HR: 1340h
AN: T23B-0580    [Abstracts]
TI: Mesozoic inversion in southeastern parts of the Neuqu\'{e}n Basin, west-central Argentina: Implications for tectonic deformation and stratigraphic development across the Andean foreland of Argentina
AU: * Grimaldi, G O
EM: grimaldi@tamu.edu
AF: Texas A&M University, Dept. of Geology and Geophysics, College Station, TX 77843 United States
AU: Dorobek, S L
EM: dorobek@geo.tamu.edu
AF: Texas A&M University, Dept. of Geology and Geophysics, College Station, TX 77843 United States
AB: The Neuqu\'{e}n Basin of west-central Argentina is a segment of the Andean foreland that has significant structural complexity due to protracted intraforeland deformation between Late Triassic to Recent time. Some structural features in the Neuqu\'{e}n Basin predate the main phases of the Andean orogeny although these structures were reactivated later and influenced basin configuration during the foreland-basin stage. The most conspicuous of these structures is the Huincul Arch, a 200-km-long right-lateral shear zone that was most active during Jurassic to Cretaceous time. Inversion structures along the Huincul Arch are associated with a restraining bend along the main east-west trending shear zone that cuts across the Argentine foreland. An extensive seismic and borehole data set was analyzed to evaluate the styles and intensity of Mesozoic foreland deformation in an approximately 10,000 sq km area north of the Huincul Arch. Transpressional and transtensional deformation is broadly distributed across the study area and other parts of the Neuqu\'{e}n foreland, although a series of inversion structures (e.g., Sierra Barrosa and Aguada Toledo anticlines) reflect more intense, localized deformation. These structures are the result of inversion of Late Triassic half-grabens and produced fault-propagation folds that affected the post-rift fill up to the Upper Jurassic (Tithonian). The most significant reactivation along the Huincul Arch south of our study area occurred during Kimmeridgian (Late Jurassic) time along the main displacement zone. To the north, however, significant inversion was slightly younger and occurred during and after deposition of the Tithonian to Berriasian (latest Jurassic-earliest Cretaceous) Vaca Muerta and Quintuco formations. Thus, early phases of tectonic inversion across the Argentine foreland were diachronous and likely reflect an accumulation of strain along the Huincul Arch was necessary before additional strain could propagate northward into our study area. Seismic-stratigraphic analyses also show that the growing inversion structures created bathymetric perturbations that affected sediment dispersal and stratigraphic development north of the Huincul Arch during deposition of the Vaca Muerta-Quintuco interval. This study contributes to the understanding of Pre-Andean deformation in the Neuqu\'{e}n Basin. 3D seismic data across the study area also provides a unique opportunity to investigate the geometries and kinematic history of inversion across the Andean foreland, as well as to evaluate tectonic controls on Mesozoic stratigraphic development in the poorly understood Northern Sub-basin of the Neuqu\'{e}n Basin.
DE: 9360 South America
DE: 9609 Mesozoic
DE: 8105 Continental margins and sedimentary basins
DE: 8110 Continental tectonics--general (0905)
DE: 8164 Stresses--crust and lithosphere
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting