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Titel |
Thermal effects of metamorphic reactions in a three-component slab |
VerfasserIn |
Zurab Chemia, David Dolejš, Gerd Steinle-Neumanna |
Konferenz |
EGU General Assembly 2010
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 12 (2010) |
Datensatznummer |
250036637
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Zusammenfassung |
Thermal evolution of a subducting crust is of primary importance for understanding physical
properties, phase transformations, fluid migration and melting regimes at convergent plate
boundaries. Various factors influencing the thermal structure of a subduction zone have been
considered previously: age, geometry and rate of subducting lithosphere, shear stress across
the subduction interface, radioactive heating, etc. Recently, emphasis has been placed on
significant heating of the slab due to rheologically favourable convection in the mantle
wedge. However, substantial heat production or consumption can occur due to metamorphic
reactions, including endothermic devolatilization. We investigate enthalpy budget in a
subducting slab using a self-consistent thermodynamic model. Petrological model of a
subducting slab consists of three layers: oceanic subducting sediment (GLOSS), oceanic
basalt (OB), and moderately serpentinized harzburgite (SHB). These layers are
examined over the range of pressure-temperature conditions of interest by computing
metamorphic phase diagrams and retrieving whole-rock thermodynamic properties. Our
results suggest that metamorphic reactions consume a significant amount of slab heat
budget and induce substantial cooling. In contrast to previous thermal models of
subduction zones, actual slab temperatures may be lower by as much as 250 -C. |
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