CAREER: Mantle Hybridization via Melt-Rock Reaction-Implications for Chemical Variability of Oceanic Basalts and Lithologic Heterogeneities in the Earth's Convecting Mantle

该CAREER奖的研究部分将集中在地球异质上地幔条件下熔融岩石反应的一系列实验研究。地球上地幔的部分熔融包括橄榄岩和再循环的地壳岩性影响地球的热演化，地壳的地球化学变化，内部的分化，关键挥发物的外逸层通量，以及地幔的地球物理性质。虽然喷发玄武岩的同位素和微量元素地球化学早已确立了洋中脊玄武岩（MORB）地壳和大陆沉积物在洋岛玄武岩（OIB）的地幔源区的存在下，合理的岩性不均匀性的身份，以及这些岩性如何赋予喷发熔岩的主要元素签名仍然没有解决。到目前为止，实验大多考虑了各种岩性的直接部分熔融，而不是对流地幔中普遍存在的涉及壳幔系统的反应过程。本实验研究将探讨俯冲地壳岩性衍生的部分熔融和橄榄岩反应如何可能产生各种各样的岩浆成分和混合岩性。这些实验将借助于活塞缸（PC）和多砧（MA）装置进行，以通过（1）MORB榴辉岩衍生的部分熔体与可育和贫化橄榄岩反应，（2）变质岩衍生的部分熔体与橄榄岩反应，（3）MORB/变岩熔体-橄榄岩相互作用产生的端元混合岩性（模态蚀变橄榄岩和辉石岩）的部分熔融。预计实验将涵盖俯冲壳和沉积物部分熔融但橄榄岩未熔融的压力和温度。反应的部分熔体和反应的矿物组合的主要元素组成将被确定为深度，温度，原始地壳熔体和橄榄岩组合物，部分反应结晶的程度，和熔体岩石比的函数。此外，使用高精度电子探针微量分析和激光烧蚀电感耦合等离子体质谱法，将确定诸如第一行过渡金属、镓和锗的元素的分馏，目的是使用这些元素，结合主要元素平衡，限制玄武岩源区的矿物学和岩性的不均匀性。这个CAREER项目整合了PI的地球科学研究通过一系列教育推广活动，学生的专业和职业发展，以及对地球科学研究的广泛领域的贡献，拟议的实验将产生与广泛的地球科学学科有关的关键数据，包括岩石学-地球化学、矿物物理学、地球动力学和地震学。推广活动将包括一个为期10周的暑期实习一个当地社区大学的学生通常来自代表性不足和少数群体，每年在PI的实验岩石学实验室，并支持一个高中或中学教师，每年为4周的课程计划发展固体地球的主题和实验室的研究经验。这两项外展活动符合莱斯大学的学校科学和技术（SST）计划的使命，并与之合作组织。此外，PI将为“21世纪世纪岩石学教学”网站开发描述拟议研究的动机、概念、结果和影响的内容和视觉效果，该网站是一个开放式资源，被岩石学教师广泛用于地球仪的本科生和研究生课程。作为本提案的一部分进行的研究将促进新的MA实验室的运作，从而有助于收集新的MA压力校准和组装数据，并与COMPRES（地球科学材料特性研究联盟）共享。所产生的实验数据的壳幔杂交（有或没有挥发物）将有助于新一代的热力学，矿物物理学和地幔物质和过程的地球动力学模型。最后，在赖斯的部分支持下，计划聘请两名博士生，并招募多达五名赖斯本科生，以推进他们的学术旅程和教育经验。

The research component in this CAREER award will focus on a series of experimental investigations of melt-rock reaction in Earth's heterogeneous upper mantle conditions. Partial melting of the Earth's upper mantle comprising peridotite and recycled crustal lithologies influences the thermal evolution of the planet, geochemical variability of the crust, differentiation of the interior, fluxes of key volatiles to the exosphere, and geophysical properties of the mantle. While isotopic and trace element geochemistry of erupted basalts have long-established the presence of subducted mid-ocean ridge basaltic (MORB) crust and continental sediment at mantle source regions of ocean island basalts (OIB), the identities of plausible lithologic heterogeneities and how such lithologies impart major element signatures on erupted lavas remain unresolved. Experiments thus far have mostly considered direct partial melting of various lithologies and not the reactive processes involving crust-mantle systems that should be ubiquitous in the convecting mantle. This experimental study will explore how subducted crustal lithologies-derived partial melts and peridotite reaction may produce a wide array of magma compositions and hybrid lithologies. These experiments will be conducted with the aid of piston cylinder (PC) and multi anvil (MA) devices, in order to constrain mantle hybridization via (1) MORB-eclogite-derived partial melts and fertile and depleted peridotite reaction, (2) metapelite-derived partial melts and peridotite reaction, and (3) partial melting of end member hybrid lithologies (modally altered peridotite and pyroxenites) produced by MORB/metapelite melt-peridotite interactions. Experiments are expected to span pressures and temperatures over which subducted crusts and sediments are partially molten but peridotite is unmolten. Major element compositions of reacted partial melts and reacted mineral assemblages will be determined as a function of depth, temperature, original crustal melt and peridotite compositions, extent of partial reactive crystallization, and melt-rock ratio. Furthermore, using high precision electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry, fractionation of elements such as first-row transition metals, Gallium, and Germanium will be determined with the goal of using these elements, in conjunction with major element equilibria, to constrain the mineralogic and lithologic heterogeneities of the basalt source regions.This CAREER project integrates the PI's Earth science research and teaching through a range of educational outreach activities, professional and career developments of students, and contributions to the broad field of earth science research. The proposed experiments will generate key data relevant to a wide range of Earth science disciplines including petrology-geochemistry, mineral physics, geodynamics, and seismology. The outreach activities will include a 10-week summer internship for one local community college student typically from underrepresented and minority groups, each year, in the PI's experimental petrology lab and supporting one high school or middle school teacher every year for a 4-week lesson plans development on solid Earth topics and research experience in the experimental lab. These two outreach activities are in line with the mission of and organized in collaboration with School Science and Technology (SST) Programs of Rice University. In addition, contents and visuals depicting the motivation, concepts, results, and implications of the proposed research will be developed by the PI for the 'Teaching Petrology in the 21st Century' website, an open-access resource widely used by petrology instructors for both undergraduate and graduate curriculum across the globe. The research performed as part of this proposal will facilitate operation of a new MA lab and will thus contribute towards collection of new MA pressure calibration and assembly data to be shared with the COMPRES (Consortium for Materials Properties Research in Earth Sciences). The generated experimental data on crust-mantle hybridization (with or without volatiles) will contribute towards newer generation thermodynamic, mineral physics, and geodynamic models of mantle materials and processes. Finally, with partial support from Rice, it is planned to engage two PhD students and recruit as many as five Rice undergraduates in order to advance their academic journey and educational experiences.