Integrated Evaluation of Mantle Xenoliths from the Fosdick Mountains, Antarctica

智力价值：PI建议对南极洲福斯迪克山脉一套约1.4 Ma的镁铁质火山中心内的地幔捕虏体进行调查。这些最近夹带的地幔包体提供了一个独特的机会来表征西南极岩石圈地幔的特征，从白垩纪到现在，西南极岩石圈地幔经历了从白垩纪到现在的板块边界过程，如垂直于斜向板块会聚、大陆内部裂谷、大陆裂解和新近纪火山作用。这些火山中心来自不均匀的地幔来源，并拥有一套成分多样的地幔捕虏体，具有不同的矿物组合和微观结构。拟议的研究有两个相辅相成的目标：评估上地幔内部结构和成分的不均一性以及各种岩石圈内部和外部变量的变异性；以及利用捕虏体套件的结构和成分特征来阐明玛丽·伯德陆地地幔岩石圈内不均匀地震各向异性的可能原因，并提供相互竞争的假设，解释南极洲西部之下的活火山活动、热异常和缓慢的地震速度。此外，对南极洲西部之下的地幔样本的描述为当代ANET/POLENET地震学研究提供了一种“地面真相”，该研究试图确定地幔的组成、温度和地震各向异性的来源。博士后研究人员将接受EBSD技术、跨学科极地研究和本科生研究人员指导方面的培训。波士顿学院的两名本科生将参与这项研究，优先选择代表性不足的少数族裔和第一代大学生。将使用经过20多年NSF赞助的实地工作而组装的现有样本套件。国际空间站将为显微结构、结构和捕虏体数据创建一个数字数据库，以便迅速传播到国际南极社区。

Intellectual Merit: The PI proposes an investigation of mantle xenoliths entrained within a suite of ~1.4 Ma mafic volcanic centers in the Fosdick Mountains, Antarctica. These recently entrained mantle xenoliths offer a unique opportunity to characterize the West Antarctic lithospheric mantle that has been subject to active modification from Cretaceous to Present by plate-boundary processes, such as orthogonal to oblique plate convergence, intracontinental rifting, continental breakup, and Neogene volcanism. These volcanic centers derive from heterogeneous mantle sources and host a compositionally diverse suite of mantle xenoliths that have varied mineral assemblages and microstructures. The proposed research has two complementary goals: to assess structural and compositional heterogeneity within the upper mantle and the variability of intrinsic and extrinsic variables at a variety of lithospheric levels; and to use textural and compositional characterization of the xenolith suite to elucidate possible causes of heterogeneous seismic anisotropy within the Marie Byrd Land mantle lithosphere and inform competing hypotheses explaining the active volcanism, thermal anomaly, and slow seismic velocities beneath West Antarctica. Furthermore, characterization of samples of the mantle beneath West Antarctica provides a type of 'ground truth' in support of contemporary ANET/POLENET seismology research that seeks to determine mantle composition, temperature, and sources of seismic anisotropy.Broader impacts: The PI is in his first-year as a tenure track faculty member at Boston College. A postdoctoral researcher will be trained in EBSD techniques, interdisciplinary polar research, and the mentoring of undergraduate investigators. Two Boston College undergraduates will participate in the research and a priority will be placed on selecting underrepresented minorities and first-generation college students. An existing sample suite assembled over more than 20 years of NSF sponsored field work, will be used. The PI will create a digital database for microstructural, textural, and xenolith data for rapid dissemination to the international Antarctic community.