3-地层学基本理论(1)

第3章地层学Stratigraphy3.1概念、定律和地层的接触关系3.1Concepts,laws&contactrelationshipsofstrata3.2地层划分和对比3.2Stratigraphicsubdivisionandcorrelation3.3地层单位和地质年代3.3Stratigraphicunitsandgeologicaltimes3.4地层的形成作用3.4Stratigraphicformation3.1概念、定律和地层的接触关系Concepts,laws&contactrelationshipsofstrata3.1.1地层与地层学3.1.1Strataandstratigraphy3.1.2地层学的基本定律3.1.2Basicstratigraphiclaws3.1.3地层的接触关系3.1.3Contactrelationshipsofstrata3.1.1Strata&stratigraphyStrata:Alllayeredrocks,whichincludeallsedimentaryrocks,apartofigneousrocksandmetamorphicrocks地层:各种层状岩石的统称.包括所有的沉积岩,部分火成岩和变质岩.layered(ICS,1994)RockcyclesStratigraphy,fromLatinstratum+Greekgraphia,isthestudyofallrockbodiesformingtheEarth'scrustandtheirorganizationintodistinctive,useful,mappableunitsbasedontheirinherentpropertiesorattributesinordertoestablishtheirdistributionandrelationshipinspaceandtheirsuccessionintime,andtointerpretgeologichistory.地层学:研究层状岩石形成的先后顺序、地质年代、时空分布规律(狭义)和形成环境条件及其物理、化学性质的地质学分支学科.她的核心目标就是建立地球科学的时间坐标。Stratigraphy太古宙+元古宙：12个GSSA显生宙:46+40=96个GSSPMa2004Internationalstratigraphicchart3.1.2地层学的基本定律3.1.2Basicstratigraphiclaws●地层叠覆律(principleofsuperposition)●原始水平律(Principleoforiginalhorizontality)●原始侧向连续律(principleoforiginallateralcontinuity)由丹麦学者N.Steno(1638-1686)于1669年一次提出(Steno’sstratigraphicaxioms)地层学三定律是构造地质学和地层学的基础地层叠覆律:原始地层自下而上是从老到新的(上新下老)原始水平律:地层沉积时是近于水平的，而且所有的地层都是平行于这个水平面的(水平摆放).原始侧向连续律:地层在大区域甚至全球范围内是连续的，或者延伸到一定的距离逐渐尖灭(侧向连续)。PrincipleofSuperpositionInanysequenceofundisturbedstrata(rocklayers),theoldestlayerisonthebottomandtheyoungestisonthetop.PrincipleofOriginalHorizontalitySedimentssettlefromfluidsundertheinfluenceofgravity,thereforethedepositsarenearlyhorizontaloratveryshallowinclines.PrincipleofLateralContinuityAwater-laidstratum,atthetimeitwasformed,mustcontinuelaterallyinalldirectionsuntilitthinsoutastheresultofnondepositionoruntilitabutsagainsttheedgeoftheoriginalbasinofdeposition.相邻美国科罗拉多州大峡谷国家公园LateralterminationofstratallayersPinchout(c),Intertonguing(d),Lateralgradation(e)abNorthIsland,NewZealandcdeAtedgeofadepositionalbasin(a);Faultingfollowedbyerosion(b)Sedimentaryfacieschangewiththedepositionalenvironments,whilethefossilschangemainlywithtime浊积岩，C1,东天山浊积岩，C1,东天山Way-upindicator倒转地层的识别方法(沉积学)ABC倒转地层的识别方法(沉积学)化石层序律（Principleoffossilsuccession）不同时代的地层含有不同的化石，含相同化石的地层其时代相同。WilliamSmith(1769-1839)----地层学之父于1817年提出。PrincipleoffossilSuccessionFossilsfoundinonerocklayerwilldifferfromlayersaboveandbelow.Bydeterminingthesequenceoffossilsinonelocation,itispossibletocorrelaterocksfromanotherlocationiftheycontainthesamefossils.化石定年J3三尾类蜉蝣J3-始祖鸟昆明鱼神奇啰哩山虫-具有成对眼睛和触角的叶足动物古囊动物D3牙形石辽宁古果Areyousure:therearethesamefossilsinthestrataofthesamegeologicaltime?Why?相同时代的地层就一定含有相同的化石吗？不一定1.相同的时代可有不同的沉积环境2.相同的时代也可有不同的埋藏和保存环境.化石层序律的意义根据化石内容1对比不同剖面的地层2确定地层的相对顺序及相对时间三剖面相距500KM不整合平行parallel/discon.角度/angularDisconformity，假整合整合连续/continuity不连续discontinuity有地层缺失，上下地层产状一致有地层缺失，上下地层产状不一致上下地层之间没有明显的沉积间断有沉积间断(hiatus/diastem),unconformityconformity非整合nonconformity沉积接触depositionalcontact侵入接触intrusivecontact地层与地层地层与其他地质体3.1.3地层的接触关系ThecontactrelationshipsofstrataDS角度不整合的形成及意义Angularunconformity昌平组景儿峪组Parallelunconformity/disconformity（北京西山）explainedobservedConformity;D1westernJunggarNonconformity,鸡冠山,北戴河沉积接触:年轻的沉积盖层直接覆盖在较古老的岩浆岩或深变质岩上,年轻沉积盖层的底部常含下覆岩石的成分或砾石.侵入接触:年轻的岩浆侵入到较古老的地层中,年轻岩体的边缘常含来源于地层的捕虏体,地层与岩体的交界部位常受到不同程度的烘烤.地层接触关系角度不整合Angularunconformity非整合nonconformity平行不整合disconformity小间断Paraconformity连续ContinuityBecareful!!!200kmContactrelationshipsmaychangeinspace,fromlandtomarinebasin.捕虏体PrincipleofCross-cuttingRelations：Ageologicfeaturewhichcutsacrossorpenetratesanotherfeaturemustbeyoungerthanwhatitcuts.PrincipleofInclusions：Rockswhichcontaininclusionsofanotherrockareyoungerthantheinclusion.Theinclusionisolderthantherockinwhichitisincluded.ABCDxenolithPrincipleofSuperpositionInanysequenceofundisturbedstrata(rocklayers),theoldestlayerisonthebottomandtheyoungestisonthetop.PrincipleofOriginalHorizontalitySedimentssettlefromfluidsundertheinfluenceofgravity,thereforethedepositsarenearlyhorizontaloratveryshallowinclines.PrincipleofLateralContinuityAwater-laidstratum,atthetimeitwasformed,mustcontinuelaterallyinalldirectionsuntilitthinsoutastheresultofnondepositionoruntilitabutsagainsttheedgeoftheoriginalbasinofdeposition.PrinciplesofGeologyPrincipleofCross-cuttingRelationsAgeologicfeaturewhichcutsacrossorpenetratesanotherfeaturemustbeyoungerthanwhatitcuts.PrincipleofInclusionsRockswhichcontaininclusionsofanotherrockareyoungerthantheinclusion.Theinclusionisolderthantherockinwhichitisincluded.PrincipleofBiologicSuccessionFossilsfoundinonerocklayerwilldifferfromlayersaboveandbelow.Bydeterminingthesequenceoffossilsinonelocation,itispossibletocorrelaterocksfromanotherlocationiftheycontainthesamefossils.Unconformitiesaresurfacesthatrepresentgapsinthegeologicrecord.Missingtime-missingsedimentDisconformity-unconformitybetweenparallellayers(sedimentaryandvolcanicrocks).Nonconformity-stratifiedrocksuponunstratifiedrocks(sedimentaryrocksoverlyingmetamorphicorplutonicrocks).AngularUnconformity-olderstratadipsatadifferenta