Dissertations and Theses
Date of Award
2019
Document Type
Thesis
Department
Earth and Atmospheric Sciences
First Advisor
Benjamin A. Black
Second Advisor
Steven B. Kidder
Third Advisor
Zhengrong Wang
Keywords
carbonatite, LIP, δ13C
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. 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 ratios. We attribute relatively heavy δ13C ratios 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 negative carbon isotope excursions and mass extinctions.
Recommended Citation
Gales, Ellen, "Carbonatites as a record of the carbon isotope composition of large igneous province outgassing" (2019). CUNY Academic Works.
https://academicworks.cuny.edu/cc_etds_theses/796