資源描述：
《第四章地質(zhì)年代ppt課件.ppt》由會(huì)員上傳分享，免費(fèi)在線(xiàn)閱讀，更多相關(guān)內(nèi)容在教育資源-天天文庫(kù)。
1、第四章地球的年齡 和地質(zhì)年代學(xué)TwoConceptionsofEarthHistoryCatastrophism（災(zāi)變說(shuō)）Assumption:GreatEffectsRequireGreatCausesEarthHistoryDominatedbyViolentEventsUniformitarianism（均變論）Assumption:WeCanUseCauseAndEffecttoDetermineCausesofPastEventsFinding:EarthHistoryDominatedbySmall-scaleEventsTypicalofthePresent.C
2、atastrophesDoHappenButAreUncommon4.1相對(duì)地質(zhì)年代N.Steno地層層序律層序地層學(xué)方法W.Smith生物地層學(xué)方法標(biāo)準(zhǔn)化石時(shí)間短、演化快、分布廣地層的缺失－不整合（角度不整合、假整合）相互切割關(guān)系地質(zhì)年代表relativeageandabsoluteageRelativeage(相對(duì)年齡)-?Relativemeansthatwecandetermine?ifsomethingisyoungerthanorolderthansomethingelse.?Relativetimedoesnottellhowoldsomethingis,all
3、weknowisthesequenceofevents.?Forexample:?thesandstoneinthisareaisolderthanthelimestone.Absoluteage(絕對(duì)年齡)-?Absoluteagemeansthatwecanmoreorlesspreciselyassignanumber(inyears,minutes,seconds,orsomeotherunitsoftime)totheamountoftimethathaspassed.?Thuswecansayhowoldsomethingis.?Forexample:?Thesa
4、ndstoneis300millionyearsold.PKUTrashPitTHUTrashPitWhatcanwesayandlearnfromtheseexcavations?RelativeageoftrashlayersSimilarculturesmusthaveexistedinbothareasandlivedatthesametimeThetrashpitscontainsomecluestoabsoluteageRecognizeahiatus,orbreakinthedepositionalsequenceattheTHUsiteIngeology,we
5、usesimilarprinciplestodeterminerelativeages,correlations,?andabsoluteages.Relativeages-?PrinciplesofStratigraphyCorrelations-Fossils,keybeds,physicalcriteriaAbsoluteages-Radiometricdating.PrinciplesofStratigraphyStratigraphy（地層學(xué)）=?thestudyofstrata(layers)intheEarth'scrust.LawsofStratigraphy
6、（地層學(xué)定律）:1.OriginalHorizontality-sedimentarystrataaredepositedinlayersthatarehorizontalornearlyhorizontal,paralleltoornearlyparalleltotheEarth'ssurface.2.StratigraphicSuperposition-BecauseofEarth'sgravity,depositionofsedimentwilloccurdepositingolderlayersfirstfollowedbysuccessivelyyoungerlay
7、ers.水平地層相對(duì)地質(zhì)年代BreaksintheStratigraphicRecord---unconformity（不整合）AngularUnconformity（角度不整合）Disconformity（平行不整合、假整合）Nonconformity（非整合、不整合）不整合關(guān)系示意圖VariationinUnconformitiesStratigraphicClassificationTwotypesofstratigraphicclassificationareused,onebasedonphy
