Subduction initiation at the Soloman back-arc basin: Contributions from
both island arc rheological strength and oceanic plateau collision
Abstract
It is generally accepted that the subduction polarity reversal (SPR)
results from the strong collision of two plates. Yet, the SPR of the
Solomon Back-arc Basin is started in the “soft docking” stage, and the
mechanism by which the “soft docking” induced subduction initiation
(SI) remains elusive. We find that the mass depletion of the plateau
influences the evolution of the subduction patterns during SI. And the
island arc rheological strength affects the development of the shear
zone between an island arc and back-arc basin which favors SI. What’s
more, with the increase of the rheological strength difference, the SI
is more easily to occur, and the contribution of the plateau collision
to SI weakens. Hence, by combining the available geological evidence, we
suggest that the Solomon Island Arc rheological strength and the
Ontong-Java plateau collision jointly controlled the SI during the
“soft docking” stage.