Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System
Abstract Fluid infiltration along seismically‐active faults and fluid‐rock interaction influence the mechanical behavior of faults. Nevertheless, how fluid infiltration and fluid‐rock interactions evolve at seismogenic depths with fault slip accumulation remain poorly constrained in the geological r...
Saved in:
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Wiley
2025-05-01
|
| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2024GC011998 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850128598851125248 |
|---|---|
| author | Simone Masoch Luigi Dallai Rodrigo Gomila Michele Fondriest Davide Novella Giorgio Pennacchioni José Cembrano Giulio Di Toro |
| author_facet | Simone Masoch Luigi Dallai Rodrigo Gomila Michele Fondriest Davide Novella Giorgio Pennacchioni José Cembrano Giulio Di Toro |
| author_sort | Simone Masoch |
| collection | DOAJ |
| description | Abstract Fluid infiltration along seismically‐active faults and fluid‐rock interaction influence the mechanical behavior of faults. Nevertheless, how fluid infiltration and fluid‐rock interactions evolve at seismogenic depths with fault slip accumulation remain poorly constrained in the geological record. We used hydrogen and oxygen isotope geochemistry to determine the origin of hydrous fluids that percolated within the exhumed Bolfin Fault Zone (BFZ)—a segment of the Early Cretaceous intra‐arc Atacama Fault System (Northern Chile)—during progressive fault evolution at seismogenic depth. The BFZ consists of D1 pseudotachylyte‐bearing cataclastic strands linked by D2 extensional to hybrid extensional‐shear, epidote‐rich fault‐vein systems that formed in a fluid‐rich, seismically active environment at 3–7 km depth and 200–300°C. The D1 pseudotachylytes and cataclasites have δD values similar to, or slightly higher than, those of unaltered hydrogen‐bearing magmatic minerals (−78‰ ≤ δD ≤ −56‰). This similarity indicates that seismic faulting occurred in a rock‐buffered environment with limited circulation of external fluids at early stages of fault evolution. Conversely, the epidote of the D2 fault‐vein systems has much heavier δD compositions (−47‰ ≤ δD ≤ −9‰) and δ18O values ranging from 3.77 to 6.71‰, suggesting infiltration of shallow fluids, likely sourced from closed, marine‐connected basins. Epidote‐quartz oxygen isotope thermometry indicates equilibration at 200–220°C for this stage of fluid infiltration. The influx of external, basin‐derived fluids within the BFZ is interpreted to indicate the increased hydraulic connectivity during slip accumulation and fault network growth. |
| format | Article |
| id | doaj-art-b40937b4ddd44831ad7a9563bc41bf0d |
| institution | OA Journals |
| issn | 1525-2027 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj-art-b40937b4ddd44831ad7a9563bc41bf0d2025-08-20T02:33:15ZengWileyGeochemistry, Geophysics, Geosystems1525-20272025-05-01265n/an/a10.1029/2024GC011998Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault SystemSimone Masoch0Luigi Dallai1Rodrigo Gomila2Michele Fondriest3Davide Novella4Giorgio Pennacchioni5José Cembrano6Giulio Di Toro7Dipartimento di Geoscienze Università Degli Studi di Padova Padua ItalyDipartimento di Scienze Della Terra Università di Roma La Sapienza Rome ItalyDipartimento di Geoscienze Università Degli Studi di Padova Padua ItalyDipartimento di Geoscienze Università Degli Studi di Padova Padua ItalyDipartimento di Geoscienze Università Degli Studi di Padova Padua ItalyDipartimento di Geoscienze Università Degli Studi di Padova Padua ItalyDepartamento de Ingeniería Estructural y Geotécnica Pontificia Universidad Católica de Chile Santiago ChileDipartimento di Geoscienze Università Degli Studi di Padova Padua ItalyAbstract Fluid infiltration along seismically‐active faults and fluid‐rock interaction influence the mechanical behavior of faults. Nevertheless, how fluid infiltration and fluid‐rock interactions evolve at seismogenic depths with fault slip accumulation remain poorly constrained in the geological record. We used hydrogen and oxygen isotope geochemistry to determine the origin of hydrous fluids that percolated within the exhumed Bolfin Fault Zone (BFZ)—a segment of the Early Cretaceous intra‐arc Atacama Fault System (Northern Chile)—during progressive fault evolution at seismogenic depth. The BFZ consists of D1 pseudotachylyte‐bearing cataclastic strands linked by D2 extensional to hybrid extensional‐shear, epidote‐rich fault‐vein systems that formed in a fluid‐rich, seismically active environment at 3–7 km depth and 200–300°C. The D1 pseudotachylytes and cataclasites have δD values similar to, or slightly higher than, those of unaltered hydrogen‐bearing magmatic minerals (−78‰ ≤ δD ≤ −56‰). This similarity indicates that seismic faulting occurred in a rock‐buffered environment with limited circulation of external fluids at early stages of fault evolution. Conversely, the epidote of the D2 fault‐vein systems has much heavier δD compositions (−47‰ ≤ δD ≤ −9‰) and δ18O values ranging from 3.77 to 6.71‰, suggesting infiltration of shallow fluids, likely sourced from closed, marine‐connected basins. Epidote‐quartz oxygen isotope thermometry indicates equilibration at 200–220°C for this stage of fluid infiltration. The influx of external, basin‐derived fluids within the BFZ is interpreted to indicate the increased hydraulic connectivity during slip accumulation and fault network growth.https://doi.org/10.1029/2024GC011998stable isotopesseismogenic faulthydrothermal systemspseudotachylyteintra‐arc fault systemAtacama Fault System |
| spellingShingle | Simone Masoch Luigi Dallai Rodrigo Gomila Michele Fondriest Davide Novella Giorgio Pennacchioni José Cembrano Giulio Di Toro Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System Geochemistry, Geophysics, Geosystems stable isotopes seismogenic fault hydrothermal systems pseudotachylyte intra‐arc fault system Atacama Fault System |
| title | Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System |
| title_full | Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System |
| title_fullStr | Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System |
| title_full_unstemmed | Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System |
| title_short | Evolving Fluid Source During the Growth of a Trench‐Parallel Seismogenic Fault System |
| title_sort | evolving fluid source during the growth of a trench parallel seismogenic fault system |
| topic | stable isotopes seismogenic fault hydrothermal systems pseudotachylyte intra‐arc fault system Atacama Fault System |
| url | https://doi.org/10.1029/2024GC011998 |
| work_keys_str_mv | AT simonemasoch evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT luigidallai evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT rodrigogomila evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT michelefondriest evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT davidenovella evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT giorgiopennacchioni evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT josecembrano evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem AT giulioditoro evolvingfluidsourceduringthegrowthofatrenchparallelseismogenicfaultsystem |