Affiliation:
1. 1Department of Geosciences, Utah State University, Logan, Utah 84322, USA
2. 2Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island 02912, USA
Abstract
Abstract
Slow slip is part of the earthquake cycle, but the processes controlling this phenomenon in space and time are poorly constrained. Hematite, common in continental fault zones, exhibits unique textures and (U-Th)/He thermochronometry data patterns reflecting different slip rates. We investigated networks of small hematite-coated slip surfaces in basement fault damage of exhumed strike-slip faults that connect to the southern San Andreas fault in a flower structure in the Mecca Hills, California, USA. Scanning electron microscopy shows these millimeter-thick surfaces exhibit basal hematite injection veins and layered veinlets comprising nanoscale, high-aspect-ratio hematite plates akin to phyllosilicates. Combined microstructural and hematite (U-Th)/He data (n = 64 new, 24 published individual analyses) record hematite mineralization events ca. 0.8 Ma to 0.4 Ma at <1.5 km depth. We suggest these hematite faults formed via fluid overpressure, and then hematite localized repeated subseismic slip, creating zones of shallow off-fault damage as far as 4 km orthogonal to the trace of the southern San Andreas fault. Distributed hematite slip surfaces develop by, and then accommodate, transient slow slip, potentially dampening or distributing earthquake energy in shallow continental faults.
Publisher
Geological Society of America
Reference35 articles.
1. Displacements on the Imperial, Superstition Hills, and San Andreas faults triggered by the Borrego Mountain earthquake, in The Borrego Mountain Earthquake of April 9, 1968;Allen;U.S. Geological Survey Professional Paper 787,1972
2. Hematite fault rock thermochronometry and textures inform fault zone processes;Ault;Journal of Structural Geology,2020
3. Nanoscale evidence for temperature-induced transient rheology and postseismic fault healing;Ault;Geology,2019
4. Polyphase kinematic history of transpression along the Mecca Hills segment of the San Andreas fault, southern California;Bergh;Geosphere,2019
5. Slow earthquakes and nonvolcanic tremor;Beroza;Annual Review of Earth and Planetary Sciences,2011
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献