MAFIC MICROGRANULAR ENCLAVE SWARMS IN 2-17 GRANITIC PLUTONS OF GASTRE, CENTRAL PATAGONIA

CLAUDIA BEATRIZ ZAFFARANA; RUBÉN SOMOZA

BOLLETTINO DI GEOFISICA TEORICA ED APPLICATA

ISTITUTO NAZIONALE DI OCEANOGRAFIA E DI GEOFISICA

Lugar: Roma; Año: 2010 vol. 51 p. 96 - 98

0006-6729

In the Gastre region, Central Patagonia, the Late Triassic-Early Jurassic Central Patagonian Batholith (Rapela et al., 1991) crops out. These authors recognized two superunits, according to field and petrographic characteristics: the Gastre Superunit, composed of biotite-hornblende granitoids, porphyritic and equigranular biotite granitoids and the younger Lipetrén Superunit, mostly composed of biotitic granitoids. One outstanding difference between them is that the Gastre Superunit granitoids host mafic microgranular enclaves (MME), mafic dikes and mafic stocks. In particular, in one of the localities where the porphyritic biotitic granitoids crop out, spectacular occurrences of homogeneous enclave swarms have been found. Mafic microgranular enclaves are interpreted as hybrids of acidic and basic magmas (Didier and Barbarin, 1991). In this contribution we describe field and petrographic characteristics of enclave swarms recognized in the Gastre  superunit.