Abstract

MONTERO LOPEZ, María Carolina et al. Upper Miocene Quaternary acid magmatism in the Cerro Blanco-La Hoyada area, southern Puna. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.3, pp.329-348. ISSN 0004-4822.

An acid volcanism was developed during the Upper Miocene-Holocene at the Southern Puna, represented by two units at the eastern portion of Cordillera de San Buenaventura (26°25'-27°00'S and 67°25'-67°50' W): the Aguada Alumbrera Ignimbrite and the Cerro Blanco Volcanic Complex. Toward the north and northwest of this area several pyroclastic deposits outcrop called Rosada Ignimbrite, which are included in this article for comparison purposes. All these units overlie the Neoproterozoic-Eopaleozoic igneous-meta-morphic basement and volcanic rocks of ca. 9-7 Ma. The Aguada Alumbrera and Rosada Ignimbrites erupted at Upper Miocene times, whereas the Cerro Blanco Volcanic Complex is as young as the Holocene. In this article, we present new field data as well as electron microprobe and geochemical analyses from which we synthesize the stratigraphy of this region. The studied rocks are all calk-alkaline rocks with rhyolitic composition and have the same characteristics as the volcanic rocks from the Central Volcanic Zone, for example, related to subduction setting where the silicic magmas formed mainly from mantle sources with a crustal component. The youngest magmatism represented by the Cerro Blanco Volcanic Complex could be related to crustal magmas, however this hypothesis must be corroborated with additional geochemical data.

Keywords : Acid volcanism; Southern Puna; Upper Miocene-Quaternary.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )