Integrated Evaluation of Mantle Xenoliths from the Fosdick Mountains, Antarctica

学术价值：该项目建议对南极洲福斯迪克山脉约1.4 Ma基性火山中心内的地幔捕虏体进行研究。这些新近携带的地幔捕虏体提供了一个独特的机会来描述南极西部岩石圈地幔的特征，从白垩纪到现在，这些岩石圈地幔受到了板块边界过程的积极改造，如正交到斜向板块辐合、大陆内裂陷、大陆分裂和新近纪火山作用。这些火山中心来源于非均匀的地幔源，并拥有一套成分多样的地幔捕虏体，这些捕虏体具有不同的矿物组合和微观结构。提出的研究有两个互补的目标：评估上地幔内部的结构和成分的非均质性以及岩石圈不同水平上的内在和外在变量的可变性；并利用包体组的结构和成分特征来阐明玛丽伯德地地幔岩石圈内不均匀地震各向异性的可能原因，并为解释南极洲西部活火山作用、热异常和慢地震速度的竞争性假设提供信息。此外，南极洲西部地幔样品的特征提供了一种“地面真相”，支持当代ANET/POLENET地震学研究，旨在确定地幔成分、温度和地震各向异性的来源。更广泛的影响：这是他在波士顿学院担任终身教职的第一年。博士后研究员将接受EBSD技术、跨学科极地研究和本科生研究指导方面的培训。波士顿学院（Boston College）的两名本科生将参与这项研究，并将优先选择代表性不足的少数族裔和第一代大学生。一个现有的样品套件组装超过20年的NSF赞助的实地工作，将被使用。PI将为微观结构、纹理和捕虏体数据建立一个数字数据库，以便迅速传播给国际南极社区。

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.