Abstract
Southeast Asia lies within one of the most complex tectonic settings on Earth and exhibits a range of features, including strongly curved subduction zones, arc-continent collision, and slab break-off, which are not well understood. To help gain insight into mantle structure and processes beneath this region, we perform an inversion for variations in V-p, V-s, and V-p/V-s structure using arrival time information from the ISC-EHB catalog. The oceanic lithosphere subducting beneath Java is imaged as a positive dV(p) and negative d(V-p/V-s) anomaly. At 200 km depth, the forearc mantle beneath Sumatra and Java is revealed by positive dV(p) and d(V-p/V-s) anomalies which cease at Sumba island, where negative d(V-p/V-s) anomalies mark the presence of cold Australian lithosphere (down to 200-250 km depth) which is colliding with Sundaland. These negative d(V-p/V-s) anomalies depict a similar to WE trending structure that appears to correspond with the underthrusting of Australian continental crust. One notable salient has a location and shape which appears to coincide with those of ancient terranes or a Gondwana-related microcontinent reconstructed by paleogeographic studies and may have been entrained in the subduction process. The velocity and d(V-p/V-s) patterns beneath the Banda Arc support the existence of a single curved subducting slab associated with rollback. The extreme extensional strike-slip setting in Seram produces the highest positive d(V-p/V-s) anomalies in the model which may be due to one or more of widespread serpentinization, high concentrations of intraslab fluid-filled faulting, and mantle upwelling.
Original language | English |
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Article number | e2019JB019152 |
Journal | Journal of Geophysical Research: Solid Earth |
Volume | 125 |
Issue number | 5 |
Early online date | 14 May 2020 |
DOIs | |
Publication status | Published - May 2020 |
Bibliographical note
Open Access via Jisc Wiley agreementKeywords
- tomography
- traveltime
- SE Asia
- joint inversion
- vp/vs
- V /V
- UPPER-MANTLE TEMPERATURES
- TOMOGRAPHY
- PLATE-TECTONICS
- SUBDUCTION ZONE
- INDONESIA EVIDENCE
- SEISMIC VELOCITIES
- TELESEISMIC TRAVEL-TIME
- EASTERN INDONESIA
- DEPTH
- BENEATH