Downloaded from gsabulletin.gsapubs.org on August 26, 2015 Progressive environmental deterioration in northwestern Pangea leading to the latest Permian extinction Progressive environmental deterioration in northwestern Pangea leading to the latest Permian extinction Stephen E. Grasby1,2,†, Benoit Beauchamp2, David P.G. Bond3, Paul Wignall4, Cristina Talavera5, Jennifer M. Galloway1, Karsten Piepjohn6, Lutz Reinhardt6, and Dierk Blomeier7 1Geological Survey of Canada, Natural Resources Canada, 3303 33rd Street NW, Calgary, Alberta T2L 2A7, Canada 2Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada 3Department of Geography, Environment and Earth Sciences, University of Hull, Hull HU6 7RX, UK 4School of Earth Sciences, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK 5Department of Imaging and Applied Physics, Curtin University, Kent Street, Bentley, WA 6102, Australia 6Bundesanstalt für Geowissenschaften und Rohstoffe, Geozentrum Hannover, Stilleweg 2, D-30655 Hannover, Germany 7Millennia Stratigraphic Consultants, 35 Swansfield, Lechlade GL7 3SF, UK ABSTRACT 70% of terrestrial vertebrates went extinct at this the Tethys and Panthalassa (Grice et al., 2005; time (Erwin, 2006). While numerous extinction Hays et al., 2007; Kump et al., 2005; Xie et al., Stratigraphic records from northwestern mechanisms have been proposed, growing evi- 2007), the extinction event has also been sug- Pangea provide unique insight into global dence supports environmental effects associated gested to occur under at least locally oxic con- processes that occurred during the latest with massive eruption of the Siberian Traps ditions in northwestern Pangea (Algeo et al., Permian extinction (LPE). We examined (Campbell et al., 1992; Grasby et al., 2011; 2010; Knies et al., 2013; Proemse et al., 2013) a detailed geochemical record of the Fest- Renne et al., 1995; Saunders and Reichow, and in the Neotethys (Korte et al., 2004; Loope ningen section, Spitsbergen. A stepwise ex- 2009; Shen et al., 2011; Wignall, 2001). The et al., 2013; Richoz et al., 2010) (Fig. 1A). tinction is noted as: starting with (1) loss of original volume of the Siberian Traps and West Given the above, the relative timing of vari- carbonate shelly macrofauna, followed by Siberian rift system is difficult to estimate, but ous environmental stresses becomes critical to (2) loss of siliceous sponges in conjunction upper-end figures of 3–4 × 106 km3 (Courtillot understanding the role they played during the with an abrupt change in ichnofabrics as well et al., 1999; Fedorenko et al., 2000) make this mass extinction. To address this question we as dramatic change in the terrestrial envi- mega-scale eruption one of the largest in Earth examined the Festningen section in Spitsbergen ronment, and (3) final loss of all trace fossils. history. Magma intruded through the Tunguska (Wignall et al., 1998), a shelf sea location on We interpret loss of carbonate producers as Basin, and was associated with combustion of northern Pangean margin during Late Permian related to shoaling of the lysocline in higher organic-rich sediments (Grasby et al., 2011; time (Figs. 1B, 1C). The Festningen section is latitudes, in relationship to building atmo- Reichow et al., 2009; Retallack and Jahren, one of the earliest locations where development spheric CO2. The loss of siliceous sponges is 2008; Retallack and Krull, 2006; Svensen et al., of anoxia in association with the mass extinc- coincident with the global LPE event and is 2009) along with release of large volumes tion event was demonstrated by Wignall et al. related to onset of high loading rates of toxic of CO2 (White and Saunders, 2005; Wignall, (1998). However, that study was based on a metals (Hg, As, Co) that we suggest are de- 2001), deleterious atmospheric gases (Beerling low sample density for carbon isotope data that rived from Siberian Trap eruptions. The final et al., 2007; Black et al., 2012, 2014; Kaiho and did not provide clarity as to detailed biogeo- extinction stage is coincident with redox-sen- Koga, 2013; Svensen et al., 2009), and toxic ele- chemical events occurring during the extinction sitive trace metal and other proxy data that ments (Grasby et al., 2011, 2013a; Sanei et al., period. Subsequent work at other sites in Spits- suggest onset of anoxia after the other extinc- 2012). Oxygen isotope records suggest that rapid bergen has pointed to the gradual development tion events. These results show a remarkable global warming and extremely high ocean tem- of anoxia across the LPE event (Dustira et al., record of progressive environmental dete- peratures developed at this time (Romano et al., 2013), as well as in correlative strata in the Sver- rioration in northwestern Pangea during the 2013; Sun et al., 2012), invoking a hothouse drup Basin (Grasby and Beauchamp, 2009). To extinction crises. scenario (Kidder and Worsley, 2010; Retallack, elucidate the relative timing of various environ- 1999; Song et al., 2014). Acid ocean condi- mental stressors, we have undertaken detailed INTRODUCTION tions may also have developed (Beauchamp and analyses of the Festningen section based on Grasby, 2012; Heydari and Hassanzadeh, 2003; high-resolution sampling through the LPE. The latest Permian extinction (LPE) repre- Kidder and Worsley, 2004, 2010; Liang, 2002; sents a period of dramatic climate change asso- Payne et al., 2007). Global anoxia has long been STUDY AREA ciated with disruption of global biogeochemical suggested to be an important environmental cycles and the worst mass extinction event in stress associated with the LPE (Isozaki, 1997; The Festningen section is located at Kapp Earth history. Over 90% of marine species and Knoll et al., 1996; Wignall and Hallam, 1992; Starostin, west of the mouth of Grønfjorden Wignall and Twitchett, 1996). While some where it enters Isfjorden on Nordenskiöld †E-mail: [email protected] regions show evidence of photic zone euxinia in Land, Spitsbergen (Fig. 1B). In Permian time GSA Bulletin; September/October 2015; v. 127; no. 9/10; p. 1331–1347; doi: 10.1130/B31197.1; 8 figures; 3 tables; published online 14 April 2015. For permission to copy, contact [email protected] Geological Society of America Bulletin, v. 127, no. 9/10 1331 © 2015 Geological Society of America Downloaded from gsabulletin.gsapubs.org on August 26, 2015 Grasby et al. Spitsbergen eastern part of the West Spitsbergen fold-and- A thrust belt, an intra-continental fold-and-thrust belt ranging over more than 300 km along the C west coast from the Brøgger Peninsula in the Siberian north to the Sørkapp in the very south (CASE Panthalassa Tethys Traps Team, 2001; Dallmann et al., 1993; Maher and Pangea Neotethys Craddock, 1988). The intense crustal shortening is a result of the northward directed movement of Greenland against the Barents shelf dur- ing the Eocene, before Spitsbergen was finally separated from Greenland. The Festningen sec- tion is part of the steeply inclined short limb of a kilometer-scale east-vergent fold structure. 0 km 100 B A sill cuts through the series (dating from the Cretaceous, 124.7 Ma) (Corfu et al., 2013). Festningen was located in the central Spits- bergen region were Upper Permian sediments, deposited in a distal shelf setting, are thickest (Wignall et al., 1998; Blomeier et al., 2013). Figure 1. Location maps of field Festningen represents the type section for both area. (A) Global Late Permian the Kapp Starostin and Vardebukta Formations reconstruction base map, after SPITSBERGEN which are examined here. R. Scotese (http:// www .scotese The Kapp Starostin Formation is a Middle .com/). (B) Location of the to Upper Permian unit that was deposited at a Festningen section on Spits- Isfjorden time of tectonic quiescence and passive sub- bergen. (C) Paleo-locations of NordenskiöldLand sidence following a major relative sea-level important sedimentary records Festningen drop coinciding with the Early Permian–Middle on the northwestern margin of Permian boundary (Blomeier et al., 2013). An Pangea at the time of the lat- N initial Roadian transgression led to the depo- est Permian extinction event sition of a widespread heterozoan carbonate (Embry, 1992). Bold black lines (Vøringen Member), which was followed by indicate present-day coastlines. a series of regressions and transgressions that led to the progradation of heterozoan carbon- RUSSIA C ates and cherts over much of the Barents Shelf ALASKA and Svalbard (Blomeier et al., 2013), as well as in the paleogeographically adjoining Sver- CROCKER- drup Basin (Van Hauen, Degerböls, and Trold LAND SVERDRUPCHUKCHI Fiord Formations; Beauchamp et al., 2009). BASI The uppermost fossiliferous carbonate unit in N SVALBARD the Kapp Starostin Formation occurs ~40 m CANADA BARENTS below the contact with the overlying uppermost SEA Permian–Lower Triassic Vardebukta Formation. The topmost part of the Kapp Starostin Forma- tion is dominated by spiculitic chert, an interval that is in part Late Permian in age (Blomeier GREENLAND et al., 2013) and considered equivalent to the Black Stripe and Lindström Formations of the Sverdrup Basin (Beauchamp et al., 2009). The Vardebukta Formation is a unit of shale, siltstone, and minor sandstone that is devoid of carbonate and chert. The formation is mostly Early Triassic (Griesbachian–Dienerian) in age the area formed part of a broad epicontinental to Late Permian (Golonka and Ford, 2000; Sco- as shown by ammonoid and conodont fauna shelf on the northwestern margin of Pangea tese, 2004). (Mørk et al., 1982; Nakrem et al., 2008; Tozer (Fig. 1C), along with correlative strata from the The Festningen section occurs as ~45° east- and Parker, 1968). While the contact between Wandel Sea (North Greenland), the Sverdrup ward-dipping beds (Fig. 2) forming a ~7 km the Kapp Starostin and Vardebukta Formations Basin (Canadian High Arctic), and the Barents coastal section exposed in a low sea cliff, includ- was for many years considered the Permian- Sea and Timan-Pechora Basin (Russia) (Stem- ing near-continuous exposure of Carbonifer- Triassic boundary (PTB) (e.g., Mørk et al., merik and Worsley, 2005).