TECTOSEDIMENTARY EVOLUTION OF THE LA TROYA AND VINCHINA DEPOCENTERS (NORTHERN BERMEJO BASIN, TERTIARY), LA RIOJA PROVINCE, ARGENTINA

CICCIOLI, P. L.; LIMARINO, C.O.,; MARENSSI, S.A.,; TEDESCO, A.M.; 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 regional distribution and thickness of Tertiary successions allow recognizing two major depocenters: La Troya to the south and Vinchina to 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 evolution of 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) stages. Retroarc stage was characterized by playa lake, eolian and low energy fluvial systems being the sedimentation controlled by a distal volcanic arc. During the early transpressive retroarc stage, dominated by fluvial sedimentation, took place movements in the main tectonic lineaments (Tucumán and Desaguadero-Valle Fértil) producing the incipient uplifts of basement blocks. These conditions evolved to the late transpressive retroarc stage characterized by basement shortening forming the Umango-Espinal block that disrupted the previous retroarc basin. During the transpressional foreland stage subsidence and accommodation space were controlled by a complex interplay between the local basement uplifts and the advance of the thrust front. Under these conditions alternating fluvial and playa lake systems prevailed. Finally, the cannibalized foreland stage is represented by synorogenic breccias and conglomerates accumulated in alluvial fans, piedmonts and proximal braided river systems.