Paleomagnetism of Mesozoic magmatic units of the Fuegian Cordillera: Implications for the Patagonian Orocline

AUGUSTO E. RAPALINI; JAVIER PERONI; TOMÁS LUPPO; ALEJANDRO TASSONE; MARÍA ELENA CERREDO; FEDERICO ESTEBAN; HORACIO LIPPAI; JUAN FRANCISCO VILAS

GEOLOGICAL SOCIETY OF LONDON SPECIAL PUBLICATION

The Geological Society

Lugar: Londres; Año: 2015 vol. 425 p. 101 - 116

0305-8719

It is not known whetherthe Patagonian Orocline, i.e. the major bend of the southern Andes at thesouthern tip of South America, is a primary or secondary feature. Paleomagneticdata along the Patagonian Orocline are still too scarce to provide a reliable andunambiguous answer to this question. New paleomagnetic results on Late Jurassicto Late Cretaceous magmatic units along the central segment of the FuegianCordillera are reported. Data from four Late Cretaceous small intrusions andthree sites on Late Jurassic-Early Cretaceous metabasalts and metagabbros showedcounterclockwise (ccw) declination deviations between 21° and 46° with respectto South America. From these and previous data a picture of a nearlyhomogeneous post-Late Cretaceous regional rotation of the central FuegianCordillera is suggested. This supports a model of nearly 30° of ccw secondarybending of the Patagonian Orocline since the Late Cretaceous (72 Ma). Lack ofrotation of post-50 Ma sedimentary rocks exposed to the north of our studyregion, and larger rotations (of around 90°) reported to the south of itsuggest that a geographical and/or temporal progression of rotation values fromsouth to north in the Fuegian part of the Patagonian Orocline should beinvestigated.