Progressive strain localization in a major strike‐slip fault exhumed from midseismogenic depths: Structural observations from the Salzach‐Ennstal‐Mariazell‐Puchberg fault system, Austria

Frost, E. K.; Dolan, James F.; Sammis, Charles G.; Hacker, B.; Cole, Joshua; Ratschbacher, Lothar

doi:10.1029/2008jb005763

Cited by 45 publications

(35 citation statements)

References 54 publications

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“…For large faults in northern California, the damage zone width inferred from Table 7 is 120 ± 40 m, in line with geologic estimates from large exhumed strike‐slip faults [ Chester et al , 2004; Frost et al , 2009], faults exposed in mines [ Wallace and Morris , 1986], and studies of fault zone trapped waves elsewhere [ Ben‐Zion et al , 2003; Lewis et al , 2005]. The narrow damage zone is consistent with a simple fault geometry comprising a single fault core bounded on one or both sides by a variably fractured material (Figure 18a), similar to exposures of the San Gabriel, San Andreas, and San Jacinto faults [ Chester et al , 2004; Dor et al , 2006].…”

Section: Rough Fault Loading Modelsupporting

confidence: 82%

Distribution of seismicity across strike‐slip faults in California

Powers¹,

Jordan²

2010

J. Geophys. Res.

114

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[1] The distribution of seismicity about strike-slip faults provides measurements of fault roughness and damage zone width. In California, seismicity decays with distance from strike-slip faults according to a power law. This scaling relation holds out to a fault-normal distance x of 3-6 km and is compatible with a "rough fault loading" model in which the inner scale d measures the half width of a volumetric damage zone and the roll-off rate g is governed by stress variations due to fault roughness. According to Dieterich and Smith's 2-D simulations, g approximates the fractal dimension of alongstrike roughness. Near-fault seismicity is more localized on faults in northern California (NoCal, d = 60 ± 20 m, g = 1.65 ± .05) than in southern California (SoCal, d = 220 ± 40 m, g = 1.16 ± .05). The Parkfield region has a damage zone half width (d = 120 ± 30 m) consistent with the SAFOD drilling estimate; its high roll-off rate (g = 2.30 ± .25) indicates a relatively flat roughness spectrum: ∼k −1 versus k −2 for NoCal, k −3 for SoCal. Our damage zone widths (the first direct estimates averaged over the seismogenic layer) can be interpreted in terms of an across-strike "fault core multiplicity" that is ∼1 in NoCal, ∼2 at Parkfield, and ∼3 in SoCal. The localization of seismicity near individual faults correlates with cumulative offset, seismic productivity, and aseismic slip, consistent with a model in which faults originate as branched networks with broad, multicore damage zones and evolve toward more localized, lineated features with low fault core multiplicity, thinner damage zones, and less seismic coupling. Our results suggest how earthquake triggering statistics might be modified by the presence of faults.Citation: Powers, P. M., and T. H. Jordan (2010), Distribution of seismicity across strike-slip faults in California,

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Section: Rough Fault Loading Modelsupporting

confidence: 82%

Distribution of seismicity across strike‐slip faults in California

Powers¹,

Jordan²

2010

J. Geophys. Res.

114

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“…Geochronological data from these cataclastic shear zones are rare (e.g., Wölfler et al 2010). Although the existing reconstructions indicate that the main part of orogen-parallel extension occurred during Early to Middle Miocene times (Frisch et al 2000), seismic events along most of these faults indicate that these are still active (e.g., Reinecker and Lenhardt 1999;Reinecker 2000;Lenhardt et al 2007;Frost et al 2009) and that a certain amount of displacement has been accommodated until recent times.…”

Section: Introductionmentioning

confidence: 99%

Polyphase movement on the Lavanttal Fault Zone (Eastern Alps): reconciling the evidence from different geochronological indicators

et al. 2011

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The Lavanttal Fault Zone (LFZ) is generally considered to be related to Miocene orogen-parallel escape tectonics in the Eastern Alps. By applying thermochronological methods with retention temperatures ranging from *450 to *40°C we have investigated the thermochronological evolution of the LFZ and the adjacent Koralm Complex (Eastern Alps). 40 Ar/ 39 Ar dating on white mica and zircon fission track (ZFT) thermochronology were carried out on host rocks (HRs) and fault-related rocks (cataclasites and fault gouges) directly adjacent to the unfaulted protolith. These data are interpreted together with recently published apatite fission track (AFT) and apatite (U-Th)/He ages. Sample material was taken from three drill cores transecting the LFZ. Ar release spectra in cataclastic shear zones partly show strongly rejuvenated incremental ages, indicating lattice distortion during cataclastic shearing or hydrothermal alteration. Integrated plateau ages from fault rocks (*76 Ma) are in parts slightly younger than plateau ages from HRs ([80 Ma). Incremental ages from fault rock samples are in part highly reduced (*43 Ma). ZFT ages within fault gouges (*65 Ma) are slightly reduced compared to the ages from HRs, and fission tracks show reduced lengths. Combining these results with AFT and apatite (U-Th)/He ages from fault rocks of the same fault zone allows the recognition of distinct faulting events along the LFZ from Miocene to Pliocene times. Contemporaneous with this faulting, the Koralm Complex experienced accelerated cooling in Late Miocene times. Late-Cretaceous to Palaeogene movement on the LFZ cannot be clearly proven. 40 Ar/ 39 Ar muscovite and ZFT ages were probably partly thermally affected along the LFZ during Miocene times.

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“…Fault zone localization within competent rock was also observed at the Punchbowl fault in California, in which the protoliths are primarily arkosic sandstone and igneous basement rock [Chester and Chester, 1998] and can be considered analogous to the localized deformation we observe in lithified Berea sandstone. Frost et al [2009] observed strain localization within a wide fault core in the Salzach-EnnstalMariazell-Puchberg (SEMP) fault in Austria. This wide fault zone is formed in carbonate rocks (dolomite and limestone) and is consistent with the wide deformation zones we observe in lithified limestone and marble.…”

Section: Implications For Slip Behavior In Natural Fault Systemsmentioning

confidence: 99%

The role of fault zone fabric and lithification state on frictional strength, constitutive behavior, and deformation microstructure

Ikari¹,

Niemeijer²,

Marone³

2011

J. Geophys. Res.

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[1] We examine the frictional behavior of a range of lithified rocks used as analogs for fault rocks, cataclasites and ultracataclasites at seismogenic depths and compare them with gouge powders commonly used in experimental studies of faults. At normal stresses of ∼50 MPa, the frictional strength of lithified, isotropic hard rocks is generally higher than their powdered equivalents, whereas foliated phyllosilicate-rich fault rocks are generally weaker than powdered fault gouge, depending on foliation intensity. Most samples exhibit velocity-strengthening frictional behavior, in which sliding friction increases with slip velocity, with velocity weakening limited to phyllosilicate-poor samples. This suggests that lithification of phyllosilicate-rich fault gouge alone is insufficient to allow earthquake nucleation. Microstructural observations show prominent, throughgoing shear planes and grain comminution in the R1 Riedel orientation and some evidence of boundary shear in phyllosilicate-poor samples, while more complicated, anastomosing features at lower angles are common for phyllosilicate-rich samples. Comparison between powdered gouges of differing thicknesses shows that higher Riedel shear angles correlate with lower apparent coefficients of friction in thick fault zones. This suggests that the difference between the measured apparent friction and the true internal friction depends on the orientation of internal deformation structures, consistent with theoretical considerations of stress rotation.Citation: Ikari, M. J., A. R. Niemeijer, and C. Marone (2011), The role of fault zone fabric and lithification state on frictional strength, constitutive behavior, and deformation microstructure,

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Progressive strain localization in a major strike‐slip fault exhumed from midseismogenic depths: Structural observations from the Salzach‐Ennstal‐Mariazell‐Puchberg fault system, Austria

Cited by 45 publications

References 54 publications

Distribution of seismicity across strike‐slip faults in California

Distribution of seismicity across strike‐slip faults in California

Polyphase movement on the Lavanttal Fault Zone (Eastern Alps): reconciling the evidence from different geochronological indicators

The role of fault zone fabric and lithification state on frictional strength, constitutive behavior, and deformation microstructure

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