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循环的建立，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”到其中。古代岩石和矿物记录的地球化学特征，但解释这些地球化学特征并不总是那么简单。在数十亿年的时间尺度上，构成地球大陆的岩石已经变形并被较年轻的岩石覆盖。为了“看透”这种复杂的演化过程，地球科学家使用不易改变和/或重新活化的元素保留的化学特征，从而为研究原生岩石提供线索。尽管随后进行了套印，但特别适合这些研究的一组元素是所谓的高场强元素（HFSE），这是一组具有独特地球化学特征的过渡金属，这使得它们不仅对了解地壳形成很重要，而且对理解地壳形成也很重要。非常特别是，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​​以提供对聚合构造边缘和大陆地壳形成过程中发生的地球化学过程的独特了解。对这些数据进行有意义的解释需要对控制观察到的同位素特征的过程有深入的了解，开发这样的框架是该项目将进行的中心研究目标。该职业项目将利用该领域的最新分析进展非传统稳定同位素 i) 对表征俯冲环境中 HFSE 钛、锆和铪的质量相关同位素分馏进行详细研究；以及 ii) 利用这些同位素变化更好地了解导致其分馏的过程和为了实现这一目标，研究小组将根据关键地质成分和数据生成一系列组合的 Ti-Zr-Hf 同位素数据集。表征“俯冲工厂”的岩石学过程以及已知会影响大块岩石和矿物尺度上与弧相关的岩浆系统的化学性质的岩石学过程将在造山橄榄岩、大洋中脊玄武岩、高海拔地区的不同地点进行确定。 -压力/低温俯冲复合体、下地壳弧堆积物以及与弧相关的玄武岩和分异火山岩，以了解 HFSE 传质整个俯冲周期中的样品和同位素分馏将使用涉及校准双尖峰和 MC-ICP-MS 测量的高精度方法进行测量。从大学预科阶段开始，促进地球科学领域更大的公平性、多样性和包容性的活动，其中包括与西班牙裔/拉丁裔高中生合作开发课外双语计划。图森联合学区 (TUSD)，积极招募 URM 本科生进行有意义的研究经历，并培训多样化的研究生和博士后。作为该项目的结果，PI 还将为感兴趣的研究人员和学生开发可访问的在线资源。在学生的积极参与下，更多地了解非传统稳定同位素。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值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.

High-precision zirconium isotope analysis of Pacific seawater reveals large mass-dependent fractionations in the ocean

• DOI: 10.1016/j.gca.2023.11.018
• 发表时间: 2023-11
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Linqing Huang;F. Tissot;M. Ibáñez-Mejia;K. Forsch;Carli Arendt;C. Anela Choy;Sarah M. Aarons