Abstract

The Cordillera Darwin orogenic core complex is a structural and topographic culmination in the southern Andes, which underwent mid-Cretaceous penetrative deformation and metamorphism associated with the deformation and incipient obduction of a partly ophiolitic back-are basin (Rocas Verdes) block along its southern boundary. Whereas structural evidence suggests uplift of the Rocas Verdes terrane relative to the Cordillera Darwin during this event, metamorphic assemblages reflect a greater net uplift of the opposite sense. New fission track ages together with existing K-Ar and Rb-Sr ages were used to estimate cooling and uplift histories and their relationships to foreland sedimentation and present-day topographic relief. The results suggest that, whereas initiation of uplift in the Cordillera Darwin and Rocas Verdes blocks may have accompanied mid-Cretaceous deformation, the major, rapid uplift (around 0.5–1.5 mm/y) occurred after the deformation. Also, uplift occurred earlier in the Rocas Verdes block than in the Cordillera Darwin block, the latter having experienced a greater net uplift since the mid-Cretaceous. The major, post-tectonic uplift of the Cordillera Darwin occurred at a slower rate (0.05–0.20 mm/y) and coincides with the deposition of thick flysch and conglomerates in the foreland basin

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.