Middle Miocene to Early Pliocene Contraction in the Chos Malal Fold‐and‐Thrust Belt (Neuquén Basin, Argentina): Insights From Structural Analysis and Apatite Fission‐Tracks Thermochronology. Issue 10 (14th October 2017)

• Record Type: Journal Article
• Authors: Sánchez, Natalia; Coutand, Isabelle; Turienzo, Martín; Lebinson, Fernando; Araujo, Vanesa; Dimieri, Luis
• Is Part Of: Tectonics. Volume 36:Issue 10(2017)
• Page Start: 1966
• Page End: 1987
• Publication Date: 2017-10-14
• Subjects: AFT apatite fission‐track analysis -- Andean tectonic -- structural evolution -- thick‐ and thin‐skinned deformation -- Argentinean Andes; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1002/2017TC004516
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: In the southern central Andes at 37–38°S latitude, the Chos Malal fold‐and‐thrust belt (FTB), which results from the Late Cretaceous closure of the Neuquén Basin, has generated increasing interest because of its potential for hydrocarbon exploration. Using detailed field mapping, seismic reflection and well data analysis, cross‐section balancing, and detrital apatite fission‐track thermochronology from 18 samples distributed along the FTB, we bring new quantitative constraints on the chronology of the Neogene structural development of the Chos Malal FTB. Our data set reveals that extensive tectonically driven exhumation through basement‐involved thrusting occurred at ~15–7 Ma in both the inner and outer sectors of the FTB. This age range is corroborated by indirect dating of the Chos Malal Formation, a syntectonic unit also deformed after deposition, which we find was deposited after 7.2 Ma ± 1.6/2.0 Ma, an age much younger than the Miocene age it was previously assigned. We document for the first time an early Pliocene rapid cooling stage that was ongoing ~5.5 to 5.1 Ma ago in the interior of the orogenic wedge, which we attribute to out‐of‐sequence thrusting along basement‐involved thrust faults bounding the Cordillera del Viento, driving the surface uplift of this prominent topographic feature. Finally, our sequential reconstruction of the thick‐ and thin‐skinned structures of the Chos Malal FTB shows that most of the horizontal shortening was accommodated after the middle Miocene, which we thus consider as being the main phase of orogenic building in this sector of the Andes. Key Points: Synorogenic deposits of the Chos Malal Formation have a maximum age of ~7 Ma, showing that deformation was ongoing at the time Most of the Andean shortening in the Chos Malal FTB was achieved between 15–7 Ma between the Cordillera del Viento and the range front Rapid Pliocene cooling was ongoing at ~5.5 to 5.1 Ma ago at the Cordillera del Viento, as a result of out‐of‐sequence thrusting