Tectosedimentary evolution of the La Troya and Vinchina depocenters (northern Bermejo Basin, Tertiary), La Rioja, Argentina

CICCIOLI PATRICIA,; LIMARINO OSCAR,; MARENSSI S,; TEDESCO, A; TRIPALDI A,

Cenozoic Geology of the Central Andes of Argentina

SCS Publisher

Lugar: Salta; Año: 2011; p. 91 - 110

The stratigraphy and tectosedimentary evolution of the northern Bermejo basins is analyzed in this paper. The regionaldistribution and thickness of Tertiary successions allow recognizing two major depocenters: La Troya to the south and Vinchinato the north, separated by the Umango-Espinal arch during the Miocene. Based on sedimentological and stratigraphic features,the record of La Troya and Vinchina depocenters has been divided in five stages that characterize the tectosedimentary evolutionof the basins: 1, retroarc (early Eocene); 2, early transpressive retroarc (middle to late Eocene); 3, late transpressive retroarc(Oligocene to early Miocene); 4, transpressional foreland (Miocene to early Pliocene), and 5, cannibalized foreland (Pliocene).The retroarc stage was characterized by playa lake, eolian and low-energy fluvial systems, sedimentation being controlled by adistal volcanic arc. During the early transpressive retroarc stage, dominated by fluvial sedimentation, movements took place in themain tectonic lineaments (Tucumán and Desaguadero-Valle Fértil) producing incipient uplifts of basement blocks. These conditionsevolved to the late transpressive retroarc stage characterized by basement shortening forming the Umango-Espinal block thatdisrupted the previous retroarc basin. During the transpressional foreland stage, subsidence and accommodation space werecontrolled by a complex interplay between local basement uplifts and advance of the thrust front. Under these conditions,alternating fluvial and playa lake systems prevailed. Finally, the cannibalized foreland stage is represented by synorogenic brecciasand conglomerates accumulated in alluvial fans, piedmonts and proximal braided river systems.