Linkages between Andean arc tectonics in central Chile and the development of petroleum systems in the Neuquén basin of western Argentina, 35°S

Jesse Mosolf
University of California, Department of Earth Science Santa Barbara, California, USA
[email protected]

Argentina’s Neuquén basin, one of South America’s most important petroleum-producing provinces, is bound to the west by the Andean volcanic arc. Tectonic linkages between the Andean arc and the evolution of the Neuquén basin, however, remain poorly documented despite their close spatial and tectonic association. Through detailed geologic mapping, stratigraphic, geochronological and structural studies of arc deposits composing the Abanico Formation in central Chile’s Tinguiririca region near 35°S, this study investigates: 1) the paleogeography, eruptive history, and sediment dispersal of the volcanic arc, and 2) the timing and structure of Cenozoic intra-arc shortening, all in context of the Neuquén basin’s tectonic evolution.

Preliminary field and geochronological results show the Abanico Formation to be composed of latest Cretaceous through Miocene volcanic and volcaniclastic rocks with a minimum composite stratigraphic thickness of ~3.6 km with no base exposed. Geologic mapping and stratigraphic relationships suggest extrusive volcanics and volcaniclastic sediment dispersal was generally restricted to the present day western Principal Cordillera. The map units are tilted and deformed by N-S trending folds and faults; radiometric dating of cross-cutting intrusions and growth strata indicate shortening was underway by ~35 Ma, with eastward propagation of the fold-thrust belt to the Neuquén basin by the ~15 Ma, creating structural traps and significant petroleum plays. Initial results and ongoing investigations promise to yield a calibrated tectonic history for the Andean arc in central Chile during Cretaceous-Cenozoic time, helping to further constrain the Neuquén basin’s regional tectonic framework.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects