Eopaleozoic Patagonia–East Antarctica connection: Fossil and U-Pb evidence from El Jagüelito Formation.

NAIPAUER, M.; SATO, A.M.; GONZÁLEZ, P.D.; CHEMALE JR., F.; VARELA, R.; LLAMBÍAS, E.J.; GRECO, G.A.; DANTAS, E.

Brasilia

Simposio; VII South American Symposium on Isotope Geology; 2010

Universidad de Brasilia

Archeocyath fossils revealed in limestone boulders within a meta-conglomerate layer of El Jagüelito Formation in the Northern Patagonia indicate an Early Cambrian age for the deposition of the original limestone, a rock type not cropping out in the area, but common in the Transantarctic Mountains in association with Archeocyath. Although the absolute age of the unit is still an open question, an upper constraint for the timing of the successive deposition of the siliciclastic El Jagüelito protolith is given by a SHRIMP U-Pb, zircon crystallization age of 472 Ma from El Molino orthogneiss, a small pluton intruded into and deformed together with El Jagüelito Formation. In order to test the validity of these correlations between East Antarctica and the El Jagüelito Formation, we have performed LA-ICPMS U-Pb provenance studies based on detrital zircon analysis on a sample from the same meta-conglomerate containing the fossils and on another sample from a meta-wacke of a different outcrop of the El Jagüelito Formation.