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Abstract The mainly deep-submarine Ontong Java Plateau (OJP) is the result of the largest outpouring of lava in the geologic record. Volcanic events of this magnitude can have dramatic environmental impacts due to volatile emissions. We report new S measurements in naturally glassy, olivine-hosted melt inclusions and pillow basalt glasses from the OJP. We combined these data with previous S measurements in OJP glasses to quantify S degassing in a suite of OJP glasses. Comparison with an S degassing model suggests OJP lavas that erupted at depths ~>1500 m did not degas S; OJP lavas that erupted at depths ~<1500 m degassed up to ~40% initial S, but these lavas likely made up a small fraction of OJP lavas. This result suggests that despite its large volume compared to continental large igneous provinces (LIPs), OJP lavas emitted less S, potentially contributing to its muted environmental impact. The OJP may provide a framework for the temporal evolution of S degassing at oceanic LIPs, with early eruptions at great water depths releasing limited to no S, and later eruptions at shallow water depths releasing larger, but still limited amounts of S. This framework may also have implications for continental LIP magmas, which may release significant amounts of CO2 but limited amounts of S during intrusive activity, with magmatic S emissions only becoming important during extrusive phases. 

Emplacement of the Siberian Traps large igneous province (LIP) around 252 Ma coincided with the most profound environmental disruption of the past 500 million years. The enormous volume of the Siberian Traps, its ability to generate greenhouse gases and other volatiles, and a temporal coincidence with extinction all suggest a causal link. Patterns of marine and terrestrial extinction/recovery are consistent with environmental stresses potentially triggered by the Siberian Traps. However, the nature of causal links between the LIP and mass extinction remains enigmatic. Understanding the origins, anatomy, and forcing potential of the Siberian Traps LIP and the spatiotemporal patterns of resulting stresses represents a critical counterpart to high-resolution fossil and proxy records of Permian–Triassic environmental and biotic shifts. This review provides a summary of recent advances and key questions regarding the Siberian Traps in an effort to illuminate what combination of factors made the Siberian Traps a uniquely deadly LIP.