Discovery of a major negative δ13C spike in the Carnian (Late Triassic) linked to the eruption of Wrangellia flood basalts

Jacopo Dal Corso*, Paolo Mietto, Robert J. Newton, Richard D. Pancost, Nereo Preto, Guido Roghi, Paul B. Wignall

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

80 Citations (Scopus)

Abstract

Major climate changes and mass extinctions are associated with carbon isotope anomalies in the atmosphere-ocean system and have been shown to coincide with the onset of large igneous provinces (LIPs) and, by association, their emissions of greenhouse gases and aerosols. However, climatic and biological consequences of some known LIP eruptions have not yet been explored. During the Carnian (Late Triassic) large volumes of flood basalts were erupted to form the so-called Wrangellia LIP (western North America). This huge volcanic province is similar in age to a major climatic and biotic change, the Carnian Pluvial Event (CPE), but no evidence of a causal relationship exists other than timing. Here we report a sharp negative δ13C excursion at the onset of the CPE recorded in organic matter. An abrupt carbon isotope excursion of ~-4% occurs in terrestrial and marine fossil molecules, whereas total organic carbon records an ~-2% shift. We propose that this carbon isotope negative shift was caused by an injection of light carbon into the atmosphere-ocean system linked to the eruption of Wrangellia flood basalts. This carbon-cycle perturbation occurs slightly before two major evolutionary innovations: the origin of dinosaurs and calcareous nannoplankton.

Original languageEnglish
Pages (from-to)79-82
Number of pages4
JournalGeology
Volume40
Issue number1
DOIs
Publication statusPublished - 1 Jan 2012

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