Extinguishing a Permian World

Elke Schneebeli-Hermann Palaeoecology, Department of Physical Geography, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, Netherlands

At the end of the Permian, ca. 252 Ma ago, marine and terrestrial fauna were facing the most extensive mass extinction in Earth history (Raup and Sepkoski, 1982). 80%–95% of all species on Earth, on land and in the oceans, became extinct (Benton et al., 2004) within an estimated time interval of less than 200 k.y. to 700 k.y. (Huang et al., 2011; Shen et al., 2011). Among the prominent Paleozoic animal groups that vanished E

P NITC class Trilobita. The numerous hypotheses about the causes of the mass South China extinction include various environmental changes, mostly related to the SITC emplacement of the Siberian Traps large igneous province. The compila- Tethys Ocean tion of radiometric U/Pb ages for the mass extinction and the Siberian Traps demonstrate a temporal overlap of both events (Svensen et al., E>P 2009). A prominent hypothesis for the mass extinction is an accentuated E

are temperature and humidity i.e., the moisture that is available for plant Land Mountain Tropical semi humid growth, and to a certain extent rainfall patterns. Climate simulations Cold temperate Cool temperate Subtropical arid model the general circulation patterns during Permian–Triassic times. The Warm temperate humid Tropical humid paleogeography was characterized by the supercontinent Pangea extend- ing nearly from pole to pole, with large land masses in the mid-latitudes Figure 1. Permian–Triassic Pangean paleogeography, modifi ed af- of the Northern and Southern Hemispheres, and with the Tethys Ocean in ter Smith et al. (1994). Paleogeographic position of South China and the tropics (e.g., Smith et al., 1994). Climate models and sensitivity experi- Meishan (star). Precipitation/evaporation ratio (P < E, P > E) after ments demonstrated that this paleogeography provided the preconditions Ziegler et al. (2003). Late Permian biomes and northern and southern intertropical convergence zones (NITC, SITC) modifi ed after Kutzbach for a monsoonal circulation with strong seasonality of temperatures and and Ziegler (1993). rainfall on the Tethyan coasts, and distinct northern and southern intertropi- cal convergence zones (Fig. 1) (e.g., Kutzbach and Ziegler, 1993; Parrish, 1993). Moist conditions prevailed in middle and high latitudes and along the genic apatite of tooth enamel is increasing. The oxygen isotope signature of western Pangea coast, contrasting with the year-round arid Pangean tropics. conodont apatite is little affected by post-depositional changes (Joachimski (Kutzbach and Ziegler, 1993; Parrish, 1993). Recent climate modeling for and Buggisch, 2002). New analytical techniques and better understanding the Permian–Triassic scenario tested the impact of rapid temperature change of isotopic changes during diagenesis have revealed the importance of the and showed that shifts in biomes were less pronounced during global warm- conodont paleothermometry for the reconstruction of ancient ocean tem- ing compared to global cooling (Roscher et al., 2011). For the Late Perm- peratures (e.g., Barham et al., 2012; Vennemann et al., 2002). ian oceans, sensitivity experiments with coupled atmosphere-ocean models The work of Joachimski et al. (2012, p. 195 in this issue of Geology)

imply that elevated CO2 levels caused signifi cant temperature increases in uses the conodont paleothermometry to reconstruct ocean temperatures high-latitude sea-surface water masses, leading to reduced global sea-sur- of a tropical site during the largest mass extinction in Earth’s history. One face temperature (SST) gradients (e.g., Kiehl and Shields, 2005). of the best studied Permian–Triassic successions is the Global Boundary A proxy record for ancient SSTs is stable oxygen isotope data of marine Stratotype Section and Point (GSSP) in Meishan, South China. Joachim- biomineralizing fauna. During biomineralization, marine fauna incorporate ski et al. measured the oxygen isotope values of P1 elements of the con- dissolved oxygen into their hard parts (e.g., calcite, aragonite, apatite) in odont genera Clarkina (or Neogondolella) and Hindeodus recovered from or close to isotopic equilibrium with the ambient sea water (Urey, 1947; the Meishan and Shangsi sections, choosing a δ18O value of –1‰ Vienna Epstein et al., 1951). Therefore, geochemical signals preserved in marine standard mean ocean water for their temperature calculation. They demon- invertebrate shells and skeletal parts can be used as a proxy for SST, if the strate that in the Meishan area, SST increased by 1–5 °C, from an average isotope composition of the ambient water is known (although isotope frac- temperature of 22 °C, before the main extinction event. Thereafter, tem- tionation during biomineralization and diagenetic alteration need to be con- peratures remained fairly stable up to the extinction event, where oxygen sidered). Oxygen isotopes measured on unaltered brachiopod shells from isotopes indicate another distinct warming by 5–8 °C, up to SST of 32–35 the Late Permian Bellerophon Formation, and from a single sample from °C in the earliest Triassic. The data of Joachimski et al. are an important the overlaying basal Werfen Formation, in southern Italy were interpreted advance in the discussion of the Permian–Triassic climate change, as they to represent a rise of 6–10 °C of tropical SST (Kearsey et al., 2009 and quantify SST change in a stratigraphically well-constrained framework. references therein). However, the resolution and stratigraphic constraints of The documented oxygen isotope shift (i.e., the warming) coincides with these data are limited. In the search for unaltered archives for oxygen iso- a negative shift in carbon isotope ratios over a period of possibly only tope records for paleotemperature reconstructions, the signifi cance of bio- ~110 k.y. (Shen et al., 2011).

© 2012 Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or [email protected]. GEOLOGY,Geology, March March 2012; 2012 v. 40; no. 3; p. 287–288; doi: 10.1130/focus032012.1. 287

Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/40/3/287/3543910/287.pdf by guest on 23 September 2021 Permian macrofl ora (distribution of biomes) largely support the of diversity gradients: Palaeogeography, Palaeoclimatology, Palaeoecology, general climate zone distribution with strong seasonality for the Late v. 239, p. 374–395, doi:10.1016/j.palaeo.2006.02.003. Epstein, S., Buchsbaum, R., Lowenstam, H., and Urey, H.C., 1951, Carbonate-water Permian, as derived from climate models (Rees et al., 2002). The glob- isotopic temperature scale: Geological Society of America Bulletin, v. 62, ally less-differentiated Early Triassic fl ora were interpreted to indicate no. 4, p. 417–426, doi:10.1130/0016-7606(1951)62[417:CITS]2.0.CO;2. warm-temperate climate up to 70°N (Ziegler et al., 1993). Unfortunately, Hermann, E., Hochuli, P.A., Bucher, H., Brühwiler, T., Hautmann, M., Ware, D., the time constraint of most macrofl oral records to infer detailed climate Weissert, H., Roohi, G., and Yasseen, A., ur-Rehman, K., 2012, Climatic os- evolution is limited by the lack of calibration. Higher chronological reso- cillations at the onset of the Mesozoic inferred from palynological records from the North Indian Margin, Journal of the Geological Society, London, lution is achieved by implementing palynological data. Despite uncertain- doi:10.1144/0016-76492010-130. ties regarding the botanical affi nities of 250 Ma spores and pollen, the Hochuli, P.A., Vigran, J.O., Hermann, E., and Bucher, H., 2010, Multiple cli- approach of distinguishing sporomorphs according to the requirements matic changes around the Permian-Triassic boundary event revealed by an of their parent plants with respect to water availability has been applied expanded palynological record from mid-Norway: Geological Society of America Bulletin, v. 122, p. 884–896, doi:10.1130/B26551.1. successfully to describe relative changes in humidity (e.g., Hochuli et al., Huang, C., Tong, J., Hinnov, L., and Chen, Z.Q., 2011, Did the great dying of life 2010). In Norway, chemostratigraphically calibrated palynological records take 700 k.y.? Evidence from global astronomical correlation of the Permian- indicate a distinct shift from pollen-dominated (conifers and seed ferns) Triassic boundary interval: Geology, v. 39, no. 8, p. 779–782, doi:10.1130/ to spore-dominated (ferns and lycophytes) assemblages across the Perm- G32126.1. Joachimski, M.M., and Buggisch, W., 2002, Conodont apatite δ18O signatures in- ian–Triassic transition. This change has been interpreted as a shift to more dicate climatic cooling as a trigger of the Late Devonian mass extinction: humid conditions in the earliest Triassic (Hochuli et al., 2010). Also, in the Geology, v. 30, p. 711–714, doi:10.1130/0091-7613(2002)030<0711:CAOSIC monsoon-dominated region of the southern subtropics, increasing spore >2.0.CO;2. abundances occur toward the Early Triassic (Hermann et al., 2012). Thus, Joachimski, M.M., Lai, X., Shen, S., Jiang, H., Luo, G., Chen, B., Chen, J., and Sun, Y., 2012, Climate warming in the latest Permian and the Permian– the warming in the latest Permian is associated with changing global and Triassic mass extinction: Geology, v. 40, p. 195–198, doi:10.1130/G32707.1. regional precipitation and evaporation patterns resulting in more humid Kearsey, T., Twitchett, R.J., Price, G.D., and Grimes, S.T., 2009, Isotope excur- conditions in the northern mid-latitudes and southern subtropics. sions and palaeotemperature estimates from the Permian/Triassic boundary The distribution and diversity of ammonoids in space and time, intro- in the Southern Alps (Italy): Palaeogeography, Palaeoclimatology, Palaeo- duced as the latitudinal gradient of generic richness (LGGR), have also ecology, v. 279, p. 29–40, doi:10.1016/j.palaeo.2009.04.015. Kiehl, J.T., and Shields, C.A., 2005, Climate simulation of the latest Permian: been interpreted to refl ect latitudinal SST gradients (Brayard et al., 2006). Implications for mass extinction: Geology, v. 33, p. 757–760, doi:10.1130/ For the earliest Triassic (Griesbachian), the LGGR is very low, which has G21654.1. initially been interpreted as refl ecting a warm equable global climate cor- Kutzbach, J.E., and Ziegler, A.M., 1993, Simulation of Late Permian climate responding to fl at SST gradients. This supports the climate models pre- and biomes with an atmosphere–ocean model: comparisons with observa- tions: Philosophical Transactions of the Royal Society of London, Series B, dicting a lower SST gradient with increased CO2 levels. However, in the v. 341, p. 327–340, doi:10.1098/rstb.1993.0118. earliest Triassic, this approach is limited because the diversity of ammo- Mutti, M., and Weissert, H., 1995, Triassic monsoonal climate and its signature noid communities was also affected by the extinction event. in Ladinian–Carnian carbonate platforms (Southern Alps, Italy): Journal of Evidence for the modeled monsoonal circulation during Permian– Sedimentary Research, v. B65, p. 357–367. Parrish, J.T., 1993, Climate of the Supercontinent Pangea: The Journal of Geol- Triassic times has been inferred from sedimentary records (e.g., Mutti and ogy, v. 101, p. 215–233, doi:10.1086/648217. Weissert, 1995). Widespread redbed deposits are assumed to represent Raup, D.M., and Sepkoski, J.J., 1982, Mass extinctions in the marine fossil re- areas with seasonal rainfall (e.g., Parrish, 1993). For the Late Permian, a cord: Science, v. 215, p. 1501–1503, doi:10.1126/science.215.4539.1501. zone of high evaporation in the tropics can be delineated by mapping the Rees, P.M., Ziegler, A.M., Gibbs, M.T., Kutzbach, J.E., Behling, P.J., and Row- ley, D.B., 2002, Permian phytogeographic patterns and climate data/model global distribution of evaporites, reef carbonate, and coal deposits (Ziegler comparisons: The Journal of Geology, v. 110, p. 1–31, doi:10.1086/324203. et al. 2003) (Fig. 1). Correlation of terrestrial sequences with marine suc- Retallack, G.J., and Krull, E.S., 1999, Landscape ecological shift at the Permian– cessions is hampered by the different biostratigraphic frameworks, but Triassic boundary in Antarctica: Australian Journal of Earth Sciences, v. 46, nevertheless the change from paleosols with coals to paleosols contain- p. 785–812, doi:10.1046/j.1440-0952.1999.00745.x. ing green–red-mottled claystones in Antarctica has been interpreted as a Roscher, M., Stordal, F., and Svensen, H., 2011, The effect of global warming and global cooling on the distribution of the latest Permian climate zones: change from a dryer, cooler climate in the Late Permian to more humid, Palaeogeography, Palaeoclimatology, Palaeoecology, v. 309, p. 186–200, warmer conditions in the Early Triassic (Retallack and Krull, 1999). doi:10.1016/j.palaeo.2011.05.042. In summary, the data of Joachimski et al. show that in the tropics, Shen, S.Z., and 21 others, 2011, Calibrating the end-Permian mass extinction: SST started to increase in the latest Permian prior to the main extinction Science, v. 334, p. 1367–1372, doi:10.1126/science.1213454. Smith, A.G., Smith, D.G., and Funnell, B.M., 1994, Atlas of Mesozoic and Ceno- event, continued increasing during the extinction into the earliest Trias- zoic Coastlines: Cambridge, UK, Cambridge University Press, 109 p. sic, and may have reached values of >32 °C. Additional paleotemperature Svensen, H., Planke, S., Polozov, A.G., Schmidbauer, N., Corfu, F., Podladchikov, records of comparable quality are now needed from less-condensed suc- Y.Y., and Jamtveit, B., 2009, Siberian gas venting and the end-Permian en- cessions (i.e., with higher stratigraphic resolution) to enable us to further vironmental crisis: Earth and Planetary Science Letters, v. 277, p. 490–500, doi:10.1016/j.epsl.2008.11.015. disentangle biotic and abiotic events around the Permian–Triassic bound- Urey, H.C., 1947, The thermodynamic properties of isotopic substances: Journal ary. Furthermore, paleotemperature data from other proxies may in turn of the Chemical Society, v. 1947, p. 562–581. strengthen the use of conodont paleothermometry in Permian to Triassic Vennemann, T.W., Fricke, H.C., Blake, R.E., O’Neil, J.R., and Colman, A., 2002, climate reconstructions. Oxygen isotope analysis of phosphates: a comparison of techniques for analysis of Ag3PO4: Chemical Geology, v. 185, p. 321–336, doi:10.1016/ S0009-2541(01)00413-2. REFERENCES CITED Ziegler, A.M., Eshel, G., Rees, P.M., Rothfus, T.A., Rowley, D.B., and Sunderlin, Benton, M.J., Tverdokhlebov, V.P., and Surkov, M.V., 2004, Ecosystem remodel- D., 2003, Tracing the tropics across land and sea: Permian to present: Le- ling among vertebrates at the Permian–Triassic boundary in Russia: Nature, thaia, v. 36, p. 227–254, doi:10.1080/00241160310004657. v. 432, p. 97–100, doi:10.1038/nature02950. Ziegler, A.M., Parrish, M., Yao, J., Gyllenhaal, E.D., Rowley, D.B., Parrish, J.T., Barham, M., Joachimski, M.M., Murray, J., and Williams, D.M., 2012, Diagenetic Nie, S., Bekker, A., and Hulver, M.L., 1993, Early Mesozoic phytogeogra- alteration of the structure and δ18O signature of Palaeozoic fi sh and conodont phy and climate: Philosophical Transactions of the Royal Society of Lon- apatite: Potential use for corrected isotope signatures in palaeoenvironmental don, Series B, v. 341, p. 297–305, doi:10.1098/rstb.1993.0115. interpretation: Chemical Geology, doi:10.1016/j.chemgeo.2011.12.026. Brayard, A., Bucher, H., Escarguel, G., Fluteau, F., Bourquin, S., and Galfetti, T., 2006, The Early Triassic ammonoid recovery: Paleoclimatic signifi cance Printed in USA

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