Abstract

During the Pliocene, subduction of the Chile ridge beneath the South American margin was coeval with the emplacement of the Cabo Raper pluton located at the seaward edge of the Taitao peninsula. The chemical characteristics of the Cabo Raper pluton combined with the available tectonic data allow us to reconstruct the paleogeometry of the Chile margin 3–4.2 m.y. ago. When compared to the modern configuration, the volume of material removed by subduction erosion can be estimated quantitatively. From 3–4.2 to 1.5–1.6 Ma, 625 km3 of rock were removed along each kilometre of margin along the Taitao peninsula transect. This leads to a conservative subduction-erosion rate of 231–443 km3ċkm−1ċm.y.−1, significantly higher than those calculated along the Japan and Peru convergent margins. It is proposed that subduction of the Chile ridge contributes fluids in addition to the subducted sediment, resulting in a higher rate of subduction erosion.

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