Gouge stability controlled by temperature elevation and obsidian addition in basaltic faults and implications for moonquakes

作者

Shutian Cao Fengshou Zhang Mengke An Derek Elsworth
单位

Department of Geotechnical Engineering,College of Civil Engineering,Tongji University Key Laboratory of Geotechnical&Underground Engineering of Ministry of Education,Tongji University Department of Energy and Mineral Engineering,EMS Energy Institute and GCenter,The Pennsylvania State University,University Park Department of Geosciences,The Pennsylvania State University,University Park State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology-Beijing School of Civil Engineering,Guangzhou University School of Ocean and Earth Sciences,Tongji University
摘要

Basalt is a major component of the earth and moon crust. Mineral composition and temperature influence frictional instability and thus the potential for seismicity on basaltic faults. We performed velocitystepping shear experiments on basalt gouges at a confining pressure of 100 MPa, temperatures in the range of 100–400 ℃ and with varied obsidian mass fractions of 0–100% under wet/dry conditions to investigate the frictional strength and stability of basaltic faults. We observe a transition from velocity-neutral to velocity-weakening behaviors with increasing obsidian content. The frictional stability response of the mixed obsidian/basalt gouges is characterized by a transition from velocitystrengthening to velocity-weakening at 200 ℃ and another transition to velocity-strengthening at temperatures >300 ℃. Conversely, frictional strengths of the obsidian-bearing gouges are insensitive to temperature and wet/dry conditions. These results suggest that obsidian content dominates the potential seismic response of basaltic faults with the effect of temperature controlling the range of seismogenic depths. Thus, shallow moonquakes tend to occur in the lower lunar crust due to the corresponding anticipated higher glass content and a projected temperature range conducive to velocity-weakening behavior. These observations contribute to a better understanding of the nucleation mechanism of shallow seismicity in basaltic faults.
基金项目(Foundation)

fundedbytheNationalNaturalScienceFoundationofChina(Nos.42320104003and42107163)；theFundamentalResearchFundsfortheCentralUniversities；supportfromtheG.AlbertShoemakerendowment；
文章目录

1. Introduction
2. Materials and methods
2.1.Sample materials
2.2.Experimental procedures
2.3.Data analysis
3. Results
3.1.Effect of obsidian content on gouge friction
3.2.Effect of temperature on gouge friction
3.3.Effect of humidity on obsidian gouge friction
3.4.Microstructural characterization
4. Discussion
4.1.Effect of mineral composition on fault friction
4.2.Impact of temperature on frictional stability
4.3.Implications for seismicity in basalt-bearing zones
5. Conclusions
Supplementary material
引用格式

[1]Cao S ,Zhang F ,An M , et al.Gouge stability controlled by temperature elevation and obsidian addition in basaltic faults and implications for moonquakes[J].International Journal of Mining Science and Technology,2024,34(09):1273-1282.