INVESTIGADORES
COLOMBO Fernando
congresos y reuniones científicas
Título:
Zonación composicional en granates de la Sierra de Pie de Palo, San Juan, Argentina: implicancias en la historia metamórfica
Autor/es:
RAMACCIOTTI, CARLOS; BALDO, EDUARDO G.; CASQUET, CÉSAR; COLOMBO, FERNANDO
Lugar:
San Juan
Reunión:
Congreso; XI Congreso de Mineralogía y Metalogenia; 2013
Institución organizadora:
Asociación Mineralógica Argentina y Universidad Nacional de SanJuan
Resumen:
Compositional zoning of garnet from two domains of the Sierra de Pie de
Palo (Western Sierras Pampeanas) evidence contrasting tectono-metamorphic histories. Garnets
from Grt-amphibolites of the underlaying Grenville-age mafic-ultramafic belt
(Complejo de Pie de Palo) on the western side of the Sierra show two
discontinuous zones, one internal (core) and one external (rim). These zones
are separated by inclusions of quartz and plagioclase arranged concentrically.
Each zone shows different composition and also different patterns of variation
for each end-member. In contrast, garnets from the Neoproterozoic Ca-metapelites
in the overlaying southeastern domain of the Sierra de Pie de Palo show a
continuous compositional zoning, characteristic of a single stage of growth
during the Famatinian orogeny (Ordovician). Alm, Prp and Grs increase regularly
outwards while Sps shows a reverse pattern. Garnet chemistry is consistent with
the existence of a polymetamorphic basement (Grenvillian + Famatinian
metamorphism) on the western side and a younger monometamorphic sedimentary
cover.