Mesozoic tectonic inversion in the Neuquen Basin of west-central Argentina

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Title: Mesozoic tectonic inversion in the Neuquen Basin of west-central Argentina
Author: Grimaldi Castro, Gabriel Orlando
Abstract: Mesozoic tectonic inversion in the Neuquen Basin of west -central Argentina produced two main fault systems : (1 ) deep faults that affected basement and syn -rift strata where preexisting faults were selectively reactivated during inversion based on their length and (2 ) shallow faults that affected post -rift and syn -inversion strata . Normal faults formed at high angle to the reactivated half -graben bounding fault as a result of hangingwall expansion and internal deformation as it accommodated to the shape of the curved footwall during oblique inversion . Contraction during inversion was initially accommodated by folding and internal deformation of syn -rift sedimentary wedges , followed by displacement along half -graben bounding faults . We suspect that late during inversion the weight of the overburden inhibited additional fault displacement and folding became the shortening -accommodating mechanism . A Middle Jurassic inversion event produced synchronous uplift of inversion structures across the central Neuquen Basin . Later inversion events (during Late Jurassic , Early Cretaceous , and Late Cretaceous time ) produced an "inversion front" that advanced north of the Huincul Arch . Synchroneity of fault reactivation during the Callovian inversion event may be related to efficient stress transmission north of the Huincul Arch , probably due to easy reactivation of low -dip listric fault segments . This required little strain accumulation along "proximal" inversion structures before shortening was transferred to more distal structures . Later inversion events found harderto - reactivate fault segments , resulting in proximal structures undergoing significant inversion before transferring shortening . The time between the end of rifting and the different inversion events may have affected inversion . Lithosphere was probably thermally weakened at the onset of the initial Callovian inversion phase , allowing stress transmission over a large distance from the Huincul Arch and causing synchronous inversion across the basin . Later inversion affected a colder and more viscous lithosphere . Significant strain needed to accumulate along proximal inversion structures before shortening was transferred to more distal parts of the basin . Timing of inversion events along the central Neuquen Basin suggest a megaregional control by right -lateral displacement motion along the Gastre Fault Zone , an intracontinental megashear zone thought to have been active prior to and during the opening of the South Atlantic Ocean .
URI: http : / /hdl .handle .net /1969 .1 /4717
Date: 2007-04-25

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Mesozoic tectonic inversion in the Neuquen Basin of west-central Argentina. Available electronically from http : / /hdl .handle .net /1969 .1 /4717 .

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