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.