Carbonatites as a record of the carbon isotope composition of large igneous province outgassing

Ellen Gales, Benjamin Black, Linda T. Elkins-Tanton

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Large igneous province (LIP) eruptions have been linked in some cases to major perturbations of Earth's carbon cycle. However, few observations directly constrain the isotopic composition of carbon released by LIP magmas because carbon isotopes fractionate during degassing, which hampers understanding of the relative roles of mantle versus crustal carbon reservoirs. Carbonatite magmatism associated with LIPs provides a unique window into the isotopic systematics of LIP carbon because the majority of carbon in carbonatites crystalizes rather than degassing. Although the volume of such carbonatites is small, they offer one of the few available constraints on the mantle carbon originally hosted in other more voluminous magma types. Here, we present new δ13C data for the Guli carbonatites in the Siberian Traps. In addition, we compile ∼260 published measurements of δ13C from carbonatites related to the Deccan Traps and the Paraná-Etendeka. We find no evidence for magmas with carbon isotope ratios lighter than depleted mantle values of δ13C=−6±2‰ from any of these LIPs, though some carbonatites range to heavier δ13C. We attribute relatively heavy δ13C in some carbonatites to either slightly 13C-enriched domains in the mantle lithosphere or carbon isotope fractionation in deep, carbon-saturated LIP magma reservoirs. The absence of a light δ13C component in LIP magmas supports the view that lithospheric carbon reservoirs must be tapped during cases of LIP magmatism linked with sharp negative carbon isotope excursions and mass extinctions.

Original languageEnglish (US)
Article number116076
JournalEarth and Planetary Science Letters
Volume535
DOIs
StatePublished - Apr 1 2020

Keywords

  • Siberian Traps
  • carbon cycle
  • carbonatite
  • large igneous province
  • δC

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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