海洋科學(xué)導(dǎo)論第10講-劉建波-Marine Sedimentology14

《海洋科學(xué)導(dǎo)論》課程安排2-18周力平緒論海洋科學(xué)若干前沿問題2-25陳永順海底地貌形態(tài)與海盆的演化3-4,11楊海軍大氣與海洋/海洋環(huán)流3-18沈興海海水的化學(xué)組成和特性3-25黃寶琦海洋生物圈與海洋生態(tài)系統(tǒng)4-1朱彤海-氣作用及化學(xué)過程4-8劉建波海洋沉積4-15胡敏海洋環(huán)境……辦公室：逸夫二樓3423室電話：59684E-mail:jbliu@第八講海洋沉積學(xué)劉建波地球與空間科學(xué)學(xué)院海洋科學(xué)導(dǎo)論(12638010)jbliu@授課內(nèi)容前言與研究歷史研究方法-樣品采集海洋沉積的類型海洋沉積的分布及其成因地質(zhì)歷史中的海洋沉積思考題海洋沉積學(xué)-定義?意義海洋沉積學(xué)是研究現(xiàn)代海底沉積物和沉積巖及其形成作用的科學(xué)，包括沉積物及沉積巖的描述、分類、成因及其解釋研究意義海洋沉積物是生物地球化學(xué)的重要的組成部分海洋沉積物記錄了大量地質(zhì)作用、

海洋和氣候條件的信息與陸地記錄相比，海洋記錄更為完整海洋沉積物具有重大的經(jīng)濟(jì)價(jià)值海洋沉積學(xué)-研究歷史起始于1872－1876年間的“挑戰(zhàn)者”號(hào)遠(yuǎn)洋考察，而Murray和Renard(1891)發(fā)表的“Deep-SeaDeposits”一書則奠定了現(xiàn)代海洋沉積學(xué)的基礎(chǔ)由美國CoastSurvey(1888)繪制的西北大西洋海底沉積物分布圖

Siliceousshoredepositsandterrigenousclaysandsiltsdominatenearshore,gradingtopteropodand/orglobigerinaoozeandredclaytothedeepAtlantic,withcoralsandsnearsomeCaribbeanislands./history/quotes/soundings/media/bottom.html粒度小，成熟度高海洋沉積學(xué)研究歷史深海沉積機(jī)理研究Kuenen(1950)通過水槽實(shí)驗(yàn)和現(xiàn)代沉積觀察，提出濁流理論，引起了沉積學(xué)理論的重大變革Bouma(1963)建立濁流沉積的標(biāo)準(zhǔn)相模式Heezen等(1966)發(fā)現(xiàn)沿陸坡分布的等深流沉積活動(dòng)的深海！海洋沉積學(xué)研究歷史60年代興起的板塊構(gòu)造理論為海洋沉積學(xué)發(fā)展增添了許多新的內(nèi)容，如不同構(gòu)造下相模式的建立及板塊運(yùn)動(dòng)造成的遠(yuǎn)洋沉積的分布規(guī)律等海洋沉積學(xué)研究歷史“深海鉆探計(jì)劃”(DSDP，1968－1983)、“大洋鉆探計(jì)劃”(ODP，1983-2003)和IODP（2003-2013）使海洋沉積學(xué)研究向地殼更深處擴(kuò)展，在時(shí)間上，可以恢復(fù)數(shù)千萬年的沉積歷史。與其他學(xué)科相互滲透和交叉，出現(xiàn)了一些新的分支學(xué)科，例如比較沉積學(xué)、沉積動(dòng)力學(xué)等。授課內(nèi)容前言與研究歷史研究方法-樣品采集海洋沉積的類型海洋沉積的分布及其成因地質(zhì)歷史中的海洋沉積思考題從洋底獲取沉積物的方法海底拖網(wǎng)Bottomdredge抓斗取樣器Grabsampler從洋底獲取沉積物的方法重力取芯器活塞取芯器沉箱取樣活塞取樣樣品的處理和保存地質(zhì)學(xué)家正在“地球（CHIKYU）”深海鉆探船上檢查采自深海巖心中沉積物粒度和成分的變化規(guī)律以解釋古代環(huán)境和氣候變化歷史蛟龍?zhí)栞d人潛水器大洋一號(hào)科學(xué)考察船授課內(nèi)容前言與研究歷史研究方法-樣品采集海洋沉積的類型海洋沉積的分布及其成因地質(zhì)歷史中的海洋沉積思考題Theoceansaredividedintohorizontallayers,orzones,definedbywatertemperature.LightpenetratestothebaseofthephoticzoneAllaby,M.(Ed.),2009.Oceans:AScientificHistoryofOceansandMarineLife.DiscoveringtheEarth.FactsonFile,208pp.Classificationofmarinesedimentsbasedonlocation(wheresedimentsarefound)濱岸帶陸棚陸坡深海平原淺海沉積物淺海和遠(yuǎn)洋沉積物大洋沉積物CLASSIFICATIONOFMARINESEDIMENTSBASEDUPONMODEOFFORMATIONTerrigenous(陸源沉積)Sandsandmudproducedbyweathering/erosionofrocksonlandBiogenic(生物沉積)CaCO3andSiO2mudsandoozescomposedofhardpartsoforganismsAuthigenic(自生沉積)formedbyprecipitationofmineralsinseawater(Manganese(Mn)andPhosphorus(P)nodules)Volcanogenic(火山)ejectedfromvolcanoes(ash)Cosmogenous(宇宙)piecesofmeteoritesthatsurvivetripthruatmosphereCLASSIFICATIONOFMARINESEDIMENTSDEPENDONTHEGRAINSIZE,SORTING,MATURATION.粘土粉砂砂礫中礫巨礫COMMONCLASTICROCKSconglomeratesandstoneshale尤里斯特隆圖解

HJULSTROM’SDIAGRAMRelationshipbetweengrainsizeandenergyforerosion,transportationanddeposition.Terrigenoussedimentsstronglyreflecttheirsourceandaretransportedtotheseabywind,riversandglaciers.Rateoferosionisimportantindeterminingnatureofsediments.Averagegrainsizereflectstheenergyofthedepositionalenvironment.沉積物粒度增大侵蝕沉積搬運(yùn)水體能量增加沉積物的分選性和磨圓性

SORTING&RONGDING無分選、角礫狀冰川沉積物分選良好、磨圓良好的海灘砂搬運(yùn)距離、作用時(shí)間增加goodfairpoor陸棚沉積作用由波浪、潮流、風(fēng)驅(qū)動(dòng)水流等介質(zhì)搬運(yùn)和改造與水深有關(guān)MODELPREDICTIONOFSHELFSEDIMENTS千年尺度里陸棚陸棚沉積作用與海平面變化

Pastfluctuationsofsealevelhasstrandedcoarsesediment(relictsed.)acrosstheshelfincludingmostareaswhereonlyfinesedimentsaredepositedtoday.殘遺沉積物第四紀(jì)氣候旋回與海平面變化冰期—間冰期氣候旋回大陸冰川增長與消融海平面的上升與下降GlaciationanditseffectonpositionofcoastlineGlaciationinQuarternary~120m海岸線變化與海平面變化Iftheworld’sicesheetscontinuetomelt,theoceanswillfloodmanyoftheworld’smajorcitiesinthefuture.FromGoogleEarth陸坡沉積物Slumps,debrisflows,turbiditycurrents陸坡沉積Jobeetal.2011.MarineandPetroleumGeology,28(3):843-860.海底峽谷與海底扇滑動(dòng)與懸浮泥漿陸坡沉積物的再分配海底峽谷與海底扇陸相/陸棚的沉積近原地沉積底棲/浮游生物沉積濁流與濁積巖

(SUBMARINEAVALANCHES)20ms-1nearGrandBanksIreland粗粒沉積物強(qiáng)底流珊瑚與生物礁Dorschel,B.,Wheeler,A.J.,Monteys,X.,Verbruggen,K.(Eds.),2010.AtlasoftheDeep-WaterSeabed:Ireland.Springer,170pp.大洋沉積類型受控于離陸地的遠(yuǎn)近、水深、生物作用等PelagicclaysoccurfarfromlandandindeepestwaterGlacialmarinesedimentsoccurinthehighlatitudesCalcareousoozesoccurabovethecalciumcarbonatecompositiondepth/content/106/50.cover-expansionAnderson,J.B.(ed.),1999.AntarcticMarineGeology,298pp.海洋冰川沉積IceRaftingPolarlatitudes,debrisfrommeltingicebergs.Glacialmarinesediment冰攜碎屑大洋沉積類型大洋沉積作用-生物軟泥與粘土軟泥TypeCompositionAtlantic(%)Pacific(%)Indian(%)Global(%)Foram.oozeCarbonate65365447PteropodoozeCarbonate20.1-0.5DiatomoozeSilica7102012RadiolarianoozeSilica-50.53RedclayAluminumsilicate26492538大洋生物沉積作用-鈣質(zhì)軟泥foraminifera,coccolithophorescover~47.5%oftheoceanfloorRadiolarian遠(yuǎn)洋生物沉積作用-硅質(zhì)軟泥主要由硅藻軟泥（12%）和放射蟲軟泥（3%）組成distributionmirrorsregionsofhighproductivitycommonathighlatitudes,andzonesofupwellingradiolarianoozesmorecommoninequatorialregionsDiatomsSize~0.01mm遠(yuǎn)洋沉積作用-大洋軟泥紅色或褐色粘土Fine-grained(0.0002–0.0004mm)Quartz,feldspar,kaolinite&chloriteminerals,>70%Terrigenous,wind-bourne,cosmogenoussourceKaoliniteintropical&subtropicalwatersChloriteintemperate&subpolarDominatebelowwaterswithlittleplanktonicproduction海洋中的自生沉積作用Slumps,debrisflows,turbiditycurrentsAuthigenicdepositsarechemicalandbiochemicalprecipitatesthatformontheseafloorandincludeferromanganesenodulesandphosphoriteEvaporiteismainlychemicalsedimentsthatarecomposedofmineralsthatprecipitatedfromsalinesolutionsconcentratedbyevaporation.Evaporitedepositsarecomposeddominantlyofvaryingproportionsofhalite(NaCl),anhydrite(CaSO4)andgypsum(CaSO4.2H2O).Evaporitesmaybeclassifiedaschlorides,sulfatesorcarbonatesonthebasisoftheirchemicalcomposition(Tucker,1991).occurinregionsofenhancedevaporation(e.g.,marginalseas)evaporativeprocessremoveswaterandleavesasaltybrinee.g.,Mediterranean'SalinityCrisis'between5and6millionyearsago

蒸發(fā)巖

(SALTDEPOSITS)地中海中新世蒸發(fā)巖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)蛟龍?zhí)栍钪娉练eCOSMOGENOUSSEDIMENTSsedimentsderivedfromextraterrestrialmaterials

includesmicrometeoritesandtektitestektitesresultfromcollisionswithextraterrestrialmaterialsfragmentsofearth'scrustmeltandsprayoutwardfromimpactcratercrustalmaterialre-meltsasitfallsbackthroughtheatmosphereforms'glassy'tektitesCosmogenicSedimentstektites(micrometeorites)玻隕石甲烷水合物

(METHANEHYDRATES)Hydratesstoreimmenseamountsofmethane,withmajorimplicationsforenergyresourcesandclimate,butthenaturalcontrolsonhydratesandtheirimpactsontheenvironmentareverypoorlyunderstoodTheworldwideamountsofcarbonboundingashydratesisconservativelyestimatedtototaltwicetheamountofcarbontobefoundinallknownfossilfuelsonEarth(USGS).Methaneboundinhydratesamountstoapproximately3,000timesthevolumeofmethaneintheatmosphere.可燃冰授課內(nèi)容前言與研究歷史研究方法-樣品采集海洋沉積的類型海洋沉積的分布及其成因地質(zhì)歷史中的海洋沉積思考題volcanicejecta0.15wind-blowndust:0.6rivers18.3ice2.0coastalerosion0.25biogenicCaCO3:1.4SiO2:0.49INPUTSOFSEDIMENTINTOTHEOCEAN(109tones/year)現(xiàn)代海洋沉積物的厚度淺水陸棚沉積B.控制河口沉積3種物理過程（河流、潮流和波浪）的變化規(guī)律

A.河口沉積示意圖

C.河口沉積物粒度和細(xì)粒懸浮物濃度的變化規(guī)律DalrympleandChoi,2007陸棚河口河流(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.拉波特的模式劃分了4個(gè)相帶，即潮上和潮間帶；位于波基面之上淺的潮下帶；波基面之下無陸源碎屑物的潮下帶，波基面之下有陸源碎屑物（粘土）的潮下帶。拉波特(1967,1969)模式WORLDWIDEDISTRIBUTIONOFRECENTSHELFSEDIMENTSCalcareousbiogenicsedimentsdominatetropicalshelvesRiver-suppliedsandsandmudsdominatetemperateshelvesGlacialtillandice-raftedsedimentsdominatepolarshelves60%oftheworld’sshelvesarecoveredwithrelictsedimentsthatwereformedabout15,000yBPunderadifferentenergyregime.冰川/冰筏沉積作用碳酸鹽巖陸棚/生物礁Ifinfluxofterrigenoussedimentislowandthewateriswarm,carbonatesedimentsandreefswilldominate.Dinwiddieetal.,2008Dinwiddieetal.,2008stromatolitecorelreefshellbed大洋陸源碎屑沉積RIVERTRANSPORTOFSEDIMENT(units106tons/yr)大洋紅色軟泥沉積Theratesofsedimentationindeepsea特點(diǎn)：沉積速率低、沉積深度大盛行風(fēng)與大洋細(xì)粒石英沉積的關(guān)系風(fēng)搬運(yùn)作用大洋海底的生物沉積作用生物軟泥的沉積速率ProductivityreproductionofplanktonicorganismsPreservationsilicadissolvesonlyveryslowlycalciumcarbonatevarieswithdepthDilutionbyterrigenoussedimentsRates

arevariable:<1to15mm/1000yrCalciumcarbonatedissolvesbetterincolderwater,inacidicwater,andathigherpressures.Thedissolutionrateofcalciumcarbonateincreasesgreatlybelowthethermocline(lysocline).ThedepthbelowwhichallcalciumcarbonateisdissolvediscalledthecarbonatecompensationdepthorCCD.大洋中碳酸鹽巖的溶解作用CCD:carbonatecompensationdepth.Atthisdepth,usuallyabout3,000~4,500meters,therateatwhichcalcareoussedimentsaccumulateequalstherateatwhichthosesedimentsdissolve.Thermocline–溫躍層Lysocline–溶躍面CCD-碳酸鹽補(bǔ)償深度全球鐵錳結(jié)核的分布Therateofsedimentationindeepsea長尺度海洋沉積歷史與地質(zhì)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