Volcanismo calcoalcalino durante el Mioceno Medio en Patagonia Central (47°S): Petrogénesis e implicaciones en la dinámica de placas

Felipe Espinoza, Diego Morata, Mireille Polvé, Yves Lagabrielle, René C. Maury, Aude de la Rupelle, Christèle Guivel, Joseph Cotten, Hervé Bellon, Manuel Suárez

Resultado de la investigación: Contribución a una revistaArtículorevisión exhaustiva

30 Citas (Scopus)


We present a chronological (K-Ar), petrologic and geochemical study (major and trace elements, Sr- Nd isotopes) of Middle Miocene (ca. 16-14 Ma) calc-alkaline rocks (basalts to andesites) extruded in the present-day back-arc region of Central Patagonia (Zeballos Volcanic Sequence (ZVS), 47°S). This magmatism started shortly alter mafic plutonism ceased in the arc region (ca. 16 Ma, 200 km west), and ended ca. 2 My before the onset of volumi- nous slab tear-related back-arc alkaline basaltic magmatism (ca. 12 to Pliocene). The studied calc-alkaline rocks have a typical subduction-related signature (high LILE/HFSE ratios, depletion in Nb, Ta and Ti; Ba/La >20; Ta/Hf <1.5; (87Sr/86Sr)o=0.70366-0.70402, εNd=+0.1-+3.8). Major and trace elements contents are consistent with their evolution by closed system fractional crystallization of a presumed parental liquid similar in composition to the most basic rock of the suite. Moreover, a strong subducted sediment imprint is recognized (increasing Th/HFSE and decreasing Ce/Pb during differentiation). However, these rocks show striking similarities with volcanic complexes emplaced above areas where a gently dipping slab occurs (high K contents; similar LREE/HREE, Nb/Zr, Ba/Nb; Th/Hf; Th/Ta, Ta/Hf<0.3), particularly the present-day Andean flat-slab region and the Neuquén Basin during the Late Miocene. A comprehensive tectono-magmatic model is here presented to explain the generation and extrusion of these calc-alkaline magmas during the Middle Miocene. The development of a transient low-angle subduction and the resulting eastward migration of the volcanic front are then proposed. Mixing between stored remnants of calc-alkaline magmatism and later primitive alkaline melts is envisioned as the most likely process accounting for the transitional signature (i.e., intermediate between calc-alkaline and alkaline, La/Nb >1; TiO2 <2 wt%) of some basalts extruded synchronously with genuine alkaline lavas in the Neogene Patagonian Plateau Lavas province.

Título traducido de la contribuciónMiddle Miocene calc-alkaline volcanism in Central Patagonia (47°S): Petrogenesis and implications for slab dynamics
Idioma originalEspañol
Páginas (desde-hasta)300-328
Número de páginas29
PublicaciónAndean Geology
EstadoPublicada - 1 dic. 2010

Palabras clave

  • Calc-alkaline magmatism
  • Central Patagonia back-arc
  • Low-angle subduction
  • Miocene

Áreas temáticas de ASJC Scopus

  • Geología
  • Geoquímica y petrología
  • Estratigrafía
  • Paleontología


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