Quantifying volcanism and organic carbon burial across Oceanic Anoxic Event 2

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 (C_org) 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 C_org 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.