About this Research Topic
Subduction zones occur where tectonic plates converge, and denser, underthrust lower plate materials are recycled to varied extents back into the Earth’s mantle. Modern subduction zones are associated with significant seismic activity in response to plate convergence, and with distinctive magmatic activity that produces volcanic arcs (e.g., the Pacific ‘Ring of Fire’) and associated intrusive complexes. Subduction-related magmatic processes commonly are viewed as contributing to the formation of continental crust over geologic time. Thus, knowledge of how subduction zones work is fundamental to understanding important aspects of Earth’s evolution, including how and to what extent the recycling of subducted materials (e.g., oceanic crust and sediments) over time has affected the composition of the Earth’s mantle. Important direct sources of such information comes from investigations of (1) the magmatic and fluid outputs in volcanic arcs, and (2) exposed sections of uplifted subduction terranes.
This Research Topic focuses on the physical and chemical processes associated with subduction, with an emphasis upon the record that can be deduced directly from the magmatic products in modern volcanic arcs, and from subduction-related rocks and associated fluids that may be reflective of the fluid and material contributors to subduction-related magmatism. Such information provides an essential foundation upon which realistic petrogenetic and physical models can be further developed and evaluated. Several key questions merit further evaluation. To what extent is the nature of arc magmatism controlled by competing tectonic processes, versus variations in compositions of arc magma sources? In what ways are magmatic sources established, and what are the processes that are involved? What tools are at our disposal to fully track the role of H2O and other volatiles through the arc magmatic cycle, from source to eruption? What roles do volatile species other than H2O play in arc magmatic systems? Also, in detail, what is the interplay of subducted fluids and volatiles (directly, via hydrous minerals, or via melts) and other material components in the production and evolution of arc magmas? And how and to what extent are these components extracted from subducted materials and adjacent mantle domains?
The validity and utility of different geochemical parameters in tracing and quantifying the role of water and other fluid phases in subduction related environments are of utmost importance. Research contributions are especially welcome that provide insights into the geochemistry and timing of fluxes of water and other volatiles and their solute components in subduction-related magmas, into how these fluxes develop and evolve through the life of an arc system and the underlying mantle wedge, and into their linkages to processes of melt generation and volcanism. Likewise we welcome contributions that pertain to the fate of recycled components and their impact on overall mantle evolution, and on the involvement of subduction-modified lithospheric mantle and crust on subsequent magmatic activity. We stress the importance of understanding (1) what gets recycled into the mantle, and (2) how arc magmatism likely modifies portions of the lithospheric mantle and crust.
Keywords: subduction complexes, mantle wedge, fluid-mobile elements, element transfer, magma sources
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