AstatineandFranciumhavethelowestabundance,accountingforabout1in1023.Theabove8elementsaccountedfor98.04%ofthetotalweightoftheearth'scrust,andtheremaining80kindsofelementsaccountedforatotalof1.96%.
Theatomicpercentageoftheaveragecontentofvariouschemicalelementsintheearth'scrustiscalledtheatomicClarkevalue.Thechemicalelementwiththelargestnumberofatomsintheearth'scrustisstilloxygen,followedbysilicon,andhydrogenisthethird.
About99%oforganismsaremadeupof10chemicalelementswithhighcontent,namelyoxygen,carbon,hydrogen,nitrogen,calcium,phosphorus,chlorine,sulfur,potassium,sodium;magnesium,Thecontentofiron,manganese,copper,zinc,boron,andmolybdenumissmall;whilethecontentofsilicon,aluminum,nickel,gallium,fluorine,tantalum,strontium,andseleniumisverysmall,whicharecalledtraceelements.Itshowsacertaincorrelationbetweenmanandtheearth'scrustonthecompositionofchemicalelements.
Themostabundantelementintheearth'scrustisoxygen,butthemostabundantmetalelementisaluminum.
Aluminumaccountsfor8.3%oftheearth'scrust,whichistwicethecontentofiron,andaccountsforaboutone-thirdofthetotalmetalelementsintheearth'scrust.
Aluminumisofgreatsignificancetohumanproductionandlife.Ithaslowdensity,goodelectricalandthermalconductivity,goodductility,andisnotpronetooxidation.Itsmaindisadvantageisthatitistoosoft.Inordertotakeadvantageofaluminumandmakeupforitsshortcomings,itisoftenmadeintoalloyswhenused.Aluminumalloyhashighstrength,butitsweightismuchlighterthanordinarysteel.Itiswidelyusedtomakeairplanes,traincars,ships,dailynecessities,etc.Becauseofitsgoodelectricalconductivity,itisusedtotransmitelectricity.Becauseithasgoodcorrosionresistanceandreflectivitytolight.Soalsoshowtheirskillsintheuseofsolarenergy.
EvolutionHistory
Archaean
(About2.5billionyearsago)
ArchaeanItistheoldestandlongestgenerationinthegeologicalage,thatis,theoriginalcrustandtheinitialstageoftheoccurrenceanddevelopmentoftheoriginalatmosphere,hydrosphere,sedimentarycircle,andorganisms.
TheArcheanstratumiscomposedofdeepmetamorphicgneissandparagneiss.Theoldestknownageismorethan4billionyears.Basedonthis,itisbelievedthatasmallgranitecrustappearedontheearthbeforethis.Theappearanceofparagneissesmetamorphosedfromsedimentaryrocksindicatesthattherewasaprimitiveatmosphereandhydrosphereatthattime,aswellaspurephysicalandchemicalweathering.Thebaseofthesecrystallinemetamorphicrocksiscoveredwithalightlymetamorphicgreenstonebelt,includingvolcanicrocksandsedimentaryrocks,whichwereformedinthedepressionzoneonthegroundatthattimeandonlylaterundergonemetamorphism.Itsageisbetween3.4billionand2.3billionyears.ItisspeculatedthatthereweremanysmallgraniticlandmassesonthesurfaceoftheEarthintheearlyArchean,andtherewerepaleo-oceanswithvaryingdepthsbetweenthem.Later,thesmalllandmasseswerecombinedintolargercontinentalplatesduringmigration.Theseoldestlandmasseshavebeenscatteredinvariouscontinents,whichisthecoreoftheso-calledstablelandmasses-thecratonorancientshieldarea.
Thearchaeancrustalmovementandmagmaticactivityarebothextensiveandintense;volcaniceruptionsarefrequent,sotheatmosphereandhydrospherecanbeformed.Theareaofthepristineoceanmaybelargerthanweknow,buttheaveragewaterdepthismuchshallower.Themetamorphiciron-manganesedepositsrichinmarinestratifiedsedimentsandgolddepositsformedbymagmaticactivitiesallovertheworldwereformedduringthisperiod.Theatmosphereatthattimemayberichincarbondioxide,watervapor,andvolcanicdust,withonlyasmallamountofnitrogenandabioticoxygen.Theseawaterisalsoacidicmineralizedwater(onlygraduallyneutralizedlater),andthelandishotandbarren.Insomesuitableshallowseaenvironments,someinorganicsubstanceshaveundergonechemicalevolutiontobecomeorganicsubstances(proteinsandnucleicacids),andthendevelopintolivingprokaryoticcells,constitutingsomesimpleformsofbacteriaandcyanobacteriawithoutrealnuclei.ThisonlyappearedinthelateArchaeanperiod.
Ingeneral,Archaeanistheformationstageoftheprimitivegeographiccircle.Thelandistheprimitivedesertlandscape,andthewateristheplacewherelifebredandoriginated.Atthattime,theexchangeofmaterialandenergybetweentheearth'scrustandtheuniverseandbetweenthemantleandtheearthwasmuchstrongerthaneversince.
Proterozoic
(2.5billion-600millionyearsago)
IntheProterozoic,thecontinentalcrustgraduallychangedfromFromsmalltolarge,fromthintothick,volcanicactivityisrelativelyreduced,andthelithologyalsochangesfrombasictoacidic.TheLowerProterozoichasahugeaccumulationofclastics,whichgreatlyfacilitatesthestronggranitizationactivityandtheformationoflargeintrusions.DuetothedecreaseofCO2concentrationintheatmosphereandtheincreaseofCaandMgionsinthewater,carbonaterockswithchemicaldepositsbegantoappear.Itwilldirectlyaffecttheevolutionofthemagmaticprocess,leadingtotheappearanceofalkalinederivativerocks.Asthefreeoxygenintheatmosphereincreases,anoxidizingenvironmentalsobeginstoappear.Asaresult,mineralssuchasoolitichematiteandsulfateandthefirstbatchofredbedswereproducedinthelaterperiod.Theappearanceoforganismshaslittleimpactontheenvironment,sothereisnolargeamountofbiochemicaldepositsintheProterozoic.MorainerockswerealsodiscoveredattheendoftheProterozoic,whichwastheproductofthefirstglobaliceage.
Atthistime,prokaryoteshaveevolvedintoeukaryotes,andanaerobicorganismshavetransformedintoaerobicorganisms(thisturningpointiscalledtheYuripoint,whichoccurswhentheoxygencontentintheatmosphereincreasestoathousandthofthecurrentatmosphericoxygenconcentrationOneofthetime),thenumberofspecieshasalsoincreasedfromsmall.Atthistime,theplantkingdomontheearthgotgreatdevelopmentforthefirsttime,andthereappearedalargenumberofrelativelyprimitivelowerplantscapableofphotosynthesisandrespiration,suchasgreenalgae,chara,brownalgae,redalgaeandsoon.Thesemicropaleontscanbeusedforstratigraphicdivisionandcomparison.InthelateProterozoic,primitiveanimalsalsoappeared.Forexample,theEdiacaranfaunainAustraliaincludesfossilsofaquaticinvertebratessuchassponges,jellyfish,arthropods,flatwormsandmolluskcorals.FossilsofspongespiculeshavealsobeenfoundinNorthAmerica.
ThereweremanycrustalmovementsintheProterozoic,includingtheWutaiMovementinmycountry,theLuliangMovement,theChengjiangMovement,andtheJixianMovement.InNorthAmerica,thereweretheKnorrMovement,theHudsonMovement,andtheGlenvilleMovement.Sports,beltsports,etc.Thefoldbeltsformedbythepreviousorogenicmovementsgraduallycombinedtheoriginalsmalllandblocksintoancientland,andlaterbecametheancientfoldbaseandcoreofeachcontinent.Theprecambrianlandplatform(orplatform),onlyexposedItaccountsfor1/5ofthelandarea.Accordingtopaleomagneticresearch,boththeNorthAmericanLorraineandtheAfricanancientlandexperiencedmultiplepoleshiftsintheProterozoic(E.lrvingetal.,1975;J.D.E.Piper,1976).
Paleozoic
(600million-230millionyearsago)
ThePaleozoicincludestheCambrian,Ordovician,Silurian,Devonian,CarboniferousandPermian.Accordingtoresearch,between600millionand700millionyearsago,thecontinentexperiencedmanydivisionsandunions.AttheendoftheProterozoic(LatePrecambrian),thescatteredcontinentsonceunitedtoformapancontinent.DuringtheCambrian,thepancontinentsplitandbecameGondwanainthesouth.Thenorthwasdividedintothreecontinents:NorthAmerica,EuropeandAsia.Mediterranean).TheCaledonianorogenicmovementbeganattheendoftheOrdovician.BytheDevonian,thepre-Caledoniantroughhadfoldedintomountains,andancientEuropeandNorthAmericacombinedintoacontinent.AftertheHercynianmovementintheLateCarboniferous,theQianhaixitroughdisappearedandtheEuropeanandAmericancontinentsmergedwiththeGondwanacontinent.InthelatePermian,theformerUralSeaalsodisappeared,theEurasiancontinentwasformed,andtheworldbecameanewpan-continent.
AccordingtothestudybyWangQuanetal.(1979),thenatureoftheancientlandoftheMiddleDynastyinthenorthofChinaandtheancientlandoftheYangtzeinthesouthareverydifferent.ThelatterisverydifferentfromtheGondwanaancientlandinthesouthernhemisphereresemblance.TheybelievethattheYangtzeancientlandwaspartoftheGondwanaancientlandintheEarlyPaleozoic,andlatersplitanddriftednorthward.ItwasonlyinthelatePaleozoicthatitcollidedandmergedwiththeChineseancientland.TheQinling-HuaiyangMountainsbetweenthetwoIt'sagroundstitch.Theophiolitesetofrocks(comprisedofserpentinite,peridotite,gabbroandpillow-shapedbasicvolcanicrocks,etc.)belongingtotheeruptionoftheoceaniccrustandmantlewasalsofoundhere.Itisanindicatorofcontinentalsutures.Rockformations).ThestudyofancientgeomagnetisminmycountryalsobelievesthatinthelateProterozoic,theYangtzeancientlandwasroughlylocatedinthenorthernIndianOcean,separatedfromtheChineseancientlandinthenorthbytheocean.
Thecrustalmovementandtheseparationandintegrationoflandandseainthegeomorphicerahavebroughtgreatchangestothegeographicalenvironment:thedivisionofcontinentscausestransgression,andthemergerofcontinentscausesregression;italsohasasignificantimpactonbiologicalevolution.SincetheCambrian,thedivisionandunionofthemainlandandthenumberofmarineinvertebrateshavechangedsignificantly.
IntheCambrian,thepan-continentsplitandcausedatransgression,thecontinentalshelfwaswidespread,andmarineinvertebratesprosperedunprecedentedly.Amongthem,arthropodtrilobitesaccountedfor60%ofthetotalfossils,brachiopodsItaccountsforabout30%,andtheothersonlyaccountfor10%.Atthistime,marineplantsalsoshowedsignsoftransitiontoterrestrialplants.Forexample,thealgalcoalfoundintheCambrianstratainmycountryisanexample.TheOrdovicianseabedexpandedextensively,andbrachiopods,hornstones,graptolites,nautilus,andcoralsbecamecosmopolitanspecies.Theprimitivefish-jawlessfish(jawfish)alsoappeared.InadditiontothecontinueddevelopmentofmarineanimalsintheSilurianperiod,duetoseverecrustalmovementandenvironmentalchanges,marineanimalsenteredthecontinentalfreshwaterarea.Therealfish-jawedfishandwater-transportingfishsuitableforshoregrowthOrganizedvascularplantswerealsoborn.SincetheLatePaleozoicEraaftertheDevonian,continentstendedtomergeandregresscontinuedtooccur.Manymarineinvertebrates'settlementsdisappeared,andtheirtypesandnumbersweregreatlyreduced.Onthecontrary,fishflourishes,andterrestrialplantsflourish.Thesurfaceoftheearthhassinceendedaneraofdesertandozone-free.WhentheCarboniferousandPermianbecametheheydayofamphibians,theplantkingdomalsodevelopedfromsporeplantstogymnosperms.IntheCarboniferousandPermiancontinents,largeforestsdominatedbyfernsweredistributed,whichbecameanimportantcoal-makingperiodingeologicalhistory.
Mesozoic
(230to70millionyearsago)
TheMesozoicincludesTriassicandJurassicAndtheCretaceousperiod.Therearealotofdatathatprovethatthere-splitofthepan-continentoccurredintheMesozoic,thatis,itbeganintheLateTriassic,mainlysplitintheJurassicandCretaceous,andcontinuedtotheCenozoic.Thispan-continentoriginallyextendedtothenorthandsouthpoles,theequatorialpartwasnarrow,andtherewastheTethysSea(theancientMediterraneanSea).DuringtheTriassic-Jurassicperiod,NorthAmericaandAfricasplit,theNorthAtlanticbegantoexpand,andthepan-continentwasdividedintoLaurasia(LawrenceandAsia)inthenorthandGondwanainthesouth.DuringtheJurassic-Cretaceousperiod,SouthAmericaandAfricasplit,andtheSouthAtlanticbegantoexpand.AfricaandIndiaalsoseparatedfromAntarcticaandAustralia(thetwowerestilltogether)duringtheJurassic,andbegantoformtheIndianOcean.DuringtheCretaceous,theNorthAtlanticwidenednorthward,theSouthAtlanticalreadyhadacertainscale,Indiadriftednortheast,theIndianOceanalsoexpanded,whiletheancientMediterraneantendedtoshrink.
IntheMesozoic,therewerestrongorogenyinvariouspartsoftheMesozoic.EuropehadtheOldAlps,theAmericasweretheNevadaandLaramymovements,andChinawastheIndosinianandYanshanmovements.Atthistime,folds,fracturesandmagmaticactivitiesareextremelyactive.AseriesofCathaysia-styleupliftsanddepressionswereformedineasternmycountry.Theformationofmanynon-ferrousandraremetaldepositswasrelatedtothemagmaticactivityatthistime.Mineralssuchascoal,petroleumandoilshalewerealsoformedinfaultedbasins.Thebasicoutlineofmycountry'smainlandwasalsoestablishedatthistime.
ThebiologicalworldhasagreatdevelopmentcomparedwiththePaleozoic.GymnospermsthatappearedattheendofthePaleozoicerahavebecomethemostprosperouscategoryintheMesozoicera.Theyreproducedbyseeds,andthefertilizationprocesscompletelygotridofthedependenceonwater,makingthemmoresuitableforterrestrialhabitats.Thisisanotherleapinplantevolution.Themassivedevelopmentofterrestrialplantssuchascycads,ginkgo,conifers,etc.,notonlycreatedfavorableconditionsforcoalformation(suchastheJurassiccoalseamswidelydistributedintheworld),butalsoprovidedabundantresourcesforthedevelopmentofreptiles.Foodbasis.
IntheMesozoicera,reptilesbecamethemostprosperouschordatesatthattime.Thereareherbivorousandmeat-eatingdinosaursonland,ichthyosaursandplesiosaursinthesea,andpterosaursintheair.Atthesametime,therewerealsolizards,turtles,turtles,crocodiles,frogsandinsects.Ammonitesamongmarineinchondratesarealsoextremelyprosperous.Therefore,somepeoplerefertotheMesozoicastheageofdinosaurs,theageofammonites,ortheageofcycads.However,bytheendoftheCretaceous,mostofthesespeciesoflifethatflourishedwereextinct,andonlyapartofthemsurvived.Atthattime,theprimitivebirdsandmammalsthathadappearedbutwereatadisadvantageenteredthespectacularnewgeneration;angiospermshavealsoflourishedsincethen.
Thenewgeneration
(70millionyearsago-the21stcentury)
ThenewgenerationincludestheoldtertiaryandthenewTheThirdEpochandtheQuaternaryEpocharethemostrecentgenerations.FollowingtheMesozoicEra,theseafloorcontinuedtoexpand,AustraliaandAntarcticaseparatedEastAfrica,andIndiacollidedwithEurasia.StrongcrustalmovementoccurredintheTertiaryPeriod,calledtheNeo-AlpineMovementinEurope,andHimalayanMovementinAsia.AseriesofhugefoldsformedintheancientMediterraneanbelt(Alps-Himalayanbelt)andthecircum-Pacificbelt.Differentialascendinganddescendingmovementssuchasarchesandfaultsalsooccurredintheancientplatformareas,andredbedswerewidelydevelopedinthefaultedbasins.ThisorogenicmovementandtheaccompanyingretreatcausedsignificantchangesinthenaturalgeographicalenvironmentinheritedfromtheMesozoic.
Fromaglobalperspective,thesurfaceoftheOldTertiaryismainlyawarmandhumidclimate.Aftertheintenseorogenicmovement,theatmosphericcirculationsystem,especiallytheregionalcirculationsystem,hasalsochanged,andmanyplacestendtobedryandcold.TheupliftoftheQinghai-TibetPlateauinwesternmycountryhasagreatimpactontheeasternmonsooncirculationsystem,especiallyinsouthernChina,whichhasbecomeawarmandhumidforestlandscapedifferentfromthatofthesamelatitude.IntheQuaternary,duetothefurthercoolingofthetemperateandpolarclimates,large-scaleglaciationstookplaceontheearthandexperiencedmanychangesinglacialandinterglacialperiods.Biologyalsochangesduetochangesinhabitat.
Intheplantkingdom,theOldTertiarywascharacterizedbythegreatdevelopmentofangiosperms.Theplantcommunitychangedfrommonotonousconiferousforeststoevergreenbroad-leavedforestswithabundantflowersandfruits.Whentheclimatebecamedryandcold,thevegetationinmanyplacesexperienceddroughtandbiochemicalphenomena.AgrasslanddominatedbymonocotyledonousplantsappearedatthebeginningoftheNeo-Tertiary,andatundraappearedintheQuaternary.Theanimalkingdomischaracterizedbytheunprecedentedprosperityofmammals,sothenewgenerationisalsocalledtheeraofmammals.Theluxuriantangiospermsinthehotandhumidforestareagreatlypromotethedevelopmentofmammals.Theprosperityofinsectsisalsorelatedtothedevelopmentofangiosperms.Thewidespreaddistributionofangiospermsandinsectshaspromotedtheprosperityofbirds.Whenthegrasslandareaexpanded,manyherbivorousgrasslandfaunaappearedintheungulatesandrodents,andthecarnivoresthatfollowedincreased.
ItisparticularlyimportantthathumansappearedintheQuaternaryPeriod.Thisisaneventofgreatsignificanceinthehistoryoftheearth.Afterthecomplicateddevelopmentprocessofhumanbeings,ithasgraduallybecomeanimportantfactorindisturbing,controllingandtransformingthenaturalenvironment.Therefore,theQuaternaryEraisalsocalledthe"spiritualgeneration".
Movement
Evidence
Sincetheformationoftheearth'scrust,ithasbeenmovingallthetime,andthismovementhascausedcontinuouschangesinthestructureoftheearth'scrust.Anearthquakeisareflectionofthecrustalmovementthatpeoplefeeldirectly.Themorecommoncrustalmovementisgoingonforalongtimeandslowly,anditisalsodifficulttodetect.Itcanonlybedetectedwiththehelpoflong-termobservationswithinstruments.Forexample,geodeticsurveydataprovesthattheHimalayasarestillrisingatarateof0.33to1.27cmperyear.
Thecrustalmovementoftheearthduringthegeologicalperiodcannotbeknownbydirectmeasurement,butithaslefttracesinthecrust.Wheretherocksareexposedinmountainousareas,thesedimentaryrocklayersareofteninclined,bent,orevenfracturedstaggered,allofwhicharetheresultofdeformationoftherocklayerunderforce.InthecoastalareaofRongcheng,Shandong,theformerbeachisnow20-40metersabovethesea.IntheareasofZhangzhouandXiameninFujian,theoldbeacheshavealsobeenabout20metersabovethesea,indicatingthatthecrustisrisingintheseplaces.AnancientHaiherivercourseofapproximately7kilometershasbeendiscoveredontheseabedoftheBohaiSeainmycountry,whichindicatesthattheBohaiSeaanditscoastalareasareareaswitharelativelyhighrateofdeclineinmoderntimes.Foranotherexample,thebeautifulYuhuaStoneswereproducedinYuhuatai,Nanjing.Thesesmoothpebbleswithbeautifulpatternsarenaturalrelicsoftheancientriverbed.AlargenumberofpebblesarepiledupinYuhuatai,whichshowsthatthereusedtobeariverinthepast.Later,thecrustroseandtheriverwasabandoned,anditbecamethegravelofYuhuataithatismuchhigherthanthewatersurfaceoftheYangtzeRiver.
Crustalmovementclassification
Crustalmovementclassificationtable
Serialnumber | Classificationbasis | Typesofcrustalmovement |
1 | Referenceobject | 1.Crustalmovementwiththeeclipticplaneasthereferenceobject;2,theearth’saxisasthereferenceobjectThecrustalmovement;3.Thecrustalmovementwithgeographiccoordinatesasthereference;4.Thecrustalmovementwiththesurfaceobjectsasthereference. |
2 | Motiondirection p> | 1.Longitude(south-north)crustalmovement;2.Latitude(east-west)crustalmovement;3.Northeast-southwestcrustalmovement;4.Northwest-South-Eastcrustalmovement. |
3 | Sportsmethod | p>1.Horizontalcrustalmovement;2.Verticalcrustalmovement; |
4 | exerciseresults | 1,bendingCrustalmovement;2.fracturedcrustalmovement. |
5 | GeologicalTimes | p>1.Precambriancrustalmovement;2.Paleozoiccrustalmovement;3.Mesozoiccrustalmovement;4.Moderncrustalmovement;5.Moderncrustalmovement. |
6 | Placename+era(WithinChina) | 1.Fupingcrustalmovement;2.Luliangcrustalmovement;3.Jinningcrustalmovement;4.Caledoniancrustalmovement;5,Hualixicrustalmovement;6.Indo-Chinesecrustalmovement;7.Yanshancrustalmovement;8.Himalayascrustalmovement. |
7 | Sourceofforce | 1.Internalcrustalmovement;2.Externalcrustalmovement. |
8 | Sportsscale | p>1.Globalcrustalmovement;2.Regionalcrustalmovement;3.Localcrustalmovement. |
9 | Causes | 1.Seismiccrustalmovement;2.Volcaniccrustalmovement;3.Weatheringanddenudationofcrustalmovement;4.Collapsedcrustalmovement;5.Sedimentarycrustalmovement;6.MeteoriteImpactingcrustalmovement;7.Man-madecrustalmovement. |
10 | Depth | 1.Surfacecrustalmovement;2.Shallowcrustalmovement;3.Deepcrustalmovement. |
11 | Mechanicalproperties | 1.Compressivecrustalmovement;2.Tensilecrustalmovement;3.Torsionalcrustalmovement;4.Crustalmovementwithmixedmechanicalproperties. |
Causesofcrustalmovement
Differenttypesofcrustalmovementhavedifferentcauses.
Crustalmotionanditsoriginusingtheeclipticplaneasthereferenceobject
Theorbitalplaneoftheearthorbitingthesuniscalledtheeclipticplane.Thepositionchangeofthecrustanditsconstituentrockswiththeeclipticplaneasthereferenceobjectisthelargestcrustalmovement.
Crustalmovement
Thistypeofcrustalmovementisdividedintothreesub-categories:oneisthepositionchangeofthecrustrelativetotheeclipticplanecausedbytherotationoftheearth;Thepositionoftheeclipticplanechanges;thethirdisthechangeintheinclinationoftheearth'saxis,andthepositionofthecrustrelativetotheeclipticplanechanges.
Thistypeofcrustalmovementcauseschangesindayandnight,seasons,andclimate,andcauseschangesinthesunandmoon'sgravitationalpullontheearth,whichinturntriggersothertypesofcrustalmovement.
Thecauseofthiskindofcrustalmovement:causedbytheoriginandevolutionofthesolarsystem.
Crustalmovementandgenesisbasedontheaxisoftheearth
Thepositionalchangesofthecrustanditsconstituentrockswiththeaxisoftheearthasthereference,followedbythescaleInthefirsttypeofcrustalmovement,theearthandmagneticpolesaredisplaced.Thechangerelativetotheearth'saxis,thatis,theearth'spolehasmoved.Thistypeofcrustalmovementcauseschangesintheearth'scrustandgroundgeographiccoordinates,aswellaschangesinseasonsandclimate,andchangesinthegravitationalbalancebetweentheearth,thesunandthemoon.
Causesofthistypeofcrustalmovement:Thelayeredearthisformedbytherotationoftheoutersphereoftheearthunderthegravitationalforceofthesunandthemoon;othercausesmayalsoexist.
Crustalmovementanditsgenesisbasedongeographiccoordinates
Thepositionalchangesofthecrustalanditsconstituentrocksbasedongeographiccoordinates,Thistypeofcrustalmovementformedlarge-scalecrustalupliftsanddepressions,formingmountainsandplateaus,formingplainsandbasins,andformingmountainsandvalleys.
Themainsourcesofpowerforthistypeofcrustalmovementareasfollows:
1.Denudation,transportandsedimentationofwaterandwind
ThistypeofgeologicalprocessnotonlyformsThecrustalmovementofvaryingscales,andtheformedsedimentsandsedimentaryrocksarethematerialbasisfortheformationofmountainsandplateaus.
Thecrustalmovementformedbytheerosion,transportationanddepositionofwaterreducestherelativeheightofthecrust,stripshighandfillsdepressions,andbalancesthecrust.
Erosion,transportanddepositionofwind,characteristicsoferosion,transportanddepositionofwindonrocks:
Winderosionoccursinlow-rainandaridareas,notonlydenudinghighmountainsandplateaus,butalsoThevalleysanddepressionsarealsodenuded.
Thetransportingeffectofwindvariesfromneartofar.Thenearerjustleavesthedenudedplace,andthefarawaycanreachtensofthousandsofkilometers.Itsdepositionareavariesinsize,uptoseveralmillionsquarekilometers.
Winddepositioncanbeonlandorwater;itcanbeindepressionsandplains,anditcanbeinmountainsandplateaus;itcanformquasi-plaindepositsormountaindeposits.
Aeolianterrainiseasytochangeandmigrate.Aeoliandepositioncanformclasticrockswithhighdipangles,andcanformsedimentaryfoldstructures.
Thedepositionofwindandwatercanoccursimultaneouslyoralternately.
2.CentrifugalforcefromthepolestotheequatorwhentheearthrotatesThesimulationtestprovesit.
3.Underthegravitationalforceofthesunandthemoon,whentheearthrotatesfromwesttoeast,blocksofdifferentmassesinthecrustwillmovefromeasttowest.Withoutthegravitationalforceofotherplanets,allpartsoftheearth'scrustmoveinauniformcircularmotionwiththerotationoftheearth.Underthegravitationalforceofthesunandthemoon,duetotheunevennessoftheconstituentmaterialsofeachpartoftheearth'scrust,differentialmotionalongthelatitudeoccurs,resultinginsqueezingandseparation.
Thecompositionoftheearth'scrustisuneveninalargeareaorasmallarea.
Inalargearea,therearelargeblocksinEuropeandAsia,Africa,NorthandSouthAmerica,andAntarcticaontheland,andseveralblocksinthePacificOcean,IndianOcean,AtlanticOcean,andArcticOceanintheocean.Theselargeblocksaredifferentintopography,materialcomposition,areasize,geometry,geographiclocation,quality,structure,etc.Therearemanysmallblocksinthebigblock.Theselargeandsmallblocksontheearth'scrustareaffectedbythegravitationalpullofthesunandthemoon.Whentheearthrotates,theymoveatdifferentspeeds.Astheearthrotatesfromwesttoeast,theselargeandsmallblocksonthecrustformarelativemovementfromeasttowest.
Crustalmotionanditsgenesiswithgroundobjectsasreferenceobjects
Crustalmotionwithgroundobjectsasreferenceobjects,therelativemovementofrockscomposedofcrustalmaterialsThedistanceissmallandbelongstoasmallrangeofcrustalmovement.Inadditiontolarge-scalecrustalmovementthatcancausethiskindofcrustalmovement,earthquakes,volcanoes,collapses,meteoriteimpacts,andsomebiologicalactivitiescanallcausethiskindofcrustalmovement.
Single-causeandmulti-causecrustalmovementtheory
Accordingtothenumberoffactorsthatcausecrustalmovement,thetheoryofcrustalmovementcanbedividedintotwoschools:oneistheschoolofsingle-causecrustalmovement,andtheotheristhetheoryofcrustalmovement.Itisaschoolofmulti-causecrustalmovement.
Single-causedcrustalmovementschoolbelievesthatthereismainlyonekindoffactorthatcausescrustalmovement.Thetraditionalcrustalmovementtheorybelongstothisschool,suchascontinentaldrifttheory,seabedexpansiontheory,platetheory,geomechanics,mosaictheory,Diwatheory,faultblocktheory,polycyclictheory,etc.
Themulti-causedcrustalmovementschoolbelievesthattherearemanyfactorsthatcausecrustalmovement,whichbelongtothemoderntheoryofcrustalmovement.ThistheorywasputforwardbyJiangFashiofourcountry.Accordingtothecrustalmovementreference,thecrustalmovementisdividedinto:1.crustalmovementwiththegalacticplaneasthereference;2.crustalmovementwiththeeclipticplaneasthereference;3.crustalmovementwiththeearthaxisasthereference;4.Thecrustalmovementwithgeographiccoordinatesasthereference;5.Thecrustalmovementwiththesurfaceobjectasthereference;6.Thecrustalmovementwiththesphericalsurfaceasthereference.Differenttypesofcrustalmovementsarecausedbydifferentfactors,differenttypesofcrustalmovementshavedifferentmodesandresults,andvarioustypesofcrustalmovementsaresuperimposedoneachother.
Continentaldrifttheory
AgeotectonichypothesisproposedbyGermanmeteorologistWegener(1880～1930)in1912.HebelievesthatinthelatePaleozoic,therewasonlyonehugejointancientlandintheworld,calledthe"Pancontinent".IntheMesozoic,duetotidalfrictionandthesqueezingforcefromthepolestotheequator,pan-continentsbegantosplit,andlightergranitecontinentsdriftedontheheavierbasaltmantle,graduallyformingtoday'ssea-landpattern.Hebelievesthatthemountainsontheeartharealsotheproductsofcontinentaldrift.TheCordilleraandtheAndesarefoldmountainsformedbythebasalticbasementofthePacificwhentheAmericancontinentdriftsandslideswestward;Theislandarcgroupisthedebrisleftbythecontinentdriftingwestward;thesoutherntipofGreenland,Florida,TierradelFuego,andotherarcsaretheresultofslidingfrictionandsheddingwestward;theeast-westAlpsandtheHimalayasThelargemountainsaretheresultofthecontinent'ssqueezingfromthepolestotheequator.Basedontheinformationavailableatthattime,Wegenerdemonstratedindetailthetheoryofcontinentaldriftintermsofgeology,topography,paleontology,paleoclimate,andgeodesy.Thishypothesisattractedtheattentionofthegeologyandgeophysicscirclesatthattime.However,manyscholarshaveexpresseddoubtsaboutthemechanismandlawsofcontinentaldrift.Sincethe1950s,paleomagneticstudieshaveshownthatthemovementofmagneticpolesingeologicalhistorycanonlybereasonablyexplainedbythetheoryofcontinentaldrift.Therefore,thetheoryofcontinentaldrifthasgainedanewlife.
TheoryofPlateTectonics
In1961and1962,DietzandHertzoftheUnitedStatesputforwardthe"submarineexpansiontheory".Onthisbasis,in1968,FrenchgeologistLePishonandotherspioneeredthe"platetectonicstheory",whichhasnowbecomethemostpopularnewtheoryofearthscience.
Thetheoryofplatetectonicsdividesthegloballithosphereintosixmajorplates:Asia-Europeplate,Africanplate,Americanplate,Pacificplate,IndianOceanplateandAntarcticaplate.Inadditiontothesixmajorplates,therearealsosomesmallplates.Somesub-levelplatescanalsobedelineatedwithinthemainland.Theplatesareboundedbystraitsortrenchesandorogenicbelts.Generallyspeaking,thecrustinsidetheplateisrelativelystable;thejunctionoftheplateandtheplateisarelativelyactivezoneofthecrust,anditsactivitiesaremainlymanifestedbyearthquakes,volcanoes,tensioncracks,dislocation,magmarise,andcrustalsubduction.Almostallvolcanoesandseismicactivitiesintheworldarelocatedneartheboundaryoftheplates.
Thetheoryofplatesbelievesthattheearth'scrustisbornanddied.Duetotheexpansionoftheoceanfloor,thebottomoftheoceanisconstantlyupdated,andthecontinentsonlymovewiththeexpansionoftheoceanfloor.Intheprocessofrelativemovement,theplateseithersplittothetwosidesorcollidedwitheachother,thusformingthebasicappearanceoftheearth'ssurface.Forexample,300millionyearsago,EuropeandAfricawereconnectedwithSouthandNorthAmerica.Later,theAtlanticridgeappeared.Newoceaniccrustcontinuedtoformandexpandedonbothsideswithitasthecentralaxis,whichseparatedtheabove-mentionedcontinents.Inthepast70millionyears,theIndianplatehascontinuouslymovednorthwardandcollidedwiththeAsia-Europeplate,creatingtheHimalayas.TheGreatRiftValleyofEastAfricaisatthebeginningoftheopeningoftheAfricancontinentandisintheembryonicstageofproducingnewoceaniccrust.TheGulfofAdenintheRedSeaistheresultoftheexpansionandcrackingofthecrustonbothsides,anditisinthejuvenilestageoftheoceaniccrust.TheMediterraneanasweknowitrepresentstheendofthedevelopmentoftheoceans.ItistheoceanthatremainsafteralongperiodofevolutioninthevastancientMediterranean.
Asforthedrivingforceofplates,somepeoplethinkthatitismantleconvection,andsomepeoplethinkthat“hotspots”and“hotplumes”inthemantlearchthelithosphereandmakeitdownwardundertheactionofgravity.Thereareotherpropositionsaboutslidingandpushingplates,andthereisnounifiedunderstanding.
Continentaldrift-submarineexpansion-platetectonics,thisisatrilogyofthedeepeninganddevelopmentofhumanunderstandingofcrustalmovement.
Thetheoryofextraterrestrialrotation
ThetheoryofextraterrestrialrotationwasproposedbyZhangWeizhiin2012andhassincebeenrevised.TheJiangfamily(JiangFashi)dividedthecrustalmovementinto:1.crustalmovementwiththegalacticplaneasthereference;2.crustalmovementwiththeeclipticplaneasthereference;3.crustwiththeearthaxisasthereference.Movement,4.crustalmovementwithgeographiccoordinatesasareference,5.crustalmovementwithasurfaceobjectasareference,6.crustalmovementwithasphericalsurfaceasareference.JiangShifaisarepresentativeofmanycausesofcrustalmovement.Thecauseofcrustalmovementwiththeaxisoftheearthasareference,JiangShifaexplainedthatitwasformedbytherotationoftheoutersphereoftheearth.Jiangreclassifiedthestructureofthesolidearth,asshowninthefollowingtable:
Tableofthestructureofthesolidearth
EarthcircleLayername | Depth (km) | Earthquake LongitudinalwaveVelocity (km/s) | Earthquake shearwavevelocity (km/s) | Density(g/cm3) | Substance Status | ||
Firstlevel Layered | Secondlevel Layered | Traditional Layered | |||||
Outside Ball | Crust | Crust | 0—33 | 5.6—7.0 | 3.4—4.2 | 2.6—2.9 | Solidmatter |
Outside Over p>cross layer | outertransitionlayer (top) | Uppermantle | 33—980 | 8.1—10.1 | 4.4—5.4 | 3.2—3.6 | Partof Meltedsubstance |
Outertransitionlayer (lower) | Lowermantle | 980—2900 | 12.8—13.5 | 6.9—7.2 | 5.1—5.6 | Liquid-solidmatter | |
Liquid State Layer | Liquidlayer | Foreignnuclear | 2900—4700 | 8.0—8.2 | Failedtopass | 10.0—11.4 | liquidsubstance |
inside p>Ball | InsideOver Level | OverLevel | 4700—5100 | 9.5—10.3 | 12.3 | Liquid-solidmatter | |
Earthcore | EarthCore | 5100—6371 | 10.9—11.2 | 12.5 | Solidmatter |
Earth'souterspheremovement
Theearthrotatesandrevolvesinanorbit.Atthesummersolstice,thenorthernhemisphereoftheearthisclosertothesun,andthesolargravitationalforcereceivedisgreaterthanthatofthesouthernhemisphere.Atthewintersolstice,thesolargravityonthenorthernandsouthernhemispheresoftheearthisoppositetothatatthesummersolstice.Astheearthrevolvesaroundthemasspointoftheearthandthemoon,thenutationoftheearth,andtheprecessionoftheearth'saxisproducetheshakingactionoftheearth.Theshakingactionoftheearthcausestheoutersphereoftheearthtorotateinthedirectionofthesun'sgravitationalforce,justlikethebeansinthedustpan.Whenthedustpanisshaken,thebeanswillrotateinthetiltdirectionofthedustpan.ThemovementoftheinnerballoftheearthPutastoneinabottlefilledwithwater,tiearope,holdoneendoftheropetomakethebottlerotate,theresultis:thestoneinthebottleisalwaysbiasedtotheothersideofgravity.Inthesameway,theinnersphereoftheearthalwaysleanstotheothersideofthesun'sgravity.Therotationoftheearth'soutersphereformsthemovementoftheearth'sandmagneticpoles,andformsthemovementoftheearth'scrustrelativetotheearth'saxis.TherotationofAntarcticafromlowlatitudestotheSouthPoleisformedbytherotationoftheoutersphereoftheearth.