Abstract
Abstract. The Hurricane fault is a ∼250 km long, west-dipping, segmented normal fault zone located along the transition between the Colorado Plateau and the Basin and Range tectonic provinces in the western USA. Extensive evidence of fault–fluid interaction includes calcite mineralization and veining. Calcite vein carbon (δ13CVPDB) and oxygen (δ18OVPDB) stable isotope ratios range from −4.5 ‰ to 3.8 ‰ and from −22.1 ‰ to −1.1 ‰, respectively. Fluid inclusion microthermometry constrains paleofluid temperatures and salinities from 45 to 160 ∘C and from 1.4 wt % to 11.0 wt % as NaCl, respectively. These data suggest mixing between two primary fluid sources, including infiltrating meteoric water (70±10 ∘C, ∼1.5 wt % NaCl, δ18OVSMOW ∼-10 ‰) and sedimentary brine (100±25 ∘C, ∼11 wt % NaCl, δ18OVSMOW ∼ 5 ‰). Interpreted carbon sources include crustal- or magmatic-derived CO2, carbonate bedrock, and hydrocarbons. Uranium–thorium (U–Th) dates from five calcite vein samples indicate punctuated fluid flow and fracture healing at 539±10.8 (1σ), 287.9±5.8, 86.2±1.7, and 86.0±0.2 ka in the upper 500 m of the crust. Collectively, data predominantly from the footwall damage zone imply that the Hurricane fault imparts a strong influence on the regional flow of crustal fluids and that the formation of veins in the shallow parts of the fault damage zone has important implications for the evolution of fault strength and permeability.
Highlights
Secondary mineralization, alteration products, and associated textures in fault rocks provide windows into past fault– fluid interaction in the crust
We present the first quantitative results on the spatiotemporal thermochemical evolution of paleofluid flow and fluid–rock interaction along the Hurricane fault zone using stable isotope geochemistry, fluid inclusion microthermometry, and U–Th geochronology of calcite vein networks exposed in the footwall damage zone
Diagenetic products are most commonly associated with zones of more intense fracturing, veins occur throughout the damage zone
Summary
Alteration products, and associated textures in fault rocks provide windows into past fault– fluid interaction in the crust. Exhumed brittle faults and fault damage zones are excellent natural laboratories for interpreting the interaction between fluids and faults with implications for fault zone permeability evolution, diagenesis, and the seismic cycle (e.g., Chester et al, 1993; Caine et al, 1996; Sibson, 1996; Caine et al, 2010; Mozafari et al, 2015; Salomon et al, 2020).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
