Evolution of the Chos Malal and Agrio fold and thrust belts, Andes of Neuquén: Insights from structural analysis and apatite fission track dating

ROJAS VERA, E.A.; MESCUA, J.; FOLGUERA, A.; FENNELL, L.M.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 418 - 433

0895-9811

The Chos Malal and Agrio fold and thrust belts are located in the western part of the Neuquen basin, anAndean retroarc basin of central-western Argentina. Both belts show evidence of tectonic inversion atthe western part during Late Cretaceous times. The eastern part is dominated by late Miocene deformationwhich also partially reactivated the western structures. This work focuses on the study of theregional structure and the deformational event that shaped the relief of this part of the Andes. Based onnew field work and structural data and previously published works a detailed map of the central part ofthe Neuquen basin is presented. Three regional structural cross sections were surveyed and balancedusing the 2d Move? software. In order to define a more accurate uplift history, new apatite fission trackanalyses were carried on selected structures. These data was used for new thermal history modeling ofthe inner part of the Agrio and Chos Malal fold and thrust belts. The results of the fission track analysesimprove the knowledge of how these fold and thrust belts have grown trough time. Two main deformationalevents are defined in Late Cretaceous to Paleocene and Late Miocene times. Based on thisregional structural analysis and the fission track data the precise location of the orogenic front for theLate Cretaceous-Paleocene times is reconstructed and it is proposed a structural evolution of thissegment of the Andes. This new exhumation data show how the Late Cretaceous to Paleocene event wasa continuous and uninterrupted deformational event.