{
  "abstract": "Crustal strength is often characterized using a strength-depth profile where laboratory-derived friction and flow laws are connected at depth (i.e., the so-called Christmas Tree diagram). Large, destructive earthquakes frequently nucleate within the transition zone from a frictional-to-viscous deformation regime, which represents the strongest part of the crust. However, microscale deformation mechanisms controlling bulk frictional-to-viscous transitional behavior remain unclear. To investigate the deformation mechanisms, we conducted shear experiments on room-dry, powdered quartz-albite mixtures under upper- to mid-crustal pressure-temperature conditions using a Griggs-type deformation apparatus. We simulated depth conditions in the range 7-30 km, by varying temperatures and confining pressures (210-900 C and 185-870 MPa, respectively, by assuming 30 C/km and 2,700 kg/m3). To assess the rate dependence and stability of shear deformation, we sequentially stepped shear strain rates between 10^-3/s and 10^-4/s. At shallower depth conditions, friction coefficients follow Byerlee's law, while at greater depth conditions they deviate from it and strain weakening is observed. Post-mortem microstructures indicate changing deformation mechanisms with increasing simulated depths. The samples deformed at shallower depth conditions (<18 km) show a predominance of cataclastic grain comminution. At greater depth conditions (>24 km), nano-grains are observed, as well as polygonal quartz grains at the greatest depth condition (30 km). These results indicate that the controlling deformation mechanisms at the frictional-viscous transition zone are grain boundary sliding and dynamic recrystallization. We conclude that nano-scale deformation mechanisms govern the frictional-viscous transitional deformation in the upper crust, and propose their importance for understanding seismic rupture processes there.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Journal of Geophysical Research: Solid Earth, 130, e2025JB031249",
  "arxiv": "2609.19645",
  "author_total": 7,
  "authors": [
    {
      "name": "M. Furukawa"
    },
    {
      "name": "B. A. Verberne"
    },
    {
      "name": "S. Sawa"
    },
    {
      "name": "H. Nagahama"
    },
    {
      "name": "M. Takahashi"
    },
    {
      "name": "O. Pluemper"
    },
    {
      "name": "J. Muto"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cd42n7kgwzyer.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.19645",
  "fulltext_url": null,
  "id": "cd42n7kgwzyer",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.19645",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.geo-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.19645",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cd42n7kgwzyer.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.19645",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.19645"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "arxiv:physics.geo-ph",
      "subfield": "geophysics"
    }
  ],
  "title": "The Brittle-Plastic Transition in Quartz-Albite Mixtures: New Insights From Shear Deformation Experiments at Mid-to-Lower Crustal Depth Conditions",
  "title_text": "The Brittle-Plastic Transition in Quartz-Albite Mixtures: New Insights From Shear Deformation Experiments at Mid-to-Lower Crustal Depth Conditions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:19Z",
  "url": "https://research.draconitic.com/paper/cd42n7kgwzyer",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1029/2025jb031249",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}