Characterizing Crustal Magmatic Processes Through Volcanic Gas Geochemistry

Abstract:

The composition and flux of volcanic gases can provide near-real-time insight into crustal magmatic processes. Due to their low density, volcanic gases can ascend to the surface in advance of their host magma, and provide near-real-time information on subsurface conditions. Volcanic gas observations can elucidate processes occurring at deep (subduction) to shallow (volcanic conduit) scales, and can be used to help forecast the occurrence, timing and style of volcanic eruptions. These crustal processes can be inferred from volcanic gas data largely due to the solubility differences (in both silicate melts and water) and the isotopic signatures of common volcanic gases such as carbon dioxide, sulfur dioxide, hydrogen sulfide, and helium. The chemical and isotopic composition and flux of volcanic gases can be used to: (1) identify magma recharge and track magma ascent, (2) identify the presence of a hydrothermal system and track its evolution, (3) assess conduit permeability, (4) estimate the volume/mass of degassing magma, and (5) help forecast the most likely eruption style (i.e. distinguish between magmatic and phreatic triggers). This submission reviews the ways in which volcanic gas data can be used as a near-real-time tool for tracking crustal magmatic processes that lead to volcanic eruptions.