CSEDI Collab. Research: A joint mineral physics and nano-seismological study on high-pressure faulting in metastable olivine and harzburgite with implications to deep earthquakes

CSEDI 合作。

• 批准号: 1661489
• 负责人: Yanbin Wang
• 金额: $ 37.4万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1661489&HistoricalAwards=false
• 关键词: CSEDI; Collab.; Research; joint; mineral

Worldwide, the number of earthquakes per year decreases rapidly with depth down to ~300 km, then peaks around 550 - 600 km, before terminating abruptly near 700 km. Deep-focus earthquakes (DFEQs), i.e., those occurring at depths below 300 km, are particularly mysterious, as we know that rocks generally deform by creep and flow, rather than by brittle fracture, at these depths, where pressures and temperatures are both very high. Understanding the mechanisms of DFEQs is important because these quakes occur in subduction zones and pose significant seismic hazards in many regions around the globe. It also helps understand properties and behaviors of rocks and how plate tectonics works in the Earth's interior. The experimental capabilities developed in the project will find broad applications in disciplines far beyond earth science, including materials science, physics, and engineering.In this project, the investigators will combine advanced experimental techniques and state-of-the-art seismological analytical tools to obtain information on the physical mechanisms of fracturing under high pressure and high temperature. The materials to be studied are (Mg,Fe)2SiO4 olivine (the dominant mineral in the oceanic lithosphere and the upper mantle) and harzburgite (the dominant rock assemblage of the oceanic lithosphere). Samples will be deformed in a new class of deformation apparatus equipped with in-situ acoustic emission (AE) monitoring as well as x-ray diffraction and imaging, under a wide range of conditions of pressure, temperature, differential stress, strain, and strain rate. Controlled deformation will be conducted on these materials at pressures up to 14 GPa. A suite of state-of-the-art seismological methods of event detection, location, and source characterization will be applied to the nanoseismograms of AE events to determine rupture mechanisms. Our goal is to understand the physics that connects earthquake mechanics and minerals/rocks at laboratory scales, to provide fundamental insight as to how and under what conditions shear localization occurs, affecting, and affected by, mineral reaction equilibrium and kinetics, and triggers dynamic mechanical instability. Attention will be paid to controlling oxygen fugacity and minimizing water content during the experiments. It must be kept in mind the vast difference in scales between laboratory and subduction zone processes. The team will conduct comparison studies to examine AE source characteristics against those of DFEQs. Thermo-chemo-mechanical models will then be developed and evaluated based on experimental data and seismic observations, and large-scale subduction zone processes. Combining these approaches, the investigators anticipate a significant enhancement of our understanding of the mechanisms for DFEQs by establishing physical models for DFEQs whose testability and scalability can be further examined by computational simulations.

在世界范围内，每年地震的数量随着深度下降到约 300 公里而迅速减少，然后在 550 - 600 公里左右达到峰值，然后在接近 700 公里时突然终止。深源地震（DFEQ），即发生在 300 公里以下深度的地震，尤其神秘，因为我们知道，在压力和温度都很高的深度，岩石通常通过蠕变和流动而不是脆性断裂而变形。非常高。了解 DFEQ 的机制非常重要，因为这些地震发生在俯冲带，并对全球许多地区造成重大地震危害。它还有助于了解岩石的特性和行为以及板块构造在地球内部的运作方式。该项目开发的实验能力将在地球科学以外的学科中得到广泛应用，包括材料科学、物理学和工程学。在该项目中，研究人员将结合先进的实验技术和最先进的地震分析工具，获得有关高压高温下压裂物理机制的信息。待研究的材料是(Mg,Fe)2SiO4橄榄石(大洋岩石圈和上地幔的主要矿物)和方辉橄榄石(大洋岩石圈的主要岩石组合)。样品将在配备原位声发射 (AE) 监测以及 X 射线衍射和成像的新型变形装置中，在各种压力、温度、差应力、应变和应变条件下变形速度。这些材料将在高达 14 GPa 的压力下进行受控变形。一套最先进的事件检测、定位和震源表征地震学方法将应用于AE事件的纳震图，以确定破裂机制。我们的目标是了解实验室尺度上连接地震力学和矿物/岩石的物理原理，提供关于剪切局部化如何以及在什么条件下发生、影响矿物反应平衡和动力学以及受矿物反应平衡和动力学影响以及触发动态力学的基本见解。不稳定。实验过程中要注意控制氧逸度并尽量减少水分含量。必须牢记实验室过程和俯冲带过程之间规模的巨大差异。该团队将进行比较研究，以检查 AE 源特性与 DFEQ 的特性。然后将根据实验数据和地震观测以及大规模俯冲带过程开发和评估热化学机械模型。结合这些方法，研究人员预计通过建立 DFEQ 的物理模型，可以显着增强我们对 DFEQ 机制的理解，该模型的可测试性和可扩展性可以通过计算模拟进一步检查。

项目成果

Reaction-induced embrittlement of the lower continental crust

• DOI: 10.1130/g45527.1
• 发表时间: 2019-03-01
• 期刊: GEOLOGY
• 影响因子: 5.8
• 作者: Incel, Sarah;Labrousse, Loic;Schubnel, Alexandre
• 通讯作者: Schubnel, Alexandre

Experimental evidence for wall-rock pulverization during dynamic rupture at ultra-high pressure conditions

超高压条件下动态破裂过程中围岩粉碎的实验证据

• DOI: 10.1016/j.epsl.2019.115832
• 发表时间: 2019
• 期刊: Earth and planetary science letters
• 影响因子: 5.3
• 作者: Incel, S.;Schubnel, A.;Renner, J.;John, T.;Labrousse, L.;Hilairet, N.;Freeman, H.;Wang, Y.;Renard, F.;Jamtveit, B.
• 通讯作者: Jamtveit, B.