Geology of the western coast of Bahía Aguirre (Península Mitre), southeastern Tierra del Fuego, Argentina.

Abstract

New field data from the western coast of Bahía Aguirre in southeastern Tierra del Fuego provide the basis for characterizing five volcanic, volcaniclastic, and sedimentary facies of the Lemaire Complex (Middle Jurassic–Berriasian), as well as a mylonitic rock developed on granite of unknown age, and sedimentary facies of the Beauvoir Formation (Lower Cretaceous), previously assigned either to the Lemaire Complex or the Yahgan Formation. The results of this study refine previous geological maps and introduce new information on the facies of the Lemaire Complex, including the first description of carbonate rocks within the unit. A detailed structural
analysis reveals a deformation sequence comprising an initial stage of ductile deformation contemporaneous with low-grade metamorphism,
overprinted by a later, more brittle deformation marked by thrust faulting. Both deformation stages are consistent with the known Late Cretaceous–Paleogene tectonic evolution of the Fuegian region.