Correlating the End-Triassic Mass Extinction and Flood Basalt

Correlating the end-Triassic mass extinction and ﬂ ood basalt volcanism at the 100 ka level

Blair Schoene1*†, Jean Guex2†, Annachiara Bartolini3†, Urs Schaltegger1†, and Terrence J. Blackburn4† 1Earth Sciences, University of Geneva, Rue des Maraîchers 13, CH-1205 Geneva, Switzerland 2Geology and Paleontology, University of Lausanne, l’Anthropole, Lausanne, Switzerland 3Muséum National d’Histoire Naturelle, Histoire de la Terre, CP 38 CR2P UMR 7207 du CNRS, 8 rue Buffon, Paris, France 4Earth, Atmosphere and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02142-1479, USA

ABSTRACT Proxies for rising atmospheric CO2 have been New high-precision U/Pb geochronology from volcanic ashes shows that the Triassic-Juras- reported from terrestrial fossil plants straddling sic boundary and end-Triassic biological crisis from two independent marine stratigraphic the Triassic-Jurassic boundary (McElwain et al., sections correlate with the onset of terrestrial ﬂ ood volcanism in the Central Atlantic Mag- 1999; Retallack, 2001), though the effects of

matic Province to <150 ka. This narrows the correlation between volcanism and mass extinc- other gases such as SO2 on such proxies may tion by an order of magnitude for any such catastrophe in Earth history. We also show that also be important (Guex et al., 2004; Tanner et a concomitant drop and rise in sea level and negative δ13C spike in the very latest Triassic al., 2007). Terrestrial correlatives to the marine occurred locally in <290 ka. Such rapid sea-level fl uctuations on a global scale require that extinction are debated (Lucas and Tanner, 2007; global cooling and glaciation were closely associated with the end-Triassic extinction and Tanner et al., 2004). An apparent palynological potentially driven by Central Atlantic Magmatic Province volcanism. event <1 m below the lowest CAMP basalt in the Newark and Fundy Basins in North America INTRODUCTION Mountain Basalt, the lowest CAMP basalt from was proposed as correlative of the Triassic- Mass extinctions refl ect important interac- the Fundy Basin, Nova Scotia (Greenough and Jurassic boundary (Whiteside et al., 2007); this tions between biology, geology, geochemical Dostal, 1992). Both the ash beds and the North has been challenged on the basis of biostrati- cycles, and climate. The end-Triassic mass Mountain Basalt were dated using chemical graphic and magnetostratigraphic work from extinction is one of the fi ve largest extinctions in abrasion–isotope dilution–thermal ionization North America and Morocco (Marzoli et al., Earth history, though considerable uncertainty mass spectrometry (CA-ID-TIMS; Mattinson, 2004, 2008). Others argue that vertebrate and remains in terms of its duration, causes, and 2005) U-Pb zircon geochronology employing a palynological biostratigraphy in the Newark and effects. Many workers suggest that the extinc- new well-calibrated 202Pb-205Pb-233U-235U tracer Fundy Basins, respectively, place the Triassic- tion was related directly or indirectly to adverse solution, which removes random uncertainty in Jurassic boundary in sedimentary slivers above climate following the onset of the Central Atlan- mass fractionation during mass spectrometry. the North Mountain Basalt (Lucas and Tanner, tic Magmatic Province (CAMP), which erupted Data with this solution are as much as 70% more 2007; Cirilli et al., 2009). >2.5 × 106 km3 of basalt, possibly in <1 Ma, precise compared to single-Pb/single-U tracers, An age for the marine Triassic-Jurassic making it perhaps the most voluminous fl ood revealing complexity in tuff zircon populations boundary comes from the Pucara basin in basalt sequence of the Phanerozoic (Marzoli et that require new data interpretation strategies. northern Peru, where Schaltegger et al. (2008) al., 2004; McHone, 2003; Nomade et al., 2007; reported a weighted-mean 206Pb/238U date of Whiteside et al., 2007). However, there remains TRIASSIC-JURASSIC BOUNDARY 201.58 ± 0.18/0.38 Ma (2σ; without/with a need for precise and accurate geochronol- Recent consensus places the Triassic-Jurassic decay constant uncertainties). Abundant CAMP ogy to correlate the onset of CAMP volcanism, boundary at the fi rst occurrence of the oldest 40Ar/39Ar data cluster at 199 Ma (e.g., Nomade recorded uniquely in terrestrial sections, with the Jurassic ammonite Psiloceras spelae, which et al., 2007), but uncertainties of 1–2 Ma on indi- well-documented marine extinction event (Mar- marks the beginning of postextinction biodi- vidual dates in addition to the well-documented zoli et al., 2008; Tanner et al., 2004; Whiteside versity recovery (Guex et al., 2004; Morton ~0.7%–1% bias between the 40Ar/39Ar and U-Pb et al., 2007). Also lacking are time constraints and Hesselbo, 2008). Pinpointing the extinction dating methods (Kuiper et al., 2008; Schoene for the rates of the Triassic-Jurassic bound- interval is more complicated, but coincides with et al., 2006) make this correlation imprecise. A ary extinction and associated geochemical and a sharp negative spike in δ13C at the end-Triassic, 206Pb/238U date from the North Mountain Basalt paleoenvironmental fl uctuations. We sampled when there were steep declines in the bio- of 201.27 ± 0.06/0.30 Ma (Schoene et al., 2006) three volcanic ash beds bracketing the Triassic- diversity of ammonites, bivalves, radiolarians, would suggest that the CAMP postdates the Tri- Jurassic boundary from the Pucara basin, north- corals, and conodonts (Morton and Hesselbo, assic-Jurassic boundary, precluding a causative ern Peru (Fig. 1A; Schaltegger et al., 2008), and 2008). This initial negative excursion is fol- relationship. However, those two U-Pb dates also the fi rst discovered ash bed from the New lowed by a gradual positive recovery (Fig. 1B), were measured using different tracer solutions, York Canyon, Nevada, which has been proposed which precedes a slow negative excursion in allowing for systematic bias and preventing as the Global Boundary and Stratotype Sec- the Early Jurassic (beginning at bend N13 in high-precision comparison. tion and Point for the Triassic-Jurassic bound- Fig. 1B; Guex et al., 2004; Hesselbo et al., 2004; ary (Guex et al., 2004). We also provide new Kuerschner et al., 2007; Ward et al., 2001). The LOCALITIES AND U-Pb U/Pb zircon data from two labs for the North end-Triassic negative δ13C excursion is recorded GEOCHRONOLOGY in marine organic and carbonate carbon and We sampled three volcanic ash beds brack- *Current address: Geosciences, Guyot Hall, Princ- continent-derived wood material, illustrating eting the Triassic-Jurassic boundary in the eton University, Princeton, New Jersey 08544, USA. †E-mails: [email protected]; Jean.Guex@ that the anomaly resulted from a global carbon Pucara basin (samples LM4–86, LM4–90, and unil.ch; [email protected]; [email protected]; cycle perturbation (Galli et al., 2005; Hesselbo LM4–100/101; Figs. 1A, 1B), which is well [email protected]. et al., 2004; Pálfy et al., 2001). calibrated biostratigraphically (Schaltegger et

© 2010 Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or [email protected]. GEOLOGY,Geology, May May 2010; 2010 v. 38; no. 5; p. 387–390; doi: 10.1130/G30683.1; 1 ﬁ gure; Data Repository item 2010109. 387

Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/38/5/387/3537956/387.pdf by Princeton University user on 19 October 2020 Figure 1. A: Location map of three sections A 2. Pucara basin (N. Peru) 3. New York Canyon (Nevada, USA) studied, with ca. 200 Ma + Sea level paleogeography. Num- M2 bers correspond to stratigraphic sections in FO Nevadaphyllites N13 B. Red area outlines ap- N11 proximate extent of Cen- tral Atlantic Magmatic B 1. Fundy Basin Hettangian (J) Province (e.g., McHone, LM4-100/101 2003) B: Stratigraphic (Nova Scotia, Canada) NYC-N10 N9 columns for sections Hettangian (J) studied; scale bars at J McCoy Brook Fm. TJB bottom. J—Jurassic; FO P. spelae Tr—Triassic. Fundy FO P. spelae Basin section is after LM4-90 Whiteside et al. (2007). North Mtn. N6c Pucara basin biostra- Basalt N6b tigraphy is detailed in LM4-86 Schaltegger et al. (2008). N3 extinction intervalextinction <<290,000 years New York Canyon stra- LO C. crickmayi intervalextinction tigraphy, biostratigraphy, bed numbers, Blomidon Formation AC5

LO C. crickmayi Cooling and glaciation Global warming

carbon isotopes, and Tr 50 m

sea-level curve are from Rhaetian 1 m Guex et al. (2004, 2008). Thick bed limestone δ13 Age of TJB Green curve in C plot Thin bed limestone is running mean of red Duration of extinction, δ13C spike, -31 -30 -29 -28 -27 -26 -25 Carb. siltstone Ash bed data points. FO—fi rst regression/transgression couplet: Rhaetian (Tr) Siltstone Black shale δ 13C occurrence. LO—last 1 m org occurrence; org— 204 organic. Stars indicate C North Mtn. Basalt ash beds sampled, with NMB-03-1 interpreted 206Pb/238U 203 deposition age. All Zircon used as eruption age uncertainties are 2σ. 202 TJB—Triassic-Jurassic boundary, defi ned as North U date (Ma) 201 Mtn. Basalt fi rst occurrence of Psilo- UNIGE 206 238 238 ceras spelae. C: Pb/ U Pb-loss Pre-eruptive growth of zircon? dates for single-grain Pb/ 200 zircons, color-coded to LM4-86 (Schaltegger et al., 2008) Antecrysts? sample locations in B. 206 Xenocrysts? Date for LM4–86 from Schaltegger et al. (2008) includes tracer calibration uncertainty. Data for North Mountain Basalt are from Massachusetts Institute of Tech- nology (MIT) and University of Geneva (UNIGE); all ash-bed data are from University of Geneva.

al., 2008). In this section, the disappearance dia plots and U-Pb data are presented in Fig- between 201.3 and 201.9 Ma; a weighted-mean of the latest Triassic ammonite Choristoceras ure DR1 and Table DR1, respectively. yields an MSWD of >2. Two younger grains crickmayi immediately precedes the peak Ash beds yielded 20–100 zircons between 50 give 206Pb/238U dates younger than 201 Ma and extinction rate (Guex et al., 2004). One ash and 200 µm in diameter (see the Data Reposi- two older grains of ca. 203 Ma (Fig. 1C). bed sample (NYC-N10) was collected ~1.5 m tory); 14 zircons from sample LM4–86 give Analyses of 13 single grains of the North above the ﬁ rst occurrence of P. spelae in the 206Pb/238U dates that span ~1.5 Ma between 201 Mountain Basalt (NMB-03–1) from the Univer- New York Canyon section, for which detailed and 203 Ma, with one older and one younger sity of Geneva and 19 analyses from the Massa- δ13C and biostratigraphic data have been pub- grain. The main population is not statistically chusetts Institute of Technology are statistically lished (Guex et al., 2004, 2008) (Figs. 1A, 1B). equivalent, with a high mean square of weighted equivalent, yielding a weighted-mean 206Pb/238U We also provide new U/Pb data from two labo- deviates (MSWD) of 12 on a weighted-mean date of 201.38 ±0.02/0.22/0.31 Ma (internal ratories for the North Mountain Basalt (NMB- 206Pb/238U date (i.e., many dates do not overlap uncertainties/with tracer calibration uncertain- 03–1). All dates were produced using CA-ID- at 2σ). Similarly, LM4–90 and LM4–100/101 ties/with decay constant uncertainties; omitting TIMS on single zircons relative to the new yield zircon populations that spread between 0.4 two analyses, MSWD = 1.2). EARTHTIME (http://www.earth-time.org/) and >1 Ma with high MSWD values. LM4–90 (±202Pb)-205Pb-233U-235U tracer solution, allow- also has one grain ca. 200.1 Ma and a popula- INTERPRETING DEPOSITION AGES ing us to ignore tracer calibration uncertain- tion of ca. 900 Ma xenocrystic zircons. Of 17 FOR ASH BEDS ties within this study (Schoene et al., 2006). zircons from NYC-N10, 15 give 206Pb/238U dates U/Pb ages for volcanic ash beds are often All uncertainties are reported at the 2σ level, determined by calculating a weighted-mean have been corrected for 230Th disequilibrium, 1GSA Data Repository item 2010109, U-Pb data date and thus assuming that there exists a single and omit decay constant uncertainties unless table, analytical details, and additional ﬁ gures, is population of zircons that crystallized immedi- 1 available online at www.geosociety.org/pubs/ft2010 other wise noted (see the GSA Data Repository .htm, or on request from [email protected] or ately prior to eruption (Ramezani et al., 2007; 206 238 for analytical details). Pb/ U dates for sin- Documents Secretary, GSA, P.O. Box 9140, Boulder, Schaltegger et al., 2008). Our ash-bed data reveal gle zircons are plotted in Figure 1C and concor- CO 80301, USA. complicated U-Pb systematics, precluding such

388 GEOLOGY, May 2010

Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/38/5/387/3537956/387.pdf by Princeton University user on 19 October 2020 an interpretation. The observed spread in dates Therefore, we use the youngest single closed- Hettangian warming. These recent studies argue

could be created by several effects: (1) analyti- system zircon to approximate the eruption date that CO2-induced global warming was not the cal bias and underestimated uncertainties, (2) (Figs. 1B, 1C). A less conservative interpretation driver for the end-Triassic biotic crisis, but allow postcrystallization loss of radiogenic Pb from uses weighted means of several zircons, with that it was important in the postextinction recov- zircons, or (3) zircons representing a range of the resulting MSWD as a guide. Those eruption ery interval. growth histories prior to eruption. The equiva- ages overlap with the single-grain interpretation The short duration (<290 ka) for the marine lency of the North Mountain Basalt data from and with the age of the North Mountain Basalt regression-transgression sequence in the New two independent laboratories using a single (Table DR3). York Canyon provided by our geochronological tracer solution, transparent data-reduction tech- data gives an additional constraint. Latest Tri- niques (Schmitz and Schoene, 2007), and care- TIMING AND RATES OF EVENTS AT assic regression-transgression is recognized in ful analytical blank calibration (see the Data THE TRIASSIC-JURASSIC BOUNDARY numerous sections in Europe and North Amer- Repository) suggests that tuff zircon data are A 206Pb/238U age of the Triassic-Jurassic ica, and is likely the result of global sea-level equally accurate and analytical uncertainties are boundary in the Pucara basin, defi ned as the fi rst change (Hallam and Wignall, 1999). Several correctly estimated. appearance of P. spelae, can be calculated using sections in Europe also show it coupled to the Despite the overall success of the chemical our new data to be 201.31 ±0.18/0.38/0.43 Ma, Late Triassic negative δ13C excursion, as seen abrasion technique at removing the effects of using the difference between the minimum age in the New York Canyon (Fig. 1B) (e.g., Galli Pb loss (Mattinson, 2005), three of four ash- of LM4-100/101 and the maximum age of LM4- et al., 2005; Hesselbo et al., 2004; Kuerschner bed samples have at least one zircon that is far 90. This correlates to the onset of the CAMP in et al., 2007). Global eustasy results from a vari- younger than the main population, and we sug- the Fundy Basin to within ±150 ka (Fig. 1B). ety of processes, including continental uplift gest that these outliers are the result of residual Our data also provide tie points between the due to thermal underplating (e.g., by a plume) Pb loss. There is a simple test suggesting that the terrestrial Triassic-Jurassic boundary, located or changes in volumes or rates of mid-ocean main population of zircons did not also undergo near the North Mountain Basalt (Cirilli et al., ridge production, but these processes occur on Pb loss: the youngest zircon from the main popu- 2009), and the marine ammonite extinction in time scales longer than 1 Ma (e.g., Miller et al., lation of each sample is younger or within uncer- two stratigraphic sections. The deposition age 2005). The rapid sea-level fl uctuation we docu- tainty than that of the sample stratigraphically from NYC-N10 in Nevada is identical to that ment for the latest Triassic can only be explained below it. This would be remarkably coincidental from LM4-100/101 in Peru, illustrating that the by glacial eustasy. A model that accounts for this if these populations had undergone Pb loss. fi rst appearance of P. spelae in both sections is observation was proposed in Guex et al. (2004), We interpret the spread in 206Pb/238U dates contemporaneous within our resolution. If we and suggested that the negative δ13C excursion in of the main population of tuff zircons to be assume that the last occurrence of C. crickmayi the uppermost Triassic (Fig. 1B) was associated the result of protracted growth of zircon in the in the New York Canyon is also correlative with extinction and primary productivity col-

magmatic system and/or the incorporation of with that in the Pucara basin, we can conclude lapse caused by volcanic SO2 and heavy metals xenocrystic zircon. Complex volcanic and plu- that the duration of the end-Triassic negative emissions, acid rain, and a cooling and glacial δ13 tonic systems involving small magma batches, Corganic excursion was 70 +220/–70 ka (the event that caused a short but major drop in sea maﬁ c and silicic replenishment, magma min- duration between LM4-86 and NYC-N10), level. This ﬁ rst phase was followed by CAMP–

gling and/or mixing, and crustal assimilation which also serves as an estimate for the duration related CO2 accumulation, greenhouse warm- can entrain antecrystic to xenocrystic zircons of the mass extinction event. ing, marine transgression, and postextinction with dates recording millions of years of mag- biotic recovery, corresponding to the positive matic activity (Charlier et al., 2005; Crowley et DISCUSSION and second negative δ13C excursions (Fig. 1B). al., 2007; Simon and Reid, 2005; Miller et al., Some numerical carbon cycle models suggest Fingerprinting the trigger for the end-Triassic

2007). Th/U ratios of zircons from each of our that CO2 released from ﬂ ood basalts is insuf- ecological disaster must come from additional ash samples plot into distinct but overlapping ﬁ cient to create the end-Triassic negative δ13C biological and environmental proxy data in com- groups (Fig. DR2). This argues that younger anomaly and that associated with the Permian- bination with high-precision geochronology in ashes came from a different magma batch, but Triassic extinction (Beerling and Berner, 2002; other Triassic-Jurassic boundary sections. Such may have incorporated reworked ash material Payne and Kump, 2007). Alternatively, it is work will better constrain the rates of CAMP and/or xenocrystic zircons. Zircon morphology hypothesized that CAMP volcanism may have eruption and corroborate that sea-level change supports this: the youngest grains had the high- destabilized methane hydrates or accessed large and extinction were everywhere fast and contem- est aspect ratios and were prismatic and euhe- carbon reservoirs by erupting through organic- poraneous (Hallam and Wignall, 1999; Hesselbo dral (typical of rhyolitic zircon), whereas older rich sediment, resulting in massive input of light et al., 2004). Our new U-Pb data show that such populations contained similarly euhedral grains carbon into the oceans and atmosphere, creat- constraints can be facilitated using new freely in addition to anhedral rounded grains. Thus, ing a <200 ka negative δ13C spike (Beerling available EARTHTIME (±202Pb)-205Pb-233U-235U although zircon selection is critical in avoiding and Berner, 2002; Pálfy et al., 2001; Retallack, tracers, by effectively eliminating interlaboratory xenocrysts, the increased precision afforded by 2001), which is consistent with our geochro- bias and substantially increasing both internal the 202Pb-205Pb-233U-235U tracer can also identify nological data. However, recent work suggests and external precision of U-Pb ID-TIMS dating.

euhedral zircons that predate eruption. The zir- that SO2 and polycyclic aromatic hydrocarbons cons from LM4–86 dated (Schaltegger et al., were drivers in rapid and widespread terrestrial ACKNOWLEDGMENTS 205 235 Guex, Schaltegger, and Schoene were supported by 2008) with a Pb- U tracer likely record the plant turnover, rather than CO2 and greenhouse the Suisse Fonds National, and Guex acknowledges same population of zircons as this study, though warming (Van de Schootbrugge et al., 2009). stimulating discussions with D. Taylor. We thank it appeared as one population due to increased Furthermore, Korte et al. (2009) provided δ18O J. Ramezani for assistance with the North Mountain uncertainties on single analyses (Fig. 1C). Such data from fossil oysters that argue for cool ocean Basalt dating at the Massachusetts Institute of Technol- ogy (MIT). Helpful suggestions from A. Marzoli and an observation demands caution when taking temperatures immediately after the initial nega- two other reviewers improved this paper. Support at 13 weighted means of large populations, especially tive δ C excursion (after the extinction event in MIT comes from National Science Foundation grant in lower precision data sets. the New York Canyon), followed by ~8 °C early EAR-0446880 and the EARTHTIME initiative.

GEOLOGY, May 2010 389

Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/38/5/387/3537956/387.pdf by Princeton University user on 19 October 2020 REFERENCES CITED chronizing rocks clocks of Earth history: Sci- Letters, v. 256, p. 264–277, doi: 10.1016/j Beerling, D.J., and Berner, R.A., 2002, Biogeochemi- ence, v. 320, p. 500–504. .epsl.2007.01.034. cal constraints on the Triassic-Jurassic boundary Lucas, S.G., and Tanner, L.H., 2007, The nonma- Ramezani, J., Schmitz, M.D., Davydov, V.I., Bow- carbon cycle event: Global Biogeochemical Cy- rine Triassic-Jurassic boundary in the Newark ring, S.A., Snyder, W.S., and Northrup, C.J., cles, v. 16, 1036, doi: 10.1029/2001GB001637. Supergroup of eastern North America: Earth- 2007, High-precision U-Pb zircon age con- Charlier, B.L.A., Wilson, C.J.N., Lowenstern, J.B., Science Reviews, v. 84, p. 1–20, doi: 10.1016/j. straints on the Carboniferous-Permian bound- Blake, S., Van Calstren, P.W., and Davidson, earscirev.2007.05.002. ary in the southern Urals stratotype: Earth and J.P., 2005, Magma generation at a large hyper- Marzoli, A., and 14 others, 2004, Synchrony of the Planetary Science Letters, v. 256, p. 244–257, active silicic volcano (Taupo, New Zealand) Central Atlantic magmatic province and the doi: 10.1016/j.epsl.2007.01.032. revealed by U-Th and U-Pb systematics in zir- Triassic-Jurassic boundary climatic and bi- Retallack, G.J., 2001, A 300-million year record cons: Journal of Petrology, v. 46, p. 3–32, doi: otic crisis: Geology, v. 32, p. 973–976, doi: of atmospheric carbon dioxide from fossil 10.1093/petrology/egh060. 10.1130/G20652.1. plant cuticles: Nature, v. 411, p. 287–290, doi: Cirilli, S., Marzoli, A., Tanner, L., Bertrand, H., Marzoli, A., Bertrand, H., Knight, K.B., Cirilli, S., 10.1038/35077041. Buratti, N., Jourdan, F., Bellieni, G., Kontak, Nomade, S., Renne, P.R., Vérati, C., Youbi, N., Schaltegger, U., Guex, J., Bartolini, A., Schoene, D., and Renne, P.R., 2009, Latest Triassic on- Martini, R., and Bellieni, G., 2008, Synchrony B., and Ovtcharova, M., 2008, Precise U-Pb set of the Central Atlantic Magmatic Province between the Central Atlantic magmatic prov- age constraints for end-Triassic mass extinc- (CAMP) volcanism in the Fundy Basin (Nova ince and the Triassic-Jurassic mass-extinction tion, its correlation to volcanism and Hettan- Scotia): New stratigraphic constraints: Earth event?: Comment: Palaeogeography, Palaeocli- gian post-extinction recovery: Earth and Plan- and Planetary Science Letters, v. 286, p. 514– matology, Palaeoecology, v. 262, p. 189–193, etary Science Letters, v. 267, p. 266–275, doi: 525, doi: 10.1016/j.epsl.2009.07.021. doi: 10.1016/j.palaeo.2008.01.016. 10.1016/j.epsl.2007.11.031. Crowley, J.L., Schoene, B., and Bowring, S.A., 2007, Mattinson, J.M., 2005, Zircon U-Pb chemical- Schmitz, M.D., and Schoene, B., 2007, Derivation U-Pb dating of zircon in the Bishop Tuff at the abrasion (“CA-TIMS”) method: Combined of isotope ratios, errors, and error correlations millennial scale: Geology, v. 35, p. 1123–1126, annealing and multi-step dissolution analysis for U-Pb geochronology using 205Pb-235U- doi: 10.1130/G24017A.1. for improved precision and accuracy of zircon (233U)-spike isotope dilution thermal ioniza- Galli, M.T., Jadoul, F., Bernasconi, S.M., and Weis- ages: Chemical Geology, v. 220, p. 47–56, doi: tion mass spectrometric data: Geochemistry sert, H., 2005, Anomalies in global carbon 10.1016/j.chemgeo.2005.03.011. Geophysics Geosystems, v. 8, Q08006, doi: cycling and extinction at the Triassic/Jurassic McElwain, J.C., Beerling, D.J., and Woodward, F.I., 10.1029/2006GC001492. boundary: Evidence from a marine C-isotope 1999, Fossil plants and global warming at the Tri- Schoene, B., Crowley, J.L., Condon, D.C., Schmitz, record: Palaeogeography, Palaeoclimatol- assic-Jurassic Boundary: Science, v. 285, p. 1386– M.D., and Bowring, S.A., 2006, Reassessing ogy, Palaeoecology, v. 216, p. 203–214, doi: 1390, doi: 10.1126/science.285.5432.1386. the uranium decay constants for geochronol- 10.1016/j.palaeo.2004.11.009. McHone, J.G., 2003, Volatile emissions from Central ogy using ID-TIMS U-Pb data: Geochimica Greenough, J.D., and Dostal, J., 1992, Cooling Atlantic Magmatic Province basalts; mass as- et Cosmochimica Acta, v. 70, p. 426–445, doi: history and differentiation of a thick North sumptions and environmental consequences, in 10.1016/j.gca.2005.09.007. Mountain Basalt ﬂ ow (Nova Scotia, Canada): Hames, W.E., et al., eds., The Central Atlantic Simon, J.I., and Reid, M.R., 2005, The pace of rhyo- Bulletin of Volcanology, v. 55, p. 63–73, doi: Magmatic Province; insights from fragments lite differentiation and storage in an ‘archetypi- 10.1007/BF00301120. of Pangea: American Geophysical Union Geo- cal’ silicic magma system, Long Valley, Califor- Guex, J., Bartolini, A., Atudorei, V., and Taylor, D., physical Monograph 136, p. 241–254. nia: Earth and Planetary Science Letters, v. 235, 2004, High-resolution ammonite and carbon Miller, J.S., Matzel, J.P., Miller, C.F., Burgess, S.D., p. 123–140, doi: 10.1016/j.epsl.2005.03.013. isotope stratigraphy across the Triassic-Juras- and Miller, R.B., 2007, Zircon growth and Tanner, L.H., Lucas, S.G., and Chapman, M.G., 2004, sic boundary at New York Canyon (Nevada): recycling during the assembly of large, com- Assessing the record and causes of Late Triassic Earth and Planetary Science Letters, v. 225, posite arc plutons: Journal of Volcanology and extinctions: Earth-Science Reviews, v. 65, p. 103– p. 29–41, doi: 10.1016/j.epsl.2004.06.006. Geothermal Research, v. 167, p. 282–299, doi: 139, doi: 10.1016/S0012-8252(03)00082-5. Guex, J., Bartolini, A., Taylor, D., Atudorei, V., The- 10.1016/j.jvolgeores.2007.04.019. Tanner, L., Smith, D.L., and Allan, A., 2007, Sto- lin, P., Bruchez, S., Tanner, L.H., and Lucas, Miller, K.G., Kominz, M.A., Browning, J.V., Wright, matal response of swordfern to volcanogenic

S.G., 2008, The organic carbon isotopic and J.D., Mountain, G.S., Katz, M.E., Sugarman, CO2 and SO2 from Kilauea volcano: Geo- paleontological record across the Triassic- P.J., Carter, B.S., Christie-Blick, N., and Pekar, physical Research Letters, v. 34, L15807, doi: Jurassic boundary at the candidate GSSP sec- S.F., 2005, The Phanerozoic record of global 10.1029/2007GL030320. tion at Ferguson Hill, Muller Canyon, Nevada, sea-level change: Science, v. 310, p. 1293– Van de Schootbrugge, B., Quan, T.M., Lindström, S., USA: Comment: Palaeogeography, Palaeocli- 1298, doi: 10.1126/science.1116412. Püttmann, W., Heunisch, C., Pross, J., Fiebig, matology, Palaeoecology, v. 273, p. 205–206. Morton, N., and Hesselbo, S., eds., 2008, Details of J., Petschick, R., Röhling, H.-G., Richoz, S., Hallam, A., and Wignall, P.B., 1999, Mass extinc- voting on proposed GSSP and ASSP for the Rosenthal, Y., and Falkowski, P.G., 2009, Floral tions and sea-level changes: Earth-Science Re- base of the Hettangian Stage and Jurassic Sys- changes across the Triassic/Jurassic boundary views, v. 48, p. 217–250, doi: 10.1016/S0012 tem: International Subcommission on Jurassic linked to fl ood basalt volcanism: Nature Geo- -8252(99)00055-0. Stratigraphy Newsletter, v. 35, part 1, Decem- science, v. 2, p. 589–594, doi: 10.1038/ngeo577. Hesselbo, S.P., Robinson, S.A., and Surlyk, F., 2004, ber, 76 p. Ward, P.D., Haggart, J.W., Carter, E.S., Wilbur, Sea-level change and facies development Nomade, S., Knight, K.B., Beutel, E., Renne, P.R., D., Tipper, H.W., and Evans, T., 2001, Sud- across potential Triassic-Jurassic boundary Verati, C., Féraud, G., Marzoli, A., Youbi, N., den productivity collapse associated with the horizons, SW Britain: Geological Society of and Bertrand, H., 2007, Chronology of the Triassic-Jurassic boundary mass extinction: London Journal, v. 161, p. 365–379. Central Atlantic Magmatic Province: Impli- Science, v. 292, p. 1148–1151, doi: 10.1126/ Korte, C., Hesselbo, S.P., Jenkyns, H.C., Rickaby, cations for the Central Atlantic rifting pro- science.1058574. R.E.M., and Spötli, C., 2009, Palaeoenviron- cesses and the Triassic-Jurassic biotic crisis: Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J., mental signifi cance of carbon- and oxygen- Palaeogeography, Palaeoclimatology, Palaeo- and Et-Touhami, M., 2007, Synchrony between isotope stratigraphy of marine Triassic Jurassic ecology, v. 244, p. 326–344, doi: 10.1016/j the Central Atlantic magmatic province and boundary sections in SW Britain: Geological .palaeo.2006.06.034. the Triassic-Jurassic mass-extinction event?: Society of London Journal, v. 166, p. 431–445, Pálfy, J., Demény, A., Haas, J., Hetényi, M., Orchard, Palaeogeography, Palaeoclimatology, Palaeo- doi: 10.1144/0016-76492007-177. M.J., and Vetö, I., 2001, Carbon isotope anom- ecology, v. 244, p. 345–367, doi: 10.1016/j Kuerschner, W.M., Bonis, N.R., and Krystyn, L., aly and other geochemical changes at the Tri- .palaeo.2006.06.035. 2007, Carbon-isotope stratigraphy and paly- assic-Jurassic boundary from a marine section nostratigraphy of the Triassic-Jurassic transi- in Hungary: Geology, v. 29, p. 1047–1050, doi: tion in the Tiefengraben section—Northern 10.1130/0091-7613(2001)029<1047:CIAAOG Calcareous Alps (Austria): Palaeogeography, >2.0.CO;2. Manuscript received 11 September 2009 Palaeoclimatology, Palaeoecology, v. 244, Payne, J.L., and Kump, L.R., 2007, Evidence for Revised manuscript received 13 November 2009 p. 257–280, doi: 10.1016/j.palaeo.2006.06.031. recurrent Early Triassic massive volcanism Manuscript accepted 13 November 2009 Kuiper, K.F., and Deino, A., Hilgen, F.J., Krijgsman, from quantitative interpretation of carbon iso- W., Renne, P.R., and Wijbrans, J.R., 2008, Syn- tope fl uctuations: Earth and Planetary Science Printed in USA

390 GEOLOGY, May 2010

Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/38/5/387/3537956/387.pdf by Princeton University user on 19 October 2020