Cuencas de la región precordillerana

ASTINI, R. A.; FEDERICO MIGUEL DAVILA; LOPEZ-GAMUNDI, O.; GÓMEZ, F.; COLLO, G.; EZPELETA, M.; MARTINA, F.; ORTIZ, A.

Fronteras Exploratorias de la Argentina

IAPG

Lugar: Buenos Aires; Año: 2005; p. 115 - 146

This work provides an up-to-date synthesis of the stratigraphic framework of the Argentine Precordillera from its earliest history during the Early Paleozoic into the most recent Andean foreland. According to its stratigraphic record six main evolutionary stages can be outlined: 1) a basal Laurentian-like passive-margin stage, 2) a first Ordovician peri-Gondwanan foreland basin stage, 3) a second Siluro-Devonian “Malvinokaffric” foreland basin stage, 4) a third more extended “Gondwanan” Carboniferous-Permian foreland, including the first broken foreland toward the Pampean craton, 5) a stage of back-arc extension and protracted unroofing, and 6) a final Andean foreland stage with development of at least two different styles; an early asymmetric simple flexural wave and a later broken foreland affecting the more external cratonward region. Whereas most of the Precordilleran thrust-fold belt (present wedge top) overlaps with the initially asymmetric foreland style, the eastward intermontane basins partly overlap earlier broken foreland stages, leading to partitioning and basement involvement in deformation. Little understanding of thickness variability and involvement within the tectonically thickened wedge-top zone has been critical in previous hydrocarbon surveys along and across the Bermejo basin and strongly impact on organic matter maturation. Any potential hydrocarbon sources or reservoirs in the Argentine Precordillera and the surrounding regions have to consider the outlined major evolutionary stages. Additionally, contrasted foreland styles greatly impact in stratigraphic continuity and potential source and reservoir rock modeling. Understanding basin dynamics and depocenter distribution within each of these different evolutionary stages has great importance in the potential hydrocarbon plays. Although, the superposed history of foreland sedimentation has resulted in various different oil-prone settings, most have suffered complex overburden and thermal histories for which few remain interesting after the most recent surveys. Particularly critical results the Andean burial history, which has partly enhanced and partly reduced the potential of Triassic and Carboniferous-Permian source rocks. Silurian and Devonian should not be completely disregarded along the Central Precordillera, where tertiary burial has not been as important.