New paleomagnetic pole for the Upper Jurassic Chon Aike Formation of southern Argentina (South America): Testing the tectonic stability of Patagonia with respect to South America, and implications to Middle Jurassic-Early Cretaceous true polar wander

RUIZ GONZÁLEZ, VÍCTOR; PUIGDOMENECH, CARLA G.; RENDA, EMILIANO M.; BOLTSHAUSER, BÁRBARA; SOMOZA, RUBÉN; VIZÁN, HAROLDO; ZAFFARANA, CLAUDIA B.; TAYLOR, GRAEME K.; HALLER, MIGUEL; FERNÁNDEZ, RAÚL

TECTONOPHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019 vol. 750 p. 45 - 55

0040-1951

A paleomagnetic pole and a new Ar-Ar date of 156.08 ± 0.05 Ma are reported for the Chon Aike Formation, anextensive plateau of ignimbrites, outcropping in the Deseado Massif (southern Patagonia, Argentina). Thegeographic coordinates and statistical parameters for the paleomagnetic pole, validated by a reversal test, are:Lat.=84.3° S, Long.=191.3° E, A95=8.6°, K=13.3, N=23. This pole shows a complete coherence with LateJurassic and Early to mid-Cretaceous poles of South America, obtained exclusively from igneous rocks, avoidingany potential inclination shallowing. It is suggested that; a) southern Patagonia was an integral part of SouthAmerica in the Late Jurassic; b) any reported vertical axis tectonic rotations must pre-date the Late Jurassic inthis region; c) according to updated paleomagnetic data from igneous rocks, South America had very limitedlatitudinal drift between about 160 and 140 Ma; and, therefore, d) its apparent polar wander (APW) path, whencompared with global apparent polar wander paths, does not support a large global shift or true polar wander(TPW) between 160 and 140 Ma.