Hayman, N. W., K. C. Burmeister, K. Kawamura, R. Anma, and Y. Yamada, Oblique deformation in Tenryu Canyon of the Nankai accretionary prism , in Accretionary Prisms and Convergent Margin Tectonics in the Northwest Pacific Basin, edited by Yujiro Ogawa, Springer, 2011, #2278
Hayman, N. W., N. R. Grindlay, M. R. Perfit, P. Mann, S. Leroy, and B. Mercier De Lepinay, Oceanic core complex development at the ultraslow spreading Mid-Cayman spreading center, Geochem., Geophys., Geosyst., 12, Q0AG02, 2011, doi:10.1029/2010GC003240, #2305 
Roughly a third of the global mid-ocean ridge system spreads at <20 mm/yr (full rate) with predicted low crustal thicknesses, great axial depths, end-member basalt compositions, and prominent axial faults. These predictions are here further investigated along the ultraslow (15-17 mm/yr) Mid-Cayman Spreading Center (MCSC) through a compilation of both previously published and unpublished data. The MCSC sits along the Caribbean-North American plate boundary and is one of the world's deepest (>6 km) spreading centers, and thought to accrete some of the thinnest (~3 km) crust. The MCSC generates end-member mid-ocean ridge basalt compositions and hosts recently discovered hydrothermal vents. Multibeam bathymetric data reveal that axial depth varies along the MCSC with intraridge rift walls defined by kilometer-scale escarpments and massifs. Dredging and near-bottom work has imaged and sampled predominantly basaltic lavas from the greatest axial depths and ~15% peridotite surrounded by gabbroic rocks from the prominent massifs. The gabbroic rocks exhibit wide compositional variation (troctolites to ferrogabbros) and in many places contain high-temperature (amphibolite to granulite facies) shear zones. Gabbroic compositions primarily reflect the accumulation of near-liquidus phases that crystallized from a range of basaltic melts, as well as from interactions with interstitial melts in a subaxial mush zone. Magnetization variations inverted from aeromagnetic data are consistent with a discontinuous distribution of basaltic lavas and structurally asymmetric spreading. These observations support an oceanic core complex model for MCSC seafloor spreading, potentially making it a type example of ultraslow seafloor spreading through mush zone and detachment fault crustal processes.
Hayman, N. W., L. Ducloue, K. L. Foco, and K. E. Daniels, Granular controls on periodicity of stick-slip events: Kinematics and force-chains in an experimental fault, Pure Applied Geophys., 168, 2239-2257, 2011, doi:10.1007/s00024-011-0269-3, #2315
It is a long-standing question whether granular fault material such as gouge plays a major role in controlling fault dynamics such as seismicity and slip-periodicity. In both natural and experimental faults, granular materials resist shear and accommodate strain via interparticle friction, fracture toughness, fluid pressure, dilation, and interparticle rearrangements. Here, we isolate the effects of particle rearrangements on granular deformation through laboratory experiments. Within a sheared photoelastic granular aggregate at constant volume, we simultaneously visualize both particle-scale kinematics and interparticle forces, the latter taking the form of force-chains. We observe stick-slip deformation and associated force drops during an overall strengthening of the shear zone. This strengthening regime provides insight into granular rheology and conditions of stick-slip periodicity, and may be qualitatively analogous to slip that accompanies longer term interseismic strengthening of natural faults. Of particular note is the observation that increasing the packing density increases the stiffness of the granular aggregate and decreases the damping (increases time-scales) during slip events. At relatively loose packing density, the slip displacements during the events follow an approximately power-law distribution, as opposed to an exponential distribution at higher packing density. The system exhibits switching between quasi-periodic and aperiodic slip behavior at all packing densities. Higher packing densities favor quasi-periodic behavior, with a longer time interval between aperiodic events than between quasi-periodic events. This difference in the time-scale of aperiodic stick-slip deformation is reflected in both the kinematics of interparticle slip and the force-chain dynamics: all major force-chain reorganizations are associated with aperiodic events. Our experiments conceptually link observations of natural fault dynamics with current models for granular stick-slip dynamics. We find that the stick-slip dynamics are consistent with a driven harmonic oscillator model with damping provided by an effective viscosity, and that shear-transformation-zone, jamming, and crackling noise theories provide insight into the effective stiffness and patterns of shear localization during deformation.
Barker, A. K., L. A. Coogan, K. M. Gillis, N. W. Hayman, and D. Weis, Direct observation of a fossil high-temperature, fault-hosted, hydrothermal upflow zone in crust formed at the East Pacific Rise, Geology, 38, 379-382, 2010, 2 citations, doi:10.1130/G30542.1, #2211
Fault zones in the ocean crust are commonly hypothesized to act as high-permeability conduits that focus fluid flow in oceanic hydrothermal systems. However, there has been little direct study of faults in crust formed at fast-spreading ridges. Here we describe the geology and geochemistry of an ∼40-m-wide fault zone within the uppermost sheeted dike complex exposed at Pito Deep (northeastern Easter microplate). Titanium in quartz thermometry gives temperatures of 392 ± 33 °C for quartz precipitation, indicating that this fault zone focused upwelling fluids at temperatures similar to those of black-smoker vent fluids. Correlated enrichment in 87Sr/86Sr and MgO in fault breccias, along with 87Sr/86Sr ratios higher than in average vent fluids, provide evidence for mixing between high-temperature upwelling fluids and a seawater-like fluid within the fault zone. Large high-temperature fluid fluxes are required to maintain high temperatures during mixing. If this fault zone is representative of upflow zones beneath hydrothermal vents on the East Pacific Rise, then it is possible that vent fluids evolve thermally and chemically during their ascent and may not record the precise conditions at the base of the hydrothermal system.
Cheney, E. S., and N. W. Hayman, The Chiwaukum structural low: Cenozoic shortening of the central Cascade Range, Washington State, USA: Reply
, Geol. Soc. Amer. Bull., 122, 2103-2108, 2010, doi:10.1130/B30220.1, CF: found pdf in UT library 20-01-2011, #2294
Hayman, N. W., W. Bach, D. K. Blackman, G. L. Christeson, K. Edwards, R. Haymon, B. Ildefonse, P. Schulte, D. A. H. Teagle, and S. White, Future scientific drilling of oceanic crust, Eos, Trans. Amer. Geophys. Un., 91, 133-134, 2010, #2198
Lin, W., M.-L. Doan, J. C. Moore, L. McNeil, T. B. Byrne, T. Ito, D. M. Saffer, M. Conin, M. Kinoshita, Y. Sanada, K. T. Moe, E. Araki, H. J. Tobin, D. Boutt, Y. Kano, N. W. Hayman, P. B. Flemings, G. J. Huftile, D. Cukur, C. Buret, A. M. Schleicher, M. Efimenko, K. Kawabata, D. M. Buchs, S. Jiang, K. Kameo, K. Horiguchi, T. Wiersberg, A. Kopf, K. Kitada, N. Eguchi, S. Toczko, K. Takahashi, and Y. Kido, Present-day principal horizontal stress orientations in the Kumano forearc basin of the southwest Japan subduction zone determined from IODP NanTroSEIZE drilling Site C0009, Geophys. Res. Lett., 37, L13303, 2010, 10 citations, doi:10.1029/2010GL043158, #2275
A 1.6 km riser borehole was drilled at site C0009 of the NanTroSEIZE, in the center of the Kumano forearc basin, as a landward extension of previous drilling in the southwest Japan Nankai subduction zone. We determined principal horizontal stress orientations from analyses of borehole breakouts and drilling-induced tensile fractures by using wireline logging formation microresistivity images and caliper data. The maximum horizontal stress orientation at C0009 is approximately parallel to the convergence vector between the Philippine Sea plate and Japan, showing a slight difference with the stress orientation which is perpendicular to the plate boundary at previous NanTroSEIZE sites C0001, C0004 and C0006 but orthogonal to the stress orientation at site C0002, which is also in the Kumano forearc basin. These data show that horizontal stress orientations are not uniform in the forearc basin within the surveyed depth range and suggest that oblique plate motion is being partitioned into strike-slip and thrusting. In addition, the stress orientations at site C0009 rotate clockwise from basin sediments into the underlying accretionary prism.
Cheney, E. S., and N. W. Hayman, The Chiwaukum structural low: Cenozoic shortening of the central Cascade Range, Washington State, USA., Geol. Soc. Amer. Bull., 121, 1135-1153, 2009, 3 citations, doi:10.1130/B26446.1, #2025
The central Cascade Range of Washington State has become a testing ground for theories surrounding the exhumation of deep-seated arcs, generation of both arc and flood-basalt volcanism, strike-slip faulting that translated crustal blocks along the Cordilleran margin, and development of fault-bounded basins. A central existing hypothesis is that the region underwent either regional extension or transtension during the Eocene. Both the extension and transtension models derive from the interpretation that clastic Eocene formations were deposited syntectonically in local basins. Geologic mapping and structural analyses presented here support an alternative hypothesis: that these formations are preserved in regional synclines, not in separate depositional basins. The type area for the Eocene history is the so-called Chiwaukum graben or Chumstick basin, here renamed the Chiwaukum Structural Low. The southwestern boundary of the Chiwaukum Structural Low includes post-depositional, northwest-striking reverse faults with adjacent northwest-striking folds. The reverse faults place the regionally extensive and arkosic, early Eocene Swauk Formation over arkosic, mid-Eocene strata that have previously been called the Chumstick Formation. Cataclastic structures provide independent evidence for the reverse faulting. Elsewhere, 39–42 Ma rocks unconformably overlie the folds. The reverse faults and fold hinges are cut by northerly striking strike-slip faults, which likely are of late Eocene age. The Eocene folds and faults were reactivated by deformation of the Miocene Columbia River Basalt Group, the gentler folding of which largely defines the regional map pattern around the Chiwaukum Structural Low. Instead of an extensional or transtensional history, the Eocene-to-Recent history of the Central Cascade region is characterized by multiple periods of folding and reverse faulting alternating with periods of strike-slip faulting.
Cheney, E. S., and N. W. Hayman, The Chiwaukum Structural Low, eastern Cascade Range, Washington, in GSA Field Guide, 15, 19-52, 2009, #2212
Daniels, K. E., and N. W. Hayman, Boundary conditions and event scaling of granular stick-slip events, in Powders and Grains 2009, Proc. 6th Int. Conf. on Micromechanics of Granular Media, 567-570, 2009, #2213
Hayman, N. W., and J. A. Karson, Crustal faults exposed in the Pito Deep Rift: Conduits for hydrothermal fluids on the southeast Pacific Rise, Geochem., Geophys., Geosyst., 10, Q02013, 2009, 4 citations, doi:10.1029/2008GC002319, #2056
The escarpments that bound the Pito Deep Rift (northeastern Easter microplate) expose in situ upper oceanic crust that was accreted ∼3 Ma ago at the superfast spreading (∼142 mm/a, full rate) southeast Pacific Rise (SEPR). Samples and images of these escarpments were taken during transects utilizing the human-occupied vehicle Alvin and remotely operated vehicle Jason II. The dive areas were mapped with a “deformation intensity scale” revealing that the sheeted dike complex and the base of the lavas contain approximately meter-wide fault zones surrounded by fractured “damage zones.” Fault zones are spaced several hundred meters apart, in places offset the base of the lavas, separate areas with differently oriented dikes, and are locally crosscut by (younger) dikes. Fault rocks are rich in interstitial amphibole, matrix and vein chlorite, prominent veins of quartz, and accessory grains of sulfides, oxides, and sphene. These phases form the fine-grained matrix materials for cataclasites and cements for breccias where they completely surround angular to subangular clasts of variably altered and deformed basalt. Bulk rock geochemical compositions of the fault rocks are largely governed by the abundance of quartz veins. When compositions are normalized to compensate for the excess silica, the fault rocks exhibit evidence for additional geochemical changes via hydrothermal alteration, including the loss of mobile elements and gain of some trace metals and magnesium. Microstructures and compositions suggest that the fault rocks developed over multiple increments of deformation and hydrothermal fluid flow in the subaxial environment of the SEPR; faults related to the opening of the Pito Deep Rift can be distinguished by their orientation and fault rock microstructure. Some subaxial deformation increments were likely linked with violent discharge events associated with fluid pressure fluctuations and mineral sealing within the fault zones. Other increments were linked with the influx of relatively fresh seawater. The spacing of the faults is consistent with fault localization occurring every 7000 to 14,000 years, with long-term slip rates of <3 mm/a. Once spread from the ridge axis, the faults were probably not active, and damage zones likely played a more significant role in axial flank and off-axis crustal permeability.
Hayman, N. W., R. Anma, and E. Veloso, Data report: Microstructure of chilled margins in the sheeted dike complex of Integrated Ocean Drilling Program (IODP) hole 1256D, Proc. Int. Ocean Drilling Prog., 309/312, 2009, #2132
Daniels, K. E., and N. W. Hayman, Force chains in seismogenic faults visualized with photoelastic granular shear experiments, J. Geophys. Res., 113, B11411, 2008, 16 citations, doi:10.1029/2008JB005781, #2026
Natural faults have many characteristics in common with granular systems, including granular fault rocks, shear localization, and stick-slip dynamics. We present experimental results which provide insight into granular behavior in natural faults. The experiments allow us to directly image force chains within a deforming granular media through the use of photoelastic particles. The experimental apparatus consists of a spring-pulled slider block which deforms the photoelastic granular aggregate at a constant velocity. Particles that carry more of the load appear brighter when viewed through crossed polarizers, making the internal stresses optically accessible. The resulting pattern is a branched, anisotropic force chain network inclined to the shear zone boundaries. Under both constant volume and dilational boundary conditions, deformation occurs predominantly through stick-slip displacements and corresponding force drops. The particle motion and force chain changes associated with the deformation can either be localized to the central slip zone or span the system. The sizes of the experimental slip events are observed to have power law (Gutenberg-Richter-like) distributions; the minimum dimensions of events and the behavior of force chains suggest that a particle scale controls the lower limits of the power law distributions. For large drops in pulling force with slip, the shape of the size distributions is strongly affected by the choice of boundary condition, while for small to moderate drops the probability distributions are approximately independent of boundary condition. These size-dependent variations in stick-slip behavior are associated with different spatial patterns: on average, small events typically correspond to localized force chain or particle rearrangements, whereas large events correspond to system-spanning changes. Such force chain behavior may be responsible for similar size-dependent behaviors of natural faults.
Hirose, T., and N. W. Hayman, Structure, permeability, and strength of a fault zone in the footwall of an oceanic core complex, the Central Dome of the Atlantis Massif, Mid-Atlantic Ridge, 30°N, J. Structural Geol., 30, 1060-1071, 2008, 7 citations, doi:10.1016/j.jsg.2008.04.009, #1993
Fault-zone samples recovered from 159 to 174 m below the seafloor (mbsf) in Hole 1309D from the Integrated Ocean Drilling Program (IODP) at the Atlantis Massif, Mid-Atlantic Ridge, 30°N, include both cataclastic and mylonitic fault rocks, and their gabbroic and ultramafic host rocks. Laboratory experiments determined the strength and permeability of nine fault-zone and host-rock samples with a triaxial apparatus under conditions that simulate present-day, in situ pressure conditions. The permeabilities of cataclasites are 10−18 m2, while host-rock and mylonite permeabilities are <2 × 10−19 m2. When subjected to increasing differential stress, visible fractures increased the permeability of most rock types to >10−17 m2. The strength of cataclasites is 260–380 MPa, weaker than that of mylonites of 600 MPa. High resolution X-ray computed tomography (HRXCT) and optical microscopy shows that experimentally produced fractures preferentially form interconnected networks within cataclastic matrices. Thus, permeability and strength are a function of the fault-zone microstructure, which evolved during exhumation from upper mantle and lower crustal depths. Localization of cataclastic zones adjacent to altered ultramafic and mylonitic gabbroic rocks likely make the cataclastic portion of this fault a long-lived fluid conduit within the Atlantis Massif Oceanic core complex.
Cheney, E. S., and N. W. Hayman, Regional Tertiary sequence stratigraphy and structure on the eastern flank of the Central Cascade Range, Washington, in GSA Field Guide, 9, 179-208, 2007, #2214
Hayman, N. W., and J. A. Karson, Faults and damage zones in fast-spread crust exposed on the north wall of the Hess Deep Rift: Conduits and seals in seafloor hydrothermal system, Geochem., Geophys., Geosyst., 8, Q10002, 2007, 7 citations, doi:10.1029/2007GC001623, #1936
The northern escarpments of the Hess Deep Rift provide cross-sectional views of in situ, ∼1-Ma-old, upper oceanic crust that underwent extensive, spreading-related brittle deformation. Most of the deformation and associated alteration occurred within the locus of magmatic construction of the East Pacific Rise, in the presence of high-temperature hydrothermal fluids. Passing laterally from undeformed host rocks, brittle deformation zones are classified as (1) damage zones where densely spaced fractures overprint the primary structure of dikes and lavas, (2) cataclastic zones where interconnected fractures, comminuted grains, and matrix minerals define deformational fabrics, and (3) very fine-grained, gouge-filled fault cores. Relative to the host rock, damage and cataclastic zones are rich in veins of chlorite and/or actinolite, and lesser amounts of titanite, epidote, and quartz. These phases mark relict hydrothermal fluid pathways. Trace and major element compositions of representative samples also indicate fault-localized hydrothermal alteration, including an increase in MgO by several weight percent within cataclastic and damage zones. In contrast, the fault cores are composed of very finely comminuted basaltic material and have MgO concentrations similar to the damage zones. Integrated compositional, textural, and outcrop-scale structural data inform an evolutionary model for fault growth from the early, widespread dilational phases of damage-zone development to more restricted noncoaxial strain in the cataclastic zones. With continued fault development, gouge develops and seals the fault cores. While the fault cores are sealed by gouge, surrounding zones remain conduits to hydrothermal fluid flow, except where sealed by secondary minerals. Sealed faults can later be reactivated as conduits with additional increments of fault slip. The dual behavior of faults as conduits and seals inevitably leads to compartmentalization of the flow regime in subaxial and ridge-flank areas.