EAGER: Collaborative Research: Continental Subduction and Deep Crustal Melting

EAGER：合作研究：大陆俯冲和深部地壳融化

• 批准号: 1062187
• 负责人: Stacia Gordon
• 金额: $ 2.89万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1062187&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Continental; Subduction

Subducted continental crust can attain pressure-temperature conditions that are above the solidus for many crustal lithologies, but the conditions, timing, and consequences of deep crustal melting are largely unexplored. Although there have been experimental investigations of ultrahigh-pressure (UHP) melting, there are very few field-based studies of natural examples; existing work has focused largely on the age and chemical characteristics of granitoid bodies that are associated with UHP terrains and not on migmatites that commonly host UHP rocks. The generation of large amounts of partially molten crust during subduction has implications for mass and heat transfer from the mantle to the crust, orogenic growth by the addition of partially molten material generated at depth, and evolution of orogenic landscapes (e.g. development of plateaux). Moreover, the role of partially molten crust must be considered in understanding the mechanisms by which (U)HP rocks are overprinted during exhumation and subsequent orogenic processes. This proposed Early Grant for Exploratory Research (EAGER) project is designed to obtain U/Pb zircon ages from magma bodies (leucosomes, pegmatites) spatially associated with eclogite to determine if zircon crystallized and thus melting occurred at UHP conditions. If this exploratory study is successful, it will set up the background canvas for a larger scale project with the ultimate goal of testing the hypothesis that, in some orogens, partial melting of continental crust occurs during continental subduction and is dynamically linked to the thermal-mechanical evolution of orogens and the exhumation of UHP rocks. The pursuit for adequate sample material will take place in the Western Gneiss Region (Norway) because it is an accessible locale with abundant exposure of UHP rocks that are hosted by migmatite; some eclogite bodies are themselves migmatitic.

俯冲的大陆壳可以达到许多地壳岩性的压力温度条件，但是深层地壳熔化的条件，时机和后果在很大程度上尚未探索。尽管已经对超高压（UHP）熔化进行了实验研究，但对自然实例的基于现场的研究很少。现有的工作主要集中在与UHP地形相关的花岗岩体的年龄和化学特征上，而不是通常载有UHP岩石的Migmatites。在俯冲过程中，大量部分层状的地壳产生对从地幔到地壳的质量和热传递的影响，造基因生长，通过添加深度时产生的部分熔融材料以及造山学景观的进化（例如，Plateaux的发展）。此外，必须考虑部分熔融地壳在理解（u）HP岩石在挖掘过程和随后的造影过程中被过多张贴的机制中的作用。这项提出的探索性研究（急切）项目旨在从空间与eclogite相关的岩浆体（白细胞，pegmatites）获得U/PB锆石年龄，以确定锆石是否结晶并在UHP条件下发生熔化。如果这项探索性研究成功，它将为一个大规模项目建立背景画布，其最终目标是测试以下假设：在某些植物中，在大陆俯冲期间发生了部分大陆壳的部分融化，并且与Ohp Rocks的Orogens和Oraumination的热机械演化有关。对足够的样品材料的追求将在西部片麻岩地区（挪威）进行，因为它是一个可通行的地点，并占据了Migmatite托管的UHP岩石的丰富暴露；一些叶绿树本身就是壮大的。