Collaborative Research: Subduction and Exhumation of Ultrahigh-Pressure Rocks -- Field and Drilling Studies in Eastern China

0003568黑客该项目的重点是中国人将在中国中东部的苏鲁超高压变质地体中钻探的一个5公里的钻孔周围区域。该项目的目标是通过研究P-T条件(即非常高的P，非常低的T)的“禁区”中的超镁铁质(地幔)岩来了解超高压岩石的形成和折返。需要解决的一些具体问题是：o当大陆被俯冲时，会发生什么类型的壳幔相互作用？O有多少大陆质量是以这种方式回收的？O流体-岩石相互作用的时间可以受到限制吗？O超高压石榴石橄榄岩告诉了我们什么关于“岩石构造”的过程？超高压橄榄岩是如何侵位到地壳中的？它们在挖掘过程中是如何演化的？为了保存它们的高P、低T组合，需要什么样的上升机制和上升速率？O板条水合相在挥发分进入地幔的再循环中起什么作用？O我们能用深地震剖面区分造山带的俯冲/碰撞构造与年轻事件之间的区别吗？O超高压变质作用和随后的折返作用发生在什么构造环境？是否需要大陆-大陆碰撞？首席调查员将在他们的研究中使用多种方法：1)测绘和构造分析；2)岩石学和地球化学；3)地质年代学；4)东海钻探现场的地球物理；5)地球动力学模型。

0003568HackerThis project is focused on the area around a 5 km drill hole the Chinese are going to drill in the Sulu ultrahigh-pressure (UHP) metamorphic terrane in east-central China. The goal of the project is to understand the formation and exhumation of UHP rocks through study of ultramafic (mantle) rocks from a "forbidden zone" of P-T conditions (i.e., very high P, very low T). Some specific questions to be addressed are: o What type of crust-mantle interaction occurs when continents are subducted? o How much of continental mass is recycled in this manner? o Can timing of fluid-rock interactions be constrained? o What do the UHP garnet peridotites tell us about "petrotectonic" processes? o How were UHP peridotites emplaced into the crust? How did they evolve during exhumation? What mechanisms and rates of ascent are necessary to preserve their high P, low T assemblages? o What roles do slab hydrous phases play in recycling of volatiles into the mantle? o Can we tell the difference between subduction/collisional architecture of orogens from younger events using deep-seismic profiles? o In what tectonic settings does UHP metamorphism and subsequent exhumation occur? Is continent-continent collision required?The Principal Investigators will employ a variety of methods in their study: 1) mapping and structural analysis; 2) petrology & geochemistry; 3) geochronology; 4) geophysics at the Donghai drill site; and 5) geodynamic modeling.***