scholarly journals Petrophysical, Geochemical, and Hydrological Evidence for Extensive Fracture-Mediated Fluid and Heat Transport in the Alpine Fault's Hanging-Wall Damage Zone

2017 ◽  
Vol 18 (12) ◽  
pp. 4709-4732 ◽  
Author(s):  
John Townend ◽  
Rupert Sutherland ◽  
Virginia G. Toy ◽  
Mai-Linh Doan ◽  
Bernard Célérier ◽  
...  
Keyword(s):  
Heat Transport ◽  
Hanging Wall ◽  
Damage Zone

scholarly journals QUANTITATIVE ANALYSIS OF DEFORMATION ALONG THE FAULT DAMAGE ZONE OF THE KLIMATIA THRUST (NW GREECE, IONIAN ZONE)

2001 ◽  
Vol 34 (4) ◽  
pp. 1643
Author(s):  
A. Kostakioti ◽  
P. Xypolias ◽  
S. Kokkalas ◽  
T. Doutsos
Keyword(s):  
Hanging Wall ◽  
Damage Zone ◽  
Deformation Pattern ◽  
Fracture System ◽  
Fracture Density ◽  
Fracture Orientation ◽  
Transport Direction ◽  
Structural Fracture ◽  
Fault Damage Zone ◽  
Northwestern Greece

In this study, we present structural, fracture orientation and fracture density (FD) data in order toquantify the deformation pattern of a damage zone that form around the slip plane of a large scalethrust fault which is located on the Ionian zone (External Hellenides) in northwestern Greece. Structuralanalysis showed at least two major deformation stages as indicated by the presence of refolding,backthrusting and break-back faulting. The fracture orientation analysis revealed three mainfracture systems, a dominant conjugate fracture system which is perpendicular to the transport direction(NW-to NNW trending sets), a conjugate fracture system trending parallel to the transport direction(ENE-trending conjugate sets) and a third diagonal conjugate fracture system (WNW andNNE trending sets). Resulting fracture density-distance diagrams display a decrease of total fracturedensity away from the studied fault, which is largely heterogeneous and irregular on both footwalland hanging wall. The conjugate fracture system trending perpendicular to the transport directionhas the dominant contribution to the accumulation of total fracture density. Based on theseresults we suggest that the observed heterogeneous and irregular distribution of fracture densityfashioned during the second deformation stage and is attributed to the formation of backthrusts andbreak-back thrust faults.

Natural fractures in deep tight gas sandstone reservoirs in the thrust belt of the southern Junggar Basin, northwestern China

2020 ◽  
Vol 8 (4) ◽  
pp. SP81-SP93 ◽  
Author(s):  
Guoping Liu ◽  
Lianbo Zeng ◽  
Xiaojun Wang ◽  
Mehdi Ostadhassan ◽  
Zhenlin Wang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Rock Mechanics ◽  
Hanging Wall ◽  
Damage Zone ◽  
Laboratory Data ◽  
Junggar Basin ◽  
Thrust Belt ◽  
Natural Fractures ◽  
Thin Sections ◽  
Sandstone Reservoirs

The development of natural fractures is a significant characteristic of the Jurassic deep tight sandstone reservoirs in the thrust belt of the southern Junggar Basin, and these reservoirs have a great potential for natural gas resources. Based on the analyses of outcrops, cores, thin sections, and other laboratory data, natural fractures in these reservoirs are mainly tectonic ones, which appear in groups and vary in scale, dip angle, and density. We have classified fractures in thin sections into intragranular, grain boundary, and transgranular ones depending on their relationship with minerals grains. Almost 58% of the whole fracture population is opening-mode fractures, and calcite is the main filling mineral for the remaining ones. Fracture apertures vary based on their types, where transgranular fractures are the widest, followed by grain boundary and intragranular ones. Lithology, rock mechanical mechanics layers, and structures control the development of natural fractures. Fractures are more frequent in siltstone and fine sandstone. Sandstones with larger mineral grains are more likely to develop grain boundary and intragranular fractures. Intralayer fractures are the dominant ones, which intersect the rock mechanics interface at high angles or perpendicularly. The linear density of these fractures decreases when the thickness of the rock-mechanics layer increases. Furthermore, fractures have a higher degree of development in the hanging wall of the faults, with the degree decreasing when the distance from the fault plane increases. Additionally, the development degree of fractures in the damage zone is better than the adjacent rocks, and the width of damage zones is a function of the amount of fault displacement.

Textural evolution and fluid-rock interaction during upper crustal, seismic deformation: Insights from the carbonate-dominated fault rock suite of the Belluno Thrust, Italian Southern Alps

2020 ◽  
Author(s):  
Renato Diamanti ◽  
Costantino Zuccari ◽  
Selina Bonini ◽  
Gianluca Vignaroli ◽  
Giulio Viola
Keyword(s):  
Structural Characterization ◽  
Strain Localization ◽  
Hanging Wall ◽  
Damage Zone ◽  
Southern Alps ◽  
Deformation Mechanisms ◽  
Pressure Solution ◽  
Time Interval ◽  
Rock Interaction ◽  
Calcite Veins

<p>A multi-scalar, multi-methodological approach has been used to characterize the deformation mechanisms and fluid-rock interaction processes within the Belluno Thrust (BT), a regional-scale thrust cutting through Mesozoic carbonates of the eastern Southern Alps of Italy. We report the first results of a systematic analysis of the deformation mechanisms that steered strain localization within the BT fault zone during seismogenic faulting. The WSW-ENE-striking BT contributed to development of the south-verging thrust-and-fold belt of the Southern Alps during the Late Oligocene – present time interval.        We studied an outstanding exposure of the BT in the greater Feltre region, where the BT juxtaposes an Early Jurassic oolitic and micritic limestone (the Calcari Grigi Group) in the hanging wall against an Upper Jurassic-Early Cretaceous pelagic and cherty limestone (the Maiolica Fm.). The BT is defined by a 2 m-thick damage zone formed at the expense of both the hanging wall and footwall blocks. Atop the damage zone is a millimetric principal slip surface (PSS) that strikes WSW-ENE and dips 40° to the NNW. Kinematic analysis confirms the top-to-the SSE transport along the BT. Several structural facies have been identified by means of detailed structural mapping and sampled from the damage zone (from within both the hanging- and the footwall blocks) and the PSS. The outcrop structural characterization has revealed a number of physically juxtaposed, yet different, structural facies: i) cohesive, weakly foliated proto- to ultracataclasite; ii) uncohesive, clay-rich gouge; iii) foliated domains with SC-C’ structures. Relatively unstrained host rock lithons are wrapped by these variably strained domains. Petrographic and microstructural analyses show evidence of pervasive pressure solution, with abundant stylolites, slickolites and foliated domains indicating an overall ductile behaviour. Calcite veins are also common in all recognised structural facies showing mutual cross-cutting relationships with the pressure-solution seams. This structural characterization has provided the basis for detailed image analysis of selected cataclastic textures to calculate fractal parameters for the particle size distribution (Ds) and morphology (Dr) of the clasts aiming at better understanding the cataclastic flow active in the BT fault rocks. Results from a range of representative samples suggest corrosive wear to be the main cataclastic process (Ds 1,41 ÷ 2,00; Dr 1,51 ÷ 1,88). Cathodoluminescence imaging revealed multiple generations of cement and permitted discriminating the first-order chemical characteristics of parental fluids and constraining the relationships between calcite veining and cementation. Two syn-tectonic cements have been identified: i) a bright-orange cement, preferentially surrounding carbonate clasts with highly irregular margins, indicative of the involvement of carbonate-reactive fluids; ii) a dull, homogeneous brown/black cement coexisting with a siliceous matrix, mantled clasts and local sigmoidal structures. The latter is at times observed as thin injections and fluidized structures.        Our preliminary results suggest that overall deformation was accommodated by creep and low-T crystal-plastic deformation possibly during inter-seismic phases as indicated by the presence of pressure-solution seams and foliated fabrics. Transient spikes of coseismic rupturing possibly promoted by multiple batches of overpressured fluids were accompanied by significant cataclasis and brittle strain localization.</p>

scholarly journals Structural characterization of fault damage zones in carbonates (Central Apennines, Italy)

2021 ◽  
Author(s):  
Miriana Chinello ◽  
Michele Fondriest ◽  
Giulio Di Toro
Keyword(s):  
Fault Zone ◽  
Hanging Wall ◽  
Damage Zone ◽  
Normal Fault ◽  
Vertical Displacement ◽  
Fault System ◽  
Normal Faults ◽  
Central Apennines ◽  
Fault Surface ◽  
Fracture Intensity

<p>The Italian Central Apennines are one of the most seismically active areas in the Mediterranean (e.g., L’Aquila 2009, Mw 6.3 earthquake). The mainshocks and the aftershocks of these earthquake sequences propagate and often nucleate in fault zones cutting km-thick limestones and dolostones formations. An impressive feature of these faults is the presence, at their footwall, of few meters to hundreds of meters thick damage zones. However, the mechanism of formation of these damage zones and their role during (1) individual seismic ruptures (e.g., rupture arrest), (2) seismic sequences (e.g., aftershock evolution) and (3) seismic cycle (e.g., long term fault zone healing) are unknown. This limitation is also due to the lack of knowledge regarding the distribution, along strike and with depth, of damage with wall rock lithology, geometrical characteristics (fault length, inherited structures, etc.) and kinematic properties (cumulative displacement, strain rate, etc.) of the associated main faults.</p><p>Previous high-resolution field structural surveys were performed on the Vado di Corno Fault Zone, a segment of the ca. 20 km long Campo Imperatore normal fault system, which accommodated ~ 1500 m of vertical displacement (Fondriest et al., 2020). The damage zone was up to 400 m thick and dominated by intensely fractured (1-2 cm spaced joints) dolomitized limestones with the thickest volumes at fault oversteps and where the fault cuts through an older thrust zone. Here we describe two minor faults located in the same area (Central Apennines), but with shorter length along strike. They both strike NNW-SSE and accommodated a vertical displacement of ~300 m.</p><p>The Subequana Valley Fault is about 9 km long and consists of multiple segments disposed in an en-echelon array. The fault juxtaposes pelagic limestones at the footwall and quaternary deposits at the hanging wall. The damage zone is < 25 m  thick  and comprises fractured (1-2 cm spaced joints) limestones beds with decreasing fracture intensity moving away from the master fault. However, the damage zone thickness increases up to ∼100 m in proximity of subsidiary faults striking NNE-SSW. The latter could be reactivated inherited structures.</p><p>The Monte Capo di Serre Fault is about 8 km long and characterized by a sharp ultra-polished master fault surface which cuts locally dolomitized Jurassic platform limestones. The damage zone is up to 120 m thick and cut by 10-20 cm spaced joints, but it reaches an higher fracture intensity where is cut by subsidiary, possibly inherited, faults striking NNE-SSW.</p><p>Based on these preliminary observations, faults with similar displacement show comparable damage zone thicknesses. The most relevant damage zone thickness variations are related to geometrical complexities rather than changes in lithology (platform vs pelagic carbonates).  In particular, the largest values of damage zone thickness and fracture intensity occur at fault overstep or are associated to inherited structures. The latter, by acting as strong or weak barriers (sensu Das and Aki, 1977) during the propagation of seismic ruptures, have a key role in the formation of damage zones and the growth of normal faults.</p>

scholarly journals Petrophysical, geochemical, and hydrological evidence for extensive fracture-mediated fluid and heat transport in the Alpine Fault's hanging-wall damage zone

2021 ◽  
Author(s):  
John Townend ◽  
Rupert Sutherland ◽  
VG Toy ◽  
ML Doan ◽  
B Célérier ◽  
...  
Keyword(s):  
Numerical Models ◽  
Hanging Wall ◽  
Damage Zone ◽  
Active Faults ◽  
Outer Zone ◽  
Earthquake Rupture ◽  
Fault Rock ◽  
Spatial And Temporal Scales ◽  
Alpine Fault ◽  
Earthquake Rupture Processes

© 2017. American Geophysical Union. All Rights Reserved. Fault rock assemblages reflect interaction between deformation, stress, temperature, fluid, and chemical regimes on distinct spatial and temporal scales at various positions in the crust. Here we interpret measurements made in the hanging-wall of the Alpine Fault during the second stage of the Deep Fault Drilling Project (DFDP-2). We present observational evidence for extensive fracturing and high hanging-wall hydraulic conductivity (∼10−9 to 10−7 m/s, corresponding to permeability of ∼10−16 to 10−14 m2) extending several hundred meters from the fault's principal slip zone. Mud losses, gas chemistry anomalies, and petrophysical data indicate that a subset of fractures intersected by the borehole are capable of transmitting fluid volumes of several cubic meters on time scales of hours. DFDP-2 observations and other data suggest that this hydrogeologically active portion of the fault zone in the hanging-wall is several kilometers wide in the uppermost crust. This finding is consistent with numerical models of earthquake rupture and off-fault damage. We conclude that the mechanically and hydrogeologically active part of the Alpine Fault is a more dynamic and extensive feature than commonly described in models based on exhumed faults. We propose that the hydrogeologically active damage zone of the Alpine Fault and other large active faults in areas of high topographic relief can be subdivided into an inner zone in which damage is controlled principally by earthquake rupture processes and an outer zone in which damage reflects coseismic shaking, strain accumulation and release on interseismic timescales, and inherited fracturing related to exhumation.

scholarly journals QUANTITATIVE ANALYSIS OF DEFORMATION ALONG THE FAULT DAMAGE ZONE OF THE KLIMATIA THRUST (NW GREECE, IONIAN ZONE)

2004 ◽  
Vol 36 (4) ◽  
pp. 1643 ◽  
Author(s):  
A. Kostakioti ◽  
P. Xypolias ◽  
S. Kokkalas ◽  
T. Doutsos
Keyword(s):  
Large Scale ◽  
Hanging Wall ◽  
Damage Zone ◽  
Deformation Pattern ◽  
Fracture System ◽  
Fracture Density ◽  
Fracture Orientation ◽  
Fracture Systems ◽  
Transport Direction ◽  
Total Fracture

In this study, we present structural, fracture orientation and fracture density (FD) data in order to quantify the deformation pattern of a damage zone that form around the slip plane of a large scale thrust fault which is located on the Ionian zone (External Hellenides) in northwestern Greece. Structural analysis showed at least two major deformation stages as indicated by the presence of refolding, backthrusting and break-back faulting. The fracture orientation analysis revealed three main fracture systems, a dominant conjugate fracture system which is perpendicular to the transport direction (NW-to NNW trending sets), a conjugate fracture system trending parallel to the transport direction (ENE-trending conjugate sets) and a third diagonal conjugate fracture system (WNW and NNE trending sets). Resulting fracture density distance diagrams display a decrease of total fracture density away from the studied fault, which is largely heterogeneous and irregular on both footwall and hanging wall. The conjugate fracture system trending perpendicular to the transport direction has the dominant contribution to the accumulation of total fracture density. Based on these results we suggest that the observed heterogeneous and irregular distribution of fracture density fashioned during the second deformation stage and is attributed to the formation of backthrusts and break-back thrust faults.

scholarly journals Tracking geothermal anomalies along a crustal fault using (U-Th)/He apatite thermochronology and REE analyses, the example of the Têt fault (Pyrenees, France)

2020 ◽  
Author(s):  
Gaétan Milesi ◽  
Patrick Monié ◽  
Philippe Münch ◽  
Roger Soliva ◽  
Audrey Taillefer ◽  
...  
Keyword(s):  
Hot Springs ◽  
Hot Spring ◽  
Hanging Wall ◽  
Regional Scale ◽  
Damage Zone ◽  
Hydrothermal Activity ◽  
Thermal Anomalies ◽  
Eastern Pyrenees ◽  
Major Fault ◽  
Surface Manifestation

Abstract. The Têt fault is a crustal scale major fault in the eastern Pyrenees along which 29 hot springs emerge mainly within the footwall damage zone of the fault. In this study, (U-Th)/He apatite (AHe) thermochronology is used in combination with REE analyses to investigate the imprint of hydrothermal activity nearby two main hot spring clusters and in between in an attempt to better define the geometry and intensity of the recent thermal anomalies along the fault and to compare them with previous results from numerical modelling. This study displays 99 new AHe ages and 63 REE analyses on samples collected in the hanging wall (18 to 43 Ma) and footwall (8 to 26 Ma) of the Têt fault. In the footwall, the results reveal AHe age resetting and apatite REE depletion due to hydrothermal circulation along the Têt fault damage zone, nearby the actual hot springs (Thuès-les-Bains and St-Thomas) but also in areas lacking actual geothermal surface manifestation. These age resetting and element depletions are more pronounced around Thuès-les-Bains hot spring cluster and are spatially restricted to a limited volume of the damage zone. Outside this damage zone, the modelling of thermochronological data in the footwall suggests the succession of two main phases of exhumation, between 30 and 24 Ma and a second one around 10 Ma. In the hanging wall, few evidences of hydrothermal imprint on AHe ages and REE signatures have been found and thermal modelling records a single exhumation phase at 35–30 Ma. Low-temperature thermochronology combined with REE analyses allows to identify the spatial distribution of a recent geothermal perturbation related to hydrothermal flow along a master fault zone in the eastern Pyrenees, opens new perspectives for the exploration of geothermal fields and provides at the regional scale new constraints on the tectonic uplift of the footwall and hanging wall massifs.

scholarly journals Controls on fault zone structure and brittle fracturing in the foliated hanging wall of the Alpine Fault

Solid Earth ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 469-489 ◽  
Author(s):  
Jack N. Williams ◽  
Virginia G. Toy ◽  
Cécile Massiot ◽  
David D. McNamara ◽  
Steven A. F. Smith ◽  
...  
Keyword(s):  
Fault Zone ◽  
Hanging Wall ◽  
Damage Zone ◽  
Ct Images ◽  
Mechanical Anisotropy ◽  
Drill Core ◽  
Fracture Density ◽  
Alpine Fault ◽  
Wide Range ◽  
Confining Pressures

Abstract. Three datasets are used to quantify fracture density, orientation, and fill in the foliated hanging wall of the Alpine Fault: (1) X-ray computed tomography (CT) images of drill core collected within 25 m of its principal slip zones (PSZs) during the first phase of the Deep Fault Drilling Project that were reoriented with respect to borehole televiewer images, (2) field measurements from creek sections up to 500 m from the PSZs, and (3) CT images of oriented drill core collected during the Amethyst Hydro Project at distances of  ∼  0.7–2 km from the PSZs. Results show that within 160 m of the PSZs in foliated cataclasites and ultramylonites, gouge-filled fractures exhibit a wide range of orientations. At these distances, fractures are interpreted to have formed at relatively high confining pressures and/or in rocks that had a weak mechanical anisotropy. Conversely, at distances greater than 160 m from the PSZs, fractures are typically open and subparallel to the mylonitic or schistose foliation, implying that fracturing occurred at low confining pressures and/or in rocks that were mechanically anisotropic. Fracture density is similar across the  ∼  500 m width of the field transects. By combining our datasets with measurements of permeability and seismic velocity around the Alpine Fault, we further develop the hierarchical model for hanging-wall damage structure that was proposed by Townend et al. (2017). The wider zone of foliation-parallel fractures represents an outer damage zone that forms at shallow depths. The distinct < 160 m wide interval of widely oriented gouge-filled fractures constitutes an inner damage zone. This zone is interpreted to extend towards the base of the seismogenic crust given that its width is comparable to (1) the Alpine Fault low-velocity zone detected by fault zone guided waves and (2) damage zones reported from other exhumed large-displacement faults. In summary, a narrow zone of fracturing at the base of the Alpine Fault's hanging-wall seismogenic crust is anticipated to widen at shallow depths, which is consistent with fault zone flower structure models.

scholarly journals Abutting faults: a case study of the evolution of strain at Courthouse branch point, Moab Fault, Utah

Solid Earth ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 513-526
Author(s):  
Heijn van Gent ◽  
Janos L. Urai
Keyword(s):  
Branch Point ◽  
Hanging Wall ◽  
Damage Zone ◽  
Published Data ◽  
Deformation Bands ◽  
Wide Range ◽  
Slip Planes ◽  
Main Fault ◽  
Extension Direction

Abstract. Slip planes and slip directions of subsequent generations of faults were measured and analysed in the interaction damage zone of two abutting faults in porous sandstones in order to understand the palaeostress/palaeostrain evolution. The Courthouse branch point of the Moab Fault in SE Utah (USA) is a much-studied, spectacular outcrop of two abutting faults, located in the footwall block of the main fault and in the hanging wall block of the abutting fault. The abutting fault is synthetic to the main fault. The outcrop shows a wide range of deformation structures and fault-related diagenesis such as striated slip planes, deformation bands, veins, Liesegang bands and copper-rich mineralization. By combining our own measurements with published data on the relative age of these structures, we classified the data in four sets. Using a Numeric Dynamic Analysis (NDA) to calculate the orientation of the kinematic axes we found three different palaeo-extension directions in the four sets, recording the evolution of stress/strain axes during the abutting process. The first phase of deformation is regional extension in the NE–SW direction. As the second fault approached the main fault from its footwall side and the two faults started to become kinematically linked, the extension direction changed so that the overall extension became perpendicular to the approaching fault (NW–SE). Finally, the extension direction changed back to being perpendicular to the first segment (NE–SW) when the two faults became geometrically linked and regional extension became dominant again.

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