Compound-specific carbon isotopes from Earth’s largest flood basalt eruptions directly linked to the end-Triassic mass extinction

Abstract

A leading hypothesis explaining Phanerozoic mass extinctions and associated carbon isotopic anomalies is the emission of greenhouse, other gases, and aerosols caused by eruptions of continental flood basalt provinces. However, the necessary serial relationship between these eruptions, isotopic excursions, and extinctions has never been tested in geological sections preserving all three records. The end-Triassic extinction (ETE) at 201.4 Ma is among the largest of these extinctions and is tied to a large negative carbon isotope excursion, reflecting perturbations of the carbon cycle including a transient increase in CO 2 . The cause of the ETE has been inferred to be the eruption of the giant Central Atlantic magmatic province (CAMP). Here, we show that carbon isotopes of leaf wax derived lipids (n-alkanes), wood, and total organic carbon from two orbitally paced lacustrine sections interbedded with the CAMP in eastern North America show similar excursions to those seen in the mostly marine St. Audrie's Bay section in England. Based on these results, the ETE began synchronously in marine and terrestrial environments slightly before the oldest basalts in eastern North America but simultaneous with the eruption of the oldest flows in Morocco, a CO 2 super greenhouse, and marine biocalcification crisis. Because the temporal relationship between CAMP eruptions, mass extinction, and the carbon isotopic excursions are shown in the same place, this is the strongest case for a volcanic cause of a mass extinction to date.astrochronology | CO2 | Jurassic | large igneous provinces | n-alkane P lants record through photosynthetic pathways the atmospheric values of δ 13 C that in turn reflect the exchangeable surface oceanic carbon reservoir (1). One of the most direct known plant proxies is the δ 13 C alk measurements of n-C 25 -n-C 31 n-alkanes derived from leaf wax lipids of plant cuticles (2). We analyzed δ 13 C alk , the carbon isotopic composition of wood (δ 13 C wood ), and total organic carbon (δ 13 C toc ) from sediments from two overlapping lacustrine sections interbedded with the lavas of the Central Atlantic magmatic province (CAMP) (3) in eastern North America to obtain a carbon isotope record unambiguously tied to the eruptions and climate proxies to compare with and calibrate organic carbon and carbonate δ 13 C records from elsewhere (3-7). This allows direct determination of the relationship between one of the largest Phanerozoic mass extinctions, the end-Triassic extinction (ETE) (8), carbon isotopic and CO 2 (9) excursions, the biocalcification crisis (10), and their proposed cause, the CAMP (3, 11-13). Core and outcrop samples were obtained from the Newark (New York, New Jersey, and Pennsylvania) and Hartford (Connecticut and Massachusetts) rift basins at 19-20°N paleolatitude (14) in the tropical humid to arid transition of central Pangea (Fig. 1). A hierarchy of Milankovitchforced lake level cycles permeate the sampled strata in these basins, and in conjunction with a high sediment accumulation rate and ...

The origin and early radiation of dinosaurs

“…Taken together, these data suggest that the Norian Stage has a duration of approximately 20 Ma, two-fifths the length of the entire Triassic Period. The end of the Rhaetian (Triassic-Jurassic boundary) is well constrained to between 202 and 201 Ma by U-Pb ages and magnetostratigraphic data (e.g., Kent and Olsen, 1999;Schoene et al, 2006;Schaltegger et al, 2008;Jourdan et al, 2009), with an estimated age of 201.3 Ma based on cyclostratigraphy (Whiteside et al, 2010).…”

“…Finally, a variety of evidence indicates severe environmental stress on land and in the ocean at the Triassic-Jurassic boundary, with a sharp increase in atmospheric CO 2 levels (e.g., Smith and Kitching, 1997;McElwain et al, 1999;Cohen and Coe, 2007;Michalík et al, 2007;Hautmann et al, 2008;Whiteside et al, 2010). These environmental changes may have been associated with a mass extinction near the Triassic-Jurassic boundary, which is recognized as one of the "big five" mass extinctions in earth history (e.g., Raup, 1986;Benton, 1995).…”

“…These environmental changes may have been associated with a mass extinction near the Triassic-Jurassic boundary, which is recognized as one of the "big five" mass extinctions in earth history (e.g., Raup, 1986;Benton, 1995). New work using records of compound-specific stable carbon isotopes from the Triassic-Jurassic boundary interval of the Newark Supergroup in eastern North America indicates that the eruption of flood basalts caused a massive input of greenhouse gases into the atmosphere, and that the release of this greenhouse gas and the earliest basalt flows are synchronous with biotic extinctions both on land and in the ocean (Whiteside et al, 2010). These data are the strongest evidence yet indicating flood volcanism caused the endTriassic mass extinction.…”

Mass extinctions of life and catastrophic flood basalt volcanism

“…Whatever the ultimate cause of the extinctions and climatic perturbations, the results of Whiteside et al (5) provide a convincing link between the ETE and the CAMP basalts. The recognition that catastrophic events such as large impacts or flood basalt episodes may be major causes of climatic and biologic change represents a sea change in the geological sciences.…”

Paleontology of the Bears Ears National Monument: history of exploration and designation of the monument

“…This biotic crisis at 201.6 Ma is thought to have been caused by eruption of the Central Atlantic Magmatic Province (CAMP) flood basalts, which were extruded on land as the Atlantic margins of North America, South America, Europe, and Africa began to rift apart (e.g., Schoene et al, 2010;Whiteside et al, 2010;Blackburn et al, 2013;Percival et al, 2017). Although the extinction event is relatively well-characterized in marine ecosystems, its severity and timing in non-marine environments is still controversial (e.g., Pálfy et al, 2000;Olsen et al, 2002;Tanner et al, 2004;Whiteside et al, 2007Whiteside et al, , 2010Lindström et al, 2017). The main difficult with non-marine records is that their geochronology is poorly constrained (e.g., Mundil et al, 2010;Irmis et al, 2010).…”