INVESTIGADORES
RAPELA Carlos Washington
capítulos de libros
Título:
The Proto-Andean Margin of Gondwana: An Introduction
Autor/es:
PANKHURST, R.J; RAPELA, C.W.
Libro:
The Proto-Andean Margin of Gondwana
Editorial:
Geological Society of London
Referencias:
Año: 1998; p. 1 - 9
Resumen:
A
basic background is presented for the discussion of the Early Palaeozoic
geology of western Argentina covered by this book. This includes the definition
and terminology of orogenic cycles on this part of the Gondwana margin,
represented by the Eastern Sierras Pampeanas. The Pampean orogeny (Early
Cambrian) relates to an intense but short-lived period of terrane collision
predating the rifting of the Precordillera terrane from Laurentia. The
Famatinian cycle is predominantly represented by intense subductionrelated
magmatism of Early-Middle Ordovician age, developed on the continental margin
of Gondwana during the rifting and drifting of the Precordillera terrane. The
Grenvillian basement of the latter is further exemplified by a new Rb-Sr
whole-rock isochron age of 1021 + 12Ma for orthogneisses from the Western
Sierras Pampeanas. A mid-Ordovician granite in this area (dated at 481 4-6 Ma
by U-Pb ion microprobe data) may be related to rifting while the Precordillera
terrane was still attached to Laurentia. A divergence of opinion is pointed out
between some authors in this book who favour mid-Ordovician collision of the
Precordillera with Gondwana, and others who place it much latter, in Silurian
or Devonian times.