Quantifying volcanism and organic carbon burial across Oceanic Anoxic Event 2

Abstract

Oceanic Anoxic Event 2 (ca. 94 Ma; OAE2) was one of the largest Mesozoic carbon cycle perturbations, but associated carbon emissions, primarily from the Caribbean large igneous province (LIP) and marine burial fluxes, are poorly constrained. Here, we use the carbon cycle box model LOSCAR-P to quantify the role of LIP volcanism and enhanced marine organic carbon (Corg) burial as constrained by the magnitude and shape of the positive stable carbon isotope (δ13C) excursion (CIE) in the exogenic carbon pool and atmospheric pCO2 reconstructions. In our best fit scenario, two pulses of volcanic carbon input—0.065 Pg C yr–1 over 170 k.y. and 0.075 Pg C yr–1 over 40 k.y., separated by an 80 k.y. interval with an input of 0.02 Pg C yr–1—are required to simulate observed changes in δ13C and pCO2. Reduced LIP activity and Corg burial lead to pronounced pCO2 reductions at the termination of both volcanic pulses, consistent with widespread evidence for cooling and a temporal negative trend in the global exogenic δ13C record. Finally, we show that observed leads and lags between such features in the records and simulations are explained by differences in the response time of components of the carbon cycle to volcanic forcing