Tectonic control on the evolution of Maastrichtian-Paleogene synorogenic sequences of the Fuegian Thrust Fold Belt, Argentina.

Abstract

A geological study of the Atlantic coast of Tierra del Fuego between the punta Gruesa (54º 21 S; 66° 38.5 W) and the río Policarpo (54º 39 S; 65º 30 W) (Figure 1), and other sectors of the Fuegian Andes, allowed us to define the stratigraphy and sedimentology of synorogenic successions from the Austral basin, and their genetic relations with the geometry and kinematics of the Fuegian thrust-fold belt. We define seven synorogenic successions between the Maastrichtian and the Miocene, bounded by unconformities: Maastrichtian-Danian (180 to 800 m), Paleocene (50 to 370 m), Ypresian (450 to 650 m), Lutetian (80 m), upper Lutetian-Priabonian (1200 m), Oligocene (1600 to 200 m) and uppermost Oligocene-Miocene (200 m). These successions are composed of marine sedimentites, mostly deposited by gravity flows bellow storm-wave base. The paleocurrent directions and the petrography indicate sediment provenance areas in the volcanic arc along the Pacific margin of the Andes, and in the core of the Fuegian Andes, the former dominant between the Maastrichtian and the Lutetian, and the latter since the late Lutetian.