Structural styles and tectonic framework of the fold and thrust belt in tierra del fuego and offshore austral-malvinas basins, argentina

BONILLO MARTINEZ, P.; GHIGLIONE, M.C.; FIGUEROA, D.

Cartagena de Indias

Simposio; Simposio Bolivariano; 2006

The Andes Patagónicos bend to the east at thelatitude of Tierra del Fuego island, were they constitutesthe Cordillera Fueguina. This cordillera plungeseastward into the offshore and represents the southernborder of Austral and Malvinas basins.The studied area includes the outer foothills of thefold and thrust belt located in Austral and Malvinasbasins and their associated tertiary foreland deposits.The regional tectonic framework is mainly aresultant of the interaction between South America,Antarctica and Scotia plates during Late Cretaceousand Tertiary times.The structural style is quite variable along theouter foothills region. It changes eastward from a thinskinneddeformation style in Tierra del Fuego(Argentina) to a thin skin combined with basementinverted faults in Malvinas basin. The main decollementsare Lower Cretaceous and Paleogene shales.The fold and thrust belt of Malvinas basin is afrontier area where no hydrocarbon exploratory wellshave been drilled so far. Most of the data available are2D regional seismic lines. Repsol -YPF, as the operatorof a consortium, recently acquired a 2500 km2 3Dsurvey on this fold and thrust belt.The evolution of the fold and thrust belt hasbeen mainly controlled by the Scotia Plate activity,resulting in an intercalation of compressional/transpressional periods with others of extensional/transtensional character.It is postulated that the structures studied in theouter foothills were developed during Oligocene andLower Miocene times. These ages correlate quite wellwith a period of high oceanic crust generation at ScotiaPlate.