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.

最大的地震和最重要的火山危害是由于构造板的俯冲而发生的。人们普遍认为，触发了这些大地震，并以某种方式触发俯冲的地壳和上覆的地幔的熔化涉及从俯冲沉积物中释放流体，并通过脱落的反应释放液体，从而导致在其结构中含有水中含有水的矿物质的分解。然而，由于俯冲通道中据信在俯冲通道中据信很常见的矿物质的特定矿物质和反应的身份是难以捉摸的，基于热力学计算，在压力和温度方面都具有适当的稳定性。这项研究将支持博士学位。来自地球科学中代表性不足的小组的研究生的论文研究将涉及阿默斯特学院的两名本科生，他们正在合作进行一些分析活动。该项目是为了测试替代假设，即在俯冲过程中产生流体的含石榴反应在特定的压力和温度下相对于其标称平衡位置明显过高。也就是说，俯冲带中发现的常见矿物可能会持续到更大的深度（地震记录的深度），因为抑制了引发反应所需的新阶段的成核。该假设将通过采用一种新型方法来检验，该方法利用拉曼光谱在矿物石榴石内部的石英夹杂物上确定石榴石成核的压力温度条件，从而确定大量脱层化的条件。这项研究的结果应有助于解决长期存在的悖论，并将对负责触发地震和地幔融化的过程有更清晰的了解，从而有助于预测这些危害的能力。该奖项反映了NSF的法定任务，并通过使用该基金会的知识优点和广泛的影响来评估，这是NSF的法定任务。

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.

On the interpretation of TitaniQ and ZiR thermobarometry in subduction complexes

关于俯冲复合体中 TitaniQ 和 ZiR 温压测量的解释