Earth Planets Space, Vol. 58 (No. 10), pp. 1255-1272, 2006
Germán Bayona1, Augusto Rapalini2, and Vincenzo Costanzo-Alvarez3
1Corporación Geológica Ares, Calle 57 No. 23-09 of 202, Bogotá, Colombia
2Instituto de Geofísica Daniel Valencio (INGEODAV), Departamento de Ciencias Geológicas, FCE y N, Universidad de Buenos Aires,
Pabellón 2, Ciudad Universitaria, 1428, Buenos Aires, Argentina
3Departamento de Ciencias de la Tierra, Universidad Simón Bolívar, Apartado 89000, Caracas 1081-A, Venezuela
(Received December 13, 2005; Revised April 11, 2006; Accepted April 28, 2006; Online published November 8, 2006)
New paleomagnetic data isolated in Upper Triassic to Aptian rocks exposed in the Colombian Andes and west of the Guyana craton, in conjunction with paleomagnetic data from the Andes of Venezuela and the South American craton, permit the interpretation of along-margin northward translations of Andean Colombian terranes during the Early-Middle Jurassic. Field tests and comparison with reference paleopoles for South America indicate that characteristic components uncovered in red-siliciclastic and igneous rocks are primary, or near-depositional, and they are carried dominantly by hematite, magnetite and Ti-magnetite. Difference in declination values of characteristic components isolated in fault-bounded blocks document counter-clockwise rotations previous to syn-extensional deposition. The Jurassic tectonic scheme proposed here for the northwestern corner of South America shows an Early Jurassic, linear subduction-related magmatic arc evolving to Late Jurassic rift-related setting associated to the opening of the Proto-Caribbean Ocean and westward retreat of the subduction zone. A similar tectonic evolution for the Jurassic has been proposed for southwestern USA and the Nazas arc in Mexico.
Key words: Paleomagnetism, Jurassic, Northern Andes, Tectonics.