INVESTIGADORES
RAPELA Carlos Washington
artículos
Título:
Basement evolution of the Sierra de la Ventana Fold Belt: new evidence for Cambrian continental rifting along the southern margin of Gondwana
Autor/es:
RAPELA, C.W.; PANKHURST, R.J; FANNING, C.M.; GRECCO, LAURA
Revista:
JOURNAL OF THE GEOLOGICAL SOCIETY
Editorial:
GEOLOGICAL SOC PUBL HOUSE
Referencias:
Lugar: Londres; Año: 2003 vol. 160 p. 613 - 628
ISSN:
0016-7649
Resumen:
U?Pb sensitive high-resolution ion microprobe data together with
geochemical and Nd isotopeanalyses obtained in the basement complex of the
Sierra de la Ventana Fold Belt indicate that the Early Palaeozoic passive
margin history of the basin followed Cambrian magmatism related to rifting in a
600 Ma Neoproterozoic crust. The Cambrian episode started with intrusion of 531±
4 and 524± 5 Ma A- and I-type granites derived from a dehydrated infracrustal
source (ENd530 -3.1 to -5.9), and culminated with eruption of
high-Zr peralkaline spherulitic rhyolites derived from an undepleted lithospheric mantle (509 ± 5 Ma; ENd509 +0.5
to +1.0). These rift-related magmatic rocks were covered by shelf sediments
deposited along a once continuous passive margin, encompassing the Sierra de la
Ventana Fold Belt, the Cape Fold Belt, the Falkland/Malvinas microplate and the
Ellsworth Mountains block in Antarctica. The Cambrian rifting event defined the
outline shape of the southern part of Gondwana, and can be regarded as the
initiation of the
supercontinent stage, which lasted until Jurassic break-up. The
conjugate continental fragments separated from Gondwana during the Cambrian
rifting could be the source for microcontinents with c. 1000 Ma basement rocks
that collided with the proto-Andean margin during Ordovician?Silurian times.