EAR-PF In-situ and bulk sulfur isotope constraints on crustal recycling: a bridged investigation of superdeep diamonds and ocean island basalts

EAR-PF 原位和散装硫同位素对地壳循环的限制：超深钻石和洋岛玄武岩的桥接研究

• 批准号: 2052944
• 负责人: James Dottin
• 金额: $ 17.4万
• 依托单位: Dottin, James Wosley
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2052944&HistoricalAwards=false
• 关键词: EAR; PF; situ; bulk; sulfur

Dr. James W. Dottin III has been awarded an NSF EAR Postdoctoral Fellowship to pursue research and education endeavors at the Carnegie Institution for Science-Earth and Planets Laboratory (CIS-EPL) under the mentorship of Dr. Steven Shirey and Dr. Michael Walter. The Earth’s crust, which can be transferred from the surface to the interior of Earth through plate tectonics, provides many of the chemical elements that control the habitability of life on our planet. However, the detailed nature, relative ages of the various crustal materials, and where they ultimately reside in the Earth’s interior are not well understood. For this project, Dr. Dottin will use chemical signatures (specifically those of the element sulfur) measured in rocks and minerals erupted from the deep interior of the Earth to provide insight into the finer details of plate tectonics. Dr. Dottin’s work involves analyzing rocks and diamonds that come from different parts of the Earth’s interior to determine how elements found in the crust move around and are distributed across the globe. The proposed research will use unique characteristics of sulfur to identify specific crustal materials that are recycled through the Earth’s interior and provide relative constraints on the timescales on which crustal recycling occurs. Dr. Dottin will also lead an education program that incorporates students from historically underrepresented minority groups directly into the research project. Student involvement will take form through a strong collaboration with Smith College, a women’s college in Massachusetts. Dr. Dottin also plans to engage with students that will be actively recruited from local high schools and the many Historically Black Colleges and Universities in the Washington, D.C. area as a mentor and advisor through a summer internship program at CIS-EPL. The Earth’s mantle is compositionally heterogeneous, comprising geochemically distinct reservoirs from the process of crust extraction and recycling of crust into the mantle. The HIMU (high μ=238U/204Pb) mantle reservoir is an enigmatic endmember with extreme Pb-isotopic compositions, and is postulated to be composed of subducted altered oceanic crust that is associated with a carbonated component. However, the nature, origin, and global distribution of the components that make up the HIMU mantle remain poorly understood. For this project, Dr. Dottin will combine sulfur isotope information from key HIMU basalts and from sulfide inclusions in superdeep diamonds using microbeam and bulk digestion techniques. Dr. Dottin aims to trace the global distribution and interaction of recycled protoliths in HIMU mantle reservoirs that are thought to reside at the base of the mantle and/or within the mantle transition zone. The proposed analytical techniques, choice of key HIMU basalts, and choice of sulfides from transition zone diamonds offers an opportunity to address the potential isotopic heterogeneities that exist among mineral, hand sample, and global scales. From this work, Dr. Dottin plans to provide insight into the finer details of plate tectonics through constraints of source heterogeneity among HIMU mantle reservoirs and the proposed depth of slab accumulation that is possibly linked to the age of the reservoir and/or hotspot location.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.

詹姆斯·W·多丁三世（James W. Dottin III）博士在卡内基科学界和行星实验室（CIS-EPL）的指导下，授予了NSF EAR博士后研究金，以追求研究和教育努力，史蒂文·舍雷（Steven Shirey）和迈克尔·沃尔特（Michael Walter）博士的指导。地壳可以通过板块构造从地面转移到地球内部，提供了许多化学元素，可控制我们星球上生命的习惯性。但是，尚不清楚各种地壳材料的详细性质，各种地壳材料的相对年龄，以及它们最终居住在地球内部的地方。对于这个项目，Dottin博士将使用从地球深内部爆发的岩石和矿物质中测量的化学特征（特别是元素硫的特征），以深入了解板块构造的细节。 Dottin博士的工作涉及分析来自地球内部不同部分的岩石和钻石，以确定地壳中发现的元素如何四处移动并分布在全球范围内。拟议的研究将使用硫的独特特征来识别通过地球内部再生的特定地壳材料，并在发生地壳回收的时间尺度上提供相对限制。 Dottin博士还将领导一项教育计划，该计划将来自历史上代表性不足的少数群体的学生直接纳入研究项目。学生的参与将通过与马萨诸塞州的一所女大学史密斯学院进行强有力的合作。 Dottin博士还计划与将在华盛顿特区的许多历史悠久的黑人学院和大学作为心理和顾问通过在CIS-EPL的暑期实习计划中作为心理和顾问进行积极招募的学生互动。地球的地幔是完全异质性的，从地壳提取和将壳的回收过程中填充了地球化学上不同的储层。 Himu（高= 238U/204pb）地幔储层是一个具有极端PB-异位组成的神秘末端，并且被张贴由与碳酸化成分相关的俯冲变化的海洋壳。但是，构成Himu地幔的组件的性质，起源和全球分布仍然很众所周知。对于这个项目，Dottin博士将使用微束和散装消化技术结合来自关键Himu玄武岩的硫同位素信息和超深钻石中的硫化物夹杂物。 Dottin博士旨在追踪据认为驻留在地幔和/或地幔过渡区内的Himu地幔储层中回收原石的全球分布和相互作用。提出的分析技术，关键的HIMU玄武岩的选择以及从过渡区钻石中选择的硫化物为解决矿物，手工样本和全球尺度之间存在的潜在同位素异质性提供了机会。通过这项工作，Dottin博士计划通过限制Himu Mantle储量中的源异质性以及拟议的平板累积深度来提供对板块构造的细节的见解，这些深度可能与储层时代和/或热点地点相关。这些奖项通过评估NSF的稳定范围和稳定的影响。 标准。

项目成果

Isotopic evidence of sulfur photochemistry during lunar regolith formation

月球风化层形成过程中硫光化学的同位素证据

• DOI: 10.7185/geochemlet.2235
• 发表时间: 2022
• 期刊: Geochemical Perspectives Letters
• 影响因子: 4.9
• 作者: Dottin III, J.W.;Farquhar, J.;Kim, S.-T.;Shearer, C.;Wing, B.;Sun, J.;Ni, P.
• 通讯作者: Ni, P.

Near-zero 33S and 36S anomalies in Pitcairn basalts suggest Proterozoic sediments in the EM-1 mantle plume

• DOI: 10.1016/j.epsl.2022.117422
• 发表时间: 2022-04
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Jabrane Labidi;J. Dottin;M. Clog;C. Hemond;P. Cartigny