87Sr/86Sr stratigraphy from the Early Triassic of Zal, Iran: Linking temperature to weathering rates and the tempo of ecosystem recovery

Abstract

Recovery from the Late Permian mass extinction was slowed by continued environmental perturbations during the Early Triassic. Rapid fluctuations of the Early Triassic marine carbonate carbon isotope record indicate instability in the global carbon cycle, and recent d 18 O apatite studies link elevated temperatures to the prolonged biotic recovery. High temperatures potentially caused enhanced continental weathering that was detrimental to marine ecosystems, but linking weathering rates to temperature has proven difficult. One proxy for weathering is the 87 Sr/ 86 Sr of marine carbonate; we present here an 87 Sr/ 86 Sr record from an upper Permian-lower Triassic succession near Zal, Iran, that is coupled to a d 13 C carbonate record. An increase in the rate of 87 Sr/ 86 Sr rise from the Dienerian to the Smithian may be linked to elevated continental weathering rates caused by warming during the Smithian.

Permian strontium isotope stratigraphy

“…This problem is particularly relevant in the Permian, for which a significant lack of internal age constraint has been noted (Henderson et al 2012). An accurate relative sample sequence can be ensured when sourcing samples from drill cores (Morante 1996), continuous successions at one locality (Sedlacek et al 2014) or small geographical areas (Denison et al 1994). Correlation problems of local biostratigraphic and lithostratigraphic schemes to other regions, however, are highly likely to lead to erroneous age interpretations (Denison et al 1994;Martin & Macdougall 1995;Henderson et al 2012).…”

“…Grey circles, whole-rock carbonate; blue hexagons, evaporates; brown triangles, conodont elements; open diamonds, unscreened or poorly preserved brachiopods; green diamonds, brachiopod calcite that passed screening for diagenesis. Values taken from Veizer & Compston (1974), Denison et al (1994), Martin & Macdougall (1995), Morante (1996), Korte et al (2003Korte et al ( , 2004Korte et al ( , 2006, Tierney (2010) and Sedlacek et al (2014). All data are adjusted to NIST SRM 987 = 0.710248 (McArthur et al 2001).…”

“…At the P-Tr boundary, the marine 87 Sr/ 86 Sr curve reaches a value of approximately 0.7071-0.7072 (e.g. Korte et al 2003Korte et al , 2004Korte et al , 2006Sedlacek et al 2014).…”

“…Also, large amounts of strontium from basaltic rocks of the Siberian Traps would have been supplied to the oceans by rapid weathering (Holser & Magaritz 1987;Grard et al 2005). In addition, volcanic aerosols causing acid rain may have accelerated weathering rates (Kozur 1998a, b;Krassilov & Karasev 2009;; see also Visscher et al 2004;Sephton et al 2005;Wignall 2007;Kraus et al 2013;Schobben et al 2014;Sedlacek et al 2014).…”

Lilliput effect in freshwater ostracods during the Permian–Triassic extinction

“…Shen et al, 2011;W.J. Shen et al, 2011;Hinojosa et al, 2012;Joachimski et al, 2012;Sedlacek et al, 2014). Recent studies demonstrate that these terrible environmental conditions were not only prevalent during the P-Tr crisis, but also lasted throughout most of the Early Triassic (Song et al, 2012;Sun et al, 2012;Grasby et al, 2013;Tian et al, 2014), which resulted in a catastrophic world with low biotic diversity in the aftermath of the P-Tr extinction (Hallam and Wignall, 1997;Song et al, 2011a;Chen and Benton, 2012).…”