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

9528158辛普森最近的研究表明，南美洲西部的构造元素，密切相关的元古代和下古生代事件在阿巴拉契亚边缘的劳伦。该项目是对阿根廷中部的帕莫山脉省进行的构造和年代学研究，该地区的高级变质沉积岩、混合岩和未知年代的音调岩被陡峭的东倾糜棱岩带切割。Sierra Pampeanas是有争议的，因为构造模型将Laurentia置于南美洲前安第斯山脉的西部边缘，而在同一时间，Sierra Pampeanas的（Brasiliano）造山带被认为已经发展。争论的焦点是古生代事件的作用，特别是奥陶纪的法玛丁造山运动，据信这涉及到前科迪勒拉的劳伦阶岩石和西Sierra Pampeanas的岩石沿沿着800 km长的东法玛丁剪切带对东Sierra Pampeanan的增生。这项工作将确定高级变质作用的年龄和随后的糜棱岩化的年龄。从而可以对主要假设进行检验。这些信息是限制这里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。

9528158 Simpson 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.