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Abstract
The Malargüe
fold and thrust belt formed by Mesozoic rift inversion during Tertiary
compressional orogeny. Mesozoic extension created the Neuquén basin
in west-central Argentina and controlled most structural styles and the
geometry of the fold and thrust belt, which is characterized by basement-cored
oppositely verging structures. Subsidence curves and palinspastically restored
isopach maps of Mesozoic sedimentary fill describe a complex pattern of
asymmetric half-grabens bounded by major faults of opposite polarity and
accommodation zones related to a rift phase during Late Triassic-Early
Jurassic time, as well as Middle Jurassic-Early Cretaceous postrift regional
subsidence. Balanced cross sections show the relationship between preexisting
extensional fabrics and contractional basement-involved thrusts and back-thrust
structures that generated the half-graben inversion. Overpressured shales
and three evaporite levels favored formation of duplexes, triangle zones,
and detachment of the cover as a result of basement-involved shortening. |
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