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Does Overstepping of Garnet-producing Reactions Delay Devolatilization in Subduction zones? Insights From the Cycladic Blueschist Belt, Greece

石榴石生成反应的过度是否会延迟俯冲带的蒸发作用？

基本信息

批准号：
1750674
负责人：
Frank Spear
金额：
$ 41.92万
依托单位：
Rensselaer Polytechnic Institute
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-03-01 至 2023-02-28
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1750674&HistoricalAwards=false
关键词：
Does Overstepping Garnet producing Reactions

项目摘要

The largest earthquakes and the most significant volcanic hazards occur as a consequence of the subduction of tectonic plates. It is generally accepted that the triggers to both these large earthquakes and the melting of the subducted crust and overlying mantle somehow involve the release of fluids from the subducted sediments and crust via devolatilization reactions that cause the breakdown of minerals that contain water in their structure. However, the identity of the specific minerals and reactions responsible for the release of fluids has been elusive because none of the minerals that are believed to be common in subduction channels have the appropriate stabilities with respect to pressure and temperature based on thermodynamic calculations. This study will support the Ph.D. dissertation research of a graduate student from an underrepresented group in geosciences, and will involve two undergraduate students from Amherst College that is collaborating on some of the analytical activities. This project is to test the alternative hypothesis that garnet-bearing reactions that produce fluids during the subduction process are significantly overstepped with respect to their nominal equilibrium location at a specific pressure and temperature. That is, the common minerals found in subduction zones may persist to significantly greater depths (the depths recorded by earthquakes) because the nucleation of the new phases necessary to initiate the reaction is suppressed. This hypothesis will be tested through application of a novel approach that utilizes Raman spectroscopy on inclusions of quartz inside of the mineral garnet to determine the pressure-temperature conditions at which the garnet nucleated and, thus, the conditions at which major devolatilization occurs. The results of this study should help resolve a long-standing paradox and will provide a much clearer understanding of the processes responsible for triggering earthquakes and mantle melting thus aiding in the ability to predict the occurrence of these hazards.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.

最大的地震和最严重的火山灾害是由于构造板块的俯冲而发生的。人们普遍认为，这些大地震和俯冲地壳和上覆地幔熔融的触发因素，在某种程度上涉及到流体从俯冲沉积物和地壳中释放，通过脱挥发分反应，导致结构中含有水的矿物分解。然而，负责释放流体的特定矿物和反应的身份一直难以捉摸，因为没有一种被认为是俯冲通道中常见的矿物具有基于热力学计算的相对于压力和温度的适当稳定性。这项研究将支持博士学位。该项目将包括一名来自地球科学领域代表性不足群体的研究生的论文研究，并将涉及来自阿默斯特学院的两名本科生，他们正在合作开展一些分析活动。该项目旨在检验另一种假设，即在俯冲过程中产生流体的石榴石反应在特定压力和温度下相对于其标称平衡位置显着超出。也就是说，在俯冲带中发现的普通矿物可能会持续到更深的深度（地震记录的深度），因为引发反应所需的新相的成核受到抑制。这一假设将通过应用一种新的方法进行测试，该方法利用拉曼光谱对矿物石榴石内部的石英夹杂物，以确定石榴石成核的压力-温度条件，从而确定主要脱挥发分发生的条件。这项研究的结果应该有助于解决一个长期存在的悖论，并将提供一个更清楚的了解的过程负责触发地震和地幔熔融，从而有助于在能力，以预测这些灾害的发生。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Revaluation of “equilibrium” P-T paths from zoned garnet in light of quartz inclusion in garnet (QuiG) barometry

DOI：
10.1016/j.lithos.2020.105650
发表时间：
2020-11
期刊：
Lithos
影响因子：
3.5
作者：
F. Spear;Oliver M. Wolfe
通讯作者：
F. Spear;Oliver M. Wolfe

P–T Evolution of the Cyclades Blueschist Unit: Constraints on the Evolution of a Nascent Subduction System From Zr‐In‐Rutile (ZiR) and Quartz‐In‐Garnet (QuiG) Thermobarometry

P-T 基克拉泽斯蓝片岩单元的演化：Zr-In-金红石 (ZiR) 和石英-In-石榴石 (QuiG) 热压法对新生俯冲系统演化的约束

DOI：
10.1029/2023gc011121
发表时间：
2024
期刊：
Geosystems
影响因子：
0
作者：
Spear, Frank S.;Wolfe, Oliver M.;Thomas, Jay B.;Hubbard, Julia E.;Castro, Adrian E.;Cheney, John T.
通讯作者：
Cheney, John T.

Implications of overstepping of garnet nucleation for geothermometry, geobarometry and P–T path calculations