Extensional fault cores in micritic carbonate – Case studies from the Gulf of Corinth, Greece

Bastesen, Eivind; Braathen, Alvar; Nøttveit, Henning; Gabrielsen, Roy H.; Skar, T.

doi:10.1016/j.jsg.2009.01.005

Cited by 46 publications

(19 citation statements)

References 101 publications

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“…The overall structure of the Tre Monti fault zone is similar to that of previously described large-displacement faults exhumed from \3 to 4 km depth, including examples that cut carbonate wall rocks (AGOSTA and AYDIN, 2006;BASTESEN et al, 2009;BILLI et al, 2003;BUSSOLOTTO et al, 2007;DE PAOLA et al, 2008;MOLLI et al, 2009). In the Tre Monti fault zone much of the deformation within the damage zone and fault core was accommodated by bulk fracturing and grain size reduction by cataclasis.…”

Section: Deformation Mechanisms and Microstructuralsupporting

confidence: 69%

“…Carbonate is an important lithology in many other seismically active areas worldwide (FAMIN et al, 2008;JACKSON, 1994). Although several previous studies have focussed on the overall structure of exposed fault zones in carbonates (AGOSTA and AYDIN, 2006;BASTESEN et al, 2009;BILLI et al, 2003;BUSSOLOTTO et al, 2007;DE PAOLA et al, 2008;MICARELLI et al, 2006;MOLLI et al, 2009;STORTI et al, 2003) to our knowledge there has been no systematic study of the localized slip zones. We aim to document the microstructures and thicknesses of slip zones that cut limestone host rocks, and to improve our understanding of highly localized deformation processes that occur during the seismic cycle.…”

Section: Introductionmentioning

confidence: 99%

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Principal Slip Zones in Limestone: Microstructural Characterization and Implications for the Seismic Cycle (Tre Monti Fault, Central Apennines, Italy)

Smith

Billi

Toro

et al. 2011

Pure Appl. Geophys.

125

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Earthquakes in central Italy, and in other areas worldwide, often nucleate within and rupture through carbonates in the upper crust. During individual earthquake ruptures, most fault displacement is thought to be accommodated by thin principal slip zones. This study presents detailed microstructural observations of the slip zones of the seismically active Tre Monti normal fault zone. All of the slip zones cut limestone, and geological constraints indicate exhumation from\2 km depth, where ambient temperatures are 100C. Scanning electron microscope observations suggest that the slip zones are composed of 100% calcite. The slip zones of secondary faults in the damage zone contain protocataclastic and cataclastic fabrics that are cross-cut by systematic fracture networks and stylolite dissolution surfaces. The slip zone of the principal fault has much more microstructural complexity, and contains a 2–10 mm thick ultracataclasite that lies immediately beneath the principal slip surface. The ultracataclasite itself is internally zoned; 200–300 lm-thick ultracataclastic sub-layers record extreme localization of slip. Syn-tectonic calcite vein networks spatially associated with the sub-layers suggest fluid involvement in faulting. The ultracataclastic sub-layers preserve compelling microstructural evidence of fluidization, and also contain peculiar rounded grains consisting of a central (often angular) clast wrapped by a laminated outer cortex of ultra-fine-grained calcite. These ‘‘clast-cortex grains’’ closely resemble those produced during layer fluidization in other settings, including the basal detachments of catastrophic landslides and saturated high-velocity friction experiments on clay-bearing gouges. An overprinting foliation is present in the slip zone of the principal fault, and electron backscatter diffraction analyses indicate the presence of a weak calcite crystallographic preferred orientation (CPO) in the fine-grained matrix. The calcite c-axes are systematically inclined in the direction of shear. We suggest that fluidization of ultracataclastic sub-layers and formation of clast-cortex grains within the principal slip zone occurred at high strain rates during propagation of seismic ruptures whereas development of an overprinting CPO occurred by intergranular pressure solution during post-seismic creep. Further work is required to document the range of microstructures in localized slip zones that cross-cut different lithologies, and to compare natural slip zone microstructures with those produced in controlled deformation experiments

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Section: Deformation Mechanisms and Microstructuralsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Principal Slip Zones in Limestone: Microstructural Characterization and Implications for the Seismic Cycle (Tre Monti Fault, Central Apennines, Italy)

Smith

Billi

Toro

et al. 2011

Pure Appl. Geophys.

125

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“…microstructures that can occur in carbonate fault cores, the controls on the variation, and 34 linking of microstructures to measured porosity and permeability, which could be used to 35 predict their impact on fluid flow (e.g. Tondi et al 2006;Agosta 2008;Bastesen et al 2009). 36…”

Section: Abstract 12mentioning

confidence: 99%

Predicting transmissibilities of carbonate-hosted fault zones

Michie¹,

Yielding²,

Fisher

2017

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12It is common practice to incorporate deterministic transmissibility multipliers into 13 simulation models of siliciclastic reservoirs to take into account the impact of faults on fluid 14 flow, but this not common practice in carbonate reservoirs due to the lack of data on fault 15 permeability. Calculation of fault transmissibilities in carbonates is also complicated by the 16 variety of mechanisms active during faulting, associated with their high heterogeneity and 17 increased tendency to react with fluids. Analysis of the main controls on fault rock 18 formation and permeability from several carbonate-hosted fault zones is used to enhance 19 our ability to predict fault transmissibility. Lithological heterogeneity in a faulted carbonate 20 succession leads to a variety of deformation and/or diagenetic mechanisms, generating 21 several fault rock types. Although each fault rock type has widely varying permeabilities, 22 trends can be observed dependent on host lithofacies, juxtaposition and displacement. microstructures that can occur in carbonate fault cores, the controls on the variation, and 34 linking of microstructures to measured porosity and permeability, which could be used to 35 predict their impact on fluid flow (e.g. Tondi et al. 2006;Agosta 2008;Bastesen et al. 2009). 36The sealing potential of faults in siliciclastic sequences, on the other hand, has been widely 37

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“…The intermittent fault thickness increase with fault displacement that we see here may be associated with the occurrence of blocks and lenses within the fault zone, and result from fault-tip bifurcation (Watterson et al, 1998;Rawling and Goodwin, 2006;Childs et al, 2009). Deflection of a fault trace may occur due to contrasting bed competencies (Antonellini and Aydin, 1995;Childs et al, 1996bChilds et al, , 2009Rawling and Goodwin, 2006;Bastesen et al, 2009) or bed friction angles (Egholm et al, 2008). This creates asperities at the mixed zone boundary that are removed with subsequent fault displacement, incorporating whole blocks of sediment within the mixed zone (Rawling and Goodwin, 2006).…”

Section: Fault Growthmentioning

confidence: 99%

Fault architecture and deformation processes within poorly lithified rift sediments, Central Greece

Loveless

Bense

Turner

2011

Journal of Structural Geology

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a b s t r a c tDeformation mechanisms and resultant fault architecture are primary controls on the permeability of faults in poorly lithified sediments. We characterise fault architecture using outcrop studies, hand samples, thin sections and grain-size data from a minor (1e10 m displacement) normal-fault array exposed within Gulf of Corinth rift sediments, Central Greece. These faults are dominated by mixed zones with poorly developed fault cores and damage zones. In poorly lithified sediment deformation is distributed across the mixed zone as beds are entrained and smeared. We find particulate flow aided by limited distributed cataclasis to be the primary deformation mechanism. Deformation may be localised in more competent sediments. Stratigraphic variations in sediment competency, and the subsequent alternating distributed and localised strain causes complexities within the mixed zone such as undeformed blocks or lenses of cohesive sediment, or asperities at the mixed zone/protolith boundary. Fault tip bifurcation and asperity removal are important processes in the evolution of these fault zones. Our results indicate that fault zone architecture and thus permeability is controlled by a range of factors including lithology, stratigraphy, cementation history and fault evolution, and that minor faults in poorly lithified sediment may significantly impact subsurface fluid flow.

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Extensional fault cores in micritic carbonate – Case studies from the Gulf of Corinth, Greece

Cited by 46 publications

References 101 publications

Principal Slip Zones in Limestone: Microstructural Characterization and Implications for the Seismic Cycle (Tre Monti Fault, Central Apennines, Italy)

Principal Slip Zones in Limestone: Microstructural Characterization and Implications for the Seismic Cycle (Tre Monti Fault, Central Apennines, Italy)

Predicting transmissibilities of carbonate-hosted fault zones

Fault architecture and deformation processes within poorly lithified rift sediments, Central Greece

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