Retraction: 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

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 Neuquen 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 dataset 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.