INVESTIGADORES
RAPELA Carlos Washington
artículos
Título:
Trace and mayor element models of granitoid genesis in the Pampean Ranges, Argentina
Autor/es:
RAPELA, C.W.; SHAW, D.M.
Revista:
GEOCHIMICA ET COSMOCHIMICA ACTA
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 1979 vol. 42 p. 1117 - 1129
ISSN:
0016-7037
Resumen:
Mathematical models
for some major and trace elements have been used to test a petrogenetic
hypothesis of granitoid rock emplacement at different levels in the metamorphic
basement of the Pampean Ranges (Sierra de Quilmes, Argentina).
Previous contributions
suggested that the second metamorphic event to affect the area reached
temperatures high enough to provoke widespread anatexis of the geosynclinal
metasediments which make up Sierra de Quilmes. Comparison of the geochemical
trends of the granitoids and metamorphic rocks with theoretical models
developed for Ca, Na, K, Rb, Sr, suggests the following conclusions: (1) trends
in both granitoid and metamorphic rocks fit reasonably well a model of
equilibrium partial melting of the metamorphic rocks; (2) major and trace
element trends in the metamorphic rocks are as predicted for the solid residues
after partial melting; (3) the anatectic liquid after 40% melting was mainly
granodioritic; (4) synkinematic and late-kinematic granitoid bodies were formed
by fractional crystallization of the granodioritic magma with successive
separation of intercumulus liquids; and (5) post-kinematic bodies were formed
by equilibrium or quasi-equilibrium crystallization of the granodioritic magma.