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Santa Maria dell'Isola is a rocky promontory surrounded by the Tyrrhenian Sea and located in Tropea municipality in Vibo Valentia Province (Calabria, southern Italy) (Fig. The preliminary results discussed herein suggest that the possible causes of the instability phenomena are imputable to the sandstone rocks' weak nature, the rock masses' high fracturing state, and the intense erosive processes by sea wave energy at the cliff foot. They show the topographic changes caused by rocks detached and the material accumulation at the foot of the cliff Conclusion Assessing the cause of the slope instability and focusing on site-specific geological characteristics are crucial steps before projecting suitable consolidation interventions. [Extracted from the article]

The present study reports structural evidences of active tectonics along the Himalayan Frontal Thrust (HFT) exposed in Kumia river section, Majhola Got, Uttarakhand, utilising remote sensing data, field investigations and Optically Stimulated Luminescence (OSL) dating. The HFT makes the southernmost boundary of the northwest frontal Himalaya, against the piedmont zone of the Indo-Gangetic Plain. Almost E–W trending and low angle (6°–20°) northerly dipping HFT plane with listric thrust geometry is exposed at the right bank of Kumia river section. Here, deformed grey-white sandstone and purple-red mudstone sequence of the Chinji/Ramnagar Formation of Lower Siwalik Subgroup override on the adjoining post-Siwalik/late Quaternary fluvial terrace deposits of piedmont zone of the Indo-Gangetic plain along the HFT plane, a direct evidence of active tectonics. A footwall sand sample of the terrace deposits collected ~1 m below the HFT plane at Kumia river section has yielded ~4.2 ± 0.2 ka BP optically stimulated luminescence (OSL) date (GSI, OSL/TL Lab, Faridabad). It indicates reactivation of the HFT segment with major paleoseismic event after ~4 ka BP. In the Kumia river section, the HFT damage zone is characterised by wide (~100 m) hanging wall brittle–ductile to brittle deformation and limited (1 m wide) footwall brittle deformation, a case of strain partitioning under same bulk compressive stress regime of the south directed HFT sheet. The thrust-related hanging wall damage zone is well differentiated into cataclastic/gouge, breccia and fractures sub-zones farther from HFT plane and shows small-scale slickensides/striations, cataclastic flow bands, south verging thrust duplexes and asymmetric shear/drag folds, obliteration/shattering of bedding planes, grain size refinement, secondary faults/fractures and brittle-ductile to brittle discrete shear zones. Slickensides/striations (16º plunge towards 010° on 270°/16°N HFT plane, with reverse sense of movement towards 190°) within the immediate hanging wall clayey cataclastic/gouge material along the main HFT plane suggests south-directed (towards 190°) movement of the HFT sheet in the area. The petrographic study of the deformed Lower Siwalik rocks of the cataclastic/gouge sub-zone reveals mudstone flow bands, thin quartz-carbonate veins, micro-scale thrust related asymmetrical, shear/drag folds, micro-thrust duplexes, micro-faults, deformed clasts of sandstone and mudstone with secondary fractures and pressure shadow tail structure without recrystallisation, formed due to HFT related brittle–ductile deformation at moderate temperature and pressure. The seismotectonic setting of the narrow Kumaun Salient having very close disposition of parallel HFT, Main Boundary Thrust, Lugad Thrust and Belgaon Thrust within ~10 km width of the frontal Himalaya, along with sparse or negligible distribution of past seismic events around the area suggest locked nature of the active HFT segment in the present tectonic regime which accumulates tectonic energy to generate future large earthquake, a potential seismic threat in the region. [ABSTRACT FROM AUTHOR]

A cataclastic rock mass is a poor type of engineering geological rock mass. The determination of the shear failure characteristics and shear strengths of cataclastic rock masses can provide key basis for the design and construction of infrastructure. Physical model samples of a sandstone cataclastic rock mass were first produced by a combination of three-dimensional (3D) printing technology and manual pouring. Shear tests were conducted with respect to the shear stresses parallel to the trace line plane and perpendicular to the trace line plane of the cataclastic rock mass model. Based on an extensive analysis of the shear failure characteristic, shear stress evolution characteristic curve and shear strength. When the shear stress was parallel to the trace line plane, and when the rock block that was cut and confined by the trace line exhibited a significant tip, the end stress concentration effect of the cataclastic rock mass was more significant during the shear process with the anisotropy of the rock block increased. In addition, the shapes of the rock blocks that were confined and cut by the joints were the main influencing factors of the strength of the cataclastic rock mass. When the shear stress was perpendicular to the trace line plane, the structure of the rock wall was the main influencing factor of the deformation and failure process of the shear failure plane and the shear strength. The physical and mechanical properties of the shear failure plane of the cataclastic rock mass were found to be closely related to the joint–rock wall system characteristics of the cataclastic rock mass. Therefore, when determining the shear strength of cataclastic rock mass, the shape and combination form of the rock block, shear direction, and structural failure characteristics of the rock wall should be comprehensively considered during the shear process. [ABSTRACT FROM AUTHOR]

A novel and really simple method for extractive photometric determination of uranium is achievable by Azur II dye with accurate and sensitive results. This has been possible through a basic dye (Azur II) that reacts firstly with a suitable ligand (benzoate) to form a triple complex. The latter is then extracted in a suitable organic solvent (Trioctylamine). Optimisation of the formed U-benzoate-Azur II complex was performed by studying several parameters such as suitable pH, dye concentration, duration time of the formed complex, solvent concentration, shaking time and U concentration (calibration curve). This reagent is extremely sensitive to uranium, with a molar absorption potential of 0.654 × 104 L. M−1 cm−1 at pH 4 at 688 nm. Absorbance measurements showed as time function that the coloured complex is stable up to 20 min. This system allows uranium content to be calculated with a detection limit (LOD) of 0.15 µg L−1, and precision expressed as relative standard deviation (RSD) of 0.368%. The tolerance limits had been calculated for several metal ions. Accuracy was confirmed by U (VI) determination in the standard reference materials. This new spectrophotometric method was applied for the determination of U(VI) in some cataclastic rock samples with accurate results. [ABSTRACT FROM AUTHOR]

A large-scale obliquely inclined bedding rockslide, activated by a heavy rainstorm, occurred on July 8, 2020, at 7:05 (UTC + 8) in Shiban Village, Songtao Miao Autonomous County, Guizhou Province, China. The loss of life in this event was greatly reduced owing to the local warning system for rainstorm-induced geohazards. To understand the failure characteristics, triggering factors, the genetic mechanism of the landslide, the geomorphological features, geological characteristics, hydrological conditions, and rainfall characteristics were systematically studied by a synthetic approach including field investigations, satellite imagery, unmanned aerial vehicle (UAV) photography, laboratory tests, and rainfall data statistics. The results indicated that the interface between the soft and hard rock, the well-developed joints, and the free face in front of the slope constituted the boundaries of this landslide. The concave topography at the back and southern edge of the landslide, the bare ground, and the cataclastic structure of the rock mass provided favorable conditions for the collection or infiltration of rainwater. The concentrated rainstorm was the direct trigger for the landslide, which led to a rapid inflow and retention of rainfall in the landslide through favorable landform and geological conditions. The groundwater recharge that cannot be drained in time caused the mechanical deterioration of rock mass and induced a rapid increase in pore water pressure in the landslide. Moreover, the water level of the Ganlong River at the toe of the slope also rose rapidly, and the uplift pressure in front of the slope increased accordingly. Under the combined action of these adverse factors, the overall anti-sliding force of the slope was less than the sliding force, finally resulting in the landslide. Remarkably, the local warning system for rainstorm-induced geohazards successfully forecasted the landslide, but the shortcoming is that the forecast time in advance is short. Nevertheless, the prediction has significantly reduced human casualties and provided valuable experience for the prediction of this type of landslide. [ABSTRACT FROM AUTHOR]

At the Tick Hill gold deposit, δ18Oquartz data for the mineralised lithologies and surrounding rocks are similar and fall within a narrow range of 10.5–13.7‰ V-SMOW. The highly mineralised quartzo-feldspathic mylonite has quartz δ18O (δ18Oquartz) values of 11.3–13.6‰, which are similar to values for the surrounding rocks both locally and regionally, i.e. δ18Oquartz by itself does not provide a useful exploration tool. The δ18Oquartz values from the Tick Hill area most likely reflect the late Isan hydrothermal overprint at 1525–1520 Ma. The origin of the altering fluids is unclear, as the δ18Oquartz values overlap with reported δ18O values calculated for both metamorphic and igneous fluids. When combining the δ18Oquartz results with δ18Ocalcite results available from the literature, a temperature of 350–550 °C was calculated, which is consistent with observed alteration assemblages associated with gold mineralisation. The δ18Oquartz values (10.5–13.7‰ V-SMOW) of Au-rich quartz–feldspar mylonite are indistinguishable from the altered host rocks both local and regional. The narrow range of δ18Oquartz values for the rock units in the Tick Hill area and Mary Kathleen Domain most likely reflect a regional fluid overprint. The post-mineralised quartz–calcite veins yield higher δ18Oquartz values (14.1–17‰), possibly reflecting (partial) re-equilibration of minerals locally formed in late cataclastic fault rocks. [ABSTRACT FROM AUTHOR]

Arranged from oldest to youngest, the main granitic rock units exposed in Khour Abalea are metagabbros, cataclastic rocks, ophiolitic melange, granitic rocks, pegmatite and lamprophyre dykes. The presence of radioactivity associated with the heavy bearing minerals in construction materials—like granite—increased interest in the extraction process. As it turns out, granitic rocks play an important economic part in the examination of an area's surroundings. The radionuclide content is measured by using an NaI (Tl)-detector. In the mineralized pegmatites, U (326 to 2667 ppm), Th (562 to 4010 ppm), RaeU (495 to 1544 ppm) and K (1.38 to 9.12%) ranged considerably with an average of 1700 ppm, 2881.86 ppm, 1171.82 ppm and 5.04%, respectively. Relationships among radioelements clarify that radioactive mineralization in the studied pegmatites is magmatic and hydrothermal. A positive equilibrium condition confirms uranium addition to the studied rocks. This study determined 226Ra, 232Th and 40K activity concentrations in pegmatites samples and assessed the radiological risks associated with these rocks. The activity concentrations of 226Ra (13,176 ± 4394 Bq kg−1), 232Th (11,883 ± 5644 Bq kg−1) and 40K (1573 ± 607 Bq kg−1) in pegmatites samples (P) are greater than the global average. The high activity of the mineralized pegmatite is mainly attributed to the presence of uranium mineral (autunite), uranophane, kasolite and carnotite, thorium minerals (thorite, thorianite and uranothorite) as well as accessories minerals—such as zircon and monazite. To assess the dangerous effects of pegmatites in the studied area, various radiological hazard factors (external, internal hazard indices, radium equivalent activity and annual effective dose) are estimated. The investigated samples almost surpassed the recommended allowable thresholds for all of the environmental factors. [ABSTRACT FROM AUTHOR]

In order to study the correlation between TBM operating parameters and different lithologic strata， taking a Xinjiang water diversion project as the background, 300 m of tunneling parameter data was selected for typical lithologic strata. The correlation between 3 tunneling parameters and 6 lithologic strata was analyzed by using mathematical statistics. By analyzing the correlation among propulsion speed, total thrust and cutter speed under the six types of lithologic strata, the tunneling suggestions were put forward. The results show that the average value of propulsion speed and total thrust varies greatly among different lithologic strata. The cutter speed fluctuates little, and the average difference is small. In siliceous, ande site and tuff strata, the total thrust, cutter speed and propulsion speed are not correlated. In mylonite and sandstone strata, the total thrust, cutter speed and propulsion speed are positively correlated. In cataclastic rock strata, the total thrust is negatively correlated with the propulsion speed. [ABSTRACT FROM AUTHOR]

3-aminomethylalizarn-N-N diacetic acid chromogenic dye (AMADA) was used for the first time in uranium and thorium spectrophotometric estimation with accurate and sensitive result, their complexes having a maximum absorbance at 575 nm for U and at 510 nm for Th. This system allows uranium and thorium content to be calculated with a detection limit (LOD) of 0.16 µg L−1 and 0.14 µg L−1, respectively. The first-derivative spectra and EDTA were investigated to eliminate interference and provide selective estimation of uranium and thorium in presence of each other. This new spectrophotometric method was applied for the determination of U(VI) and Th(IV) in the standard reference materials (granite and Syenite) and some cataclastic rock samples with accurate results. [ABSTRACT FROM AUTHOR]

In hard cataclastic surrounding rock with high geostress, the rock monomer strength is high and the rock is broken, and tunnel excavation in it is apt to cause large deformation, collapsing, and breaking, causing initial support crack and even intruding of the initial support deformation. The characteristics of the support system under different support parameters and shapes are analyzed, and the reasonable support section shape and support parameters are determined. The results showed that (1) under the condition of high geostress and hard cataclastic surrounding rock, the initial support deformation is large, the horizontal convergence is much larger than the settlement of arch, and the deformation duration is relatively short; (2) the distribution of pressure and stress in initial support are very uneven on the cross-section and greatly affected by the construction process; (3) in the case of large horizontal tectonic stress, the use of large curvature side wall support is beneficial to improve the quality of support and control the deformation of the structure, especially to improve the stress of concrete; (4) the closure time of the supporting system greatly influences the stress state and deformation, so it is necessary to shorten the length of the lower bench and the distance of the invert as possible so as to close the support as early as possible; (5) different location of the tunnel surrounding rock stress distribution is very uneven, the measured value is much larger than calculated value in level III based on the specification of surrounding rock; (6) under high strength and ground stress, the initial supporting stress of steel frame increases rapidly, and the measured stress is larger. This indicates that the steel frame structure bears heavy early load. Therefore, the stiffness of the steel frame should be as large as possible to meet the loading requirements. [ABSTRACT FROM AUTHOR]

The research on the ultimate crushing state of coarse aggregates is beneficial to analyze and predict the evolutionary process of crushing. The Growing Path method uses the two-dimensional fractal geometry structure to simulate the size variation of particle size fraction during the particle breakage of coarse aggregates and it serves to investigate the ultimate fractal dimension corresponding to the ultimate crushing state of coarse aggregates. This method manifests the self-growing characteristics of particle size distribution in the process of particle crushing. This study found that the two-dimensional image of ultimate fractal model was precisely similar to that of the Sierpinski gasket of fractal theory when the ultimate crushing state was reached. The results from the model analysis show that the theoretically ultimate fractal dimension is about 2.585, which is consistent with the existing results calculated from the three-dimensional ultimate fragmentation model of cataclastic rock located in the fault zones. The relationship between two fractal models was analyzed. Furthermore, the application of fractal geometry presented in this study will also serve as a reference for the analysis of the other chaos phenomena observed in geotechnical engineering. [ABSTRACT FROM AUTHOR]

Grain size reduction due to cataclasis is a key process controlling fault frictional properties during the seismic cycle. We investigated the role of cleavage planes on fracturing and microstructural evolution during cataclasis in wet and dry carbonate fault gouges (50 wt% calcite, 50 wt% dolomite) deformed in a rotary-shear apparatus over a wide range of slip rates (30 μms−1 to 1 ms−1) and displacements (0.05–0.4 m). During shearing, progressive strain localization forms a narrow slip zone that undergoes significant frictional heating (at high slip rates), but the bulk gouge always accommodates low finite shear strains and deforms at low temperatures. Microstructural analysis of the bulk gouges indicates that deformation occurred by brittle fracturing and twinning. Microfractures in calcite are closely spaced, often exploit { 10 1 ¯ 4 } cleavage r -rhomb planes, and occur mainly subparallel to the expected principal stress orientation (σ 1). Instead, twin planes typically occur sub-perpendicular to σ 1. Electron backscatter diffraction analysis of the bulk gouges shows that calcite develops a well-defined crystallographic preferred orientation (CPO) at all investigated deformation conditions. The CPO is defined by a clustering of the calcite c-axes around an orientation sub-parallel to σ 1. The calcite CPO is interpreted to result from grain rotation during granular flow, followed by brittle fracturing that occurred preferentially along calcite cleavage planes. This interpretation is supported by measurements of calcite grain shape-preferred orientations that show a population of elongate calcite grains oriented with their long axes sub-parallel to σ 1. Our experimental results indicate that well-defined CPOs can form at low temperature in cataclastic fault rocks, and that mineral cleavage can strongly influence the evolution of grain sizes and shapes during comminution. • CPO developed in coarse-grained, low-temperature carbonate fault gouges. • CPO formed by brittle processes at all studied slip rates and displacements. • Closely-spaced microfractures exploit { 10 1 ¯ 4 } rhomb cleavage planes in calcite. • CPO interpreted to form by grain rotation and cleavage-controlled fracturing. [ABSTRACT FROM AUTHOR]

Vein networks of pseudotachylytes and ultracataclastic rocks are composed mainly of ultrafine-to fine-grained materials, including fault gouge and microbreccia, and are widely considered indicators of past seismic faulting events. I show that such vein networks of pseudotachylyte with both melt and crush origins, as well as ultracataclastic rocks, form by the rapid injection of ultrafine-to fine-grained material sourced from pulverized ultracataclastic rocks in seismogenic fault zones under thermal pressurization and fluidization during seismic events. The thermal expansion of seismic slip zones caused by frictional heating results in the rapid fluidization of ultrafine-to fine-grained materials along with expanded fluids and gases (e.g., water vapor and melt) that are injected under pressure into fracture void spaces within fault zones in a gas–solid–liquid system during large earthquakes. I propose that the thermal expansion of water vapor and ultrafine-to fine-grained materials caused by frictional heating in the fault slip zone is the main mechanism responsible for the dramatic increase in pore pressure that results in the dynamic coseismic weakening of faults. • Vein networks of pseudotachylyte (Pt) are indicators of seismic faulting. • Pt veins are sourced from by pulverized ultracataclastic rocks in seismic fault zones. • Thermal pressurization and fluidization occurred in fault zone during seismic faulting. • Thermal expansion of seismic slip zones caused by frictional heating in fault zones. • Thermal expansion is a main mechanism of dynamic coseismic weakening of faults. [ABSTRACT FROM AUTHOR]

The structural plane of a rock mass is the indispensable premise for studying and understanding cataclastic texture rock masses, and it is the main reason for the intense heterogeneity of cataclastic structural rock masses. The plane is also the key to classifying the characteristics of cataclastic texture rock masses and quantifying the degree of fragmentation. In this paper, through a thorough investigation of structural plane characteristics, a statistical analysis of the geometric characteristics of structural planes, a network simulation and an analysis of structural planes, a quantitative description index and a quantitative evaluation index are proposed and analyzed from the "point-pine-plane" perspective. A quantitative description index for trace line node density, trace line segment length and crack surface polygon area are proposed based on the structural characteristics of cataclastic texture rock masses. To evaluate fragmentation degree, a trace line node index, a trace line segment length index and a crack surface polygon index are proposed as quantitative evaluation indices. Results show that the relevant indices can effectively identify the structural characteristics and fragmentation degree of cataclastic rock masses. According to the "classification of rock mass from the structural characteristics and fragment degree" approach, a cataclastic texture rock mass classification method is proposed. Taking the example of the cataclastic texture rock mass in the Daguangbao landslide, the quantitative evaluation index and the cataclastic texture rock mass classification method are applied to effectively solve the problem of quantitative evaluation and classify the cataclastic texture rock. [ABSTRACT FROM AUTHOR]

Abstract Structures, lithofacies and semi-quantitative sedimentological analysis of volcanic debris-avalanche deposits are essential to constrain syn-emplacement processes along avalanche fault zones in the setting of mass-flow runout distances. At a distance of 28 km from the extinct Pichu Pichu compound volcano, we show how internal structures of thrust lobes, faulted as to form horst- and graben-like structures, have recorded the brecciation with granular segregations. Cataclastic gradients have been recognized in more than eleven breccia structures with statistical grain-size parameters, among them fractal D -values between 1.96 and 2.53 related to an extensional fracturing in DADs with fractal D -values between 2 and 2.5 leading to granular disaggregation with fractal D -values between 2.13 and 2.22. Primary fractures related to transport processes and the secondary cataclasis produced during emplacement are quantified as having <50% matrix, while the avalanche transformations into lahar deposits occur with >50% matrix. The hybrid lithofacies in graben-like structures may be the precursory stages of the matrix transformation into lahar deposits. Volcanic debris-avalanche structures of eleven worldwide volcanoes that belong to the Central Andes and the Cascades volcanic arc have been compared using sedimentary and statistical methods (156 sieved samples and Shape Preferred Orientation measured on 30,342 clasts). Median diameter, sorting index, skewness and kurtosis values help differentiate four deposits and processes: (1) the proximal gravitational collapse deposits; (2) the avalanche thrust lobes, located in inverted extensional fault zones, and (3) the hybrid and mixed deposits with polymodal distributions; and (4) the bimodal, transformed matrix with clast sorting. The fractal D -values of avalanche matrix range between 2.3 and 2.7, suggesting that extensional fractures have led to granular disaggregation. From the available statistical dataset, a few equations have been developed that help pointing to a syn-emplacement cataclastic gradient along avalanche fault zone. Three textural classes of avalanche fault zones have been identified based on the ellipse/ a / b values of ~2.14 for the planar collapse in fault zone, 1.75 to 2 for the crushing of volcanic avalanche breccias, and <1.7 due to the thermal effect of clast fragmentation. Inherited clast shapes with a / b = 2.5 and ellipse = 4 suggests a co-evolution of avalanche lithofacies. A sedimentological classification of avalanche fault zones proposed here has been related to the syn-emplacement processes of DAD structural units. As a result, the semi-quantitative texture dataset helps constrain the different stages of avalanche runout and the transformation steps into lahar deposits. Highlights • We study internal structures of the Pichu Pichu thrust lobe in extensional fault. • Cataclastic gradient is correlated to granular segregations in transformed matrix. • Precursory stages of the avalanche transformations include the mixed lithofacies. • We compare Pichu Pichu DAD with avalanche textures of eleven worldwide volcanoes. • Semi-quantitative textural classes of avalanche fault zone are established. [ABSTRACT FROM AUTHOR]

Study on the quality of dam foundation rock mass will help to reasonably select the foundation surface, and provide a scientific basis for engineering design, construction and safe operation. Taking the dam foundation rock mass of Sanhekou reservoir for Hanjiang-to-Weihe river water diversion project as the research object, the rock mass exposed by the dam foundation excavation was re-explored; meanwhile, the weathering characteristics, structural characteristics, relationship between longitudinal wave velocity and deformation modulus of dam foundation rock mass were elaborated comprehensively by using the test of the downhole television, longitudinal wave velocity, deformation modulus with prospecting holes; and the utilization of fault fracture zone and cataclastic rock of the dam foundation was analyzed emphatically, and a detailed engineering geological classification of dam foundation rock mass was discussed. Finally, the practical foundation surface is selected to raise elevation of the dam foundation plane from 501.0 m to 504.5 m, which optimizes the excavation depth of dam foundation, reduces the difficulty of dam foundation treatment and concrete pouring, and saves construction period and project investment. [ABSTRACT FROM AUTHOR]

Hydrosphere interactions and alteration of the terrestrial crust likely played a critical role in shaping Earth's surface, and in promoting prebiotic reactions leading to life, before 4.03 Ga (the Hadean Eon). The identity of aqueously altered material strongly depends on lithospheric cycling of abundant and water-soluble elements such as Si and O. However, direct constraints that define the character of Hadean sedimentary material are absent because samples from this earliest eon are limited to detrital zircons (ZrSiO4). Here we show that concurrent measurements of Si and O isotope ratios in Phanerozoic and detrital pre-3.0 Ga zircon constrain the composition of aqueously altered precursors incorporated into their source melts. Phanerozoic zircon from (S)edimentary-type rocks contain heterogeneous δ18O and δ30Si values consistent with assimilation of metapelitic material, distinct from the isotopic character of zircon from (I)gneous- and (A)norogenic-type rocks. The δ18O values of detrital Archean zircons are heterogeneous, although yield Si isotope compositions like mantle-derived zircon. Hadean crystals yield elevated δ18O values (vs. mantle zircon) and δ30Si values span almost the entire range observed for Phanerozoic samples. Coupled Si and O isotope data represent a constraint on Hadean weathering and sedimentary input into felsic melts including remelting of amphibolites possibly of basaltic origin, and fractional addition of chemical sediments, such as cherts and/or banded iron formations (BIFs) into source melts. That such sedimentary deposits were extensive enough to change the chemical signature of intracrustal melts suggests they may have been a suitable niche for (pre)biotic chemistry as early as 4.1 Ga. [ABSTRACT FROM AUTHOR]

Clusters of cataclastic deformation bands represent potential barriers or baffles to reservoir fluid flow, and their processes of formation remain debated. In this work, we rely on an integrated field study at seven sites to describe the extent of clusters, their morphology and their density of deformation as a function of several parameters: the tectonic loading, the burial depth of deformation, the Andersonian stress regime and the lithology of the sandstone. We perform porosity, sorting and grain shape analyses of the deformed material to improve the understanding of microscopic process of cluster development. In agreement with previous works on cataclastic deformation bands, our results reveal that the tectonic loading constrains the extent and the morphology of the clusters. Extensional tectonics favors the formation in normal-fault Andersonian regime of series of hundreds of meter long, rather thin and dense clusters, forming kilometer long networks associated with faults. We find that the formation of major slip-surfaces (faulting) can occur at any stage of cluster thickening. Contractional tectonics favors the formation of strike-slip clusters of medium-thickness, and more rarely the formation of tens of meter long, low-density, thick thrust clusters. The clusters formed in contractional tectonic settings are sparse. Since 15%–79% of the bands/slip-surface of the clusters have permeabilities close to or lower than 1 × 10 1 mD, and because clusters can have significant dimensions, they may be significant baffles, particularly in extensional tectonics. Our analysis of the porosity and shape evolution of the clasts with increasing deformation corroborates the hypothesis of strain hardening of the band by combined increase of cohesion and friction induced by the cataclasis. We propose that the variability of hardening associated with the variable packing and related cementation in specific parts of the deformed material controls the development and the morphology of the clusters as a function of the tectonic loading. [ABSTRACT FROM AUTHOR]

To explore the mechanical properties of cataclastic rock masses and the laws of their permeability changes under hydraulic pressure, cataclastic rock masses in shattered fault zones are sorted according to their particle size. Rubble is sorted under the same conditions to acquire digital images in sections and extract spatial distribution information. Due to significant numerical differences between rocks and pores in pixel functions and image matrices, MATLAB functions are developed for threshold segmentation. Using linear interpolation, three-dimensional digital analysis models are built. Based on these models, interconnected networks of spatial structures and spatial distribution features of stress, seepage and speed are identified for cataclastic rock masses. The seepage flow of cataclastic rock masses is approximated based on the maximum and minimum particle sizes. Additionally, an experimental study is performed with a seepage tester on cataclastic rock masses. According to the results, the impacts of the particle size on seepage differ significantly under different stress conditions. The seepage flow curve determined from the experiment is within the hydraulic pressure flow scope determined based on the maximum and minimum particle sizes. The seepage is in line with Forchheimer’s equations, but sharply contrasts with the theoretical results of Darcy’s law. This simulation method can be used as a reference for studying seepage-stress coupling of cataclastic rock masses. [ABSTRACT FROM AUTHOR]

Deformation bands have been extensively studied in sandstones, whereas far less is known about bands occurring in porous volcaniclastic rocks. Here we investigate spectacular outcrop exposures of late Miocene tuffaceous rocks in the Coastal Range of Taiwan, which host several deformation band types: (i) disaggregation-dominated, layer-bound, sub-vertically-dipping pure compaction bands (PCB); (ii) cataclastic, layer-bound, reverse-sense compactional shear bands (RCSB); and (iii) non-layer-bound and intensely cataclastic transverse-sense compactional shear bands (TCSB). RCSBs and TCSBs host discrete slip surfaces on individual bands. The bands formed in an overall compressive stress regime related to convergence of the Eurasian and Philippine Sea plates. PCBs and RCSBs formed first, whereas progressive burial caused a shift to a transverse stress state and formation of TCSBs. The occurrence of cataclasis in RCSBs but not PCBs is inferred to be shear-driven, rather than confining-pressure-driven. Our findings suggest that cataclasis in deformation bands in volcaniclastic rocks is bimodal. Shear localization preferentially affects weak glass shards, causing intense comminution of volcanic glass. Feldspar, pyroxene and amphibole phenocrysts are comparatively less crushed, and cataclasis is strongly controlled by mineralogic cleavage planes. We conclude that increasing glass content reduces shear resistance, and that deformation bands in volcaniclastic rocks effectively exhibit a strain-weakening behavior. [ABSTRACT FROM AUTHOR]

The expansion of engineering and development of porous materials for the bio-adsorbents synthesis from agro-waste-derived as superior efficient extractors is a significant economic and environmental breakthrough. Here, a novel spongy mesoporous hybrid silica (SMS-L) was successfully prepared from wheat straw by developed dissolution/precipitation methodology. This manuscript aims to extract/preconcentrate 232Th isotope from Egyptian cataclastic rock (ECR) using SMS and SMS-L bio-adsorbents. The proposed bio-adsorbents/extractors provide high adsorption capacity toward the 232Th isotope ions depending on the pH value of the extraction process. The optimum conditions of leaching (batch procedure), adsorption and elution (batch and permanent-bed columnar procedures) were investigated through a series of practical experiments. The physical parameters like isotherm, kinetic, and thermodynamics were studied. The SMS and SMS-L are considered promising bio-adsorbents for the adsorption/trapping of 232Th isotope from real leach solutions of ECR. These characteristic features may attribute to (i) the recycling and management of sustainable wheat straw wastes, (ii) the low-cost and eco-friendly, (iii) superior adsorption capacity of 232Th isotope, (iv) selective-trapping of 232Th isotope ions among other competitive ions such as Cr3+, Pb2+, Sr2+, Zn2+, Zr4+, Ba2+, Cu2+, Ni2+, V3+ and REEs, and (v) the structural stability of SMS and SMS-L bio-adsorbents even after 10 adsorption-desorption recycles without marked reduction in the Th(IV)-extraction efficacy. This report offers a foundation for additional advancement in clean energy applications. [Display omitted] • Agricultural wheat straw was used to fabricate spongy mesoporous hybrid silica (SMS-L). • SMS-L offered selective thorium (Th) ions recovery adsorbent. • SMS-L bio-adsorbent extract 232Th isotope from Egyptian cataclastic rock (ECR). • The multiple reuse/cycles of SMS-L confirmed its stability and successful design. • ∼87% of Th isotope can be extracted selectively at pH 4 using SMS-L bio-adsorbents. [ABSTRACT FROM AUTHOR]

The objective of this paper is to realise the elastoplastic modelling of the creep behaviour of cataclastic rock under multi-stage deviatoric stress. The multi-stage triaxial creep tests show that the cataclastic rock exhibits pronounced irreversible time-dependent deformations which enlarge with the increase in deviatoric stress. The plastic shearing mechanism of the rock can be identified based on the observation that the rock shows typical plastic strain and large strain rate during the creep tests. Towards this, a unified creep model is developed to describe both the instantaneous and the time-dependent elastoplastic behaviour of the cataclastic rock. The elastoplastic model for describing the instantaneous behaviour is developed based on classic plasticity using a revised Drucker-Prager criterion and a non-associated flow rule, and the time-dependent deformation is described in terms of evolution of microstructure in the context of irreversible thermodynamics. The time-dependent deformation is considered as a macroscopic consequence of progressive degradation of material structure in microscopic scale. Finally, the proposed model is applied to predict the material responses in short-term triaxial compression tests and multi-stage creep tests. Comparisons between experimental and simulated results show that the proposed model is able to describe the main features of the creep behaviours observed in this material. [ABSTRACT FROM AUTHOR]

In this paper, several mechanical deformation curves of limestone are reviewed, and the effects of temperature, confining pressure, and fluid are discussed. Generally, Mohr-Coulomb is used for limestone brittle fracture. The characteristic of low temperature cataclastic flow and the conditions and constitutive equations of intracrystal plastic deformation such as dislocation creep, diffusion creep, and superplastic flow are discussed in detail. Specifically, from the macroscopic and microscopic view, inelastic compression deformation (shear-enhanced compaction) of large porosity limestone is elaborated. Compared with other mechanics models and strength equations, the dual porosity (macroporosity and microporosity) model is superior and more consistent with experimental data. Previous research has suffered from a shortage of high temperature and high pressure limestone research; we propose several suggestions to avoid this problem in the future: (1) fluid-rock interaction research; (2) mutual transition between natural conditions and laboratory research; (3) the uniform strength criterion for shear-enhanced compaction deformation; (4) test equipment; and (5) superplastic flow mechanism research. [ABSTRACT FROM AUTHOR]

In this work we describe the deformation mechanisms and processes that occurred during the evolution of cataclastic deformation bands developed in the feldspar-rich conglomerates of the Rio do Peixe Basin, NE Brazil. We studied bands with different deformation intensities, ranging from single cm-thick tabular bands to more evolved clustering zones. The chemical identification of cataclastic material within deformation bands was performed using compositional mapping in SEM images, EDX and XRD analyses. Deformation processes were identified by microstructural analysis and by the quantification of comminution intensity, performed using digital image processing. The deformation bands are internally non homogeneous and developed during five evolutionary stages: (1) moderate grain size reduction, grain rotation and grain border comminution; (2) intense grain size reduction with preferential feldspar fragmentation; (3) formation of subparallel C-type slip zones; (4) formation of S-type structures, generating S-C-like fabric; and (5) formation of C′-type slip zones, generating well-developed foliation that resembles S-C-C′-type structures in a ductile environment. Such deformation fabric is mostly imparted by the preferential alignment of intensely comminuted feldspar fragments along thin slip zones developed within deformation bands. These processes were purely mechanical (i.e., grain crushing and reorientation). No clays or fluids were involved in such processes. [ABSTRACT FROM AUTHOR]

The impact of lithological heterogeneities on deformation, fluid flow and ore deposition is discussed based on the example of the Lavrion low-angle detachment partly accommodating gravitational collapse of the Hellenides orogenic belt in Greece. The Lavrion peninsula is characterised by a multiphase Pb-Zn-Fe-Cu-Ag ore system with a probable pre-concentration before subduction followed by progressive remobilisation and deposition coeval with the development of a low-angle ductile to brittle shear zone. The mylonitic marble below the detachment shear zone is composed of white layers of pure marble alternating with blue layers containing impurities (SiO 2 , Al 2 O 3 , carbonaceous material). Ductile mylonitic deformation is more pervasive in the less competent impure blue marble. We propose that localised deformation in the impure marble is associated with fluid circulation and dolomitisation, which in turn causes an increase in competence of these layers. Mineralised cataclastic zones, crosscutting the mylonitic fabric, are preferentially localised in the more competent dolomitic layers. Oxygen and carbon isotopic signatures of marble invaded by carbonate replacement deposits during ductile to ductile-brittle deformation are consistent with decarbonation coeval with the invasion of magmatic fluids. Mineralised cataclastic zones reflecting brittle deformation evolve from low 13 C to low 18 O signatures, interpreted as local interaction with carbonaceous material that trends toward the contribution of a surface-derived fluid. These features indicate that the Lavrion area records a complex deposition history influenced by the evolution of fluid reservoirs induced by the thermal and mechanical evolution of the marble nappe stack. Ore remobilisation and deposition associated with the activity of the low-angle detachment is (i) firstly related to the intrusion of the Plaka granodiorite leading to porphyry-type and carbonate replacement mineralisation during ductile-brittle deformation and (ii) then marked by progressive penetration of surface-derived fluids guided by strain localisation in the more competent levels leading to epithermal mineralisation associated with brittle deformation. [ABSTRACT FROM AUTHOR]

The Alpine Fault has a <50 m wide geochemically distinct hanging-wall alteration zone. Using a combination of petrological and cathodoluminescence (CL) microscopy, Energy Dispersive Spectroscopy and X-ray diffraction, we document the habitat and mineralising phases of macro- and micro-fractures within the alteration zone using samples derived from outcrop and the Deep Fault Drilling Project. Veins predominantly contain calcite, chlorite, K-feldspar or muscovite. Gouge-filled fractures are also observed and reflect filling from mechanical wear and chlorite mineralisation. CL imaging suggests that each calcite vein was opened and sealed in one episode, possibly corresponding to a single seismic cycle. The thermal stability of mineralising phases and their mutually cross-cutting relationships indicates a cyclic history of fracture opening and mineralisation that extends throughout the seismogenic zone. Cataclasites contain intragranular veins that are hosted within quartzofeldspathic clasts, as well as veins that cross-cut clasts and the surrounding matrix. Intragranular calcite veins formed prior to or during cataclasis. Cross-cutting veins are interpreted to have formed by fracturing of relatively indurated cataclasites after near-surface slip localisation within the Alpine Fault's principal slip zone gouges (PSZs). These observations clearly demonstrate that shear strain is most localised in the shallowest part of the seismogenic zone. [ABSTRACT FROM AUTHOR]

The Jiaodong peninsula contains the most important concentration of gold deposits in China, which can be divided into Jiaojia-type and Linglong-type deposits based on mineralization style. The former is characterized by disseminated- and stockwork-style mineralization hosted in first-order regional faults, with relatively larger tonnages and lower gold grades. The latter is characterized by massive auriferous quartz veins commonly hosted in subsidiary second- or third-order faults, with smaller tonnage but higher grade orebodies. Despite these differences, both groups of deposits have the same alteration assemblages, mineral paragenesis, element concentrations, and ore-forming ages. The mainly Jiaojia-type Luoshan gold deposit and the mainly Linglong-type Fushan gold deposit are characterized by H-O-S-Pb isotope data that indicate the ore-forming fluids have a dominantly metamorphic source. The fluids were derived during the Yanshanian orogenic event, and were most likely associated with dehydration and decarbonization processes near the top of the subducting paleo-Pacific plate. The Linglong-type ores have relatively lighter calculated δ 18 O compositions (−3.9 to −2.3‰) than the Jiaojia-type ores (0.3–8.0‰), possibly because of a greater degree of mixing with meteoric water. Petrographic, cathodoluminescence, microthermometric, and laser Raman spectroscopic analyses of fluid-inclusion assemblages in quartz from the two types of ores indicate fluids were similar, in both cases characterized by medium–high homogenization temperatures (211–393 °C), significant CO 2 (∼15% mol), minor CH 4 (⩽18% in the carbonic phase), and low salinity (⩽11.2 wt% NaCl eq.). The Linglong-type ores, however, have a wider range of CO 2 and CH 4 concentration and salinity than the Jiaojia-type ores. Fluid immiscibility, occurred in main ore stage of both ore types, with the trapping conditions of 77–185 MPa and 284–328 °C, although the unmixing is more intense and widespread in the Linglong-type ores. Both fluid-wallrock interaction and fluid immiscibility are important gold-deposition processes in the two types, but immiscibility is more important in the Linglong-type ores and that has led to the typical higher gold grade. In general, there is little geochemical differences between the ore-forming fluids for Jiaojia- and Linglong-type gold deposits. Both Jiaojia- and Linglong-type ores can exist in a single deposit and form in the same metallogenic event. The Linglong-type ores developed as more massive veins, because of their location in zones of more extensive extension and they lack significant post-ore cataclastic deformation. [ABSTRACT FROM AUTHOR]

Kinematic compatibility of the western and eastern limbs of the Makarwal Anticline has been studied in the Shinawah and its adjoining area of Takhti-e-Nasrati, District Karak, KPK to understand the propagated structures and general structural model of the area. The study area is tectonically active and observed the deposition of post Pleistocene gravel deposits. In the Shinawah Nala, even younger gravel deposits are present indicating recent to sub-recent tectonic activity. Moreover, the channel avulsion of different nalas in Kurram River also reveals the existence of younger active deformations. Standard procedure has been adopted for the calculation of joint density and their other attitude data. For this purpose, the circle inventory and rectangular method has been espoused. The circle inventory method is valuable where highest numbers of fracture sets are exposed. The obtained data through this could be used for the establishment of their frequency diagrams and statistical density calculations. The shear zones that generally cut across the strata are typical cataclastic strike slip in character showing distinct asymmetric kinematic indicators of redial assemblages (Marwar, 1989). It is observed regionally, where the shear zones cut across each other; evolve a composite geometry of the conjugate joint patterns viewing mesoscopic displacements. Tensional joint sets of orthogonal symmetry are well developed. The pattern of these joint sets is observed systematic in nature and may have evolved in response to the forced folding deformational and uplifting phase of the Makarwal Anticline. This fusion of joints and conjugate fractures is properly penetrated on the strata of Dhok Pathan Formation. The general structural trend of the area is north-south. The younger joints are dipping toward east and crosscutting the older joint sets developed on the eastern limb of Makarwal Anticline. This frontal faulted limb of the Makarwal Anticline i s highly de formdand eroded w h i l e exposing t h e older formations and splays of Surghar Thrust dipping towards west. Thus, we interpret that the origin of the shear zones in the studied area is dynamically related with the neo tectonic of the Makarwal Anticline, while tensional joints are episodically related with the formation and uplifting of the Makarwal Anticline. The synchronous relationship of tensional joints and shear zones further suggests that Makarwal Anticline could be developed as a result of inversion tectonic as positive flower structure under transtensional regime. [ABSTRACT FROM AUTHOR]

In this work, we consider application of an original method for determining the indicators of the tectonic stress fields in the northern Baikit anteclise based on 3D seismic data for further reconstruction of the stress state parameters when analyzing structural maps of seismic horizons and corresponded faults. The stress state parameters are determined by the orientations of the main stress axes and shape of the stress ellipsoid. To calculate the stress state parameters from data on the spatial orientations of faults and slip vectors, we used the algorithms from quasiprimary stress computation methods and cataclastic analysis, implemented in the software products FaultKinWin and StressGeol, respectively. The results of this work show that kinematic characteristics of faults regularly change toward the top of succession and that the stress state parameters are characterized by different values of the Lode-Nadai coefficient. Faults are presented as strike-slip faults with normal or reverse component of displacement. Three stages of formation of the faults are revealed: (1) partial inversion of ancient normal faults, (2) the most intense stage with the predominance of thrust and strike-slip faults at north-northeast orientation of an axis of the main compression, and (3) strike-slip faults at the west-northwest orientation of an axis of the main compression. The second and third stages are pre-Vendian in age and correlate to tectonic events that took place during the evolution of the active southwestern margin of the Siberian Craton. [ABSTRACT FROM AUTHOR]

We have studied pebbles of igneous rocks from the Lower Jurassic sedimentary succession of Hall Island, Franz Josef Land. Pebbles are represented by felsic intrusive and extrusive rocks, often cataclased and greisenized. The U-Pb age of crystallization for zircons of the studied samples yielded the Latest Devonian-Early Carboniferous and Early-Middle Permian ages. In addition, the studied zircons demonstrate a broad scatter of ages, from Middle Paleozoic to Mesozoic, suggesting repeated thermal reworking and metamorphism of granites. It is shown that coeval Late Paleozoic magmatism indicates the similarity of the geological evolution of the northern Barents Sea and the Severnaya Zemlya archipelago. [ABSTRACT FROM AUTHOR]

The present study provides evidence that the NW-SE normal faults in Nubian Sandstone reservoirs (Malha and Naqus formations) are surrounded by damage zones in which the rocks are affected by cataclastic deformation bands and small scale faults. The paleostress analysis of the small faults indicates that σ3 has NE-SW direction while σ1 is sub-vertical. The thickness of the bands is ranging from 3 mm to 1 cm. The density and thickness of the bands increase toward the faults and decrease backward. The deformation bands form two prominent sets. The first set is running in the NW-SE direction parallel to the main faults and dip towards the northeast and southwest, i.e. synthetic and antithetic conjugate sets. The second set has NE-SW direction and dip mainly in the NW in the Malha Formation and in the SE in Naqus Formation. The two sets of deformation bands mutually crosscut each other, suggesting that both sets developed during the same deformation event. The deformation bands are planar features and occur singly or form braided clusters. The microscopic studies indicate that the host rock is mainly quartz arenite and composed of fine to very fine, well sorted quartz grains which weakly fractured and cemented by calcite. The microscopic studies of the bands indicate that they composed of strong grain crushing (cataclasis) and clay minerals. This composition is probably causes reduction of porosity and permeability within the deformation bands. The reservoir rocks in the damage zones of the normal faults are divided into polygonal areas by the deformation bands. [ABSTRACT FROM AUTHOR]

This paper presents the results of reconstruction of the modern tectonic stress field of the northern part of the Kuril-Okhotsk region prior to the May 24, 2013 deep-focus earthquake. This earthquake is the strongest deep-focus earthquake not only in the Okhotsk region but also in the world over the entire period of seismic observations. The tectonic stress field is reconstructed using the method of cataclastic analysis (MCA) of the earthquake source mechanism data. New data on the depth variations of regional tectonic stress field are obtained. [ABSTRACT FROM AUTHOR]

The origin of amphibolite-facies aluminous gneiss from the gold-hosting Neoarchean Storø Supracrustal Belt in the Nuuk region of southern West Greenland is investigated in this study. An improved understanding of the formation of such aluminous gneiss has implications for genetic models (epithermal vs. orogenic style) for a local gold occurrence, which is hosted by sheeted quartz-veins within amphibolite in the hanging wall adjacent to the aluminous gneiss on the island of Storø. The aluminous gneiss mainly consists of garnet, plagioclase, sillimanite, quartz and biotite, which suggest a pelitic protolith. However, it has previously been postulated that the aluminous gneiss represents a hydrothermal alteration product, formed by leaching of a mafic precursor that was subsequently transformed to the current mineral assemblage during later regional metamorphism. In support of this hypothesis are decimeter-scale relicts of amphibolite, found within the decameter-wide aluminous gneiss, that share similar ratios of commonly fluid immobile elements, such as Al, Ti, Zr, Hf, Nb and Lu. Metasedimentary rocks sensu stricto are also present within the Storø Supracrustal Belt. These mostly comprise biotite schist with a similar mineralogy as the aluminous gneiss, and are located adjacent to the latter in the footwall. The aluminous gneiss has high bulk-rock Al 2 O 3 contents and low SiO 2 relative to the biotite schist, which is less aluminous, has higher SiO 2 , and is more potassic than the aluminous gneiss. The immobile element ratios of the biotite schist are significantly different from those of the amphibolite and the aluminous gneiss. Additionally, the biotite schist yields distinct detrital zircon age populations, whereas only metamorphic zircon has been found in the aluminous gneiss and amphibolite. In the present study, the isocon method was applied to provide mass balance constraints on the alteration of basalt to the protolith of the aluminous gneiss prior to regional metamorphism of the entire Storø supracrustal sequence. Accepting minor fractionation among otherwise immobile elements, an error of at least ± 20% is estimated for the isocon mass-balance model. The results indicate that all major elements, except for K 2 O were leached from the basaltic precursor, resulting in a net mass loss ranging from − 20 to − 40 wt.%. However, despite the similar trace element patterns and ratios of the aluminous gneiss and the adjacent amphibolite, in situ alteration or weathering of the basaltic precursor rock is not possible given the small, but persistent, fractionation among fluid immobile elements, due to the unusual accumulation of Cr, U, Ni and Th, as well as the observed modal layering within the aluminous gneiss. Instead, this points to physical transport during sedimentary reworking of a mafic protolith and potentially the addition of redox-sensitive elements such as U and Cr from the water column, and therefore suggest that this aluminous gneiss simply represents a metasediment with a mafic provenance. The implication of this study for gold exploration within the Archean supracrustal belts of the SW Greenland is that aluminous gneiss is unlikely to represent an indicator of acidic hydrothermal alteration as previously postulated. Instead, aluminous gneisses within these supracrustal belts are likely of sedimentary origin and may provide a venue to further understand the exogenous environments of the Archean Earth, and thus further geochemical studies of such rocks are recommended in order to place constraints on the composition of the hydrosphere at that time. [ABSTRACT FROM AUTHOR]

The core of the Tauern tectonic window (Eastern Alps) consists of pre-Alpine granitoids (∼295 Ma) variably deformed during Alpine (∼30 Ma) amphibolite-facies metamorphism. Episyenites occur as local alteration haloes (as wide as a few meters) surrounding steeply dipping, strike-slip faults, with offsets <1 m, overprinting the metamorphic deformation structures. Episyenites are well recognizable in the field by their macroscopic porosity, ranging between 25–35 vol% (meta-granodiorite) and 13% (meta-aplite), mainly derived from dissolution of quartz. Glacier-polished outcrops allow the detailed investigation of the relationships between the episyenites and the structure of the associated faults. Field mapping indicates that episyenites: (i) are spatially linked to pre-existing faults and statically overprinted these structures; (ii) are discontinuous along faults; (iii) have a thickness (of as much as a few meters) that does not correlate with either the amount of slip along the pre-existing faults or the spatial density of the fracture network; (iv) developed with a similar extent in rocks with conspicuous variations of the original quartz grain size and structure. The studied outcrop includes a relatively large volume of episyenite associated with faults. However, despite the pervasiveness of faulting, episyenites are rare in the Tauern meta-granitoids. This localized occurrence of episyenite is inferred to represent a section of a vertical pipe structure exploiting a portion of the fault network. Our study indicates that the location and the extent of episyenite alteration cannot be simply predicted from the geometry and the fracturing patterns of the pre-existing cataclastic faults. Quartz dissolution during episyenitization was accompanied and/or followed by: (i) pervasive substitution of oligoclase and biotite/chlorite of the meta-granodiorite by albite and vermicular chlorite, respectively; and (ii) precipitation of adularia, albite, anatase, calcite, hematite and zeolites within pores. Isotopic data from the calcite filling of the pores suggest a surficial source of fluids associated with this calcite precipitation (δ 18 O (SMOW) ≈−2‰ and −3‰). In contrast, fluids syn-kinematic with the older episodes of fluid-rock interaction, during faulting and ductile shearing, had a deeper origin (δ 18 O (SMOW) ≈8–9‰). In the structural history, episyenite marks the transition from diffuse deformation to almost rigid-block behaviour of the Tauern tectonic unit, during progressive exhumation and cooling (at T <300 °C). This transition reflects the transfer of deformation to localized slip along the Brenner extensional detachment. [ABSTRACT FROM AUTHOR]

The earth's gravity changes are attributed to the redistribution of masses within and/or on the surface of the earth, which are due to the frictional sliding, tensile cracking and/or cataclastic flow of rocks along the faults and detectable by earthquake events. Inversely, the gravity changes are useful to describe the earthquake seismicity over the active orogenic belts. The time variable gravimetric data are hardly available to the public domain. However, Gravity Recovery and Climatic Experiment (GRACE) is the only satellite mission dedicated to model the variation of the gravity field and an available source to the science community. Here, we have tried to envisage gravity changes in terms of gravity anomaly (Δg), geoid ( N ) and the gravity gradients over the Indo-Pak plate with emphasis upon Kashmir earthquake of October 2005. For this purpose, we engaged the spherical harmonic coefficients of monthly gravity solutions from the GRACE satellite mission, which have good coverage over the entire globe with unprecedented accuracy. We have analysed numerically the solutions after removing the hydrological signals, during August to November 2005, in terms of corresponding monthly differentials of gravity anomaly, geoid and the gradients. The regional structures like Main Mantle Thrust (MMT), Main Karakoram Thrust (MKT), Herat and Chaman faults are in closed association with topography and with gravity parameters from the GRACE gravimetry and EGM2008 model. The monthly differentials of these quantities indicate the stress accumulation in the northeast direction in the study area. Our numerical results show that the horizontal gravity gradients seem to be in good agreement with tectonic boundaries and differentials of the gravitational elements are subtle to the redistribution of rock masses and topography caused by 2005 Kashmir earthquake. Moreover, the gradients are rather more helpful for extracting the coseismic gravity signatures caused by seismicity over the area. Higher positive values of gravity components having higher terrain elevations are more vulnerable to the seismicity and lower risk of diastrophism otherwise. [ABSTRACT FROM AUTHOR]

The article focuses on a study regarding time-dependent behavior of cataclastic rocks. It mentions the use of cataclastic rocks as host rock medium in various applications of hydraulic engineering, such as tunnel support design, dam foundation stability and hydraulic fracturing. It also mentions the characteristics of cataclastic rocks including loose textural structure, poorly cemented contact surface and high moisture content.

We investigated the potential of common crystalline rocks to facilitate the geochemical evolution of continental basement brines and to serve as a metal source for hydrothermal ore deposits. We performed leaching experiments on typical crystalline basement rocks (granite and gneiss), a redbed sandstone and their mineral separates (feldspar, quartz and biotite) at variable T (25, 180, 275 and 350 °C), P (ambient pressure, 0.9, 1.4 and 1.9 kbar), grain-size fractions (< 0.01 mm, 0.063–0.125 and 2–4 mm) and variable fluid/rock ratios (10 to 1.1) with ultrapure water and 25 wt.% NaCl solution as solvents. The modification of the fluid chemistry during water–rock interaction strongly depends on grain-size: leachates (using pure H 2 O) of fine-grained rock powders have lower Na/Cl and Cl/Br ratios but much higher chlorinities (by a factor of up to 40) compared to leachates from coarse-grained rock powders. The Cl/Br ratios of all leachates are lower than that of their respective whole-rocks. Smaller grain-sizes of the starting materials yield element ratios (Cl/Br and Na/Cl) similar to those found in natural fluids, emphasizing the influence of cataclastic deformation on the fluid chemistry of crustal fluids. During our leaching experiments, Pb, Zn, Cu and W are released by felsic minerals, while biotite alteration releases Ni, As and additional Zn and Cu. Our experiments confirm that crystalline rocks may serve as metal source for hydrothermal ore deposits. Short-term water–rock interactions along cataclastic fault zones in the brittle crust may influence the geochemical evolution of upper crustal fluids. This is further suggested by low F/Cl and Cl/Br ratios in some of the leachates being very similar to halogen systematics in natural fluid samples. [ABSTRACT FROM AUTHOR]

Paleostress variations and microstructural imprints of a subducted carbonate slab record changes in mechanical strength during its exhumation. The slab studied here forms part of the high-P Samaná Terrane located on the north-eastern margin of the Hispaniola Island. Cold-cathodoluminescence images reveal relict cataclastic fabrics within the highest-pressure marbles of the Punta Balandra and Santa Bárbara Schists structural units, formed in the early stages of exhumation at P-T conditions ca. 2.0 GPa − 500 °C. Cataclastic flow was triggered after a moderate increase of water content (1.2% < w.t. H 2 O < 1.8%). Accordingly, grain sizes larger than equivalent radius r i = 40 μm preserve distribution of power law type with fractal dimensions D 2 = 2.43 in Punta Balandra unit and D 2 = 2.72 in Santa Bárbara unit. After cataclastic flow, the stress dropped and grain comminution conducted the marbles to the dissolution-precipitation domain. Then, as exhumation progressed, the effective stress increased and calcite intracrystalline plasticity process dominated. Calcite-twinning incidence and recrystallized grain-size indicate maximum paleostress ca. 350 MPa and mean flow paleostress ≈ 130 MPa. SEM-EBSD analyses show similar weak type- c calcite fabrics in all high-P carbonate units, even though they record different metamorphic P peak. Therefore, intracrystalline plasticity was probably dominant during the development of the final tectonic fabric. Finer grain-size distributions are out of fractal range, with D 1 < 1, because of the further superposed deformation. Most of the data are consistent with an initial forced exhumation model of the carbonate slab in a brittle-ductile rheology of the confined plate interface. [ABSTRACT FROM AUTHOR]

This study presents a comparative, field-based hydrogeological characterization of exhumed, inactive fault zones in low-porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic importance supplying 60 % of the drinking water of Austria's capital, Vienna. Cataclastic rocks and sheared, strongly cemented breccias form low-permeability (<1 mD) domains along faults. Fractured rocks with fracture densities varying by a factor of 10 and fracture porosities varying by a factor of 3, and dilation breccias with average porosities >3 % and permeabilities >1,000 mD form high-permeability domains. With respect to fault-zone architecture and rock content, which is demonstrated to be different for dolostone and limestone, four types of faults are presented. Faults with single-stranded minor fault cores, faults with single-stranded permeable fault cores, and faults with multiple-stranded fault cores are seen as conduits. Faults with single-stranded impermeable fault cores are seen as conduit-barrier systems. Karstic carbonate dissolution occurs along fault cores in limestones and, to a lesser degree, dolostones and creates superposed high-permeability conduits. On a regional scale, faults of a particular deformation event have to be viewed as forming a network of flow conduits directing recharge more or less rapidly towards the water table and the springs. Sections of impermeable fault cores only very locally have the potential to create barriers. [ABSTRACT FROM AUTHOR]

Paleozoic and Mesozoic stratigraphic sequences in the Puerto Libertad area, NW Sonora, Mexico, are intruded by Laramide granitic plutons with dominantly alkaline affinity. We conducted a petrogenetic study of these bodies across a north-south 35 km long transect at oriented NW-SE which includes the Sierra Picú (SP), El Destierro (ED), Sierra Tordilla (ST) and Sierra Los Mochos (SLM). The intrusive bodies display abundant Mafic Microgranular Enclaves (MME) and are intruded by aplitic and pegmatitic dike swarms. U/Pb zircon dates of the intrusive rocks yield crystallization ages between 71.9 and 74.9 Ma. Granodioritic and mozogranitic rocks dominate the SP and ED, while syenogranitic rocks dominate the ST and SLM regions. In addition, these rocks show notable effects, by normal and listric faults which includes cataclastic rocks. Geothermobarometry data from amphiboles and plagioclase of the granodiorites suggest that the temperatures and pressures reached 711–740 °C and 1.67–2.43 kb. respectively, and were emplaced at depths between ∼5 and 6 km. Geochemically, this magmatism shows a relatively high silica content (56–75 wt%), values of Sr/Y = 29–50, La/Yb = 26–39, Sr up to 600 ppm and Ba up to 1400 ppm and depleted in highfield strength elements. Collectively these geochemical traits accentuate the adakite signature of these rocks. This work raises the current problems related to the petrogenetic and tectonic aspects for the generation of calc-alkaline and adakitic magmas while proposing ternary discrimination diagrams to aid in the discrimination from classic calk-alkaline, adakites and adakitic affinity magmatism. • Geochronology analyses from intrusives yield crystallization ages between 71.9 and 74.9 Ma. • Geothermobarometry show temperatures and pressures reached 711–740 °C and 1.67–2.43 kb. • Northern localities show adakitic signatures while Sierra Los Mochos show adakitic affinity. • We propose discrimination diagrams between calc-alkaline, adakites and adakitic affinity magmas. [ABSTRACT FROM AUTHOR]

Fault rocks in the brittle regime are often the result of large-displacement shearing. Traditional direct shear tests that perform small displacements can only study one episode of the whole faulting process. Ring shear apparatuses that can achieve large-displacement shearing are mostly used to study incohesive soil or friction granular materials. The objective of this paper is to study the brittle cataclastic process of fault rocks from the damage of intact rock to the frictional movement of the incohesive cataclastic rocks. A large-displacement direct shear model with a constant contact area of fault walls based on the particle-based discrete element method is proposed to simulate the structural evolution and mechanical behavior of dry brittle fault rocks. The results show that the crushing and rounding of irregular fragments are responsible for the reduction in the friction coefficient. The sharp fall is due to the crushing of rock fragments, while a moderate decline indicates grain rotation in the postpeak stress-displacement curve. This model helps to understand the cataclasis of brittle fault rocks. • A large displacement direct shear model with constant shear surface is proposed. • The structural evolution of the brittle shear zone of the rock was recorded. • Crushing and rounding of irregular rock fragments reduces friction angle. • The sharp drop in stress indicates fragments crush. • The moderate decrease in stress indicates grains rotation. [ABSTRACT FROM AUTHOR]

The macroscopic description of deformation and fluid flow in mudrocks can be improved by a better understanding of microphysical deformation mechanisms. Here we use a combination of Scanning Electron Microscopy (SEM) and Broad Ion Beam (BIB) polishing to study the evolution of micro structure in samples of Callovo-Oxfordian Clay that were previously tested in the lab. Digital Image Correlation (DIC) enabled for the measurement of strain fields in the specimens, which were used as a guide to select regions in the sample for BIB-SEM analysis. Microstructures show evidence for dominantly cataclastic mechanisms (intergranular, transgranular, intragranular cracking, grain rotation, clay particle bending) down to nm- scale. At low strain, the dilatant fabric contains individually recognizable open fractures, while at high strain the reworked clay gouge contains broken non-clay grains, with a clear change towards smaller pores than the undeformed material and corresponding resealing of initial fracture porosity. This study might provide a first step towards a micro scale basis for constitutive models of deformation and fluid flow in cemented mudstones. [ABSTRACT FROM AUTHOR]

The Alpine nappe stack in the Penninic-Austroalpine boundary zone in the Rätikon (Austria) contains a 4×1 km tectonic sliver of meta-diorite, known as the Schwarzhorn Amphibolite. It was deformed and metamorphosed in the amphibolite facies and is unconformably overlain by unmetamorphic Lower Triassic sandstone, indicating pre-Triassic metamorphism. Cataclastic deformation and brecciation of the amphibolite is related to normal faulting and block tilting during Jurassic rifting. Zircon dating of the Schwarzhorn Amphibolite using LA-ICP-MS gave a U-Pb age of 529+9/--8 Ma, interpreted as the crystallization age of the protolith. Geochemical characteristics indicate formation of the magmatic protolith in a supra-subduction zone setting. The Cambrian protolith age identifies the Schwarzhorn Amphibolite as a pre-Variscan element within the Austroalpine basement. Similar calc-alkaline igneous rocks of Late Neoproterozoic to Early Cambrian age are found in the Upper Austroalpine Silvretta Nappe nearby and in several other Variscan basement units of the Alps, interpreted to have formed in a peri-Gondwanan active-margin or island-arc setting. [ABSTRACT FROM AUTHOR]

Cataclastic deformation bands on the Waterpocket Fold in southern Utah contain cross-cutting joints that terminate at the contacts between the deformation bands and surrounding sandstone. The mechanical contrast between sandstone host rock and stronger deformation bands is analogous to inter-bedded weak and strong layers in a sedimentary sequence, a situation known to result in joints preferentially forming in the stronger layers with joints perpendicular to layer boundaries. Deformation bands in the field area represent conjugate strike-slip shear zones, many with internal Riedel shear geometry, creating a three-dimensional network of mechanically strong zones in variable orientations. Joint attitudes were found to vary systematically as a function of deformation band strike, and the angle between each deformation band and its associated joints is perpendicular to neither the deformation band nor the far-field extension direction. Field observations are confirmed by 2D finite element models showing that local stress reorientation at boundaries between layers affects the mechanics of jointing. The stiffness contrast results in conditions for initiating joints contained in the deformation band, and also results in variable joint orientations in deformation bands with strike orientations oblique to the far-field extension direction. A higher stiffness contrast results in a greater angle between deformation band strike and band-contained joint strike. [ABSTRACT FROM AUTHOR]

Shatter cones are one of the most widely recognized pieces of evidence for meteorite impact events on Earth, but the process responsible for their formation is still debated. Evidence of melting on shatter cone surfaces has been rarely reported in the literature from terrestrial impact craters but has been recently observed in impact experiments. Although several models for shatter cones formation have been proposed, so far, no one can explain all the observed features. Shatter cones' from the Vista Alegre impact structure, Brazil, formed in fine-grained basalt of the Jurassic-Cretaceous Serra Geral Formation (Paraná large igneous province). A continuous quenched melt film, consisting of a crystalline phase, mica, and amorphous material, decorates the striated surface. Ultracataclasites, containing subrounded pyroxene clasts in an ultrafine-grained matrix, occur subparallel to the striated surface. Several techniques were applied to characterize the crystalline phase in the melt, including Raman spectroscopy and transmission electron microscopy. Results are not consistent with any known mineral, but they do suggest a possible rare or new type of clinopyroxene. This peculiar evidence of melting and cataclasis in relation with shatter cone surfaces is interpreted as the result of tensile fracturing at the tip of a fast propagating shock-induced rupture, which led to the formation of shatter cones at the tail of the shock front, likely during the early stage of the impact events. [ABSTRACT FROM AUTHOR]