Global perturbation of the Permian-Triassic marine calcium cycle Global perturbation of the marine calcium cycle during the Permian-Triassic transition Juan Carlos Silva-Tamayo1,2,3,†, Kimberly V. Lau3, Adam B. Jost4, Jonathan L. Payne3, Paul B. Wignall5, Robert J. Newton5, Anton Eisenhauer6, Donald J. Depaolo7, Shaun Brown7, Kate Maher3, Daniel J. Lehrmann8, Demir Altiner9, Meiyi Yu10, Sylvain Richoz11,12, and Adina Paytan13 1Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77004, USA 2Testlab Geo-Ambiental, Cra 45D #60-16, Medellin, Antioquia, Colombia 3Department of Geological Sciences, Stanford University, Stanford, California 94305, USA 4Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 5Department of Earth and Environmental Sciences, The University of Leeds, Leeds LS2 9JT, UK 6Helmholtz Center for Ocean Research, GEOMAR- Kiel, 94148 Kiel, Germany 7Department of Earth and Planetary Sciences, University of California, Berkeley, Berkeley, California 94720, USA 8Department of Geosciences, Trinity University, San Antonio, Texas 78212, USA 9Department of Geological Engineering, Middle East Technical University, Ankara, 06800 Çankaya, Turkey 10College of Resource and Environment Engineering, Guizhou University, Caijiaguan, 550003 Guiyang, Guizhou, China 11Institut für Erdwissenschaften, Bereich Geologie und Paläontologie, Karl-Franzens-Universität Graz, Nawi Graz, 8010 Graz, Austria 12Department of Geology, Lund University, 223 62 Lund, Sweden 13Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064, USA ABSTRACT ture. Based on the results of a coupled box INTRODUCTION model of the geological carbon and calcium A negative shift in the calcium isotopic cycles, we interpret the excursion to reflect a The Late Permian to Early Triassic transition composition of marine carbonate rocks series of consequences arising from volcanic spans the most severe environmental and bio- spanning the end-Permian extinction hori- CO2 release, including a temporary decrease logical crisis of the Phanerozoic (e.g., Erwin, zon in South China has been used to argue in seawater δ44/40Ca due to short-lived ocean 1994; Wignall and Twitchett, 1996; Erwin for an ocean acidification event coincident acidification and a more protracted increase et al., 2002; Payne and Clapham, 2012). Nega- with mass extinction. This interpretation in calcium isotope fractionation associated tive excursions in the carbon isotope (δ13C) has proven controversial, both because the with a shift toward more primary arago- values of carbonate rocks and organic matter excursion has not been demonstrated across nite in the sediment and, potentially, subse- in Upper Permian–Lower Triassic sedimentary multiple, widely separated localities, and be- quently elevated carbonate saturation states sequences (reviewed in Korte and Kozur, 2010) cause modeling results of coupled carbon and caused by the persistence of elevated CO2 suggest that the mass extinction event was asso- calcium isotope records illustrate that cal- delivery from volcanism. Locally, changing ciated with a major perturbation of the exogenic cium cycle imbalances alone cannot account balances between aragonite and calcite pro- carbon cycle. However, the source and amount for the full magnitude of the isotope excur- duction are sufficient to account for the cal- of carbon released and its impact on surface sion. Here, we further test potential controls cium isotope excursions, but this effect alone environments cannot be constrained via car- on the Permian-Triassic calcium isotope does not explain the globally observed nega- bon isotope data alone (Berner, 2002; Payne record by measuring calcium isotope ratios tive excursion in the δ13C values of carbonate et al., 2010). from shallow-marine carbonate successions sediments and organic matter as well. Only The geological carbon cycle is coupled to spanning the Permian-Triassic boundary in a carbon release event and related geochemi- the geological calcium cycle via the weathering Turkey, Italy, and Oman. All measured sec- cal consequences are consistent both with and deposition of carbonate rocks. Because cal- tions display negative shifts in δ44/40Ca of up calcium and carbon isotope data. The carbon cium isotopes (δ44/40Ca) in carbonate sediments to 0.6‰. Consistency in the direction, magni- release scenario can also account for oxygen are fractionated relative to calcium in seawater, tude, and timing of the calcium isotope excur- isotope evidence for dramatic and protracted imbalances in the rates of calcium delivery to sion across these widely separated localities global warming as well as paleontological the oceans relative to calcium removal in sedi- implies a primary and global δ44/40Ca signa- evi dence for the preferential extinction of ments can affect seawater δ44/40Ca (e.g., Fantle, marine animals most susceptible to acidifica- 2010). Therefore, calcium isotopes hold po- †jsilva -tamayo@ uh .edu tion, warming, and anoxia. tential for further quantification of the nature GSA Bulletin; Month/Month 2016; v. 128; no. X/X; p. 1–16; https://doi .org /10 .1130 /B31818 .1 ; 9 figures; Data Repository item 2018081. ; published online XX Month 2016. For permission to copy, contact [email protected] Geological Society of America Bulletin, v. 1XX, no. XX/XX 1 © 2018 Geological Society of America Silva-Tamayo et al. of the Permian-Triassic global change (Fantle, South China as alternative explanations for the the Tesero section belong to the Bellerophon 2010; Payne et al., 2010; Fantle and Tipper, negative shift in δ44/40Ca at the Permian- Triassic and Werfen Formations (Wignall and Hallam, 2014; Komar and Zeebe, 2016). To date, there transition (e.g., Lau et al., 2017). Second, the 1992). The section (Fig. 4) consists of Chang- exist three high-resolution calcium isotope rec- modeling approaches employed in previous hsingian dolomicrites capped by a thin bed of bio- ords spanning the Permian-Triassic transition studies included scenarios that can now be bet- clastic packstone belonging to the Bellerophon (late Changhsingian–early Griesbachian), two ter constrained with experimental and theoreti- Formation, followed by alternating oosparites measured in shallow-marine limestones from cal data, including the effects of precipitation and micrites (the Tesero oolite horizon of the South China and Turkey, and one measured on rate and changing proportions of aragonite ver- Werfen Formation) deposited at shallow depths conodont microfossils (Figs. 1–3; Payne et al., sus calcite in marine sediments. on a carbonate ramp located along the western 2010; Hinojosa et al., 2012; Lau et al., 2017). Additional calcium isotope records from limit of the Tethys Ocean (Wignall and Hal- Each record exhibits a negative excursion in widely spaced stratigraphic sections located lam, 1992; Brandner et al., 2012). Carbon iso- δ44/40Ca values across the Changhsingian-Gries- on other continental margins are critical for tope stratigraphy (Fig. 4) and fossil occurrences bachian transition lasting ~500 k.y., which has testing the primary, global nature of the nega- indi cate that the end-Permian mass extinction previously been interpreted to reflect variation tive calcium isotope signature. To address this horizon occurs within the basal 3–4 m of the in the δ44/40Ca values of seawater during that need, we measured the calcium isotope com- Tesero oolite horizon and that the PTB occurs time (Payne et al., 2010; Hinojosa et al., 2012). positions of marine carbonate strata spanning a few meters higher (Figs. 2 and 5; Perri, 1991; Payne et al. (2010) used a forward box model the Upper Permian to Lower Triassic transition Wignall and Hallam, 1992; Wignall and Twitch- of the marine calcium cycle to argue that the (uppermost Changhsingian to lowermost Gries- ett, 1996). The Tesero oolite horizon is overlain negative excursion in δ44/40Ca of marine car- bachian) at the Tesero Road section in the Dolo- by a series of lower Griesbachian pyritic marls bonate sediments resulted from an interval of mite Mountains of northern Italy and at the Saiq and micrites, which are in turn overlain by series reduced carbonate production during a transient Plateau section in the Sultanate of Oman (Figs. of upper Griesbachian ostracod packstones of ocean acidification event combined with in- 4–5). Thus, our combined data set includes the Mazzin Member of the Werfen Formation creased continental weathering, each of which high-resolution records from five geographic (Fig. 4). The lower Isarci cella isarcica cono- was in turn caused by the rapid release of vol- areas and both carbonate rocks and conodont el- dont zone occurs within the basal 2 m of the canic CO2 to the atmosphere (10,000–50,000 ements. We use coupled forward box models of Mazzin Member (Fig. 4; Perri, 1991; Perri and petagrams [Pg] of carbon). Komar and Zeebe the marine calcium and carbon cycles to assess Farabegoli, 2003). (2016) used a coupled model of the geological the potential isotopic effects of rapid volcanic The studied Upper Permian–Lower Triassic carbon and calcium cycles to argue that ocean CO2 outgassing, changes in ocean alkalinity and carbonate succession from the Saiq Plateau sec- acidification could not have been the only mech- phosphate, and changes in the dominant car- tion, Al Jabal Al-Akhdar, Sultanate of Oman, anism responsible for the negative excursion in bonate