Metamorphic records of multiple seismic cycles during subduction

Viete, D.R.; Hacker, B.R.; Allen, M.B.; Seward, G.G.E.; Tobin, M.J.; Kelley, C.S.; Cinque, G.; Duckworth, A.R.

Abstract

Large earthquakes occur in rocks undergoing high-pressure/low-temperature metamorphism during subduction. Rhythmic major-element zoning in garnet is a common product of such metamorphism, and one that must record a fundamental subduction process. We argue that rhythmic major-element zoning in subduction zone garnets from the Franciscan Complex, California, developed in response to growth-dissolution cycles driven by pressure pulses. Using electron probe microanalysis and novel techniques in Raman and synchrotron Fourier transform infrared microspectroscopy, we demonstrate that at least four such pressure pulses, of magnitude 100–350 MPa, occurred over less than 300,000 years. These pressure magnitude and time scale constraints are most consistent with the garnet zoning having resulted from periodic overpressure development-dissipation cycles, related to pore-fluid pressure fluctuations linked to earthquake cycles. This study demonstrates that some metamorphic reactions can track individual earthquake cycles and thereby opens new avenues to the study of seismicity.

Citation

Viete, D., Hacker, B., Allen, M., Seward, G., Tobin, M., Kelley, C., …Duckworth, A. (2018). Metamorphic records of multiple seismic cycles during subduction. Science Advances, 4(3), Article eaaq0234. https://doi.org/10.1126/sciadv.aaq0234

• Journal Article Type: Article
• Acceptance Date: Feb 7, 2018
• Online Publication Date: Mar 21, 2018
• Publication Date: Mar 21, 2018
• Deposit Date: Nov 22, 2017
• Publicly Available Date: Mar 12, 2018
• Journal: Science Advances
• Publisher: American Association for the Advancement of Science
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 3
• Article Number: eaaq0234
• DOI: https://doi.org/10.1126/sciadv.aaq0234
• Public URL: https://durham-repository.worktribe.com/output/1343885