Middle-Late Permian mass extinction on land Gregory J. Retallack† Christine A. Metzger Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403-1272, USA Tara Greaver A. Hope Jahren Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA Roger M.H. Smith Department of Karoo Palaeontology, Iziko South African Museum, P.O. Box 61, Cape Town 8000, South Africa Nathan D. Sheldon Department of Geology, Royal Holloway University of London, Egham, Surrey TW20 OEX, England ABSTRACT carbon isotope excursions, which are interpreted report both end-Guadalupian and end-Permian as global perturbations in isotopic composition extinctions among fossil plants and vertebrates The end-Permian mass extinction has been of atmospheric CO2 (Jahren et al., 2001; Berner, on land in Antarctica and South Africa (Fig. 1). envisaged as the nadir of biodiversity decline 2002). The global marine negative δ13C excur- Instead of a 9 m.y. decline in biodiversity on due to increasing volcanic gas emissions over sion at the Permian-Triassic boundary (Baud et land to terminal Permian extinction (Benton et some 9 million years. We propose a different al., 1989) was the fi rst of at least four profound al., 2004; Ward et al., 2005), we demonstrate tempo and mechanism of extinction because we carbon-isotope excursions (Payne et al., 2004) that terrestrial mass extinctions were abrupt, like recognize two separate but geologically abrupt within the fi rst 6 m.y. of the Triassic Period those in the sea at the end of both the Guadalu- mass extinctions on land, one terminating the (time scale of Gradstein et al., 2005). All four pian and Permian. Furthermore, our examination Middle Permian (Guadalupian) at 260.4 Ma excursions have been found on land as well of end-Guadalupian paleosols and paleochan- and a later one ending the Permian Period at (Krull and Retallack, 2000), and confi rm corre- nels in South Africa and Antarctica show strik- 251 Ma. Our evidence comes from new paleo- lation of the Permian-Triassic boundary on land ing similarities, indicative of excursions in soil botanical, paleopedological, and carbon isoto- with the boundary-stratotype marine sequence erosion, stream stability, soil oxidation, mean pic studies of Portal Mountain, Antarctica, and in China (Retallack et al., 2005). By compari- annual temperature, and mean annual precipi- comparable studies in the Karoo Basin, South son, the Late Permian (Lopingian) atmospheric tation. The end-Guadalupian mass extinction Africa. Extinctions have long been apparent carbon dioxide record shows less variability in was followed by landscape destabilization and among marine invertebrates at both the end isotopic composition, with the next oldest car- warm-wet postapocalyptic greenhouse compa- of the Guadalupian and end of the Permian, bon isotopic perturbation some 9 m.y. earlier rable to that already documented for the end- which were also times of warm-wet greenhouse (time scale of Gradstein et al., 2005) at the stra- Permian mass extinction (Retallack et al., 2003, climatic transients, marked soil erosion, tran- totype-marine Guadalupian-Lopingian (Middle- 2005; Ward et al., 2005; Sheldon, 2006). sition from high- to low-sinuosity and braided Late Permian) boundary (Wang et al., 2004). A streams, soil stagnation in wetlands, and pro- carbon isotope excursion at a comparable strati- MATERIALS AND METHODS found negative carbon isotope anomalies. Both graphic position has been found at Graphite mass extinctions may have resulted from cata- Peak in Antarctica (Krull and Retallack, 2000), In November 2003, we measured a strati- strophic methane outbursts to the atmosphere and here we report additional end-Guadalupian graphic section and collected Late Permian fos- from coal intruded by feeder dikes to fl ood carbon isotope excursions at Portal Mountain, sil plants from the east ridge of Portal Mountain, basalts, such as the end-Guadalupian Emei- Antarctica, and near Beaufort West in the Karoo southern Victoria Land, Antarctica (78.10784°S, shan Basalt and end-Permian Siberian Traps. Basin, South Africa. This advance in land-sea 159.29979°E, 2107 m). Samples collected in tin- correlation of the Late Permian has implications foil and plastic bags were analyzed for organic Keywords: Permian, Triassic, extinction, paleo- for understanding Late Permian mass extinc- matter released by HCl and HF digestion, then sol, palynology, vertebrates. tions and environmental changes on land. combusted in sealed tubes with Cu, CuO, and The end-Permian mass extinction was the Ag. Released CO2 was purifi ed cryogenically, INTRODUCTION greatest biotic crisis of the Phanerozoic, but and collected for 13C/12C measurement relative an earlier end-Guadalupian mass extinction of to Vienna Peedee belemnite using an Isoprime Carbon isotope chemostratigraphy is a marine invertebrates was comparable with end- mass spectrometer at Johns Hopkins University. method for international correlation of marked Cretaceous mass extinction in the sea (Stanley South African paleosol data were obtained and Yang, 1994; Wang et al., 2004). With our during November 2001 while examining the †E-mail: [email protected]. new chemostratigraphic correlation, we now Beaufort Group along a transect through the GSA Bulletin; November/December 2006; v. 118; no. 11/12; p. 1398–1411; doi: 10.1130/B26011.1; 10 fi gures; 1 table; Data Repository item 2006216. 1398 For permission to copy, contact [email protected] © 2006 Geological Society of America Middle-Late Permian mass extinction continental ice Drakensberg and Lebombo Groups °S Stormberg Group sea ice Tarkastad Subgroup Beacon Supergroup Beaufort Group paleolatitude 60 Harrismith Cambrian-Ordovician Adelaide Subgroup Senekal Kilburn Dam granitoids Bergville Bloemfontein Precambrian- °S Early Paleozoic Bulwer Allan Hills itude 66 °S Mount Crean Bethulie Portal Mountain McMurdo paleolat Base Carlton Heights Teekloof Pass Lootsberg Pass Graaff Reinet Ross Ice Beaufort West Shelf Modderdrift Ecca paleolatitudeCoalsack 66 Bluff Graphite Peak Group Dwyka paleolatitude 72°S Cape Town Formation South Pole Station other A 500 km B 500 km Figure 1. Localities examined on simplifi ed geological maps of Antarctica (A) and South Africa (B), showing Late Permian paleolatitude. lower Beaufort Group from the Ecca-Beau- Antarctica, show two negative carbon isotopic isotopic composition plotted in Figure 2 all have fort contact near Modderdrift in the Prince anomalies, one of −2.9‰ low in the section and different meter scales, refl ecting variations in − δ13 Albert district to the top of Teekloof Pass in another of 1.1‰ Ckerogen high in the section local subsidence rate, yet the proportional strati- the Fra serburg district (Retallack et al., 2003; (Figs. 2 and 3). The carbon isotopic composition graphic spacing of the carbon isotope anomalies Retallack, 2005a). South African palynologi- of pedogenic carbonate and of therapsid tooth is strikingly similar. This pattern persists through cal data and ranges are from Falcon (1975a, enamel from South Africa also shows two nega- documented increases in sediment accumulation 1975b), Anderson (1977), Stapleton (1978), tive carbon isotope anomalies, one of –7.7‰ rate following the end-Permian mass extinction MacRae (1988), Horowitz (1990), and Steiner in the middle of the sequence and another of in South Africa (Retallack et al., 2003), Antarc- δ13 et al. (2003) and have been updated to current –2.8‰ Capatite high in the sequence (Fig. 2). tica (Retallack and Krull, 1999), and Australia taxonomic usage (for stratigraphic levels, syn- These two anomalies correlate with end-Guada- (Retallack, 1999). Such consistently aligned car- onymies, and taxonomic authorship details, see lupian and end-Permian carbon isotope anoma- bon isotope anomalies may represent a succes- GSA Data Repository item1). South African ver- lies for the following reasons. sion of globally synchronous events unequally tebrate data are from Ward et al. (2005), with End-Guadalupian and end-Permian negative spaced in time and of unequal magnitude. minor corrections for misnumbering and dupli- isotopic anomalies appear to be global (Fig. 2). Local biostratigraphic, pedostratigraphic, and cation of names. South African carbon isotope The end-Permian anomaly is known from 55 sedimentologic evidence from Portal Moun- data are from both organic carbon (Keith, 1969; sites worldwide (tabulated by Retallack and tain in Antarctica also constrains international Faure et al., 1995; MacLeod et al., 2000; Ward Krull, 2006). The end-Guadalupian anomaly is correlation of carbon isotope excursions. Fos- et al., 2005) and from phosphatic tusks of Diict- known from 17 sites worldwide (Table 1). Addi- sil leaves of Glossopteris, and the distinctive odon and Lystrosaurus (Thackeray et al., 1990). tional end-Cisuralian and several Early Trias- chambered root of the same plant named sepa- The tusk data have been replotted with newly sic negative carbon isotope anomalies (265.5, rately as Vertebraria, known to have been extin- determined stratigraphic levels based on sub- 250.5, 247.6, and 245 Ma in Fig. 2) also appear guished at the end of the Permian (Retallack et sequent biostratigraphic refi nement (Rubidge, to be global and may have had similar causes al., 2005), range through to the upper isotopic 1995) and reexamination of museum records and consequences (Payne et al., 2004; Retal- excursion (Fig. 3). The lower isotopic excur- (see GSA Depository item [footnote 1]). lack,