Abstract

SALANI, Flavia M  and  CHERNICOFF, Carlos J. Jurassic calderas associated with Chon Aike formation volcanism near by Puesto Salado, east of Santa Cruz province, Argentina. Geoacta [online]. 2017, vol.42, n.1, pp.63-72. ISSN 1852-7744.

The aeromagnetic survey of the Deseado Massif, Santa Cruz province, Argentina, has allowed to interpret the occurrence of two conspicuous caldera structures of 30 and 23 km in diameter, respectively centered at 48º 52’ S / 68º 02’ W and 48º 53’ S/ 68º 29’ W, i.e. located roughly about 7 km apart. The identified calderas -herein referred to as Puesto Salado calderas- are associated with the Chon Aike Jurassic acid volcanites which, although are locally covered by Cenozoic sediments, are largely spread in the southern Patagonian region. The estimated depth for the Puesto Salado caldera structures ranges 350 to 550 m; its dimension (diameter) is notably larger than that of other calderas associated with the Jurassic volcanism in the extra-Andean region of the Santa Cruz province. The possible volume of pyroclastic material erupted from the identified calderas has been estimated in terms of their dimension, ranging between 1000 km3 for the eastern Puesto Salado Caldera and 200 km³ for the western Puesto Salado caldera. Additionally, preliminary characterization of the magnetic signatures associated with the Jurassic volcanic-pyroclastic sequence of the Chon Aike Formation in two neighboring areas has been carried out for comparative purposes.

Keywords : Calderas; Chon Aike; Acidic volcanism; Santa Cruz; Aeromagnetism.

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