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Cold Plumes Initiated by Rayleigh‐Taylor Instabilities in Subduction Zones, and Their Characteristic Volcanic Distributions : The Role of Slab Dip

Ghosh, Dip; Maiti, Giridas; Mandal, Nibir; Baruah, Amiya

Abstract (englisch):
Dehydration melting in subduction zones often produces cold plumes, initiated by Rayleigh-Taylor instabilities in the buoyant partially molten zones lying above the dipping subducting slabs. We use scaled laboratory experiments to demonstrate how the slab dip (α) can control the evolution of such plumes. For α > 0°, Rayleigh-Taylor instabilities evolve as two orthogonal waves, one trench perpendicular with wavelength λL and the other one trench parallel with wavelength λT (λT > λL). We show that two competing processes, (1) λL-controlled updip advection of partially molten materials and (2) λT/λL interference, determine the modes of plume growth. The λT/λL interference gives rise to an areal distribution of plumes (Mode 1), whereas advection leads to a linear distribution of plumes (Mode 2) at the upper fringe of the partially molten layer. The λT wave instabilities do not grow when α exceeds a threshold value (α* = 30°). For α > α*, λL-driven advection takes the control to produce exclusively Mode 2 plumes. We performed a series of 2-D and 3-D computational fluid dynamics simulations to test the criticality of slab dip in switching the Mode 1 to Mode 2 transition at α*. ... mehr

Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 08.2020
Sprache Englisch
Identifikator ISSN: 2169-9313, 2169-9356
KITopen-ID: 1000140022
Erschienen in Journal of geophysical research / Solid earth
Verlag John Wiley and Sons
Band 125
Heft 8
Seiten e2020JB019814
Vorab online veröffentlicht am 24.07.2020
Nachgewiesen in Scopus
Web of Science
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