oceanography - smc faculty home pages · • the ac7on of acids “corrodes” rocks and turns them...
TRANSCRIPT
![Page 1: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/1.jpg)
OCEANOGRAPHY
4.MarineSediments-part1
notesfromtextbook,integratedwithoriginalcontribu7ons
AlessandroGrippo,Ph.D.
DredgingoftheharborchannelinMarinadelRey,CA,2012©AlessandroGrippo
![Page 2: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/2.jpg)
ChapterOverview
• MarinesedimentscontainarecordofEarthhistory
• Marinesedimentsprovideavarietyofimportantresources
• Marinesedimentshaveavarietyoforigins
![Page 3: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/3.jpg)
whataresediments?
• therearethreekindofrocks– igneous(fromcoolingofmagma
orlava)– metamorphic(fromexposureto
hightemperaturesand/orpressures)
– sedimentary(fromcementa7onofrockfragmentsand/orprecipita7onfromasolu7on)
• allrockscanbeweathered,producingsediments– mechanicalweathering– chemicalweathering
![Page 4: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/4.jpg)
mechanicalweathering– allphysicalprocessesthatbreakdownrocksinsmallerfragments
– fragmentsareiden7fiedbytheirsizeasgravel,sand,silt,andclay(siltandclaytogetheraredefinedasmud)
![Page 5: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/5.jpg)
chemicalweathering:ac7onofoxygen
• allchemicalprocessesthatchangethecomposi7onofrocks
• twoagents:oxygenandacids
• theac7onofoxygenintheatmosphereandinwatercausesironmineralspresentinrocksto“rust”(ironoxides)
• 4Fe+3O2!2Fe2O3(hema7te)
![Page 6: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/6.jpg)
chemicalweathering:ac7onofacids
• theac7onofacids“corrodes”rocksandturnsthemintoquartz,clayminerals,andionsinsolu7on
• Quartz– averycommon,resistantmineral– typicalcomponentofsandatthebeach
• ClayMinerals– averycommonbyproductofweathering– havespecialproper7es:theyareflat,theyabsorbwaterand
ions,they“swell”,• IonsinsoluKon
– anythingmineralthatcanbedissolvedinwater(Ca2+,Mg2+,Fe2+,Na+,K+,CO3
2-,etc.)
![Page 7: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/7.jpg)
whatisnext?
• nowwehaveabunchofloosefragmentsatearth’ssurface,andionsinsolu7on
• theyarepickedup(eroded),movedaround(transported)andrese\ledsomewhereelse(deposi7on)by:– water(rivers)– wind– glaciers– directlybyrockfall/landslides
![Page 8: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/8.jpg)
sand is picked up
then it is moved aroundby rivers, wind, waves;
it gets more weathered
it is then deposited(but it can also be picked up again)
it will get finally buriedby more recent sediment
the weight compacts the sand
water enters the pores
ions in solution are released (cement),turning the sand into a sandstone
EXAMPLEerosion
transportation
deposition
burialcompactioncementation
(lithification)}
![Page 9: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/9.jpg)
andwhataboutionsinsolu7on?
• theyneedto“stayhydrated”(ionssurroundedbywatermolecules)
• ifthereisnotenoughwater,ionscrystallizeandformrocks(orcement,asseenbefore)
• maintypes:– carbonates(mostcommontype;limestone)– siliceousrocks(richinsilica;chert)– evaporites(formindryenvironments–notintheocean;halite,orrocksalt,gypsum)
![Page 10: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/10.jpg)
MarineSediments• Intheend,manysedimentsareproducedonland
(lithogenoussediments)
• Whilesomeofthesearedepositedonland,mostarecarriedtotheocean(marinesediments)
• Someothertypesofsediments(biogenousandhydrogenous)areproduceddirectlyintheocean
• Whatevertypeofsedimentreachesorisproducedintheoceanwouldeventuallyse\lethroughthewatercolumn
• OceanographersdecipherEarthhistorythroughstudyingsediments
![Page 11: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/11.jpg)
4.1–HowAreMarineSedimentsCollected,andWhatHistoricalEventsDoTheyReveal?
• Marinesedimentsoftodaycanbecollecteddirectlyfromtheoceanbo\om– difficulttogetto
• Marinesedimentsofthepastthathaveturnedintosedimentaryrockscanbefoundinlandoutcrops– easiertogettobutsca\eredsamples
![Page 12: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/12.jpg)
collec7ngMarineSediments
• dredge• gravitycorer• rotarydrilling– NSFfundedaprogramforborrowingdrillingtechnologiesfromtheindustry
– Fouroceanographicins7tu7ons(Scripps,Rosens7el,WoodsHole,Lamont-Doherty)unitedtoformJOIDES(JointOceanographicIns7tu7onsforDeepEarthSampling)
– OtherschoolslaterjoinedJOIDES
![Page 13: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/13.jpg)
collec7ngMarineSediments
• JOIDESprograms– DSDP(DeepSeaDrillingProject)
• 1966,GlomarChallenger,sampledto6000mofdepth• evidenceofspreading(ageofsediment,thicknessofsediments,magne7creversals)
– ODP(OceanDrillingProgram)• 1975,1983becameinterna7onal,underTexasA&M• broaderobjec7veofdrillingclosetoshelf• in1985,JOIDESResolu7onreplacedGlomarChallenger• newshipcandrillupto2100mbelowseafloor
![Page 14: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/14.jpg)
GlomarChallenger&JOIDESResolu7on
• IODP(IntegratedOceanDrillingProgram)– 2003,thenin2013asIntegratedOceanDiscoveryProgram– mul7plevessels,includingChikyu– collec7onofsedimentscoresfromallovertheworld
![Page 15: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/15.jpg)
Chikyu
• “PlanetEarth”• howdowedrill– (www.youtube.com/watch?v=yuu0QcnOVbo)
![Page 16: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/16.jpg)
ThedrillingsystemofChikyu
![Page 17: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/17.jpg)
Upperler:drillingpipesonthedeckofJOIDESResolu7on
Upperright:diamonddrillingbit(adrillingbitwouldnotgiveusacore,butrather“rockcusngs’,orfragments
Bo\omler:analysisofhalvedcoresonboardtheJOIDESResolu7on
![Page 18: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/18.jpg)
EnvironmentalCondi7onsRevealedbyMarineSediments
• MarineSedimentspreservematerialsthatexistedintheoverlyingwatercolumns
• Thesematerialsarefunc7onofthecondi7onsoftheenvironment
• Analysisofcoresprovidesuswithinfoabout:– ancientseasurfacetemperature– abundanceofmarinelifeandmajorex7nc7onevents– atmosphericwindsandvolcanicerup7ons– oceancurrentpa\ernsandchangesinEarth’sclimate– movementoftectonicplates
![Page 19: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/19.jpg)
Paleoceanography
• Thestudyofhowocean,atmosphere,andlandinterac7onshaveproducedchangesinoceanchemistry,circula7on,biology,andclimate
• Marinesedimentsprovidecluestopastchanges
![Page 20: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/20.jpg)
Marinesedimentsalsoexistonland:turnedintorocks,andbroughtabovesealevelbyplatetectonics
TheseareturbiditesfromtheGreatFallsoftheMissouri,bythecityofGreatFalls,Montana(atthisloca7ontheexplorerLewisandClarkcouldnotproceedanyfurtherontheriver,andhadtostarttheirportageontheGreatPlains)
©AlessandroGrippo
![Page 21: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/21.jpg)
MarineSedimentClassificaKon
• Classifiedbyorigin– Lithogenous–derivedfromland(lithos=rock)
• gravel,sand,silt,clay• ionsinsolu7on
– Biogenous–derivedfromorganisms• shells,reefs,animalandalgalstructures
– HydrogenousorAuthigenic–derivedfromwater• formingchemicallyintheocean
– Cosmogenous–derivedfromouterspace• cosmic“dust”
![Page 22: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/22.jpg)
4.2–WhatAretheCharacterisKcsofLithogenousSediment?
• Erodedrockfragmentsfromland• Alsocalledterrigenous• Reflectcomposi7onofrockfromwhichderived• Producedbyweathering
– Breakingofrocksintosmallerpieces
![Page 23: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/23.jpg)
• Par7clesareeroded,transported,deposited• Carriedtowardstheoceanby:
– Streams,Wind,Glaciers,Gravity
• Greatestquan7tyfoundaroundcon7nentalmargins– mostlyonshelves– alsoincon7nentalrisesortrenches
![Page 24: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/24.jpg)
Composi7onandTexture• Reflectcomposi7onofrockfromwhichderived• Coarsersedimentsclosertoshore• Finersedimentsfartherfromshore• Mainlymineralquartz(SiO2)
![Page 25: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/25.jpg)
• Grainsizepropor7onaltoenergyintheenvironmentofdeposi7on
• Grainsizesor7ng– Indica7onofselec7vityoftransporta7onanddeposi7onprocesses
• Texturalmaturity– Increasingmaturityif
• Claycontentdecreases• Sor7ngincreases• Non-quartzmineralsdecrease• Grainsaremorerounded(abraded)
![Page 26: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/26.jpg)
Wheredowefindthesesedimentsinouroceans?
• Marinesedimentarydepositscanbefoundinvirtuallyallplacesontheoceanfloor,evenifsome7mesinveryminorpercentages.
• Thecanbecategorizedaseitherneri7corpelagic
• NeriKcDepositsarearefoundoncon7nentalshelvesandinshallowwatersaroundislands– usuallycoarse-grained(sands)
• PelagicDepositsarefoundindeep-oceanbasins– usuallyfine-grained(siltsandclays)
![Page 27: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/27.jpg)
Neri7cDeposits• Beachdeposits– Grainsofallkindsbroughttothecoastbyrivers– Weatheringslowlymodifiesgraincomposi7onintoquartz-richsands
– Wavemo7oncausestransporta7on
SloughandbeachinGoleta,CA
©AlessandroGrippo
![Page 28: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/28.jpg)
• Con7nentalshelfdeposits– Relictsediments:leroverasunderwaterformerbeachsediment
– formedduringthelast(oranyprevious)iceagepeak,thenfloodedduringtheinterglacial
– some7messhowingabovesealevelasbarrierislands
![Page 29: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/29.jpg)
• Turbiditedeposits– SandsandmudsinCon7nentalRise– Gradedbedding
• Glacialdeposits– Highla7tudecon7nentalshelf– Currentlyformingbyiceraring(icebergscarryingrocksintoocean,calleddropstones)
![Page 30: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/30.jpg)
Above:anicebergcarryingsedimenttotheoceaninPortageLake,ChugachNa7onalForest,ChugachMountains,Alaska.Photo©USGS
Right:adropstoneincross-sec7onalview,NamibiaPhoto©DavidL.Reid
bothimagesfrom:h\p://serc.carleton.edu/NAGTWorkshops/sedimentary/images/dropstones.html
![Page 31: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/31.jpg)
PelagicDeposits
• Fine-grainedmaterial• Accumulatesslowlyondeepoceanfloor• Pelagiclithogenoussedimentfrom
– Volcanicash(volcanicerup7ons)– Wind-blowndust– Fine-grainedmaterialtransportedbydeep
oceancurrents
• AbyssalClay– Atleast70%claysizedpar7clesfrom
con7nents– Redfromoxidizediron(Fe)– Abundantifothersedimentsabsent
Rhythmicalterna7onsofdeep-marine(pelagic)biogenous(whitelimestones)andterrigenous(redabyssalclays)sediments
MidCretaceousPiobbicoCore,Pesaro-Urbino,Italy
©AlessandroGrippo
![Page 32: OCEANOGRAPHY - SMC Faculty Home Pages · • the ac7on of acids “corrodes” rocks and turns them into quartz, clay minerals, and ions in solu7on • Quartz – a very common, resistant](https://reader033.vdocument.in/reader033/viewer/2022060302/5f0898c87e708231d422cb4d/html5/thumbnails/32.jpg)
• endofpart1