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Fate of Forearc Lithosphere at Arc‐Continent Collision Zones: Evidence From Local Earthquake Tomography of the Sunda‐Banda Arc Transition, Indonesia
Author(s) -
Supendi P.,
Nugraha A. D.,
Widiyantoro S.,
Abdullah C. I.,
Rawlinson N.,
Cummins P. R.,
Harris C. W.,
Roosmawati N.,
Miller M. S.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl086472
Subject(s) - forearc , geology , subduction , seismology , lithosphere , volcanic arc , transition zone , seismic tomography , magma , volcano , island arc , collision zone , convergent boundary , oceanic crust , geophysics , tectonics , mantle (geology)
A new 3‐D seismic P wave velocity model of the Sunda‐Banda Arc Transition from local earthquake tomography reveals (i) northward subduction of oceanic lithosphere, associated with the convergence of Australia and Sundaland, as a high‐velocity zone extending down to ~200 km depth; (ii) two distinct low‐velocity zones, one immediately above the slab, which is likely a zone of partial melt, and one in the 0–40 km depth range, which is probably a magma chamber associated with active volcanoes above; and (iii) a northerly dipping high‐velocity zone that bisects the two low‐velocity anomalies, which we interpret as an underthrust forearc sliver of continental origin. Based on He 3 /He 4 measurements from volcanic outflows, it is possible that the magma supply is contaminated by interaction with this forearc sliver as it ascends from the melt region below.