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FLOODBASALTSorLARGEIGNEOUSPROVINCES(LIP)(ArmageddonVolcanoes?)

Civilizationlivesbygeologicalconsent,subjecttochangewithoutnotice.WillDurant,1946

Therearebothcontinental(yellow)andoceanic(orange)floodbasaltprovincesTheyarecharacterizedby: Hugevolumes Thickpilesofflows Relativelyshortduration(16Ma) ClosesthistoricaleruptionistheLaki eruption,Iceland(1783)

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SiberianFloodBasalts

FaroeIslands NorthAtlanticFloodBasalts

Greenland NorthAtlanticFloodBasalts

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EasternGreenland NorthAtlanticFloodBasalts

HowaretheyFormed?

Meteorite or Comet impact.

Melting the head of mantle plumes.

De-lamination of the lithosphere.

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ThePlumeModel

ManyFloodBasaltsareassociatedwithcontinentalbreakupandtheformationofvolcaniccontinentalmargins

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TheDeccanFloodbasaltsandReunionhotspottail

WherearethefloodbasaltsassociatedwiththeHawaiiantail?

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TheColumbiaRiverBasalts

Ginko overGrandeRondeBasaltsinPalouseCanyon

Vastpilesofthick(20 100m)lavaflows,someofwhichareupto600kminlength.

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Stratigraphy,AgeandVolumeoftheColumbiaRiverBasaltsTotalVolume=174,400Km3

Over90%eruptedwithin

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Typicalcolumnarjointinginaflow

Pillowbasaltsandpalagonite atthebaseofaflow

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ComparisonofRozawithothernormalflows

1. Kupainaha Flows,Kilauea 0.5km3 in5.6yrs =25m3/sec

2. MaunaLoa,1859 0.27km3 in10months=4m3/sec

3. Laki 1783,Iceland 14.7km3 in9months=709m3/sec

4. Roza Flow(CRB) 1300km3 in6 14yrs 2600 8100m3/sec

EstimatesofthetimetakentoeruptColumbiaRiverBasaltflows

Swansonsuggeststhe1300km3 Roza flowwasemplacedin7days! HoandCashmanestimatethe500kmlongGinko flowwasalsoemplacedin7days. Reidel estimatesmonthsforthePomonaflow. Selfetal.(basedonworkofMartin)estimate6 14yearsfortheRoza flow.

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GrowthoftheRoza flow(1300km3 )in6to14years

ComparisonofthestructureoftheRoza flowunitwithexamplesfromIcelandandKilauea

VF=VesiclefeaturesJH=Jointingfeatures

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Inflationmodelforthegrowthoffloodbasaltflows(Selfetal.,1997)

AreFloodBasaltsResponsibleforMassExtinctions?IstheMantleaSerialKiller?WhatistheKillMechanism?

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TheGeologicalTimeScale(BreaksbetweenPeriodsandEpochsbasedonmajor

changesinfaunaandflora(extinctions))

Amazingcorrelationbetweenthetimeofmajorextinctionsandtheagesoffloodbasalts.Onlyone knownimpactevent(Chicxulub)atendofCretaceous.

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Correlations,althoughsuggestive,arenot proofTimingisCritical

Problems Needtoknowpreciseageanddurationofextinctions. Needtoknowpreciselywhenandforhowlongfloodbasaltswereerupted.

Dating EarlyK/Ar datingindicatederuptionsover4050Myr. Modern40Ar/39Ardatingnarrowsthisdowntounder2

Myr for80 90%oftheeruptiveevent. NewPb datingofzirconnarrowsthisdownfurtherto

lessthan1Myr.

ExampleofrefiningagesofKarrooFloodBasalts,S.Africa

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EXAMPLE SIBERIANTRAPS

TheendofPermianextinction(90%ofallmarinespeciesandlargestlossoffloralandfaunaldiversityinearthshistory)occurredabout250Myr ago.

EarlyK/Ar datingoftheSiberianTrapsgaveagesfrom235 220Myr.

Conclusion noconnection. Subsequent40Ar/39ArdatingincreasedandrefinedtheagesfortheTrapsto250+/ 1.6Myr.

SmokingGun! New(2013)veryprecisezircondatingshowsthefollowing:1) AgeofendofPermianextinction(Meishan,China)between

251.94and251.88Myr (inotherwordstheextinctionoccurredinlessthan100thousandyears!).

2) Thebeginningoftheeruptionoccurredat252.28Myr (thatis,before theextinctionevent).

CauseandEffect!

TheLakiEruption,Iceland(17831784)

Duration 9months(June February) Volume 14.7km3 Nodirectfatalitiesbutseveralfarms

destroyed 50percentofcattledied 75percentsheep 24percentofentireIcelandpopulation

diedofstarvationandillness

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EffectsonEuropeandNorthAmerica

Dropinwintertemperatureof1 3oC Volcanichaze(VOG)blanketedmuchof

EuropeandnorthernN.America. 40%highermortalityratethanexpectedin

Englandinbothsummerandwinter.

TotalSO2 fromeruption=122MtTotalSO2 inplume=99Mt(81%)TotalSO2 fromflows=23Mt(19%)

EstimatedsulfurreleasefromtheLaki eruption

Amegatonne(Mt)=1millionmetrictons(1000x106 kg)

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ReleaseofSulfurandothergasesduringtheeruptionoftheentireRosaflows(1300km3 )

SO2 HCl HFOriginalamountinMagma(Mt) 13795 1065 4840Amountreleasedlocallybylava(Mt) 2808 307 333Amountreleasedfromvents(Mt) 9617 397 1442Totalamountreleased(Mt) 12425 704 1774

Comparewith122MtofSO2 releasedfromtheLakieruption

PossibleKillMechanisms

VolcanicwinterduetoSO2 gasinvolcanicplumes. GlobalwarmingduetoreleaseofvolcanicCO2. Acidrain(fromSO2,HCl,HF)involcanicplumes. Acidificationandanoxicconditionsoftheoceans(fromSO2,

HCl,HF)involcanicplumes. OzonedestructionduetoreleaseofHCl andHFgases Releaseofmethane(greenhousegas)duetoeruptionof

submarinefloodbasalts MassivereleaseofCO2 (globalwarming)duetocontact

metamorphismofunderlyingcarbonateandcoalsediments. Anoxicconditionsintheoceansduetocontact

metamorphismandassimilationofsaltbeds.

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Twostagedegassingoffloodbasalts:ExamplefromDeccanBasalts(Selfetal.199XXXXX)

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