Internal geometry of fault damage zones in interbedded siliciclastic sediments

Johansen, Tord Erlend Skeie; Fossen, Haakon

doi:10.1144/sp299.3

Cited by 36 publications

(24 citation statements)

References 57 publications

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“…Statigraphic thickness estimates place the sequence at 1-to 4-km depth during Laramide activity in and around the San Rafael Swell (Davatzes, 2003;Doelling & Willis, 2008;Fossen et al, 2011;Shipton, 1999). Available stratigraphic evidence suggests minimal differences in burial depths of the formations and inferred depth of faulting in the different study areas (Johansen & Fossen, 2008). The Navajo Sandstone is a massive, 150-m-thick, well-sorted, well-cemented, and highly porous quartz arenite with a mean grain size of ∼0.1 mm (Aydin, 1977).…”

Section: Geological Contextmentioning

confidence: 99%

Smoothing of Fault Slip Surfaces by Scale‐Invariant Wear

2018

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Previous field observations suggest that fault slip surface roughness may decrease with slip. However, measurements have yet to confidently isolate the effect of slip from other possible controls, such as lithology or tectonic setting. We describe the evolution of slip surfaces in normal faults in SE Utah that cut well‐sorted, high‐porosity sandstones and accommodated regional extension at 1‐ to 4‐km depth. Tight controls on fault offset and uniform tectonic history allowed us to isolate the effect of slip during early stages of faulting (0‐ to 55‐m slip). Slip surfaces progress from rough joints and deformation bands toward smooth, continuous, and mirror‐like surfaces with increasing slip. We collected 123 scans of pristine slip surfaces, which measure surface geometry from micrometers to meters in length scale. Results indicate that slip surface roughness is systematically smoother than joint surfaces and deformation band edges. Over the best resolved length scales (0.1–10 mm), we observe roughness decreases with slip according to a power law with exponent −1 in the slip direction. Slip‐perpendicular profiles, though rougher, exhibit the same smoothing trend. The Hurst scaling exponent does not change with slip. These observations require wear to be multiscale. Boundary element method models suggest that mechanical wear of completely mated surfaces occurs by asperity failure and that the wear rate depends on the aspect ratio of asperities. These results indicate that at large slip, asperity failure at all length scales can cause slip surfaces to smooth while maintaining the fractal geometry characteristic of faults.

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Section: Geological Contextmentioning

confidence: 99%

Smoothing of Fault Slip Surfaces by Scale‐Invariant Wear

2018

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“…thick and up to 100 m (328 ft) long but can form clusters in which faults (slip surfaces) can initiate, as envisaged by Aydin and Johnson (1978). Clusters of bands can accumulate several hundred bands over a zone less than a meter wide (Johansen and Fossen, 2008), in which case the zone can be several hundred meters long. They can also form and grow in the damage zone of an existing fault, for instance as a response to geometric complications during fault slippage (e.g., Rykkelid and Fossen, 2002).…”

Section: Introductionmentioning

confidence: 99%

Spatial variation of microstructure and petrophysical properties along deformation bands in reservoir sandstones

Torabi

Fossen

2009

Bulletin

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A series of deformation bands from various reservoir sandstones deformed at different burial depths have been studied with respect to microstructural and petrophysical variations. In many of the examples explored, the internal microstructure, porosity, and permeability vary along the bands at the centimeter or even millimeter scale, changing and in most cases reducing the ability of the bands to act as barriers to fluid flow. Porosity varies by up to 18% and permeability by up to two orders of magnitude. Such petrophysical variations are found along different types of deformation bands, but the range depends upon the deformation mechanisms, in particular on the degree of cataclasis and dissolution in cataclastic and dissolution bands, and on the phyllosilicate content in disaggregation bands. For cataclastic bands, the grain-size distribution changes along the bands with regard to the degree of cataclasis. Furthermore, the increased specific surface area of the pore-grain interface as a result of cataclasis causes higher permeability reduction in cataclastic bands than in other types of deformation bands. Phyllosilicate content can influence the thickness of phyllosilicate bands. However, no apparent correlation between thickness and intensity of cataclasis in the studied cataclastic deformation bands is observed.Anita Torabi received her B.S. degree in geology from the University of Tehran (1993) and her Ph.D. in petroleum structural geology from the University of Bergen (2008). She joined the Center for Integrated Petroleum Research at the University of Bergen in 2004 and is currently a senior researcher. Her scientific interests include the analysis of faulted and fractured reservoirs in different stress regimes, fault-related folding and its role in hydrocarbon entrapment, and the effect of faulting on the petrophysical properties of rocks and fluid flow.

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“…[75] At the Sage Flat Hollow site, the cross-sectional distribution of deformation bands as seen in Figure 10 does not show the distinct architecture of a damage zone that would be expected around a normal fault of this size [e.g., Johansen and Fossen, 2008]. This is especially surprising given the well-developed deformation band damage zones observed around the much lower-strain fault at First Spring Hollow.…”

Section: Damage Zone Architecturementioning

confidence: 99%

Spatial distribution of damage around faults in the Joe Lott Tuff Member of the Mount Belknap Volcanics, Utah: A mechanical analog for faulting in pyroclastic deposits on Mars

Okubo

2012

J. Geophys. Res.

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Volcanic ash is thought to comprise a large fraction of the Martian equatorial layered deposits and much new insight into the process of faulting and related fluid flow in these deposits can be gained through the study of analogous terrestrial tuffs. This study identifies a set of fault‐related processes that are pertinent to understanding the evolution of fault systems in fine‐grained, poorly indurated volcanic ash by investigating exposures of faults in the Miocene‐aged Joe Lott Tuff Member of the Mount Belknap Volcanics, Utah. The porosity and granularity of the host rock are found to control the style of localized strain that occurs prior to and contemporaneous with faulting. Deformation bands occur in tuff that was porous and granular at the time of deformation, while fractures formed where the tuff lost its porous and granular nature due to silicic alteration. Non‐localized deformation of the host rock is also prominent and occurs through compaction of void space, including crushing of pumice clasts. Significant off‐fault damage of the host rock, resembling fault pulverization, is recognized adjacent to one analog fault and may reflect the strain rate dependence of the resulting fault zone architecture. These findings provide important new guidelines for future structural analyses and numerical modeling of faulting and subsurface fluid flow through volcanic ash deposits on Mars.

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Internal geometry of fault damage zones in interbedded siliciclastic sediments

Cited by 36 publications

References 57 publications

Smoothing of Fault Slip Surfaces by Scale‐Invariant Wear

Smoothing of Fault Slip Surfaces by Scale‐Invariant Wear

Spatial variation of microstructure and petrophysical properties along deformation bands in reservoir sandstones

Spatial distribution of damage around faults in the Joe Lott Tuff Member of the Mount Belknap Volcanics, Utah: A mechanical analog for faulting in pyroclastic deposits on Mars

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