High T/P evolution and metamorphic ages of the migmatitic basement of northern Sierras Pampeanas, Argentina: Characterization of a mid-crustal segment of the Famatinian belt

Detrital zircon U–Pb ages of metasedimentary rocks from Sierra de Valle Fértil: Entrapment of Middle and Late Cambrian marine successions in the deep roots of the Early Ordovician Famatinian arc

“…The eastern province is dominated by CambrianeOrdovician turbidite successions and their Early Ordovician metamorphic equivalents. These rocks were deposited in large basins between the Early Cambrian Pampean orogen and the proto-Pacific oceanic plates (Benedetto, 2004) and later underwent back-arc extension during the construction of the Early Ordovician arc (Astini and Dávila, 2004;Büttner et al, 2005;Larrovere et al, 2011). Like the eastern section, the western province also contains CambrianeOrdovician turbidite successions, but it differs in that it is dominated by plutonic, volcanic and volcaniclastic rocks generated at the Early Ordovician active margin (Mannheim and Miller, 1996;Bahlburg, 1998;Bahlburg and Hervé, 1997;Coira et al, 1999;Astini, 2003).…”

Across-arc variation of the Famatinian magmatic arc (NW Argentina) exemplified by I-, S- and transitional I/S-type Early Ordovician granitoids of the Sierra de Velasco

“…480e430 Ma (e.g. Bachmann et al, 1986;Sims et al, 1998;Lucassen and Becchio, 2003;Büttner et al, 2005;Larrovere et al, 2011;de los Hoyos et al, in press) and the development of the Famatinian magmatic arc along the continental margin of western Gondwana. It is widely accepted that Famatinian magmatism preceded the collisional accretion of the Precordillera terrane (i.e.…”

Reassessment of the volume of the Las Aguilas mafic-ultramafic intrusives, San Luis, Argentina, based on an alternative geophysical model

“…Thus, the high heat flow that provoked granulite facies conditions in the Pringles Metamorphic Complex may have been inherited from the backarc stage previous to the collisional event, and was not exclusively provoked by the intrusion of the mafic-ultramafic bodies (even though they may have contributed at a local scale as well). The same backarc heating mechanism was invoked by Larrovere et al (2011) to explain the high-temperature, relatively low-medium pressure metamorphic conditions and retrograde cooling ages existing throughout the Famatinian belt. Besides, since dehydration of the subducting oceanic slab occurs at w60e105 km depth (Arcay et al, 2005), Larrovere et al (2011) suggest that a relatively shallow-dipping slab was required to cause the continental ward wide zone of partial melting of the Famatinian middle crust, thus supporting the previous shallow-dipping subduction hypothesis of Willner et al (1987).…”

“…It is suggested that the one suitable cause for the thermal input in the metamorphic gradient could have been the inheritance from a hot, weak backarc. The same backarc heating mechanism was invoked by Larrovere et al (2011) to explain the high-temperature, relatively low-medium pressure metamorphic conditions and retrograde cooling ages existing throughout the Famatinian belt. Alternatively, the Pringles Metamorphic Complex could represent the roots of the Famatinian arc (Steenken et al, 2011) and so this tectonic setting could provide the necessary heat for the granulite facies conditions and for the genesis of mafic-ultramafic roughly coetaneous with synorogenic felsic magmas.…”