CAREER: Investigating the Relationship Between Mantle Shear Localization, Melt Flow and Water Content

剪切局部化的发生是板块构造的特征之一，但剪切局部化的驱动机制缺乏约束。熔体和水都被认为是导致地球--S地幔--韧性局部化的介质。这项职业研究项目通过分析保存完好的地幔橄榄岩之一的俄勒冈州约瑟芬橄榄岩中的剪切带，研究了剪切局部化、熔体流动和水的关系。地面激光扫描将被用来绘制高分辨率的剪切带地图，这项调查是作为本科生野外课程的一部分进行的。调查结果将与关于剪切带和熔体通道的位置和方向的GPS数据合并。将对实地考察期间收集的样品进行显微结构分析，以确定矿物取向与熔体和水分含量变化之间的关系。橄榄岩辉石中的水含量分析将被用来限制与剪切变形有关的水的露头尺度变化。这一职业项目的教育部分将通过使用地面激光扫描向本科生和研究生提供先进实地方法的经验。具有尖端分析技术和实地活动计划的经验将为学生未来在地球科学领域的职业生涯做好准备。在这个项目中，教学和研究的结合将使学生接触到一系列学科的各种主题和技术，包括岩石学、地球化学、岩石变形、构造学和地震学。该项目的研究涉及岩石学、地球化学、岩石变形、构造学和地震学。项目成果将广泛适用于各学科。例如，显微构造分析与橄榄岩地球化学的结合将提供对控制地震各向异性的因素的洞察。该项目的成果也将适用于2011年GeoPRISMS实施计划中确定的主题，包括：(I)了解地幔楔体的动力学；(Ii)弧前到弧后的挥发通量；(Iii)地幔楔体中的变质作用、熔融和流体/熔体迁移。

The occurrence of shear localization is one of the defining properties of plate tectonics, but the mechanisms driving shear localization are poorly constrained. Both melt and water have been proposed as agents that lead to ductile localization within the Earth?s mantle. This CAREER research project investigates the relationship between shear localization, melt flow and water through analysis of well-preserved shear zones in one of the best examples of mantle peridotite, the Josephine peridotite in Oregon. Terrestrial laser scanning will be used to map shear zones at high resolution, with the survey being carried out as part of an undergraduate field class. The survey results will be merged with GPS data on the location and orientation of shear zones and melt channels. Microstructural analysis of samples collected during fieldwork will be carried out to determine the relationship between mineral orientations and variations in melt and water contents. Analysis of water concentrations in peridotite pyroxenes will be used to constrain the outcrop-scale variation in water in relation to shear deformation. The education component of this CAREER project will provide undergraduate and graduate students with experience in advanced field methods through the use of terrestrial laser scanning. Experience with cutting-edge analytical techniques and field campaign planning will prepare students for future careers in the geosciences. Integration of teaching and research in this project will expose students to a variety of topics and techniques across a range of disciplines, including petrology, geochemistry, rock deformation, tectonics and seismology.The research in this proposal lies at the intersection of petrology, geochemistry, rock deformation, tectonics, and seismology. Project results will be widely applicable across disciplines. For example, the combination of microstructural analyses with peridotite geochemistry will provide insight into the factors that control seismic anisotropy. Results of this project will also be applicable to themes identified in the 2011 GeoPRISMS Implementation Plan, including (i) understanding mantle wedge dynamics; (ii) fore-arc to back-arc volatile fluxes and (iii) metamorphism, melting, and fluid/melt migration in the mantle wedge.