Lower Cretaceous provenance in the northern Austral basin of Patagonia from sedimentary petrography

BARBERON, VANESA; RONDA GONZALO; LEAL PABLO R.; CHRISTIAN SUE; GHIGLIONE, MATIAS

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 498 - 510

0895-9811

The northern Austral basin from Patagonia is characterized by an Early Cretaceous (BarremianeAlbian) coarse-grained regressive sequence. These littoral to continental deposits conform a 150 km long basin cropping out along the Southern Patagonian Andes between 47 and 48S. The basin fill consist of basal deltaic sandstones with interbedded shales and limestones from the Río Belgrano Formation, topped by up to 350 m of fluvial conglomerates and reworked tuffs of the Río Tarde and Kachaike formations. This continental depocenter represent a major geodynamic and paleoenviromental change from the underling marine Río Mayer Formation. In this study we analyze the tectonic setting and provenance during deposition of the coarse-grained sequence using sedimentary petrography of 37 thin sections in four stratigraphic profiles covering the northern basin. Our dataset indicates mainly a recycled orogenic sandstones provenance, in agreement with potential surrounding basement sources.