General Levalle Basin, Argentina: A Buried Lower Cretaceous Rift*

Introduction The General Levalle Basin is a long, narrow, and deep Lower Cretaceous intracratonic rift basin buried beneath the southern Pampean plains in southern Cordoba province, Argentina. The basin trends approximately north-south for over 150 km, ranges from 5 to 50 km wide, and is over 6500 m deep. Below a prominent Upper Cretaceous unconformity, mantled by an unstructured Pleistocene through Upper Cretaceous clastic sequence, steeply dipping normal faults bound tilted graben and half-graben fault blocks (Figure 1). Major basin-bounding faults are part of a longer regional zone of crustal weakness that extends from the western Colorado basin in a north-northwesterly direction through the Macachin and General Levalle basins, the eastern Pampean Ranges west of Cordoba, and probably as far north as the Northwest Cretaceous basin (Figure 2). In 1995-96, Hunt Oil Company drilled the Cd. GL x-1, the first well in the basin, to 5179 m to test the petroleum potential of the basin.