COLLABORATIVE RESEARCH: Timing of Orogenic Events in the Sierra Pampeanas of West-Central Argentina

最近的研究表明，南美洲西部具有与Laurentia的Appalachian边缘的元古代和下古生代事件密切相关的构造元素。本项目是对阿根廷中部潘潘山脉省的构造和地质年代学研究，在那里，东倾的糜棱岩带切割出了高品位的变质沉积岩、混杂岩和年龄未知的调性岩。帕米亚山脉是有争议的，因为构造模型将劳伦西亚置于南美洲前安第斯西部边缘，与此同时，帕米亚山脉的一个（巴西利亚）造山带被认为已经发育。争论的焦点是古生代事件的作用，特别是奥陶系法马提纪造山运动，该运动被认为涉及到沿800公里长的东法马提纪剪切带，前科迪勒拉的劳伦岩石和西帕米亚山脉的岩石与东帕米亚山脉的岩石的增生。这项工作将确定高变质作用的年龄和随后糜棱岩化的年龄。这样就可以对主要假设进行检验。这一信息是限制前安第斯构造发展的关键，以及与劳伦西亚阿巴拉契亚边缘事件的可能关系。

9628285 Gromet Recent research has suggested that western South America has tectonic elements that are closely related to proterozoic and lower paleozoic events in the Appalachian margin of Laurentia. This project is a structural and geochronological study of the Pampean Ranges Province of Central Argentina, where high grade metasedimentary rocks, migmatites and tonalities of unknown age are cut by steeply east-dipping mylonite zones. The Sierra Pampeanas are controversial because tectonic models place Laurentia against the pre-Andean western margin of South America during the same time that a (Brasiliano) orogenic belt in the Sierra Pampeanas is thought to have developed. At issue is the role of Paleozoic events, particularly the Ordovician Famatinian Orogeny, which is believed to have involved the accretion of Laurentian rocks of the Pre-Cordillera and rocks of the Western Sierra Pampeanas against the eastern Sierra Pampeanan along the 800 km-long Eastern Famatinian shear zone. This work will determine the ages of the high grade metamorphism and the age of subsequent mylonitization. Thus allowing a test of the main hypotheses. This information is key to constraining the pre-Andean tectonic development here, and the possible relationship to events in the Appalachian margin of Laurentia.