Volcanogenic Sedimentation in the Lesser Antilles Arc

Abstract

Combination of deep-sea coring and land-based studies has provided a quantitative view of volcano genic sediments in and around the Lesser Antilles arc in the late-Quaternary. Of the total of $$527 km^{3}$$ of volcanics produced in the arc in the last $$10^{5}$$ years, over 80% has been deposited as volcanogenic sediments in the adjacent marine basins as ash-fall layers, pyroclastic debris flow deposits and volcanic sands. Over 70% of total volcanogenic sedimentation from the arc is received by the back-arc Grenada Basin west of the arc in the form of sediment gravity flows. The volumetric role of ash-fall layers is thus relatively small. Approximately 40% of the ash-fall in the Atlantic is dispersed in the sediment. The asymmetric distribution of volcanogenic sediments around the arc, with pyroclastic debris flow deposits predominating west of the arc and ash-fall layers in the Atlantic east of the arc, is attributed to the effects of prevailing high-altitude wind direction, different submarine arc slope and ocean currents. The magma production rate in the arc during the last $$10^{5}$$ years is approximately $$0.1 m^{3}/sec$$ Magma generation in this period has taken place along 400 km of arc and thus the eruption rate in this arc (excluding intrusions) amounts to $$7 km^{3}$$ per km of arc per million years.