INVESTIGADORES
RAPELA Carlos Washington
artículos
Título:
Involvement of the Argentine Precordillera terrane in the Famatinian Mobile Belt: U-Pb SHRIMP and metamorphic evidence from the Sierra de Pie de Palo
Autor/es:
CASQUET, C.; BALDO, E.G; PANKHURST, R.J; RAPELA, C.W.; GALINDO, C.; FANNING, C.M; SAAVEDRA, J.
Revista:
GEOLOGY
Editorial:
GEOLOGICAL SOC AMER, INC
Referencias:
Lugar: Boulder; Año: 2001 vol. 29 p. 703 - 706
ISSN:
0091-7613
Resumen:
New data suggest
that the eastern margin of the Argentine Precordillera terrane comprises
Grenvillian basement
and a sedimentary cover derived from it that were together
affected by Middle
Ordovician deformation and metamorphism during accretion to the
Gondwana margin. The
basement first underwent low pressure/temperature (P/T) type
metamorphism,
reaching high-grade migmatitic conditions in places (686 ±40 MPa, 790
6 17 C),
comparable to the Grenvillian M2 metamorphism of the supposed Laurentian
counterpart of the
terrane. The second metamorphism, recognized in the cover sequence,
is of Famatinian age
and took place under higher P/T conditions, following a clockwise
P-T path (baric peak:
1300 ±
100 Mpa, 600 ± 50 C). Low-U zircon overgrew detrital
Grenvillian cores as
pressure fell from its peak, and yields U-Pb SHRIMP ages of ca. 460
Ma. This is
interpreted as the age of ductile thrusting coincident with early uplift;
initial
accretion to
Gondwana must have occurred before this. The absence of late Neoproterozoic
detrital zircons is
consistent with a Laurentian origin of the Argentine Precordillera
terrane.