PINNING DOWN THE REAL CULPRIT: INTEGRATING DATASETS TO DETERMINE THE DEADLIEST ATTRIBUTE(S) OF LIP MAGMATISM (Invited Presentation)
Recent datasets permit assessment of these questions, as the onset, duration, and tempo of coupled mass extinction and LIP events are well constrained, as is the temporal relationship between magmatism, global chemical cycles, and the biosphere. Here we focus on the end-Permian couplet, wherein the initial phase of LIP magmatism was characterized by primarily effusive eruptions, which generated ~2/3 of the total extrusive volume and began ~300 kyr prior to the onset of extinction. Extrusion halted for ~500 kyr during and after the mass extinction event. A dearth of shallow sills existed prior to the onset of mass extinction, but widespread sill intrusion coincided with cessation of extrusive magmatism and onset of mass extinction, continuing unabated for ~500 kyr. Given these associations, we posit that the thick LIP lava section provided a lithospheric barrier to magma ascent, thereby shifting the primary emplacement mechanism from extrusion to intrusion. This change significantly increased the volume of volatile-rich sediments with which LIP magmas were in contact. Massive volumes of greenhouse gases generated and released via contact metamorphism subsequently drove atmospheric change and biosphere collapse.