Continental and island arc segmentation: Implications for retro-arc and pro-arc foreland basin and backarc basin geometries and sediment distributions

Abstract

Segmented magmatic arcs create arc-parallel variable loads and influence associated foreland basins through flexural isostasy along strike, in addition to standard subduction-perpendicular foredeep/forebulge/backbulge models. Segmentation occurs in both continental and island arcs (Aleutians, Calabria, Japan, Kuril/Kamchatka, Lesser Antilles, Solomon Islands and Sumatra/Java). Some segments have variable gravity anomalies and elastic thicknesses (Te). In standard theory, the load created by an orogenic belt/magmatic arc depresses the lithosphere modelled as a thin elastic plate floating on a fluid mantle substrate, leading to an arc-perpendicular foredeep, forebulge and backbulge. Arc-parallel topographic and gravitational features should influence loading along strike in a similar way, resulting in a checkerboard pattern of foredeeps, forebulges and backbulges in both pro-arc and retro-arc foreland basins. This pattern exercises profound controls on sediment and facies distribution in a here-to-fore un-envisaged manner, with implications for resource exploration in foreland basins.