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The Permo - Triassic Mass Extinction Manuel Queisser Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion What happened? Maybe the largest extinction of the Phanerozoic What happened? Maybe the largest extinction of the Phanerozoic 85% of all marine species and 70% of all terrestrial species died out What happened? Maybe the largest extinction of the Phanerozoic 85% of all marine species and 70% of all terrestrial species died out E.g. trilobites, rugose corals, pelycosaurs vanished E.g. brachiopods, ammonoids substantially reduced What happened? 320 Ma ago (late Carboniferous) forests developed - CO2 drawdown (level as high as today) What happened? 320 Ma ago (late Carboniferous) forests developed - CO2 drawdown (level as high as today) Pangea assembled - little volcanic CO2 output What happened? 320 Ma ago (late Carboniferous) forests developed - CO2 drawdown (level as high as today) Pangea assembled - little volcanic CO2 output 4th great glaciation took place What happened? 320 Ma ago (late Carboniferous) forests developed - CO2 drawdown (level as high as today) Pangea assembled - little volcanic CO2 output 4th great glaciation took place However, in Permian warming occured Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion Methods of resolution- Cosmic impact Consistent with abruptness (< 1Ma) Methods of resolution- Cosmic impact Consistent with abruptness (< 1Ma) Iridium findings not convincing enough Methods of resolution- Cosmic impact Consistent with abruptness (< 1Ma) Iridium findings not convincing enough Dust layer could have also been created by volcanism Methods of resolution- Volcanism Volcanism in Siberia (1-3 Mio km3) produced toxicity and enhanced cooling, then caused greenhouse effect Methods of resolution- Volcanism Volcanism in Siberia (1-3 Mio km3) produced toxicity and enhanced cooling, then caused greenhouse effect Characteristic ash layer in South China (shocked quartz, acidic,…) Consistent with drop in 13C relative and O18 Meishan section, south China. Bowring et al. 1998 Methods of resolution- Volcanism Volcanism in Siberia (1-3 Mio km3) produced toxicity and enhanced cooling, then caused greenhouse effect Characteristic ash layer in South China (shocked quartz, acidic,…) Consistent with drop in 13C relative and O18 Kidder & Worlsley, 2004 Methods of resolution- Volcanism critics say this all is not enough to explain the huge 13C drop Could have never triggered a mass extinction on its own Methods of resolution- Formation of Pangea reduced spreading and number of marine provinces (shelves), which regressed species Methods of resolution- Formation of Pangea reduced spreading and number of marine provinces (shelves), which regressed species Explains only marine extinction Methods of resolution- Formation of Pangea reduced spreading and number of marine provinces (shelves), which regressed species Explains only marine extinction Occurred in early/mid Permian, before mass extinction Methods of resolution- Salinity drop First formed by Beurlen in 1956 Methods of resolution- Salinity drop First formed by Beurlen in 1956 Evidence that mainly stenohaline organisms suffered Methods of resolution- Salinity drop First formed by Beurlen in 1956 Evidence that mainly stenohaline organisms suffered Among other reasons: brine-reflux hypothesis: Methods of resolution- Salinity drop First formed by Beurlen in 1956 Evidence that mainly stenohaline organisms suffered Among other reasons: brine-reflux hypothesis: Evaporation deposited dense salt brines that sank to the ocean bottom and left the surface water “salt free” (drinkable) Methods of resolution- Salinity drop First formed by Beurlen in 1956 Evidence that mainly stenohaline organisms suffered Among other reasons: brine-reflux hypothesis: Evaporation deposited dense salt brines that sank to the ocean bottom and left the surface water “salt free” (drinkable) Consistent with a climate warming Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion From icehouse to hothouse All this factors alone seem to be too weak to cause such a devastating event From icehouse to hothouse All this factors alone seem to be too weak to cause such a devastating event System of feedbacks: Theory of D. Kidder and Th. Worsley, Ohio State University Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion From icehouse to hothouse 320 Ma ago (late Carboniferous) forests developed - CO2 drawdown (level as high as today) Pangea assembled - little volcanic CO2 output 4th great glaciation took place From icehouse to hothouse 320 Ma ago (late Carboniferous) forests developed - CO2 drawdown (level as high as today) Pangea assembled - little volcanic CO2 output 4th great glaciation took place Cessation of orogeny lowered silicate weathering - kickoff From icehouse to hothouse In the mid Permian volcanism in Siberia outpoured CO2 Kidder & Worsley, 2004 From icehouse to hothouse In the mid Permian volcanism in Siberia outpoured CO2 Interior of waste Pangea already hot and arid Kidder & Worsley, 2004 From icehouse to hothouse In the mid Permian volcanism in Siberia outpoured CO2 Interior of waste Pangea already hot and arid Now methane hydrates from ocean bottom melted Kidder & Worsley, 2004 From icehouse to hothouse …warming more latent heat transfer warming of high latitudes From icehouse to hothouse …warming more latent heat transfer warming of high latitudes meridional temp. gradient weakened From icehouse to hothouse …warming more latent heat transfer warming of high latitudes meridional temp. gradient weakened less advection and further drying of Pangea From icehouse to hothouse …warming more latent heat transfer warming of high latitudes meridional temp. gradient weakened less advection and further drying of Pangea forests shrink & withdraw to higher latitudes From icehouse to hothouse …warming more latent heat transfer warming of high latitudes meridional temp. gradient weakened less advection and further drying of Pangea forests shrink & withdraw to higher latitudes CO2 burial and weathering decreases, less nutrients for plankton (positive feedback), dead material oxidized, O2 drawdown From icehouse to hothouse The Searing of Pangea: Kidder & Worsley, 2004 From icehouse to hothouse What happened in the oceans? From icehouse to hothouse What happened in the oceans? - like in atmosphere O2 content decreased (anoxia) From icehouse to hothouse What happened in the oceans? - like in atmosphere O2 content decreased (anoxia) – HOW? From icehouse to hothouse …warming ice shields melt From icehouse to hothouse …warming ice shields melt weaken thermohaline circulation From icehouse to hothouse …warming ice shields melt weaken thermohaline circulation cold, O2 rich bottom water substituted by warmer, saline, anoxic water (WSBW), due to enhanced evaporation, possibly released the methane hydrates (another positive feedback) From icehouse to hothouse Kidder & Worsley, 2004 From icehouse to hothouse In late Permian last forests vanished, increased feedbacks (lessened O2) Kidder & Worsley, 2004 From icehouse to hothouse In late Permian last forests vanished, increased feedbacks (lessened O2) CO2 level 8 times of today’s level Kidder & Worsley, 2004 From icehouse to hothouse In late Permian last forests vanished, increased feedbacks (lessened O2) CO2 level 8 times of today’s level Average ocean temp. doubled to 30 deg. C in this model Kidder & Worsley, 2004 Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion Recovery Unusually long (5 Ma) Recovery Unusually long (5 Ma) Possible reasons: - strong system of feedbacks Recovery Unusually long (5 Ma) Possible reasons: - strong system of feedbacks - lots of rotting vegetation – methane Recovery Unusually long (5 Ma) Possible reasons: - strong system of feedbacks - lots of rotting vegetation – methane - interior of Pangea still very hot and arid, no forests – hard to recover Recovery However: moist, warm high latitudes good for chemical weathering and probably the first place for conifers to reconquer Recovery However: moist, warm high latitudes good for chemical weathering and probably the first place for conifers to reconquer atmospheric CO2 decreases, more nutrients available in ocean, increased O2 production and CO2 drawdown by phytoplankton Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Warming Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Warming Siberian trap volcanism Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Warming Siberian trap volcanism More warming Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Warming Siberian trap volcanism More warming Feedbacks lowered O2 in ocean & atmosphere Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Warming Siberian trap volcanism More warming Feedbacks lowered O2 in ocean & atmosphere Pangea bleak, hot and dry, oceans anoxic and warm Rough Summary Pangea assembled, less chemical weathering (less weatherable silicate rock) Warming Siberian trap volcanism More warming Feedbacks lowered O2 in ocean & atmosphere Pangea bleak, hot and dry, oceans anoxic and warm Recovery at higher latitudes by increasing weathering Outline What happened? Methods of resolution A profound theory: From icehouse to hothouse - The extinction process - Recovery - Summary Discussion Discussion Model is consistent with the most of the evidences and possible causes of the extinction (e.g. 13C drop, deep water anoxia, Siberian volcanism) Discussion Model is consistent with the most of the evidences and possible causes of the extinction (e.g. 13C drop, deep water anoxia, Siberian volcanism) There are questions left… Discussion What exactly caused the huge 13C drop? Discussion What exactly caused the huge 13C drop? What is its magnitude? Discussion What exactly caused the huge 13C drop? What is its magnitude? Were the marine and terrestrial extinction cotemporary? Discussion What exactly caused the huge 13C drop? What is its magnitude? Were the marine and terrestrial extinction cotemporary? Was the extinction cotemporary across the planet? Discussion What exactly caused the huge 13C drop? What is its magnitude? Were the marine and terrestrial extinction cotemporary? Was the extinction cotemporary across the planet? When exactly started the extinction (241 – 250 Ma BP)? Discussion Other evidences are contradictory to this model, e.g.: Discussion Extinction was gradually rather than abruptly (Clark et al., 1985 and Magaritz et al., 1988): sections in the Alps show gradual change in the C-13 content of marine organisms across the PTB Discussion Extinction was gradually rather than abruptly (Clark et al., 1985 and Magaritz et al., 1988): sections in the Alps show gradual change in the C-13 content of marine organisms across the PTB to volcanic (or impact?) dust layer Discussion There was no salinity drop but an increase (Bowen in 1968): “salinity level 20% of today’s level” due to large evaporation and deposition Discussion There was no salinity drop but an increase (Bowen in 1968): “salinity level 20% of today’s level” due to large evaporation and deposition to salinity drop proposed by model Discussion There was no salinity drop but an increase (Bowen in 1968): “salinity level 20% of today’s level” due to large evaporation and deposition to salinity drop proposed by model Others (Erwin) say there are no consistent evidences for a salinity change as a cause, because not all stenohaline organisms suffered Discussion There was no global warming but a cooling! Discussion There was no global warming but a cooling! Sedimentary evidences for drying and glaciation, such as dunes, evaporites in mid latitudes and glacial deposits in polar zones, reduced carbonate limestones in tropics due to cooling Discussion There was no global warming but a cooling! Sedimentary evidences for drying and glaciation, such as dunes, evaporites in mid latitudes and glacial deposits in polar zones, reduced carbonate limestones in tropics due to cooling Siberian volcanism could have had a cooling effect (aerosols) instead of warming Discussion Nobody knows for sure the cause(s) for the mass extinction