Collaborative Research: Revisiting the water-saturated granite solidus

合作研究：重新审视水饱和花岗岩固相线

基本信息

批准号：
2120598
负责人：
Jay Thomas
金额：
$ 25.36万
依托单位：
Syracuse University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2120598&HistoricalAwards=false
关键词：
Collaborative Research Revisiting water saturated

项目摘要

Earth’s uppermost continental crust is composed on average of granitic material. Granites are igneous rocks, a subset of rocks that form by the cooling and subsequent crystallization of molten materials. The temperature at which a water-bearing granite melts (or, upon cooling of a magma, the temperature at which the last drop of molten material crystallizes) is known as the granitic water-saturated solidus (G-WSS). The G-WSS is one of the most important phase boundaries in all of geology. Its location in pressure-temperature space controls the formation of our continents, the generation of economically important gem and ore deposits (e.g., sapphire, lithium, gold, and copper), the eruption of devastating and explosive volcanic eruptions, and how rapidly our planet has cooled over eons. The position of the G-WSS changes with depth (pressure; P), temperature (T) and bulk composition. The G-WSS is analogous to the freezing point of aqueous fluids, and the compositional effect on magmatic freezing points is analogous to changes to the freezing point depression of water caused by addition of various salts (e.g., NaCl, KCl, CaCl, etc.). Pioneering work performed over 60 years ago remains the basis for our understanding of the G-WSS. However, numerous observations from natural systems suggests igneous rocks crystallize at temperatures ~75–100 degrees C lower than the widely accept¬¬ed G-WSS. These observations combined with advances in experimental and analytical techniques provide the motivation and opportunity to re-investigate the location of the G-WSS. The PI’s preliminary work surprisingly demonstrated that the G-WSS is 100 degrees C lower than previous findings, which will transform long-standing views on granite formation processes, continental crust formation, thermal structure in terrestrial bodies, plate tectonics, innumerable aspects in hard-rock petrology and affect explorations of economically important ores. The PIs will conduct a series of laboratory-based experiments to systematically re-define the G-WSS, and then apply observations to the natural rocks contained in the National Museum of Natural History collections. Beyond providing research opportunities to PhD students and Washington DC high school students from under-served communities, the PIs will also produce a series of educational outreach experiences to teach National Mall visitors how ancient magmatic systems generated building stone rocks that compose many of the National Mall’s most famous monuments and buildings.Granitic and rhyolitic rocks are the end-product of continental crust differentiation. Most magmatic systems evolve towards granitic bulk compositions during crystallization, and the first melts of many rocks are broadly granitic. The granitic water-saturated solidus (G-WSS) is the lowest temperature phase boundary fundamentally separating metamorphic and igneous realms; thus, understanding its location in -pressure-temperature-composition space is critical for interpreting the rock record. The accepted G-WSS was largely determined 60 years ago using experimental and analytical techniques that leave open the possibility that the G-WSS may be inaccurate. In natural systems, various thermobarometric applications to granitic and rhyolitic composition rocks commonly return temperature estimates ~75–100 degrees C lower than the widely accept¬¬ed G-WSS. The availability of modern experimental and analytical approaches and the low temperature estimates for mineral crystallization in granitic rocks raise two overarching questions that will be resolved by performing work outlined in this proposal: (1) What is the P–T position of the G-WSS?, and (2) What are the compositions of melts and crystals that coexist along the G-WSS? The PIs will perform a systematic experimental and analytical program to determine the P–T position of the G-WSS and related compositional variations over conditions that span the continental crust. Experiments will be conducted in cold-seal pressure vessels (P5 kbar) and piston-cylinder devices (P5 kbar). The PIs will use electron probe microanalysis to measure major element compositions of experimental run products. Fourier transform infrared and Raman spectroscopy will be used to measure water concentrations in the melt. A statistically rigorous experimental approach, called a design of experiments, will be employed to determine compositions along the G-WSS over a range of pressures spanning the continental crust. Geochemical analyses and thermobarometry of natural granitic rocks will reveal the extent to which low temperatures are recorded in the rock record. Preliminary results from experiments performed from 0.5 to 10 kbar on granitic composition rocks demonstrate that the G-WSS is significantly lower than unanimously accepted estimates. A more accurate understanding of the position of the G-WSS will help to reconcile interpretations of granite formation and storage conditions within silicic magmatic systems, provide new opportunities to understand the thermal structure of the crust on Earth and other terrestrial bodies, and will influence myriad aspects of hard-rock petrology, geophysics, and mineral/ore exploration that will benefit from an accurate description of the G-WSS. This program also includes research opportunities for graduate students, DC-local high school students from underserved communities, development/implementation of Next Generation Science Standards for 5-8 grade students across the country, and an outreach program called “Magmas on the Mall” aimed at educating the broad public on magmatism and how it created the building stones used across the National Mall.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.

地球最高的连续地壳平均是花岗岩材料的。花岗岩是火成岩，是通过冷却和随后的熔融材料结晶形成的岩石子集。水含水花岗岩融化的温度（或在冷却岩浆后，最后一滴熔融材料结晶的温度称为花岗岩饱和水饱和固体（G-WSS）。 G-WSS是所有地质学中最重要的相位边界之一。它在压力温度空间中的位置控制着我们持续的形成，经济上重要的宝石和矿石沉积物（例如蓝宝石，锂，金和铜），毁灭性和爆炸性的火山喷发的喷发以及我们的星球对eons的速度迅速。 G-WSS的位置随深度（压力; P），温度（T）和大量组成而变化。 G-WSS类似于水性流体的冰点，并且对岩浆冰点的组成效应类似于因添加各种盐（例如NACL，KCL，CACL等）引起的水的冰点抑郁症的变化。 60年前，开创性的工作仍然是我们对G-WSS理解的基础。然而，自然系统的许多观察结果表明，在温度下结晶的火成岩比广泛接受的G-WS降低了75-100摄氏度。这些观察结果与实验和分析技术的进步相结合，为重新投资G-WS的位置提供了动力和机会。 PI的初步工作令人惊讶地表明，G-WSS比以前的发现低100度C，这将改变对花岗岩形成过程的长期观点，连续的地壳形成，陆地构造中的热结构，板块构造，硬岩石岩石学的无数方面，硬岩石学和影响经济重要的矿石的探索。 PI将进行一系列基于实验室的实验，以系统地重新定义G-WSS，然后将观测值应用于国家自然历史集合中包含的自然岩石。除了为来自服务不足社区的博士生和华盛顿特区的高中学生提供研究机会外，PI还将产生一系列的教育外展经验，以教导国家购物中心访问者如何产生建筑石头岩石，这些石材岩石构成许多国家购物中心最著名的纪念碑和建筑。大多数岩浆系统在结晶过程中朝着花岗岩大块的成分演变，许多岩石的第一层融化都是花岗岩的。花岗岩水饱和固相（G-WSS）是最低温度相边界，从根本上分离变质和火成岩域。因此，了解其在压力 - 温度组成空间中的位置对于解释岩石记录至关重要。公认的G-WS在60年前使用实验和分析技术确定，这使G-WSS可能是不准确的可能性。在天然系统中，在花岗岩和节奏组合物岩石上的各种热体测量应用通常比广泛接受的g-ws低75-100 c。现代实验和分析方法的可用性以及花岗岩岩石中矿物结晶的低温估计值提出了两个总体问题，通过执行此提案中概述的工作将解决：（1）G-T的P – T位置是什么？ PI将执行系统的实验和分析程序，以确定跨越连续地壳的条件的G-WSS和相关组成变化的P – T位置。实验将在冷 - 密封的压力容器（P5 KBAR）和活塞缸装置（P5 KBAR）中进行。 PI将使用电子探针微分析来测量实验运行产物的主要元素组成。傅立叶变换感染和拉曼光谱将用于测量A统计严格的实验方法中的水浓度（称为实验设计），以确定沿G-WSS的组成，这些压力涉及连续地壳的一系列压力。天然花岗岩岩石的地球化学分析和热压测量法将揭示在岩石记录中记录低温的程度。在花岗岩成分岩石上从0.5到10 kbar进行的实验的初步结果表明，G-WSS显着低于一致接受的估计值。对G-WSS位置的更准确了解将有助于调和对硅岩浆系统内花岗岩形成和存储条件的解释，为了解地壳上地壳和其他陆地身体的热结构提供了新的机会，并将影响近岩石学，地球物理学和矿物探索的硬岩石学岩石学，从而受益于G-g-g-g-w s wers g-w n the Hard-Rock petrock ockology coptrology coptrology coptrology。 This program also includes research opportunities for graduate students, DC-local high school students from underserved communities, development/implementation of Next Generation Science Standards for 5-8 grade students across the country, and an outreach program called “Magmas on the Mall” aimed at educating the broad public on magmatism and how it created the building stones used across the National Mall.This award reflects NSF's statutory mission and has been deemed Worthy of support through evaluation using the Foundation's智力优点和更广泛的影响审查标准。