Processes and Timescales of Magma Genesis and Differentiation Leading to the Great Tambora Eruption in 1815

Abstract

The cataclysmic eruption of Tambora volcano (Sumbawa, Indonesia) in 1815 has long been recognized as one of the largest explosive eruptions in historical time. It yielded extensive pyroclastic deposits from the emptying of a 30–33 km3 trachyandesite (latite)–tephriphonolite (herein referred to as trachyandesite) magma body. The parental trachybasalt magma of the trachyandesite erupted in 1815 can be produced by ~2% partial melting of a garnet-free, Indian-type mid-ocean ridge basalt (I-MORB)-like mantle source contaminated with ~3% fluids from altered oceanic crust and 8000 years old) provide physical evidence for incorporation of ‘antecrystic’ material into the 1815 magma. Magma accumulation and differentiation at shallow depth prior to the eruption were accompanied by continuous degassing of sulphur (and other volatile species), which is thought not to have accumulated within or towards the top of the magma reservoir to contribute to the volatile budget of the eruption, but to have escaped to the surface passively through the permeable wall rocks.