Re-evaluating plume-induced uplift in the Emeishan large igneous province

Numerical and fluid dynamic modelling predicts that mantle plumes should generate a broad domal uplift (>1,000 km wide, 500 to 1,000 m high) preceding volcanism in large igneous provinces. The Emeishan large igneous province (southwest China) has been offered as the best example of plume-induced uplift, where kilometre-scale pre- and syn-volcanic relief was interpreted to develop in response to the impingement of a plume head. Here, we document voluminous mafic hydromagmatic deposits and submarine extrusions that formed during the initiation and early stages of the Emeishan large igneous province: these deposits were previously interpreted to be alluvial fan sediments shed from a pre-volcanic domal high. The abundance of such deposits—consisting of variable proportions of marine limestone and basaltic fragments—strongly suggests that the bulk of this province was emplaced at sea level. Evidence for dynamic pre-volcanic uplift as predicted by plume models is lacking, and such a lack may be the more general case. Any positive relief that developed was more likely the result of the formation of a volcanic edifice and rapid accumulation of the volcanic pile.