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AGU: Tectonics

 

Keywords

  • central Andes
  • Bolivian Orocline
  • Paleogene tectonics
  • paleomagnetism

Index Terms

  • Tectonophysics: Continental tectonics: general
  • Tectonophysics: Continental margins: convergent
  • Geomagnetism and Paleomagnetism: Paleomagnetism applied to tectonics: regional, global
  • Information Related to Geologic Time: Paleogene
  • Geographic Location: South America
Abstract
Cited By (0)
 

Abstract

Paleogene building of the Bolivian Orocline: Tectonic restoration of the central Andes in 2-D map view

C. Arriagada

Departamento de Geología, Universidad de Chile, Santiago, Chile

P. Roperch

Géosciences Rennes, UMR6118, Université de Rennes, CNRS, Rennes, France

LMTG, Université de Toulouse, IRD, Toulouse, France

C. Mpodozis

Antofagasta Minerals, Santiago, Chile

P. R. Cobbold

Géosciences Rennes, UMR6118, Université de Rennes, CNRS, Rennes, France

Using available information on the magnitude and age of tectonic shortening, as well as paleomagnetically determined tectonic rotations, we have run a series of 2-D map view restorations of the central Andes. Neogene shortening in the foreland belt induced only slight orogenic curvature of the central Andes. The constraints on the ages of the large observed fore-arc rotations (average of 37° counterclockwise in southern Peru and 29° clockwise in northern Chile) indicate that the Bolivian Orocline formed during the Eocene-Oligocene as a consequence of differential shortening focused in the Eastern Cordillera. To minimize local block rotations along the fore arc, the restoration that best fits the central Andean rotation pattern requires about 400 km of total (Paleogene plus Neogene) shortening near the Arica bend. This value corresponds to the upper bound of estimates of maximum horizontal shortening for the central Andes. Along-strike variations in horizontal shortening in the back arc induced bending of the continental margin, block rotations with fore-arc along-strike extension, and/or orogen-parallel transport of upper crustal material toward the symmetry axis of the orocline.

Received 26 January 2008; accepted 9 October 2008; published 24 December 2008.

Citation: Arriagada, C., P. Roperch, C. Mpodozis, and P. R. Cobbold (2008), Paleogene building of the Bolivian Orocline: Tectonic restoration of the central Andes in 2-D map view, Tectonics, 27, TC6014, doi:10.1029/2008TC002269.

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