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

Name: Frictional Melting in Hydrothermal Fluid-Rich Faults: Field and Experimental Evidence From the Bolfín Fault Zone (Chile)
Published: 2023
Keywords: Bolfín Fault Zone, pseudotachylytes, Atacama Fault System, Rotary shear experiments, vesiculated pseudotachylytes, hydrothermal fluid-rich environment, Mineralogy, petrology, igneous petrology, metamorphic petrology, Geology, tectonics, volcanology, Physics of earth's interior, seismology, volcanology

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]

Related publications

https://doi.org/10.1029/2021GC009743 (Publisher)

Collection description

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:

Creators	Email	ORCID
Gomila, Rodrigo	r.gomilaolmosdeaguilera@unipd.it	orcid.org/0000-0001-5807-2769
Fondriest, Michele	UNSPECIFIED	orcid.org/0000-0002-1294-0820
Jensen, Erik	UNSPECIFIED	orcid.org/0000-0003-0790-6270
Spagnuolo, Elena	UNSPECIFIED	orcid.org/0000-0002-1377-5812
Masoch, Simone	UNSPECIFIED	orcid.org/0000-0001-9976-9423
Mitchell, Thomas	UNSPECIFIED	orcid.org/0000-0003-0809-1528
Magnarini, Giulia	UNSPECIFIED	orcid.org/0000-0002-5200-261X
Bistacchi, Andrea	UNSPECIFIED	orcid.org/0000-0002-0139-2785
Mittempergher, Silvia	UNSPECIFIED	orcid.org/0000-0002-7278-1200
Faulkner, Daniel	UNSPECIFIED	orcid.org/0000-0002-6750-3775
Cembrano, José	UNSPECIFIED	orcid.org/0000-0003-4247-8259
Di Toro, Giulio	UNSPECIFIED	orcid.org/0000-0002-6618-3474