Cretaceous large igneous provinces: from volcanic formation to environmental catastrophes and biological crises

The Cretaceous Period was marked by the formation of numerous large igneous provinces (LIPs), several of which were associated with geologically rapid climate, environmental and biosphere perturbations, including the early Aptian and latest Cenomanian oceanic anoxic events (OAEs 1a and 2, respectively). In most cases, magmatic CO2 emissions are thought to have been the major driver of climate and biosphere degradation. This work summarizes the relationships between Cretaceous LIPs and environmental perturbations, focusing on how volcanism caused climate warming during OAE 1a using osmium-isotope and mercury concentration data. The new results support magmatic CO2 output from submarine LIP activity as the primary trigger of climate warming and biosphere stress before/during OAE 1a. This submarine volcanic trigger of OAE 1a (and OAE 2), two of the most climatically/biotically severe Cretaceous events, highlights the capacity of oceanic LIPs to impact Earth's environment as profoundly as many continental provinces. Cretaceous magmatism (and likely output of CO2 and trace-metal micronutrients) was apparently most intense during those OAEs; further studies are needed to better constrain the eruption histories of those oceanic plateaus. Another open question is why the Cretaceous Period overall featured a higher rate of magmatic activity and LIP formation compared with before and afterwards.