MIT OpenCourseWare http://ocw.mit.edu 12.007 Geobiology Spring 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. Geobiology 2009 Lectures 17& 18 Mass Extinctions in the Geological Record Carbon Cycle Dynamics and Importance of Timescales virtually all mass extinctions are accompanied by carbon isotopic ‘excursions’ or anomalies indicating disruption of the biogeochemical carbon cycle. An extinction at the Precambrian-Cambrian Boundary??? Biocomplexity was not fully developed so, although the Cambrian Radiation is undisputed, the existence of an extinction beforehand is The Devonian Event (Frasnian-Famennian) in passing The Permian Triassic Boundary (PTB) C-isotopic anomalies, possible mechanisms of extinction The Paleocene Eocene Boundary (PEB) or Late Paleocene Thermal Maximum C-isotopic anomalies, evidence for temperature changes, extinction The K-T Extinction (Cretaceous Boundary Event) An impact-related phenomenon?? Readings and Sources • A. D. Anbar A. H. Knoll, Proterozoic Ocean Chemistry and Evolution: A Bioinorganic Bridge? Science 2002:Vol. 297, 1137 - 1142 • Erwin D.H. (1994) The Permo-Triassic Extinction Nature 367, 231-236 • A.H. Knoll, R. K. Bambach, D. E. Canfield, J. P. Grotzinger (1996) Comparative Earth History and Late Permian Mass Extinction Science 273, 455. • Erwin D.H. (1996) The Mother of Mass Extinctions Scientific American 275, 72-78. • Erwin D.H. (2006) Extinction, Princeton Other Readings and Sources • Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia L. Becker, R. J. Poreda, A. R. Basu, K. O. Pope, T. M. Harrison, C. Nicholson, and R. Iasky Science 4 June 2004; 304: 1469-1476; published online 13 May 2004 • Photic Zone Euxinia During the Permian-Triassic Superanoxic Event Kliti Grice, Changqun Cao, Gordon D. Love, Michael E. Böttcher, Richard J. Twitchett, Emmanuelle Grosjean, Roger E. Summons, Steven C. Turgeon, William Dunning, and Yugan Jin Science 4 February 2005; 307: 706-709; published online 20 January 2005 • Cao C., Love G.D., Hays L.E., Wang W., Shen S. and Summons R.E., 2009. Biogeochemical Evidence for a Euxinic Ocean and Ecological Disturbance Presaging the end-Permian Mass Extinction Event. Earth and Planetary Science Letters 288, 188-201. Need to Know • Nature of evidence for mass extinctions • Names and ages of five mass extinctions – Importance of geochronology • Which ones attributed to ‘extraterrestrial’ causes and why • Those which are matched to geobiological hypotheses – Types of geobiological evidence (isotopes, evidence of oceanic euxinia, climate change and the characteristics of these at events) Major Divisions of Earth History I II III Earth’s Surface Archean Proterozoic Phanerozoic pO < 0.002 pO2 > 0.03 Redox vs Time 2 pO2 > 0.2 bar bar bar ferrous sulfidic oxic oceans oceans oceans Later Snowball Episodes cyano- Earlier Snowball Episodes algae, complex Solar System Formation bacteria protists animals Late Heavy Bombardment & plants 5.0 4.0 3.0 2.0 1.0 0.0 Figure by MIT OpenCourseWare. Intervals between Redox stages marked by putative Snowball Image removed due to copyright restrictions. Episodes and Extreme Isotopic Please see Fig. 2 in Shields, Graham, and Veizer, Ján. “Precambrian Marine Carbonate Excursions Isotope Database: Version 1.1.” Geochemistry Geophysics Geosystems 3 (June 6, 2002): 12 pages. Anbar and Knoll, 2002 Text removed due to copyright restrictions. Please see Abstract in Anbar, A. D., and Knoll, A. H. “Proterozoic Ocean Chemistry and Evolution: A Bioinorganic Bridge?” Science 297 (August 16, 2002): 1137-1142. d13C (VPDB) Seawater proxy d13C -10 -5 0 5 10 carb 1000 531 850-530 Ma U-Pb ages Morocco Arthropods Global Compilation of Late Cambrian (Ma) Adoudounian Formation Magaritz et al. (1991) Neoproterozoic Carbon 0 Vendian 543.3 + _ 1 A.C. Maloof (unpubl.) Isotope Excursions and their 545.1 + _ 1 Siberia Relationships to Glaciations Ediacara Turkut Formation _ 548.1 + 1 Bartley et al. (1998) Namibia Varanger Glaciation 580? Nama Group Saylor et al. (1998) Australia Wonoka Formation Spiny plankton Calver (2000) Oman Huqf Group - Shuram Fm Burns and Matter (1993) Namibia Marinion Glaciation 650 Otavi Group Halverson and Hoffman (2003) Stratigraphic thickness Namibia Sturtian Glaciation Gariep Group _ 746 + 2 " 758 + _ 4 Folling and Frimmel (2002) (common scale except arbitrary for glaciation) Svaibard Akademikerbreen Group Halverson (2003) Australia 827 + _ 6 Bitter Springs Formation Hill and Walter (2000) Compilation modified from -10 -5 0 5 10 Halverson (2003: in prep.) Figure by MIT OpenCourseWare. Carbon Reservoirs, Fluxes and Residence Times Species Amount Residence Time (yr)* δ 13 C 18 (in units of 10 gC) %o PDB** Sedimentary carbonate-C 62400 342000000 ∼ 0 Sedimentary organic-C 15600 342000000 ∼ -24 Oceanic inorganic-C 42 385 ∼ +0.46 Necrotic-C 4.0 20-40 ∼ -27 Atmospheric-CO2 0.72 4 ∼ -7.5 Living terrestrial biomass 0.56 16 ∼ -27 Living marine biomass 0.007 0.1 ∼ -22 Nemotodes most abundant Summary of Animal Phylogeny animals Ecdysomes- most diversity Individual body plans Protostomes Bilateral symmetry, Organs Tissues Deuterostomes Animal multicellularity more compl. jelly tissues, not organs Radial symmetry 2layers with jelly Monophyletic= ‘sister’ to everything single common ancestor fungi ‘animal protist’ single cell 0 40 80 489.0 +_ 1.0 Ma 490 491.0 +_ 1.0 Ma Temporal Late 500 Orders Constraints for Middle Burgess shale fauna 510 510.0 +_ 1.0 Ma Neoproterozoic­ Botomian 522.0 +_ 1.0 Ma Classes 520 Cambrian Atdabanian First Cambrian history trilobites Tommotian Early 530 531.0 +_ 1.0 Ma Nemakit- Treptichnus pedum 540 Daldynian -542.0 543.0 _ 1.0 Ma + Ma Namacalathus Shelly fossils ? and Cloudina 550 Is the base of the 555.0 +_ 0.3 Ma Kimberella 560 565.0 +_ 3.0 Ma Cambrian an 570 Doushantuo Fm. embryos (570 Ma?) 575.4 +_ 0.4 Ma Assemblage Ediacaran extinction event?? Neoproterozoic III Millions of Years Before Present Years Millions of _ 580 580.7 + 0.7 Ma Gaskiers glaciation 590 600 610 Cryogenian 620 -5 0 5 Figure by MIT OpenCourseWare. Namacalathus: more skeletal diversity in terminal Proterozoic reefs. Image removed due to copyright restrictions. Please see Fig. 8a in Grotzinger, John P., et al. “Calcified Metazoans in Thrombolite- Stromatolite of the Terminal Proterozoic Nama Group, Namibia.” Paleobiology 26 (September 2000): 334-359. Models of Namacalathus morphology, based on serial sections through rocks. Living scyphopolyps Image removed due to copyright restrictions. (cnidarians) for comparison. Please see Fig. 10 in Grotzinger, John P., et al. “Calcified Metazoans in Thrombolite- Stromatolite Reefs of the Terminal Proterozoic Nama Group, Namibia.” Paleobiology 26 (September 2000): 334-359. Precambrian-Cambrian Boundary Extinction ? Image removed due to copyright restrictions. Please see Fig. 5 in Knoll, Andrew H., et al. “Early Animal Evolution: Emerging Views from Comparative Biology and Geology.” Science 284 (June 25, 1999): 2129-2137. Image removed due to copyright restrictions. Please see Fig. 4.1-1 in Global Biodiversity Assessment. Dowdeswell, Elizabeth, and Heywood, Vernon H., ed. Cambridge, England: Cambridge University Press, 1996. ISBN: 0521564816. Permo-Triassic Boundary zWhere is it and how is it defined? z Marine extinctions observed worldwide in the Upper Permian (Changhsingian) z Base Triassic (Griesbachian) defined at the Global Stratotype, Section and Point , Meishan, China at the first appearance of a specific marine taxon, the conodont Hindeodus parvus zFloral extinction: well defined ‘coal gap’ in terrestrial sediments worldwide z eg demise of Glossopteris flora in Australia z No precisely agreed way to correlate marine and terrestrial sections and an absence of sufficiently accurate geochronology z Terrestrial faunal extinction (eg Ward et al, Science 2005) Composite δ13C & Diversity Profiles Payne et al. Science 305, 506 (2004) Image removed due to copyright restrictions. Characteristics of Permian-Triassic Event • Global regression of seal level; aggregation of supercontinent of Pangea; rarity of continuous sedimentation • Massive volcanism and emplacement of Large Igneous Provinces (LIPS) – 400 to 3700m thick basalts over ca 5 Ma • Uneven marine extinction; sessile animals worst hit and a terrestrial extinction as well • Immediate radiation of different physiological groups (disaster species??) than before and then stabilization of the classic Mesozoic fauna and flora. • More complex and sophisticated ecosystems; new insects like today’s and evidence of metabolic versatility eg Claraia which apparently could survive low pO2. Frequently used decay schemes; half-lives vary by a factor of > 100 238U Æ 206Pb 4.5 x 109 235U Æ 207Pb 0.71 x 109 40K Æ 40Ar 1.25 x 109 87Rb Æ 87Sr 47 x 109 147Sm Æ 144Nd 106 x 109 Courtesy of USGS. http://volcano.und.nodak.edu/vwdocs/volc_ images/north_americaZircons:/ washington.ht mlNature’s Acasta:Time Worlds Capsules oldest rock: (Ages in My) Images removed due to copyright restrictions. Boundary Clay Bed 25 251-4 Ma (Bowring et al, 1998) Zone of volcanic microspherules Image and text removed due to copyright restrictions. Please see Fig. 4 and the final paragraph in Jin, Y. G., et al. “Pattern of Marine Mass Extinction near the Permian-Triassic Boundary in South China.” Science 289 (July 21, 2000): 432-436. Image and text removed due to copyright restrictions. Please see Abstract and Fig. 1 in Mundil, Roland, et al. “Age and Timing of the Permian Mass Extinctions: U/Pb Dating of Closed-System