University of Padua

Frictional Melting in Hydrothermal Fluid-Rich Faults: Field and Experimental Evidence From the Bolfín Fault Zone (Chile)

Gomila, Rodrigo and Fondriest, Michele and Jensen, Erik and Spagnuolo, Elena and Masoch, Simone and Mitchell, Thomas and Magnarini, Giulia and Bistacchi, Andrea and Mittempergher, Silvia and Faulkner, Daniel and Cembrano, José and Di Toro, Giulio (2023) Frictional Melting in Hydrothermal Fluid-Rich Faults: Field and Experimental Evidence From the Bolfín Fault Zone (Chile). [Data Collection]

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Tectonic pseudotachylytes are thought to be unique to certain water-deficient seismogenic environments and their presence is considered to be rare in the geological record. Here, we present field and experimental evidence that frictional melting can occur in hydrothermal fluid-rich faults hosted in the continental crust. Pseudotachylytes were found in the >40 km-long Bolfín Fault Zone of the Atacama Fault System, within two ca. 1 m-thick (ultra)cataclastic strands hosted in a damage-zone made of chlorite-epidote-rich hydrothermally altered tonalite. This alteration state indicates that hydrothermal fluids were active during the fault development. Pseudotachylytes, characterized by presenting amygdales, cut and are cut by chlorite-, epidote- and calcite-bearing veins. In turn, crosscutting relationship with the hydrothermal veins indicates pseudotachylytes were formed during this period of fluid activity. Rotary shear experiments conducted on bare surfaces of hydrothermally altered rocks at seismic slip velocities (3 m s−1) resulted in the production of vesiculated pseudotachylytes both at dry and water-pressurized conditions, with melt lubrication as the primary mechanism for fault dynamic weakening. The presented evidence challenges the common hypothesis that pseudotachylytes are limited to fluid-deficient environments, and gives insights into the ancient seismic activity of the system. Both field observations and experimental evidence, indicate that pseudotachylytes may easily be produced in hydrothermal environments, and could be a common co-seismic fault product. Consequently, melt lubrication could be considered one of the most efficient seismic dynamic weakening mechanisms in crystalline basement rocks of the continental crust.

DOI: 10.25430/researchdata.cab.unipd.it.00000887
Keywords: Bolfín Fault Zone, pseudotachylytes, Atacama Fault System, Rotary shear experiments, vesiculated pseudotachylytes, hydrothermal fluid-rich environment
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 > Mineralogy, petrology, igneous petrology, metamorphic petrology
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
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 > Physics of earth's interior, seismology, volcanology
Department: Departments > Dipartimento di Geoscienze
Depositing User: Rodrigo Alfonso Gomila Olmos de aguilera
Date Deposited: 16 May 2023 14:03
Last Modified: 16 May 2023 14:03
Creators/Authors:
CreatorsEmailORCID
Gomila, Rodrigor.gomilaolmosdeaguilera@unipd.itorcid.org/0000-0001-5807-2769
Fondriest, MicheleUNSPECIFIEDorcid.org/0000-0002-1294-0820
Jensen, ErikUNSPECIFIEDorcid.org/0000-0003-0790-6270
Spagnuolo, ElenaUNSPECIFIEDorcid.org/0000-0002-1377-5812
Masoch, SimoneUNSPECIFIEDorcid.org/0000-0001-9976-9423
Mitchell, ThomasUNSPECIFIEDorcid.org/0000-0003-0809-1528
Magnarini, GiuliaUNSPECIFIEDorcid.org/0000-0002-5200-261X
Bistacchi, AndreaUNSPECIFIEDorcid.org/0000-0002-0139-2785
Mittempergher, SilviaUNSPECIFIEDorcid.org/0000-0002-7278-1200
Faulkner, DanielUNSPECIFIEDorcid.org/0000-0002-6750-3775
Cembrano, JoséUNSPECIFIEDorcid.org/0000-0003-4247-8259
Di Toro, GiulioUNSPECIFIEDorcid.org/0000-0002-6618-3474
Type of data: Text
Research funder: Marie Skłodowska-Curie Actions, European Research Council, Fondo Nacional de Desarrollo Científico y Tecnológico
Research project title: FRICTION, NOFEAR
Grant number: 896346
Collection period:
FromTo
20182021
Resource language: English
Metadata language: English
Publisher: Research Data Unipd
Related publications:
Date: 16 May 2023
Copyright holders: The Author
URI: https://researchdata.cab.unipd.it/id/eprint/887

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