Abstract
Volatile elements outgassing into the environment from active volcanoes and volcanic systems can act as important nutrients and/or pollutants. Yet, previous estimates of the global flux of volatiles from volcanic systems focused primarily on mid-ocean ridges and arc volcanic systems, neglecting the numerous hotspot volcanic chains across the globe. Here, we take advantage of newly estimated hotspot volcanic effusion rates along 12 oceanic hotspot chains covering >80 Ma of Earth history to estimate the hotspot trace element degassing flux through time. Our calculation brings together three data sets including: 1) recent estimates of erupted lava effusion rates (i.e., lavas emplaced atop pre-existing oceanic crust and contributing directly to edifice construction), 2) mean concentrations of approximately 50 trace elements in erupted lavas at each hotspot, and 3) emanation coefficients that approximately quantify the mass transfer of each element from the melt to the vapor phase prior to solidification. Using a model of volcano height incorporating elastic flexure as a function of plate age and volcano volume, we estimate that approximately 80% of trace element degassing occurs during submarine eruptions yielding new constraints on the hotspot volcanic contribution to ocean chemistry and estimates of the gradual depletion of the Earth's mantle over geologic time. Our summed estimates suggest that the fluxes from hotspots into the oceans for several trace elements are comparable to modern anthropogenic atmospheric fluxes from countries such as Italy, the United States, and China. We will discuss the implications of these estimates to pre-industrial element cycling in the context of an extrapolation of trace element fluxes to worldwide hotspot volcanic chains.