Dynamic Magma Evolution / Динамическая эволюция магмы

Редактор(ы):Vetere F.
Издание:Wiley, 2021 г., 210 стр., ISBN: 978-111-952-1136
Dynamic Magma Evolution / Динамическая эволюция магмы

The rates and timescales of crustal magma transfer, storage, emplacement, and eruption are a key to understanding subvolcanic processes, characterizing volcanic hazards, and developing mitigation strategies. In this chapter, we review the most pertinent open questions in this field, as well as the many geochemical and geophysical methods that are available to address these questions. Results point to long storage timescales, of up to ~106 years, in deep (i.e., ~20–30 km), crustal hot zones. Estimated ascent velocities from deep reservoirs to shallower systems span a vast range of ~10 orders of magnitude, and are a function of the thermophysical parameters of the ascending magma (e.g., density, viscosity, and overpressures in the reservoirs) and the host rocks. At mid‐ to upper crustal levels (i.e., < 15–20 km), we elucidate the cold storage of magma mushes for long periods, which can be unlocked during short‐term events to form ephemeral magma chambers. Unlocking timescale estimates range from minutes to thousands of years, indicating a variability of about ~8 to ~10 orders of magnitude. This large variation results from the interplay among many processes, often nonlinearly coupled, occurring before an eruption. For example, exsolved volatile species have a significant role in modulating preeruptive dynamics and relative timescales; they increase the buoyancy of magmas, affect phase equilibria, promote convective dynamics, and may ultimately trigger eruptive events. As a consequence, understanding the role of volatiles in subvolcanic magmatic processes, including ascent rates, storage mechanisms, and relative timescales, will be paramount for future studies. <...>

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