Abstract

JAPAS, María S. et al. Kinematics of the Jurassic extension linked to the Chon Aike Siliceous Province, Santa Cruz province, Argentina. Rev. Asoc. Geol. Argent. [online]. 2013, vol.70, n.1, pp.16-30. ISSN 0004-4822.

Bracketed between 188-152 Ma, the Chon Aike Silicic Province developed in Patagonia covering an area of about 1,7 x 10⁶ km² with volcanic products. An extensional tectonic regime that was active since at least the Jurassic-Cretaceous boundary accompanied this volcanic megaevent. Kinematic analyses focused in four selected localities (El Dorado - Monserrat, Norte de Cerro Vanguardia and El Fénix, in the Deseado region; and Lago Ghío, in the southern Patagonian Cordillera) allowed to define the main kinematic axes and to recognize two different kinematic events (a main and a secondary ones). Additionally these data certified the transtensional character of the Jurassic deformational event. When comparing directions of kinematic axes of all the selected localities, two kinematic domains: west and east could be discriminated. Whereas the eastern domain (El Dorado - Monserrat, Cerro Vanguardia north) shows ENE and NNW directions of extension for the main and the secondary kinematic events respectively, the western domain (El Fénix and Lago Ghío) indicate NE and NW directions of extension for the two events. The two kinematic events could be related or correspond to different volcanic facies. Considering the diachronism of the Chon Aike province (younger volcanic rocks westwards), the different kinematic fields could be linked to a large scale, non-coaxial deformation regime that controlled the emplacement of the Chon Aike volcanic province.

Keywords : Chon Aike Silicic Province; Jurassic extension; Transtensional kinematics.

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