Tectonic inversion events in the western San Jorge Gulf Basin from seismic, borehole and field data

NAVARRETE CESAR; GIANNI GUIDO; FOLGUERA ANDRES

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 1 - 17

0895-9811

The SanJorge Gulf Basin, located in Central Patagonia and the Atlantic passive margin,has been interpreted as a Jurassic-Cretaceous rift basin that was inverted inNeogene times. Consequently, the Bernardides System formed as a set of forelandimbricate structures that constitute the core of the Patagonian broken foreland,exhuming continental deposits of the Cretaceous Chubut Group, 500 km away fromthe Pacific trench. In spite of the intense research done in the San Jorge Gulf Basinin the last decades many aspects remain under discussion, particularly thoseregarding the age of uplift of the Bernárdides System. In order to unravel the tectonic evolution of thewestern San Jorge Gulf Basin (Río Mayo Sub-Basin), we analyzed subsurfaceinformation (2D and 3D seismic lines and oil wells) located in the western areaof the basin and compared this with surface data of the southern BernárdidesSystem. Based on our interpretation, the western part of the basin could havebeen uplifted in a series of deformational events that began as early as lateEarly Cretaceous, related to the initial uplift of the Patagonian broken foreland,during the early stages of South Atlantic opening. Subsequent stages of tectonicreactivation identified in this system have selectively inverted previousextensional structures according to the variable direction of the greatest horizontal stress (σ1) acting at each time.