Collaborative Research: RUI: Using K-feldspar megacryst and mineral inclusion T-X-t histories to assess batholith growth and evolution in the Tuolumne intrusive complex, CA

合作研究：RUI：利用钾长石巨晶和矿物包裹体 T-X-t 历史来评估加利福尼亚州图奥勒米侵入岩杂岩的岩基生长和演化

• 批准号: 2223332
• 负责人: Valbone Memeti
• 金额: $ 33.78万
• 依托单位: CSU Fullerton Auxiliary Services Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2223332&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Using; feldspar

Volcanoes are well-known but poorly understood. How does magma build up beneath active volcanoes, and how long does it take to do so? What controls whether it erupts or cools deep underground to form plutons? How long does it stay molten there, and how much of it is eruptible for how long? Hundreds of millions of people live within 100 miles of active volcanoes. They are at risk of being exposed to volcanic hazards. Volcanic eruptions also affect climate and the environment. Yet decades of research have not answered some of these basic questions. This project will address these questions in the Tuolumne pluton. It is home to the spectacular rock exposures of Yosemite National Park. Uranium-lead age dates of small minerals will determine when the plutons cooled to the rocks that are exposed at the surface today. They will also reveal the duration of time that magma was present. Additionally these much smaller minerals are found included in several-inch-large potassium feldspar crystals. The chemistry of the feldspars serves like fingerprints in a crime scene. They will determine when, where and how much magma was stored 90 million years ago to feed volcanic eruptions. How sticky and hot magma was will help determine what these eruptions might have looked like. This project supports two research groups: 1) Researcher Memeti, a woman at Hispanic-serving, undergraduate-focused California State University Fullerton, and 2) Researcher Schoene at research-focused Princeton University. The team will train several graduate students in age dating and chemistry methods. Graduate students help train undergraduate students involved in different parts of the project. All students take part in all aspects of research activities including field work and publishing. Memeti will complete following activities: 1) update authored Yosemite audiotour mobile app based on this project’s results, 2) continue to organize field trips to Yosemite National Park, and 3) share research results with park rangers. 4) She will develop introductory geology labs for geology students, and 5) continue her outreach efforts on volcanic hazards at southern California public events. Schoene will teach local K-12 teachers on volcanoes and hazards in a seminar at Princeton University. This 3-yr collaborative RUI project between California State University Fullerton and Princeton University seeks to determine the time and length scales of magma bodies in magmatic arcs and their changes in composition, crystallinity, and volume over time. The study will use K-feldspar pheno- and megacrysts up to 12 cm long and megacryst-hosted mineral inclusions from the Half Dome and Cathedral Peak units of the 95-85.5 Ma Tuolumne intrusive complex in the central Sierra Nevada. K-feldspar textures and zoning will be imaged in 3D with CT scans and CL images and quantitatively analyzed with electron microprobe and laser ablation ICPMS for geochemistry. K-feldspar mineral inclusions will be measured for TIMS-TEA U-Pb zircon and titanite geochronology, SIMS Ti-in-zircon and Zr-in-titanite thermometry, and EMP and LA-ICPMS plagioclase and hornblende thermometry and chemometry (determining melt compositions). These data will be synthesized to test the hypotheses that the Tuolumne intrusive complex matured thermally during incremental construction, creating interconnected magma bodies many kilometers in length, capable of magma flow, fractionation, mixing, and likely eruption. These data will reflect on current debates about whether long-lived and large composite intrusions like the Tuolumne complex are characterized by “hot” or “cold” storage. “Cold” storage is characterized by small, rigid magma mushes that spend most of their time at temperatures near or at the solidus, limiting interaction with coeval magma bodies, only occasionally, if ever, “defrosting” by magma recharge to feed volcanic eruptions. In contrast, “hot storage” allows for dynamic inter-unit magma mixing and crystal recycling in large (10-100s of square kilometers) magma bodies at significantly higher temperatures above the solidus and lower crystallinities and at time scales of up to millions of years.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.

火山是众所周知的，但却鲜为人知。岩浆是如何在活火山下形成的，形成需要多长时间？是什么控制着它是喷发还是冷却到地下深处形成深埋岩？它在那里保持熔融状态多长时间，有多少是可以喷发的，持续多长时间？数亿人居住在距离活火山100英里的范围内。他们有暴露在火山危险中的危险。火山爆发也会影响气候和环境。然而，几十年的研究并没有回答其中的一些基本问题。该项目将在Tuolumne岩体中解决这些问题。这里是优胜美地国家公园壮观的岩石暴露的所在地。小矿物的铀-铅年龄测定将决定今天暴露在地表的岩石是在何时冷却的。它们还将揭示岩浆存在的时间。此外，这些小得多的矿物质被发现包含在几英寸大的钾长石晶体中。长石的化学成分就像犯罪现场的指纹。他们将确定9000万年前火山喷发所需的岩浆储存的时间、地点和数量。岩浆的粘性和热度将有助于确定这些喷发的样子。该项目支持两个研究小组：1)研究人员Memeti，她是一名女性，就职于以拉美裔为主的加州州立大学富勒顿分校；2)研究人员Schoene就职于以研究为主的普林斯顿大学。该团队将在年龄测定和化学方法方面培训几名研究生。研究生帮助培训参与项目不同部分的本科生。所有学生都要参与研究活动的各个方面，包括实地工作和出版。Memeti将完成以下活动：1)根据该项目的结果更新约塞米蒂有声旅游手机应用程序；2)继续组织约塞米蒂国家公园的实地考察；3)与公园管理员分享研究成果。4)她将为地质学专业的学生开发入门地质学实验室，5)继续在南加州的公共活动中宣传火山灾害。舍恩将在普林斯顿大学的一个研讨会上向当地K-12教师讲授火山和危险。这个由加州州立大学富勒顿分校和普林斯顿大学合作的为期3年的RUI项目旨在确定岩浆弧中岩浆体的时间和长度尺度，以及它们的组成、结晶度和体积随时间的变化。该研究将使用内华达山脉中部95-85.5 Ma Tuolumne侵入杂岩的半圆顶和大教堂峰单元的长达12厘米的k长石辉岩和巨晶岩矿物包裹体。利用CT扫描和CL图像对k长石的结构和分区进行三维成像，并利用电子显微探针和激光烧蚀ICPMS进行定量分析。k -长石矿物包裹体将用于TIMS-TEA U-Pb锆石和钛矿地质年代学测量，SIMS ti -in-锆石和zr -in-钛矿测温，EMP和LA-ICPMS斜长石和角闪石测温和化学测量（测定熔体成分）。这些数据将被综合起来，以验证Tuolumne侵入复合体在增量构造过程中热成熟的假设，创造了许多公里长的相互连接的岩浆体，能够岩浆流动，分馏，混合和可能的喷发。这些数据将反映当前关于长期存在的大型复合侵入物（如Tuolumne复合体）的特征是“热”还是“冷”储存的争论。“冷”储存的特点是小而坚硬的岩浆，大部分时间都处于接近或接近固体的温度，限制了与同时期岩浆体的相互作用，只有偶尔，如果有的话，通过岩浆补给来“解冻”火山爆发。相比之下，“热储存”允许在大型（10-100平方公里）岩浆体中进行动态的单元间岩浆混合和晶体循环，其温度明显高于固体，结晶度较低，时间尺度长达数百万年。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。