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

在重建过去板块构造方面，最近取得的主要进展之一是认识到阿根廷的Precordillera地体是从现今北美的Ouachita地体演化而来的，从而提供了一个罕见的确切了解外来地体来源的例子。然而，裂谷的时间和随后与冈瓦纳碰撞的时间，对古生代的重建至关重要，是有问题的。此前，根据碳酸盐岩台地淹没的时间，认为碰撞时间为中晚奥陶世，可能是由于大陆边缘的接近和俯冲。然而，最近的研究表明，碳酸盐岩台地的淹没是由于与裂谷有关的沉降，如果正确的话，可以确定裂谷来自北美，而不是随后与冈瓦纳的碰撞。该项目旨在通过暴露的缝合带岩石的辐射测量方法确定碰撞的年代，包括在碰撞相关变形的几个阶段或脉冲期间和之后侵入的岩浆体。结果将澄清前科迪勒拉的到达时间，这些数据将对建立古生代板块位置历史至关重要。

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.