Field Testing Raman Microspectroscopic Therobarometers in Garnet

该项目将使用一种新的分析技术--共聚焦拉曼显微光谱--来研究其宿主矿物中的天然矿物包裹体的物理特征。这些信息对于了解岩石形成的物理条件，以及岩石在冷却过程中保留这些信息的程度很重要。这项工作还将确定测量结果是否受到包裹体几何形状或岩层高温的影响。如果成功，拉曼显微光谱学可能会对岩石形成的压力和温度的研究产生革命性的影响，这对包括火成岩、变质和成矿过程在内的各种领域都很重要。我们还可以确定是什么将岩石结合在一起，这将在材料合成科学中有广泛的应用。资金将支持研究和培训一名新的博士生。这项研究将被用来利用博伊西州立大学本科和研究生课程的教育机会，该大学覆盖的学生群体与其他美国大学不同。该项目的中心焦点是对石榴石石英石(Quig)气压计和石榴石锆石(ZIG)温度计进行严格测试。三个主要问题包括：(1)石榴石的拉曼吸热试验是否存在一个阈值温度，超过该温度，石榴石的拉曼吸热试验失败？(2)包裹体的负压是否可靠地保存？(3)夹杂物形状重要吗？五组基本数据将解决这些问题：(1)将在一系列压力-温度(P-T)条件下收集拉曼光谱，以查看石榴石是否可靠地编码了所有P-T空间的捕获P-T条件。ZIG的应用在识别是否保存T‘s圈闭方面尤为重要。(2)包裹体周围的化学分带研究，看看包裹体的膨胀或收缩所产生的压力是否会导致石榴石摩尔体积的化学修饰。(3)收集低P、高T岩石的拉曼光谱，并与预期的Pincl进行比较。(4)具有一定长宽比范围的石英和锆石包裹体的PINCL(拉曼峰位移)将在微米尺度上进行空间绘制。(5)采集石榴石亚毫米斑点的红外光谱，以确定石榴石中的羟基含量以及水解性弱化对石榴石强度的可能影响。这些数据将检验支撑热拉曼实验应用的假设，并经验地确定P-T空间中该方法可应用于石榴石包裹体的区域。数据还将允许扩大对火成岩和矿藏形成的P-T条件的研究，而不依赖于化学或热力学模型。

This project will use a novel analytical technique - confocal Raman microspectroscopy - to investigate the physical character of natural mineral inclusions inside their host minerals. This information is important for understanding the physical conditions under which rocks form, and the degree to which rocks retain that information during cooling. This work will also identify whether measurements are biased by inclusion geometry or high temperatures of rock formation. If successful, Raman microspectroscopy could revolutionize investigations of the pressures and temperatures of rock formation, which are important to a variety of fields including igneous, metamorphic, and ore-forming processes. We may also identify what holds rocks together, which would have broad applications to materials synthesis science. Funding will support the research and training of a new PhD student. This research will be used to leverage educational opportunities in undergraduate and graduate courses at Boise State University, which reaches a different student demographic than other American universities. The central focus of this project is to critically test the Quartz-in-Garnet (QuiG) barometer and Zircon-in-Garnet (ZiG) thermometer. Three main questions include: (1) Is there a threshold temperature above which thermoba-Raman-try fails in garnet? (2) Are inclusion underpressures reliably preserved? and (3) Does inclusion shape matter? Five basic sets of data will address these questions: (1) Raman spectra will be collected over a range of pressure-temperature (P-T) conditions to see whether garnet reliably encodes entrapment P-T conditions over all P-T space. Application of ZiG is particularly important in identifying whether entrapment T's are preserved. (2) Chemical zoning will be investigated around inclusions to see whether pressures induced by expanding or contracting inclusions induce chemical modification to garnet molar volumes. (3) Raman spectra will be collected for low-P, high-T rocks, where QuiG underpressures are expected, and compared against expected Pincl. (4) Pincl (Raman peak shifts) in quartz and zircon inclusions with a range of aspect ratios will be spatially mapped at a µm scale. (5) Infrared spectra will be collected on sub-mm spots in garnet to identify OH contents and possible impact of hydrolytic weakening on garnet strength. These data will test assumptions that underpin applications of thermoba-Raman-try and empirically identify the region of P-T space over which the method can be applied to inclusions in garnet. Data will also permit expanded research into the P-T conditions of igneous and ore deposit formation, independent of chemical or thermodynamic models.