LCT and NYF pegmatites as an indicator for the magmatic evolution of the Las Chacras Batholith, central Argentina

ALTENBERGER, U; TRUMBULL, R.; RIBACKI, E.; LÓPEZ DE LUCHI, M. G.

Hamburg

Conferencia; 25th Latin-American Colloquium of Geoscience, Universität Hamburg; 2019

Universitat Hamburg

Pegmatites open the door to study the last stages of crystallizationprocesses of fractionated granitic systems. This study compares pegmatitesin the Devonian Las Chacras batholith (LCB) and pegmatiteswithin the Ordovician metamorphic basement of the Sierra de SanLuis, which cover a wide range of LCT (Li, Cs, Ta) and NYF (Nb, Y andREE, F) character. The LCB batholith is composed of nestedgranitic intrusions, emplaced within a pull-apart structure and controlledby major strike slip fault systems. Stocks and syn-plutonicdikes of lamprophyres demonstrate a strong mantle componentin the Devonian magmatism. The intrusions show anorth-to-south increase in magma differentiation and an increasingdegree of crustal contamination (shown by radiogenic Sr and Nd-isotoperatios).