Low temperature thermal history and denudation along the Liquiñe-Ofqui Fault Zone in the southern Chilean Andes, 41-42 S

Abstract

Fission track (FT) thermochronology of zircon and apatite combined with structural analyses on deformed rocks was applied to investigate the cooling and denudation history of the Southern Chilean Andes at 41ʿ-42ʿS in relation to the late Cenozoic activity of the Liquiñe-Ofqui Fault Zone (LOFZ). At the Main Range, three different types of intrusives of the North Patagonian Batholith were characterized by their cooling histories: (a) Cretaceous intrusions in the upper crust with rapid initial cooling after emplacement, followed by slow cooling and rapid exhumation along the LOFZ in the late Miocene-Pliocene, (b) Cretaceous to Early Miocene deep intrusions, with steady cooling rates during the Miocene, denuded along the LOFZ in the Late Miocene-Pliocene, (c) Miocene shallow intrusions, distributed over the batholith, and with younger ages towards the LOFZ. The denudation episode is coeval to the arrival and subduction of the Chile Rise beneath the Taitao Peninsula.