HR: 0830h
AN: T31D-0869    [PDF]
TI: Grenvillian History Of The SW Amazon Craton: The Accretionary History Of The Paragua Craton In A Rodinia Framework.
AU: * Tohver, E
EM: etohver@umich.edu
AF: University of Michigan, 2534 C.C. Little Bldg., Ann Arbor, MI 48103-1069 United States
AU: van der Pluijm, B
EM: vdpluijm@umich.edu
AF: University of Michigan, 2534 C.C. Little Bldg., Ann Arbor, MI 48103-1069 United States
AU: Geraldes, M C
EM: geraldes@uerj.br
AF: Universidade Estadual do Rio de Janeiro, Rua Sao Francisco Xavier, 524 sala 4006A, Rio de Janeiro, 20550-013 Brazil
AB: The tectonic history of the Amazon craton plays an essential role in the amalgamation of the Rodinia supercontinent, with many postulating a position of the Amazon along the eastern margin of Laurentia. Recognition of a two-stage Grenvillian history of the SW margin of the Amazon craton is based on recently obtained U-Pb, 40Ar/39Ar, and Rb-Sr data that demonstrate at least two discrete metamorphic and deformational events during end Mesoproterozoic times. The record of the younger ca. 1.09 Ga event is preserved almost exclusively in the metasediments of the E-W trending Nova Brasilandia belt, whereas the older ca. 1.18 Ga event is recorded entirely in the polydeformed basement rocks of the Amazon craton to the N. We interpret the Nova Brasilandia belt to record the accretion of the Paragua craton to the Amazon craton in the final stages of the construction of Rodinia. We report new 40Ar/39Ar data from the Paragua craton that record the original igneous age distributions of 1.35 - 1.55 Ga. These data are interpreted to reflect the rigid behavior of the Paragua craton in the Rodinia framework, suggesting that accretion of this cratonic block took place largely through strike-slip motion. We propose a Cordilleran-type margin for the Grenville collision between the nuclei of North and South America, a scenario that allowS for the polychronous tectonic evolution observed in the North American Grenville province and the emplacement of exotic terranes.
DE: 1035 Geochronology
DE: 8102 Continental contractional orogenic belts
SC: Tectonophysics [T]
MN: 2003 Fall Meeting