Collaborative Research: Kinematics and Timing of Early Paleozoic Tectonic Events In the Easternmost Precordillera Terrane, Argentina:An Evaluation of Gondwana-Laurentia Interaction

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One of the major recent advances in reconstructing past plate configurations was the recognition that the Precordillera Terrane of Argentina was derived (rifted from) the Ouachita embayment of present day North America, thus providing a rare example of knowing exactly where an exotic terrane came from. However, the timing of the rifting and the timing of the subsequent collision with Gondwana, critical to Paleozoic reconstructions is problematic. Previously the timing of the collision was thought to Middle to Late Ordovician based on when the carbonate platform drowned, presumably by close approach and subduction of the continental margin. However, more recent work suggests that the drowning of the carbonate platform was due to rift-related subsidence, and if correct, dates the rifting from North America, not the subsequent collision with Gondwana. This project aims to date the collision by radiometric methods from rocks in the exposed suture zone, including magmatic bodies that intruded during and after the several phases or pulses of collision-related deformation. Results will clarify the arrival time of the Precordillera, data that will be critical in establishing a Paleozoic plate position history.