海洋科学导论第10讲-刘建波-Marine Sedimentology14

《海洋科学导论》课程安排2-18周力平绪论海洋科学若干前沿问题2-25陈永顺海底地貌形态与海盆的演化3-4,11杨海军大气与海洋/海洋环流3-18沈兴海海水的化学组成和特性3-25黄宝琦海洋生物圈与海洋生态系统4-1朱彤海-气作用及化学过程4-8刘建波海洋沉积4-15胡敏海洋环境……办公室：逸夫二楼3423室电话：59684E-mail:jbliu@第八讲海洋沉积学刘建波地球与空间科学学院海洋科学导论(12638010)jbliu@授课内容前言与研究历史研究方法-样品采集海洋沉积的类型海洋沉积的分布及其成因地质历史中的海洋沉积思考题海洋沉积学-定义•意义海洋沉积学是研究现代海底沉积物和沉积岩及其形成作用的科学，包括沉积物及沉积岩的描述、分类、成因及其解释研究意义海洋沉积物是生物地球化学的重要的组成部分海洋沉积物记录了大量地质作用、

海洋和气候条件的信息与陆地记录相比，海洋记录更为完整海洋沉积物具有重大的经济价值海洋沉积学-研究历史起始于1872－1876年间的“挑战者”号远洋考察，而Murray和Renard(1891)发表的“Deep-SeaDeposits”一书则奠定了现代海洋沉积学的基础由美国CoastSurvey(1888)绘制的西北大西洋海底沉积物分布图

Siliceousshoredepositsandterrigenousclaysandsiltsdominatenearshore,gradingtopteropodand/orglobigerinaoozeandredclaytothedeepAtlantic,withcoralsandsnearsomeCaribbeanislands./history/quotes/soundings/media/bottom.html粒度小，成熟度高海洋沉积学研究历史深海沉积机理研究Kuenen(1950)通过水槽实验和现代沉积观察，提出浊流理论，引起了沉积学理论的重大变革Bouma(1963)建立浊流沉积的标准相模式Heezen等(1966)发现沿陆坡分布的等深流沉积活动的深海！海洋沉积学研究历史60年代兴起的板块构造理论为海洋沉积学发展增添了许多新的内容，如不同构造下相模式的建立及板块运动造成的远洋沉积的分布规律等海洋沉积学研究历史“深海钻探计划”(DSDP，1968－1983)、“大洋钻探计划”(ODP，1983-2003)和IODP（2003-2013）使海洋沉积学研究向地壳更深处扩展，在时间上，可以恢复数千万年的沉积历史。与其他学科相互渗透和交叉，出现了一些新的分支学科，例如比较沉积学、沉积动力学等。授课内容前言与研究历史研究方法-样品采集海洋沉积的类型海洋沉积的分布及其成因地质历史中的海洋沉积思考题从洋底获取沉积物的方法海底拖网Bottomdredge抓斗取样器Grabsampler从洋底获取沉积物的方法重力取芯器活塞取芯器沉箱取样活塞取样样品的处理和保存地质学家正在“地球（CHIKYU）”深海钻探船上检查采自深海岩心中沉积物粒度和成分的变化规律以解释古代环境和气候变化历史蛟龙号载人潜水器大洋一号科学考察船授课内容前言与研究历史研究方法-样品采集海洋沉积的类型海洋沉积的分布及其成因地质历史中的海洋沉积思考题Theoceansaredividedintohorizontallayers,orzones,definedbywatertemperature.LightpenetratestothebaseofthephoticzoneAllaby,M.(Ed.),2009.Oceans:AScientificHistoryofOceansandMarineLife.DiscoveringtheEarth.FactsonFile,208pp.Classificationofmarinesedimentsbasedonlocation(wheresedimentsarefound)滨岸带陆棚陆坡深海平原浅海沉积物浅海和远洋沉积物大洋沉积物CLASSIFICATIONOFMARINESEDIMENTSBASEDUPONMODEOFFORMATIONTerrigenous(陆源沉积)Sandsandmudproducedbyweathering/erosionofrocksonlandBiogenic(生物沉积)CaCO3andSiO2mudsandoozescomposedofhardpartsoforganismsAuthigenic(自生沉积)formedbyprecipitationofmineralsinseawater(Manganese(Mn)andPhosphorus(P)nodules)Volcanogenic(火山)ejectedfromvolcanoes(ash)Cosmogenous(宇宙)piecesofmeteoritesthatsurvivetripthruatmosphereCLASSIFICATIONOFMARINESEDIMENTSDEPENDONTHEGRAINSIZE,SORTING,MATURATION.粘土粉砂砂砾中砾巨砾COMMONCLASTICROCKSconglomeratesandstoneshale尤里斯特隆图解

HJULSTROM’SDIAGRAMRelationshipbetweengrainsizeandenergyforerosion,transportationanddeposition.Terrigenoussedimentsstronglyreflecttheirsourceandaretransportedtotheseabywind,riversandglaciers.Rateoferosionisimportantindeterminingnatureofsediments.Averagegrainsizereflectstheenergyofthedepositionalenvironment.沉积物粒度增大侵蚀沉积搬运水体能量增加沉积物的分选性和磨圆性

SORTING&RONGDING无分选、角砾状冰川沉积物分选良好、磨圆良好的海滩砂搬运距离、作用时间增加goodfairpoor陆棚沉积作用由波浪、潮流、风驱动水流等介质搬运和改造与水深有关MODELPREDICTIONOFSHELFSEDIMENTS千年尺度里陆棚陆棚沉积作用与海平面变化

Pastfluctuationsofsealevelhasstrandedcoarsesediment(relictsed.)acrosstheshelfincludingmostareaswhereonlyfinesedimentsaredepositedtoday.残遗沉积物第四纪气候旋回与海平面变化冰期—间冰期气候旋回大陆冰川增长与消融海平面的上升与下降GlaciationanditseffectonpositionofcoastlineGlaciationinQuarternary~120m海岸线变化与海平面变化Iftheworld’sicesheetscontinuetomelt,theoceanswillfloodmanyoftheworld’smajorcitiesinthefuture.FromGoogleEarth陆坡沉积物Slumps,debrisflows,turbiditycurrents陆坡沉积Jobeetal.2011.MarineandPetroleumGeology,28(3):843-860.海底峡谷与海底扇滑动与悬浮泥浆陆坡沉积物的再分配海底峡谷与海底扇陆相/陆棚的沉积近原地沉积底栖/浮游生物沉积浊流与浊积岩

(SUBMARINEAVALANCHES)20ms-1nearGrandBanksIreland粗粒沉积物强底流珊瑚与生物礁Dorschel,B.,Wheeler,A.J.,Monteys,X.,Verbruggen,K.(Eds.),2010.AtlasoftheDeep-WaterSeabed:Ireland.Springer,170pp.大洋沉积类型受控于离陆地的远近、水深、生物作用等PelagicclaysoccurfarfromlandandindeepestwaterGlacialmarinesedimentsoccurinthehighlatitudesCalcareousoozesoccurabovethecalciumcarbonatecompositiondepth/content/106/50.cover-expansionAnderson,J.B.(ed.),1999.AntarcticMarineGeology,298pp.海洋冰川沉积IceRaftingPolarlatitudes,debrisfrommeltingicebergs.Glacialmarinesediment冰携碎屑大洋沉积类型大洋沉积作用-生物软泥与粘土软泥TypeCompositionAtlantic(%)Pacific(%)Indian(%)Global(%)Foram.oozeCarbonate65365447PteropodoozeCarbonate20.1-0.5DiatomoozeSilica7102012RadiolarianoozeSilica-50.53RedclayAluminumsilicate26492538大洋生物沉积作用-钙质软泥foraminifera,coccolithophorescover~47.5%oftheoceanfloorRadiolarian远洋生物沉积作用-硅质软泥主要由硅藻软泥（12%）和放射虫软泥（3%）组成distributionmirrorsregionsofhighproductivitycommonathighlatitudes,andzonesofupwellingradiolarianoozesmorecommoninequatorialregionsDiatomsSize~0.01mm远洋沉积作用-大洋软泥红色或褐色粘土Fine-grained(0.0002–0.0004mm)Quartz,feldspar,kaolinite&chloriteminerals,>70%Terrigenous,wind-bourne,cosmogenoussourceKaoliniteintropical&subtropicalwatersChloriteintemperate&subpolarDominatebelowwaterswithlittleplanktonicproduction海洋中的自生沉积作用Slumps,debrisflows,turbiditycurrentsAuthigenicdepositsarechemicalandbiochemicalprecipitatesthatformontheseafloorandincludeferromanganesenodulesandphosphoriteEvaporiteismainlychemicalsedimentsthatarecomposedofmineralsthatprecipitatedfromsalinesolutionsconcentratedbyevaporation.Evaporitedepositsarecomposeddominantlyofvaryingproportionsofhalite(NaCl),anhydrite(CaSO4)andgypsum(CaSO4.2H2O).Evaporitesmaybeclassifiedaschlorides,sulfatesorcarbonatesonthebasisoftheirchemicalcomposition(Tucker,1991).occurinregionsofenhancedevaporation(e.g.,marginalseas)evaporativeprocessremoveswaterandleavesasaltybrinee.g.,Mediterranean'SalinityCrisis'between5and6millionyearsago

蒸发岩

(SALTDEPOSITS)地中海中新世蒸发岩Afterdryingout,seawaterfromtheAtlanticOceancascadeddownthefaceoftheGibraltarSill,refillingitinabout100years.AnhydriteandstromatolitesofMioceneageindicatethattheMediterraneansea”dried”outbetween5and25millionyearsagoAUTHIGENICDEPOSITSFormedbychemicalorbiochemicalreactionsonoceanfloorNodulesofferromanganese(FeandMn)orphosphorite(P)Concentriclayersofmetaloxidesaccreteonparticlesovermillionsofyears(1-4mmper106y)ContaineconomicallyimportantmetalsCu,Zn,CoandPb(buttooexpensivetoharvest)Originuncertain(biological?)Lowersedimentaryrateand/orhighproductivityareessentialconditionsslopetooceanicbasinFERROMANGANESENODULESFloorofSouthPacificOcean.Nodulesize1-5cmdiametersurficialdepositsofmanganese,iron,copper,cobalt,andnickelbychemicalprocessesinseawateraccumulateonlyinareasoflowsedimentationrate(e.g.,thePacific)developextremelyslowly(1to10mm/millionyears)蛟龙号宇宙沉积COSMOGENOUSSEDIMENTSsedimentsderivedfromextraterrestrialmaterials

includesmicrometeoritesandtektitestektitesresultfromcollisionswithextraterrestrialmaterialsfragmentsofearth'scrustmeltandsprayoutwardfromimpactcratercrustalmaterialre-meltsasitfallsbackthroughtheatmosphereforms'glassy'tektitesCosmogenicSedimentstektites(micrometeorites)玻陨石甲烷水合物

(METHANEHYDRATES)Hydratesstoreimmenseamountsofmethane,withmajorimplicationsforenergyresourcesandclimate,butthenaturalcontrolsonhydratesandtheirimpactsontheenvironmentareverypoorlyunderstoodTheworldwideamountsofcarbonboundingashydratesisconservativelyestimatedtototaltwicetheamountofcarbontobefoundinallknownfossilfuelsonEarth(USGS).Methaneboundinhydratesamountstoapproximately3,000timesthevolumeofmethaneintheatmosphere.可燃冰授课内容前言与研究历史研究方法-样品采集海洋沉积的类型海洋沉积的分布及其成因地质历史中的海洋沉积思考题volcanicejecta0.15wind-blowndust:0.6rivers18.3ice2.0coastalerosion0.25biogenicCaCO3:1.4SiO2:0.49INPUTSOFSEDIMENTINTOTHEOCEAN(109tones/year)现代海洋沉积物的厚度浅水陆棚沉积B.控制河口沉积3种物理过程（河流、潮流和波浪）的变化规律

A.河口沉积示意图

C.河口沉积物粒度和细粒悬浮物浓度的变化规律DalrympleandChoi,2007陆棚河口河流(A)Conceptualsketchesofsedimentsdepositedunderquasi-permanentfair-weatherorswellwaveagitation.(B)Sedimentsdepositedbelowthepermanentlywave-agitatedupperwatercolumnbutwithinthereachofstormwavesandstorm-generatedcurrents(episodicwaveagitation)arecommonlymuddierwithpunctuated,well-washedtempestiteintervalslocallycappedbywaveripples.(C)Sedimentsdepositedbelowthereachoftheeffectiveaveragestormwavebasemightrecordtheeffectsofexceptionalstormeventsintheformofthintempestitesandorhummockycross-stratificationImmenhauser,A.,2009.Estimatingpalaeo-waterdepthfromthephysicalrockrecord.Earth-ScienceReviews,96(1-2):107-139.Thecomplexityofphenomenaduringstormeventscanbe

simplifiedbydistinguishingthreemaincategoriesofphysical

processes:(i)Barometriceffectscausingcoastalwaterset-up;(2)

windeffectsresultinginonshoredirectedwinddriftcurrentsin

surfacewaters,thatarecompensatedbyoffshoredirectedgradient

currentsinbottomwaters;(3)waveeffectsthatmobilizebottom

sedimentandmakesitavailableforlateraltransport.Simplecaseof

onshoreblowingstorm,interactionswithtidesandtheCorioliseffect

notconsidered.Aigner,T.,1985.StormDepositionalSystems:DynamicStratigraphyinModernandAncientShallow-MarineSequences.LectureNotesinEarthSciences3.Springer,Berlin/Heidelberg,174pp.拉波特的模式划分了4个相带，即潮上和潮间带；位于波基面之上浅的潮下带；波基面之下无陆源碎屑物的潮下带，波基面之下有陆源碎屑物（粘土）的潮下带。拉波特(1967,1969)模式WORLDWIDEDISTRIBUTIONOFRECENTSHELFSEDIMENTSCalcareousbiogenicsedimentsdominatetropicalshelvesRiver-suppliedsandsandmudsdominatetemperateshelvesGlacialtillandice-raftedsedimentsdominatepolarshelves60%oftheworld’sshelvesarecoveredwithrelictsedimentsthatwereformedabout15,000yBPunderadifferentenergyregime.冰川/冰筏沉积作用碳酸盐岩陆棚/生物礁Ifinfluxofterrigenoussedimentislowandthewateriswarm,carbonatesedimentsandreefswilldominate.Dinwiddieetal.,2008Dinwiddieetal.,2008stromatolitecorelreefshellbed大洋陆源碎屑沉积RIVERTRANSPORTOFSEDIMENT(units106tons/yr)大洋红色软泥沉积Theratesofsedimentationindeepsea特点：沉积速率低、沉积深度大盛行风与大洋细粒石英沉积的关系风搬运作用大洋海底的生物沉积作用生物软泥的沉积速率ProductivityreproductionofplanktonicorganismsPreservationsilicadissolvesonlyveryslowlycalciumcarbonatevarieswithdepthDilutionbyterrigenoussedimentsRates

arevariable:<1to15mm/1000yrCalciumcarbonatedissolvesbetterincolderwater,inacidicwater,andathigherpressures.Thedissolutionrateofcalciumcarbonateincreasesgreatlybelowthethermocline(lysocline).ThedepthbelowwhichallcalciumcarbonateisdissolvediscalledthecarbonatecompensationdepthorCCD.大洋中碳酸盐岩的溶解作用CCD:carbonatecompensationdepth.Atthisdepth,usuallyabout3,000~4,500meters,therateatwhichcalcareoussedimentsaccumulateequalstherateatwhichthosesedimentsdissolve.Thermocline–温跃层Lysocline–溶跃面CCD-碳酸盐补偿深度全球铁锰结核的分布Therateofsedimentationindeepsea长尺度海洋沉积历史与地质作用Foratimeframeupto100,000,000(108)years,sedimentationcontrolledby:Platetectonicsanditseffectontypeofmargin.Platetectonics&sedimentationonshelfAPASSIVEATLANTIC-TYPEMARGIN(a)TheAtlanticcontinentalmarginofNorthAmericabeganwhentensionbrokethecrustintoaseriesoffault-boundedridgesandbasins.TheriftbasinswerefirstfilledinwithriverdepositsandthenwithshallowmarinedepositsasseawaterfloodedthejuvenileAtlanticbasin.(b)50Maaftertheinitialrifting,subsidenceofthegraniticcrustanddepositionledtothedevelopmentofathickcoverofmarinesedimentarydeposits.Faroffshore,athrivingcoralreefgrewupward,keepingpacewithcrustalsubsidence.(c)Thepresent-daycontinentalmarginoffNewEnglandshowsathick,broadsedimentaryprismthatcompletelyburiestheoffshorereef,whichdiedsometimeduringtheCretaceousperiod.ACTIVE(PACIFIC)TYPEMARGINSubductiontectonicsandsedimentation.(a)Asubductionboundaryincludesthreeprincipalzones:thevolcanicarc,thearc-trenchgap(consistingofasedimentbasinandanaccretionaryprism),andadeep-seatrench.Sedimentisaddedtothearc-trenchintwoways:(1)debriserodedfromthevolcanicarcslumpsorisdumpedbybottomcurrentsintotheoceanbasin;or(2)deep-seadepositsandtrenchsedimentsarescrapedoffthedescendingplateandplasteredontotheaccretionaryprism.(b)Theaccretionaryprismwidenswithtimeasslicesoftrenchturbiditesanddeep-seaoozesareaddedsystematical