“Anatectic Leucogranites of Molinos Range, Easthern Cordillera, NW Argentina: some issues concerning Nd-isotopic system”

SOLA, A, BECCHIO, R. A, PIMENTEL, M. M

Brasilia

Simposio; VII SSAGI South American Symposium on Isotope Geology; 2010

Universidad de Brasília

INTRODUCTION Two compositional groups were distinguished within migmatites leucosomes and leucogranite from Molinos igneous/metamorphic complex. The first one is syenogranitic (K-rich, high K/Na ratio) and the second one displays a trondhjemitic trend (Na-rich and low K/Na ratio). A detailed geochemical and isotopic study for these rocks reveals heterogeneities among the same rock type, even within the same pluton, the Pumayaco leucogranite. These heterogeneities may have potential origin in the nature of the melt-producing reactions and the stability of accessory minerals during the anatexis. The role of crustal anatexis at various crustal levels in generating geochemical and isotopic heterogeneities is poorly understood. Thus, characterization of the geochemical and isotopic nature of anatectic melts in high grade metamorphic terrains would help to better understand the sources of such heterogeneity and their potential magnitude Zeng et al. (2005c).