CAREER: Redefining the high field strength element systematics of subduction systems using non-traditional stable isotopes

职业：使用非传统稳定同位素重新定义俯冲系统的高场强元素系统学

• 批准号: 2143168
• 负责人: Mauricio Ibanez-Mejia
• 金额: $ 67.96万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2143168&HistoricalAwards=false
• 关键词: CAREER; Redefining; field; strength; element

Reconstructing the nature of the geologic processes responsible for the evolution of our planet, including when and how continents formed and plate-tectonic cycles were established, has been a long-standing goal of Earth Scientists. Clues for answering these questions are ‘coded’ into the geochemistry of the ancient rock and mineral record, but interpreting these geochemical signatures is not always straightforward. Over billion-year timescales, the rocks that constitute Earth’s continents have been deformed and overprinted by younger geologic processes, significantly obscuring their original structural and chemical characteristics. In order to ‘see through’ this complex evolution, geoscientists use chemical signatures retained by elements that are not easily altered and/or remobilized, and thus that can provide clues into primary rock-forming processes despite subsequent overprinting. A group of elements particularly suited for these investigations are the so-called high-field strength elements (HFSE), a group of transition metals with unique geochemical characteristics which make them not only important to understand crust formation but also very resilient to alteration. In particular, the isotopic compositions of these elements, which can now be measured with great accuracy and precision, can provide unique glimpses into the geochemical processes taking place in convergent tectonic margins and during formation of continental crust. Nevertheless, making geologically meaningful interpretations from these data requires a robust understanding of the processes that control the observed isotopic signatures, and developing such framework is the central research goal this project will undertake.This CAREER project will leverage recent analytical developments in the field of non-traditional stable isotopes to i) conduct a detailed study of the mass-dependent isotope fractionations that characterize the HFSE titanium, zirconium, and hafnium in subduction environments; and ii) utilize these isotopic variations for better understanding the processes leading to their fractionation and fluxes during formation of continental crust. To achieve this, the research team will generate a series of combined Ti-Zr-Hf isotopic datasets from key geologic components and petrologic processes characterizing the ‘subduction factory’ and that are known to influence the chemistry of arc-related magmatic systems. Isotopic fractionations at the bulk-rock and mineral scales will be determined in various global localities of orogenic peridotites, mid ocean ridge basalts, high-pressure/low-temperature subduction complexes, lower-crustal arc cumulates, and arc-related basalts and differentiated volcanic rocks, to understand HFSE mass-transfer and isotopic fractionations across the entire subduction cycle. Samples will be measured using high-accuracy methods involving calibrated double-spikes and MC-ICP-MS measurements. In addition to the broader scientific impacts that will result from this research, the PI will develop educational activities that foster greater equity, diversity, and inclusivity within the Geosciences starting from a pre-college stage. These include the development of an afterschool bilingual program for Hispanic/Latinx high-school students in collaboration with the Tucson Unified School District (TUSD), active recruitment of URM undergraduates into meaningful research experiences, and training of diverse graduate students and postdocs. As a result of this project, the PI will also develop an accessible on-line resource for researchers and students interested in learning more about non-traditional stable isotopes, constructed with active student involvement.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

重建导致地球演化的地质过程的性质，包括大陆形成的时间和方式以及板块构造旋回的建立，一直是地球科学家的长期目标。回答这些问题的线索被编码到古代岩石和矿物的地球化学记录中，但解释这些地球化学特征并不总是一目了然。在数十亿年的时间尺度上，构成地球大陆的岩石已经被更年轻的地质过程变形和叠加，显著地掩盖了它们最初的结构和化学特征。为了“看穿”这一复杂的演化，地球科学家使用不易改变和/或重新动员的元素所保留的化学特征，因此可以为主要的岩石形成过程提供线索，尽管随后会进行叠印。一组特别适合于这些研究的元素是所谓的高场强元素(HFSE)，这是一组具有独特地球化学性质的过渡金属，使它们不仅对了解地壳形成很重要，而且对蚀变具有很强的弹性。特别是，这些元素的同位素组成现在可以非常准确和精确地测量，可以提供独特的一瞥在汇聚的构造边缘和大陆地壳形成期间发生的地球化学过程。然而，从这些数据中做出有地质意义的解释需要对控制观测到的同位素特征的过程有一个强有力的理解，而开发这样的框架是这个项目将承担的主要研究目标。这个职业项目将利用非传统稳定同位素领域的最新分析进展来：i)详细研究HFSE在俯冲环境中表现出的与质量有关的同位素分馏；以及ii)利用这些同位素变化来更好地理解导致它们在大陆地壳形成期间的分馏和通量的过程。为了实现这一目标，研究小组将从关键的地质成分和岩石学过程中产生一系列组合的Ti-Zr-Hf同位素数据集，这些成分和岩石学过程表征了“俯冲工厂”，并已知会影响与弧相关的岩浆系统的化学。将在全球不同地点测定造山橄榄岩、大洋中脊玄武岩、高压/低温俯冲杂岩、下地壳弧堆体以及与弧有关的玄武岩和分异火山岩的整体岩石和矿物尺度的同位素分馏，以了解整个俯冲旋回的高频SE质量转移和同位素分馏。样品将使用高精度方法进行测量，包括校准的双尖峰和MC-ICPMS测量。除了这项研究将产生的更广泛的科学影响外，PI还将开展教育活动，从大学预科阶段开始在地球科学领域促进更大的公平性、多样性和包容性。这些措施包括与图森联合学区合作，为拉美裔/拉丁裔高中生制定课外双语计划，积极招募URM本科生进入有意义的研究经历，以及培训不同的研究生和博士后。作为这个项目的结果，PI还将为有兴趣了解更多非传统稳定同位素的研究人员和学生开发一个可访问的在线资源，并由学生积极参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Zirconium stable isotope fractionation during intra-crustal magmatic differentiation in an active continental arc

• DOI: 10.1016/j.gca.2023.11.023
• 发表时间: 2023-11
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: L. Zieman;M. Ibáñez-Mejia;F. Tissot;H. Tompkins;Natalia Pardo;E. Bloch

Redox and mineral controls on Fe and Ti isotopic fractionations during calc-alkaline magmatic differentiation

• DOI: 10.1016/j.gca.2023.06.016
• 发表时间: 2023-08
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Aleisha C. Johnson;Zhe J. Zhang;N. Dauphas;R. Rudnick;J. Foden;Magali Toc

Zircon growth experiments reveal limited equilibrium Zr isotope fractionation in magmas

锆石生长实验揭示岩浆中有限平衡Zr同位素分馏

• DOI: 10.7185/geochemlet.2310
• 发表时间: 2023
• 期刊: Geochemical Perspectives Letters
• 影响因子: 4.9
• 作者: Tompkins, H.G.D.;Ibañez-Mejia, M.;Tissot, F.L.H.;Bloch, E.;Wang, Y.;Trail, D.
• 通讯作者: Trail, D.

A community-led calibration of the Zr isotope reference materials: NIST candidate RM 8299 and SRM 3169

由社区主导的 Zr 同位素参考材料校准：NIST 候选 RM 8299 和 SRM 3169

• DOI: 10.1039/d3ja00167a
• 发表时间: 2023
• 期刊: Journal of Analytical Atomic Spectrometry
• 影响因子: 3.4
• 作者: Tissot, François L.;Ibañez-Mejia, Mauricio;Rabb, Savelas A.;Kraft, Rebecca A.;Vocke, Robert D.;Fehr, Manuela A.;Schönbächler, Maria;Tang, Haolan;Young, Edward D.
• 通讯作者: Young, Edward D.

Temperature and co-crystallization effects on Zr isotopes

• DOI: 10.1016/j.gca.2023.05.004
• 发表时间: 2023-05
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: H. Kirkpatrick;T. Mark Harrison;M. Ibáñez-Mejia;F. Tissot;S. MacLennan;Elizabeth Bell