IGEBA   23946
INSTITUTO DE GEOCIENCIAS BASICAS, APLICADAS Y AMBIENTALES DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A post Late Cretaceous partial bending of the Patagonian Orocline?.
Autor/es:
RAPALINI, A.; PERONI J. I.; LUPPO, T.; TASSONE A.; CERREDO, M. E.; LIPPAI, H.; VILAS, J. F.
Lugar:
Viña del mar
Reunión:
Congreso; International Congress on the Southern hemisphere (GEOSUR); 2013
Institución organizadora:
Geosur
Resumen:
The southern Andes show a major bending at the southern tip of South America, where the Fuegian
Cordillera shows a nearly E-W trend. This curvature is widely known as the Patagonian Orocline and
whether this is a primary or secondary feature remains controversial. Paleomagnetism is a powerful tool
to determine the primary or secondary origin of curved orogens. Paleomagnetic data along the Patagonian
Orocline are still scarce to provide a reliable and unambiguous answer to this question. In recent years
several paleomagnetic studies, some of them still unpublished, have provided a better and enlarged database
to test the origin of this major curvature. Paleomagnetic data from three Late Cretaceous intrusives in the
Fuegian Cordillera (the Jeujepén, Krank and Santa Rosa plutons) and a dacite exposed neaar Ushuaia show
consistent ccw rotations between 28° and 35°. Meanwhile, four sites on Late Jurassic-Early Cretaceous
metabasalts and metagabbros of the Lemaire Formation exposed at different localities in this range also
show significant counterclockwise rotations (26-50°). A small area of the Santa Rosa pluton, affected by
an E?W sinistral strike-slip fault, however, presented a much larger declination anomaly indicating the
presence of a local tectonic rotation. From these and previous data a picture of a nearly homogeneous post-
Late Cretaceous regional rotation of the Fuegian Cordillera is suggested. This supports a model of nearly
30° of ccw secondary bending of the Patagonian Orocline since the latest Cretaceous (72 Ma). Occasional
larger declination anomalies are likely related to local rotations associated to strike-slip tectonics.