TY  - JOUR
A1  - Baes, Marzieh
A1  - Gerya, Taras V.
A1  - Sobolev, Stephan Vladimir
T1  - 3-D thermo-mechanical modeling of plume-induced subduction initiation
JF  - Earth & planetary science letters
N2  - Here, we study the 3-D subduction initiation process induced by the interaction between a hot thermochemical mantle plume and oceanic lithosphere using thermo-mechanical viscoplastic finite difference marker-in-cell models. Our numerical modeling results show that self-sustaining subduction is induced by plume-lithosphere interaction when the plume is sufficiently buoyant, the oceanic lithosphere is sufficiently old and the plate is weak enough to allow the buoyant plume to. pass through it. Subduction initiation occurs following penetration of the lithosphere by the hot plume and the downward displacement of broken, nearly circular segments of lithosphere (proto-slabs) as a result of partially molten plume rocks overriding the proto-slabs. Our experiments show four different deformation regimes in response to plume-lithosphere interaction: a) self-sustaining subduction initiation, in which subduction becomes self-sustaining; b) frozen subduction initiation, in which subduction stops at shallow depths; c) slab break-off, in which the subducting circular slab breaks off soon after formation; and d) plume underplating, in which the plume does not pass through the lithosphere and instead spreads beneath it (i.e., failed subduction initiation). These regimes depend on several parameters, such as the size, composition, and temperature of the plume, the brittle/plastic strength and age of the oceanic lithosphere, and the presence/absence of lithospheric heterogeneities. The results show that subduction initiates and becomes self-sustaining when the lithosphere is older than 10 Myr and the non dimensional ratio of the plume buoyancy force and lithospheric strength above the plume is higher than approximately 2. The outcomes of our numerical experiments are applicable for subduction initiation in the modern and Precambrian Earth and for the origin of plume-related corona structures on Venus. (C) 2016 Elsevier B.V. All rights reserved.
KW  - subduction initiation
KW  - mantle plume
KW  - oceanic lithosphere
KW  - numerical models
Y1  - 2016
U6  - https://doi.org/10.1016/j.epsl.2016.08.023
SN  - 0012-821X
SN  - 1385-013X
VL  - 453
SP  - 193
EP  - 203
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Ishizuka, Osamu
A1  - Hickey-Vargas, Rosemary
A1  - Arculus, Richard J.
A1  - Yogodzinski, Gene M.
A1  - Savov, Ivan P.
A1  - Kusano, Yuki
A1  - McCarthy, Anders
A1  - Brandl, Philipp A.
A1  - Sudo, Masafumi
T1  - Age of Izu-Bonin-Mariana arc basement
JF  - Earth & planetary science letters
N2  - Documenting the early tectonic and magmatic evolution of the lzu-Bonin-Mariana (IBM) arc system in the Western Pacific is critical for understanding the process and cause of subduction initiation along the current convergent margin between the Pacific and Philippine Sea plates. Forearc igneous sections provide firm evidence for seafloor spreading at the time of subduction initiation (52 Ma) and production of "forearc basalt". Ocean floor drilling (International Ocean Discovery Program Expedition 351) recovered basement-forming, low-Ti tholeiitic basalt crust formed shortly after subduction initiation but distal from the convergent margin (nominally reararc) of the future IBM arc (Amami Sankaku Basin: ASB). Radiometric dating of this basement gives an age range (49.3-46.8 Ma with a weighted average of 48.7 Ma) that overlaps that of basalt in the present-day IBM forearc, but up to 3.3 m.y. younger than the onset of forearc basalt activity. Similarity in age range and geochemical character between the reararc and forearc basalts implies that the ocean crust newly formed by seafloor spreading during subduction initiation extends from fore-to reararc of the present-day IBM arc. Given the age difference between the oldest forearc basalt and the ASB crust, asymmetric spreading caused by ridge migration might have taken place. This scenario for the formation of the ASB implies that the Mesozoic remnant arc terrane of the Daito Ridges comprised the overriding plate at subduction initiation. The juxtaposition of a relatively buoyant remnant arc terrane adjacent to an oceanic plate was more favourable for subduction initiation than would have been the case if both downgoing and overriding plates had been oceanic. (C) 2017 The Authors. Published by Elsevier B.V.
KW  - subduction initiation
KW  - Izu-Bonin-Mariana arc
KW  - arc basement
KW  - Ar-40/Ar-39 age
Y1  - 2017
U6  - https://doi.org/10.1016/j.epsl.2017.10.023
SN  - 0012-821X
SN  - 1385-013X
VL  - 481
SP  - 80
EP  - 90
PB  - Elsevier
CY  - Amsterdam
ER  -