Facies in Submarine Canyons on the Continental Slope of the Argentine Patagonia (SW Atlantic)

Abstract

The lithological study of Recent sediments, as well as planktonic foraminiferal tests and macrobenthos therein, within transverse sections of four submarine canyons in the northern sector of the Argentine Patagonia gravitite–contourite system revealed a considerably more complex facies variability within the canyons than on the Perito Moreno Terrace between them. The facies variability in canyons is controlled by a combination of along-slope contour currents and down-canyon gravity flows. Two southern canyons contain the channel facies of terrigenous glauconite-rich sand that separate the flank facies of sand with a high content of foraminiferal tests. Two northern canyons include the facies of mixed sediments with a high content of <0.1 mm fraction, whose analogs are lacking on the surrounding terrace. They were likely deposited from the down-canyon gravity flows of dense suspension in the still-water bottom environment. Attached macrobenthos with calcareous skeletal elements (commonly corals) inhabits the mainly ice- or iceberg-rafted coarse rock fragments in all canyons and on the surrounding Perito Moreno Terrace.