Seismic vs. sub-seismic Experimental Mirror-like Fault Surfaces in Bituminous Dolostones

Name: Seismic vs. sub-seismic Experimental Mirror-like Fault Surfaces in Bituminous Dolostones
Published: 2025
Keywords: Mirror-like Surfaces, seismic cycle, slip zones, friction experiments, seismic markers, Geology, tectonics, volcanology

Chinello, Miriana and Aretusini, Stefano and Spagnuolo, Elena and Nava, Jacopo and Tesei, Telemaco and Fondriest, Michele and Di Toro, Giulio (2025) Seismic vs. sub-seismic Experimental Mirror-like Fault Surfaces in Bituminous Dolostones. [Data Collection]

Collection description

Mirror-like Surfaces (MSs) are ultra-polished surfaces frequently found in exhumed seismogenic fault zones in carbonates. They form under a wide range of pressure-temperature conditions and slip rates, from seismic (≈1 m/s) to sub-seismic (≈0.1-100 μm/s), reflecting distinct phases of the seismic cycle. Motivated by the abundance of MSs in bituminous dolostones from the Central Apennines (Italy), we performed rotary-shear experiments at seismic and sub-seismic slip rates, under water-dampened and room-humidity conditions, to determine the conditions favoring MSs formation. The resulting fault surfaces were analyzed using FEG-FIB-SEM to identify micro- and nano-structural indicators of slip rate. MSs developed under all tested conditions, regardless of water content. All experimental MSs consist of a 10s-nm-thick film of rounded nanoparticles (5-15 nm in diameter) overlying a 10-100 µm-thick Cataclastic Slip Zone (CSZ). Under room-humidity conditions, subtle differences emerged. The “seismic” MS is cut by micro-cracks due to thermal contraction or desiccation, and nanoparticles are arranged in flat, sub-rounded aggregates measuring 5-150 nm. Differently, in “sub-seismic” MSs, the nanoparticles are arranged in sub-spherical aggregates measuring few tens of nanometers. The CSZ displays micro- to nano-porosity in the first 2-3 µm beneath the “seismic” MS, while it is finer-grained and free of porosity in the “sub-seismic” slip zone. We conclude that MSs are the morphological convergence of physical and chemical processes acting across a broad range of deformation conditions. However, micro- to nano-scale structural features, if preserved in nature, may help distinguish between the “seismic” and “sub-seismic” origin of MSs.

DOI:

10.25430/researchdata.cab.unipd.it.00001707

Keywords:

Mirror-like Surfaces, seismic cycle, slip zones, friction experiments, seismic markers

Subjects:

Physical:Sciences and Engineering > Earth System Science: Physical geography, geology, geophysics, atmospheric sciences, oceanography, climatology, cryology, ecology, global environmental change, biogeochemical cycles, natural resources management > Geology, tectonics, volcanology

Department:

Departments > Dipartimento di Geoscienze

Depositing User:

Miriana Chinello

Date Deposited:

16 Dec 2025 07:30

Last Modified:

16 Dec 2025 07:30

Creators/Authors:

Creators	Email	ORCID
Chinello, Miriana	miriana.chinello@phd.unipd.it	orcid.org/0009-0002-7244-7779
Aretusini, Stefano	stefano.aretusini@ingv.it	orcid.org/0000-0001-7211-3838
Spagnuolo, Elena	elena.spagnuolo@ingv.it	orcid.org/0000-0002-1377-5812
Nava, Jacopo	jacopo.nava@unipd.it	orcid.org/0000-0003-3755-0500
Tesei, Telemaco	telemaco.tesei@unipd.it	orcid.org/0000-0002-0178-7672
Fondriest, Michele	michele.fondriest@unipd.it	orcid.org/0000-0002-1294-0820
Di Toro, Giulio	giulio.ditoro@unipd.it	orcid.org/0000-0002-6618-3474