CAREER: Tracing sulfur in subducting slabs with apatite oxybarometry

职业：用磷灰石氧压计追踪俯冲板片中的硫

• 批准号: 2236903
• 负责人: Megan Holycross
• 金额: $ 81.95万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2028-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2236903&HistoricalAwards=false
• 关键词: CAREER; Tracing; sulfur; subducting; slabs

Tectonic plate boundaries are important loci of mass transfer in the Earth system. The transfer of volatile elements from Earth’s deep interior to its surface and atmosphere at subduction zones enables a habitable planet. Magmas erupted at arc volcanoes, located at subduction zones, are more oxidized than magmas erupted at mid-ocean ridges. Arc volcanoes are the basis of the continental crust and host economic ore deposits. Quantifying the processes that lead to the oxidation of magmas in subduction zones is then critical for understanding the formation of continents and ores. This project will investigate the hypothesis that the transfer of sulfur throughout the subduction system is responsible for the elevated oxidation state of arc magmas. High-pressure experiments will be executed to measure the behavior of sulfur in rocks at subduction zone conditions. Experimental results will be used to inform observations of natural subduction-related rocks. This project includes research and mentoring experiences for a postdoctoral associate, a PhD student and two undergraduate students from underrepresented groups. Project results will be assimilated into new open access Earth science educational content. A hybrid capstone outreach event will be held to disseminate research outcomes to the public.This study will examine the hypothesis that the oxidized signature of arc magmas is due to the transfer of sulfate from metamorphosed oceanic crust on the down-going slab to the overlying arc mantle. High-pressure experiments will be executed to calibrate a new proxy for the oxidation state of subduction-related rocks based on the incorporation and valence state of sulfur in the mineral apatite. Experimental apatite will be co-crystallized with sulfide or sulfate phases such that the behavior of sulfur in apatite can be used to provide indirect information on the relative stabilities of sulfide vs. sulfates in subducted oceanic crust. Results from the experiments will be applied to determine the oxidation states of suites of apatite-bearing metabasites to determine if subducting slabs record an increase in oxidation state concurrent with the increase in dissolved oxygen in the deep oceans and rise in seawater sulfate in the Early Phanerozoic.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.

构造板边界是地球系统中质量转移的重要局部。挥发性元素从地球深内部到其表面和俯冲区域的大气的转移使一个可居住的行星。位于俯冲带的弧火山爆发的岩浆比在中山山脊上爆发的岩浆更被氧化。弧火山是连续地壳和托管经济矿床的基础。然后，量化导致俯冲带中岩浆氧化的过程对于理解持续和矿石的形成至关重要。该项目将调查以下假设：硫酸在整个俯冲系统中的转移负责弧形岩浆的氧化状态升高。将执行高压实验，以测量俯冲带条件下岩石中硫的行为。实验结果将用于告知对自然俯冲相关岩石的观察。项目包括针对博士后同学的研究和心理经历，博士生和来自代表性不足的团体的两名本科生。项目结果将被吸收到新的开放访问地球科学教育内容中。将举行一场混合盖石宣传活动，以向公众传播研究成果。这项研究将研究以下假设：弧岩浆的氧化特征是由于硫酸盐从变形的海洋壳转移到向下的厚板上的硫酸盐转移到上覆的弧形地幔。将执行高压实验，以根据矿物磷灰石中的保险和硫磺状态来校准俯冲相关岩石氧化状态的新代理。实验性磷灰石将与硫化物或硫酸盐相结合，以便可以使用硫酸盐中硫的行为来提供有关硫化物与硫酸硫酸盐在俯冲的海洋壳中的相对稳定性的间接信息。实验的结果将应用于确定含有磷灰石的含有磷灰石的套件的氧化状态，以确定俯冲板是否会记录氧化状态的增加，这与深海中溶解的氧气的增加并增加，并在硫酸盐中的硫酸盐中的硫酸盐中升高，并通过智力授予nsf的构建，并以表达了nsf的基础。和更广泛的影响审查标准。