Cenozoic denudation of Corsica in response to Ligurian and Tyrrhenian extension: Results from apatite fission track thermochronology

摘要

The island of Corsica (France) occupies a unique position in the western Mediterranean, since it has recorded both the Cenozoic Alpine orogenic history of the area as well as subsequent extensional collapse and oceanic basin formation. We present 41 new apatite fission track (AFT) ages and 23 measurements of track length distributions from Corsica, in order to elucidate its Cenozoic thermal and morphological evolution. AFT ages vary from 10.5 +- 0.8 Ma to 53.8 +- 4.1 Ma and form a clear spatial pattern: oldest ages are encountered in the southwest of the island, with a broad band of ages between 20 and 30 Ma running across the mountainous central area and ages <20 Ma confined to the eastern half of the island. Samples along the western and northwestern coasts record kilometer-scale erosional denudation linked to rifting in the Ligurian-Provencal basin, whereas samples from close to the extensionally inverted Alpine deformation front record a later cooling phase related to Tyrrhenian extension. The eastward younging pattern of AFT ages suggests the migration of a "wave" of erosional denudation from west to east across the island, apparently controlled by the migrating locus of extension. Our AFT data therefore support models of Mediterranean extension controlled by slab rollback.