Cretaceous to Cenozoic denudation, tectonics and mass transfer at the South Chilean active continental margin (37°S - 42°S): the apatite fission track perspective

Apatite fission track analysis is applied to study the Cretaceous to Recent tectonic, thermal and denudational history of the active South-Central Chilean continental margin (37°S-42°S). Apatite fission track (FT) ages from the fore-arc (Coastal Cordillera) and the magmatic arc (Main Cordillera) are presented. First, preliminary apatite FT data suggest that only minor basal accretion and corresponding exhumation took place in the forearc since the Late Cretaceous. In the magmatic arc, the apatite FT data imply a significant decrease on denudation from S to N. At ca. 40°S, Pliocene and Quaternaiy denudation is as rapid as about 1 km/Ma, whereas further north at ca. 38°30 'S, denudation rates are lower by nearly an order ofmagnitude. We suggest a climatic control on the denudation pattern. The apatite FT data also indicate that no significant vertical displacements took place along the Gastre Fault Zone since the Late Cretaceous and along the Liquihe-Ofqui Fault Zone since the Pliocene.