Palaeomagnetism of Mesozoic magmatic bodies of the Fuegian Cordillera: implications for the formation of the Patagonian Orocline

PERONI J. I.; CERREDO M.E.; VILAS J.F.; LUPPO T.; ESTEBAN F.; RAPALINI A.; TASSONE A.; LIPPAI H.

GEOLOGICAL SOCIETY OF LONDON SPECIAL PUBLICATION

The geological society

Lugar: Londres; Año: 2016 vol. 425 p. 65 - 80

0305-8719

It is not known whether the Patagonian Orocline, the major bend of the southern Andesat the southern tip of South America, is a primary or secondary feature. Palaeomagnetic data alongthe Patagonian Orocline are still too scarce to provide a reliable and unambiguous answer to thisquestion. New palaeomagnetic results on Late Jurassic?Late Cretaceous magmatic units along thecentral segment of the Fuegian Cordillera are reported. Data from four Late Cretaceous small intrusionsand three sites on Late Jurassic?Early Cretaceous metabasalts and metagabbros showedanticlockwise declination deviations between 218 and 468 with respect to South America. Fromthese and previous data, a picture of a nearly homogeneous post-Late Cretaceous regional rotationof the central Fuegian Cordillera is suggested. This supports a model of nearly 308 of anticlockwisesecondary bending of the Patagonian Orocline since the Late Cretaceous (72 Ma). Lack of rotationof post-50 Ma sedimentary rocks exposed to the north of our study region, and larger rotations (of c.908) reported to the south of it suggest that a geographical and/or temporal progression of rotationvalues from south to north in the Fuegian part of the Patagonian Orocline should be investigated.