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 EMILIO; MESCUA JOSE; ANDRÉS FOLGUERA A,; BECKER, T

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 64 p. 1 - 17

0895-9811

The Chos Malal and Agrio fold and thrust belts are located in thewestern part of the Neuquén basin, an Andean retroarc basin of central-westernArgentina. Both belts show evidence of tectonic inversion at the western partduring Late Cretaceous times. The eastern part is dominated by late Miocenedeformation which also partially reactivated the western structures. This workfocuses on the study of the regional structure and the deformational event thatshaped the relief of this part of the Andes. Based on new field work andstructural data and previously published works a detailed map of the centralpart of the Neuquén basin is presented. Three regional structural crosssections were surveyed and balanced using the 2d MoveTM software. Inorder to define a more accurate uplift history, new apatite fission track analyseswere carried on selected structures. These data was used for new thermalhistory modeling of the inner part of the Agrio and Chos Malal fold and thrustbelts. The results of the fission track analyses improve the knowledge of howthese fold and thrust belts have grown trough time. Two main deformationalevents are defined in Late Cretaceous to Paleocene and Late Miocene times. Basedon this regional structural analysis and the fission track data the preciselocation of the orogenic front for the Late Cretaceous-Paleocene times isreconstructed and it is proposed a structural evolution of this segment of theAndes. This new exhumation data show how the Late Cretaceous to Paleocene eventwas a continuous and uninterrupted deformational event.