--> ABSTRACT: Tectonic Evolution and Paleogeography of the Neuquen Basin, Argentina, by Gustavo D. Vergani, Anthony J. Tankard, Hugo J. Belotti, Herman J. Welsink; #91020 (1995).

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Tectonic Evolution and Paleogeography of the Neuquen Basin, Argentina

Gustavo D. Vergani, Anthony J. Tankard, Hugo J. Belotti, Herman J. Welsink

The Neuquen basin of west-central Argentina is a triangular-shaped depocenter covering more than 160,000 km2. It accounted for about 44 % of Argentinian oil production in 1992. The tectonic evolution spans about 220 m.y. of subsidence which preserved a Mesozoic-Cenozoic basin fill of at least 7,000 m thick. Initial rifting in the Triassic is characterized by basement-involved normal extensional faults which bound discrete half grabens that are separated by transfer faults. From the Aalenian onward, fault-controlled subsidence was replaced by regional subsidence and the rifts and their intervening highs were yoked together in a broad post-rift basin.

The stratigraphic record is punctuated by several unconformities which reflect intermittent subsidence as well as multiple episodes of structural inversion. From the Callovian onward, the Neuquen basin was subjected to periodic inversion of earlier extensional structures which modified the shape of the basin and rejuvenated fringing sedimentary source areas. The most conspicuous inversion structure is the Dorsal de Huincul. This Late Jurassic inversion marks a fundamental reorganization of regional stress fields and the start of a new phase of basin subsidence that is related to the opening of the South Atlantic.

The period of extensional subsidence resulted in several source rock intervals, while some of the main reservoirs and traps resulted from structural inversion.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995