U-Pb and Ar-Ar dating of minerals from metamorphic and syn-orogenic sedimentary rocks as a key to understanding architecture and evolution of collisional orogens

中欧华力西期内叠层是基底单元、推覆体遗迹和同造山沉积的拼贴，它们具有不同的起源，并显示出广泛的年龄和变质变形程度。一个突出的例子是来自Erzgebirge和Saxon麻粒岩地块的大陆地壳岩石，它们分别在早石炭世超高压（UHP）和超高温（UHT）条件下变形和变质。这些岩石从地幔深处的初始近等温折返非常快。麻粒岩侵位在上地壳中形成接触变质晕，这在世界上可能是独一无二的。高级变质作用和大变形作用在具有晚维森期结晶年龄的花岗岩侵入之前已经结束。与此相反，上覆的弗兰肯贝格飞来峰和相邻的卢萨蒂亚地块则没有受到变质作用的影响。海尼陈盆地的碎屑岩沉积与高级基底单元的变质和折返是同时代的，记录了折返、冷却和侵蚀的历史。利用40 Ar/39 Ar和U-Pb年代学研究了华力西造山带东部超高压/高压和超高温单元的折返和剥蚀历史。选定的基底单元将有针对性地进行对比，以检测它们之间的年龄不连续性，以限制重结晶和折返年龄，并进行证据和氩继承性研究。此外，通过研究海尼陈盆地沉积物的性质和来源如何随时间变化，我们将能够确定折返率，以及UHP/HP和UHT单元的暴露时间和初始侵蚀。关键词：大陆碰撞造山，折返作用，同造山沉积，Ar-Ar和U-Pb年代学，欧洲华力西带

The Variscan internides in central Europe are a collage of basement units, nappe relics, and syn-orogenic deposits that have varying origins and show a wide range in age and degree of metamor-phism and deformation. An outstanding example are continental crust rocks from the Erzgebirge and the Saxon Granulite Massif, which were deformed and metamorphosed in the Early Carboniferous un-der, respectively, ultrahigh-pressure (UHP) and ultrahigh-temperature (UHT) conditions. The initial near-isothermal exhumation of these rocks from mantle depths was very fast. Probably unique in the world, granulite emplacement in the upper crust caused a contact metamorphic aureole. High-grade metamorphism and major deformation had ended before granites with Late Viséan crystallization ages intruded. In contrast, the overlying Frankenberg Klippe and the contiguous Lusatian Block escaped this metamorphism. Locally-derived clastic sediments of the Hainichen Basin are coeval with meta-morphism and exhumation of the high-grade basement units, thus recording the history of exhumation, cooling, and erosion. Our primary aim is to investigate the exhumation and denudation history of the UHP/HP and UHT units in the eastern Variscan internides by using a combination of 40Ar/39Ar and U-Pb geochronology. Selected basement units will be targeted for correlation purposes in order to detect age discontinuities between them, to constrain recrystallization and exhumation ages, and for prove-nance and argon inheritance studies. In addition, by studying how the sediments of the Hainichen Ba-sin change over time in character and origin we will be able to establish exhumation rates, and the time of exposure and initial erosion of the UHP/HP and UHT units. Key words: continental collision orogeny, exhumation, syn-orogenic deposition, Ar-Ar and U-Pb geo-chronology, European Variscan Belt