Cataclastic Research Articles

In-site Investigation of Rock Mass Structure Effect on Tunnel Smooth Blasting Quality

Smooth blasting controls tunnel excavation contours and rock stability; however, it can lead to overbreaks and underbreaks due to rock mass anisotropy. Studying the Zigaojian tunnel of the Hangzhou-Huangshan Expressway, this research examined the effect of rock mass structure on smooth blasting quality. Four rock mass structure types–massive, layered, and cataclastic–were determined through manual measurements, three-dimensional scanning, point loading tests, and wave velocity measurements. The blasting overbreak and underbreak of the tunnel section were measured using a tunnel section laser distance measuring instrument, and the relationship between the blasting overbreak and rock mass structure type, surrounding rock grading, structural plane spacing, structural plane number, uniaxial compressive strength, and density was studied using multiple regression analysis. The results show that the overbreak area and maximum overbreak increase as the integrity of massive, massive, layered, and cataclastic rock masses decreases. The intersection of the rock mass structural plane and tunnel section was overbroken. The overbreak is positively correlated with the rock structure type, surrounding rock grading, and structural plane number and negatively correlated with the uniaxial compressive strength, density, and structural plane spacing. The results of this study can provide a reference for smooth blasting in similar projects.

The Effect of Excavation Disturbance on the Stability of Bedding Cataclastic Rock Mass High Slope Containing Multimuddy Interlayers

In China, slope engineering occasionally faces landslides in rocky slopes containing muddy interlayers, primarily triggered by excavation activities. These incidents lead to considerable human casualties and substantial economic losses. However, existing studies predominantly concentrate on the excavation-induced impacts on the stability of rocky slopes characterized by single-layered soft and weak interlayers. Conversely, reports on how excavation influences the stability of bedding cataclastic rock mass high slope containing multimuddy interlayers remain notably absent in the literature. Moreover, unloading due to excavation can swiftly compromise the mechanical integrity and overall quality of the rock mass, consequently impacting the stability of slopes postexcavation. Therefore, this paper modeled the unstable slope excavated at a waste incineration power plant in Yuxi, Yunnan, using the finite element strength reduction method. This approach was employed to comprehensively simulate the entire process of artificial multilevel excavation in a bedding cataclastic rock mass high slope containing multimuddy interlayers. This study investigated the impact of multilevel artificial excavation on slope stability by thoroughly considering factors including alterations in slope morphology, unloading effects, and the degradation of geotechnical parameters. The research yielded the subsequent conclusions. Multimuddy interlayers were the key to the slope’s instability. For slopes subjected to such multilevel excavation, efforts were made to minimize the exposure of muddy interlayers. Slopes above exposed muddy interlayers did not require additional support, while those below needed prioritized reinforcement. The likely instability mode of the actual slope was local destabilization leading to landslides. Furthermore, when using numerical simulation methods to study the impact of excavation disturbances on the stability of such slopes, it was necessary to consider the deterioration of geotechnical parameters to obtain results more reflective of actual conditions. These research findings provided valuable theoretical and empirical support for studies on similar excavated slopes.

Reconstructing the stratigraphy and structure of the Alaşehir Graben (Western Anatolia): Evidence for a high-angle origin of the Alaşehir detachment fault and layer-parallel shortening during the Miocene time

Western Anatolia is a well-known continental extension province in the world. The most distinctive structural elements of the region are E-W trending grabens. The Alaşehir Graben forms the boundary between the northern and central parts of the Menderes Massif. It trends E-W from Ahmetli to Turgutlu and NW-SE from Salihli to Alaşehir. This paper documents the outcomes of fieldwork along the southern margin of the Alaşehir Graben between the Salihli and Alaşehir areas.
 
 The tectonostratigraphy of the southern margin of the Alaşehir Graben is divided into the footwall and hanging wall of the Alaşehir detachment fault. The footwall comprises the Bayındır and Bozdağ Nappes and the syn-extensional Salihli granitoid intruding the Bayındır Nappe. The hanging wall consists of the Çine Nappe and Neogene-Quaternary sedimentary rocks, and Miocene fills tectonically overlying the Çine Nappe, which is above the Alaşehir detachment fault in the Alaşehir area.
 
 Structural data show three types of master fault sets, including (i) the low-angle Alaşehir detachment fault, which is composed of cataclastic rocks; (ii) low-angle normal faults, which are devoid of any cataclastic rocks; and (iii) Plio-Quaternary high-angle normal faults cutting them. Two different low-angle normal faults were coeval and active during the Miocene, and low-angle normal faults were synthetic and antithetic faults of the Alaşehir detachment fault. Their initial position was high-angle and the original position had 55°-75° dip during the Miocene. In the Salihli and Alaşehir segments, several major fold geometries are defined in the footwall and hanging wall of the Alaşehir detachment fault. The fold axis is NE-trending and plunges mainly northeast in the Salihli segment in the footwall of the Alaşehir detachment fault. The other is ~ E–W-trending and plunges mainly west in the Alaşehir segment in the footwall and hanging wall of the Alaşehir detachment fault. They are associated with extensional structures formed by layer-parallel shortening during the Miocene. The Alaşehir detachment fault, as indicated by the difference in fold axes between the Salihli and Alaşehir segments, was cut and back-rotated by Plio-Quaternary high-angle normal faults and tilted to the south.

An Investigation on Stress States of the Cataclastic Rock Specimen under Confined Compression Based on Modified Thick-walled Cylinder Model

In high in-situ stress zones, cataclastic rocks have exerted a significant influence on the stability of engineering structures. However, the mechanical properties of cataclastic rocks can not be accurately studied due to difficulties in sampling and laboratory testing. In this paper, laterally confined compression tests for specimens that were obtained by the developed in-situ sampling devices were performed to investigate the stress states. A modified thick-walled cylinder model considering axial shear stress was introduced. The interaction mechanics model for a compressed sample and an equivalent single-layer cylinder was established. Based on the principle of elasticity, the laterally confined stress, the axial shear stress, and the axial stress of the sample were derived and obtained. Moreover, the effects of mechanical and geometric parameters of the equivalent cylinder on the force condition of the specimen were analyzed. The results show that the confined stress is positively correlated with the equivalent elastic modulus and the geometric factor. Therefore, the confined stress can be strengthened by increasing the elastic modulus, alternatively, increasing the outer diameter and decreasing the inner diameter. However, the axial stress is little affected by the equivalent elastic modulus and the geometric factor and is not affected by the equivalent Poisson's ratio. As the distance from the center height increases, the axial stress decreases linearly and the difference in axial stress becomes larger considering axial shear stress and ignoring axial shear stress.

Research on Deformation Failure Mechanism and Stability of Bedding Cataclastic Rock Slope Containing Multi-Muddy Interlayers

Based on the excavated slope of a waste incineration power plant in Yuxi, Yunnan Province, China, the finite element strength reduction method was used to investigate the variation rules of the safety factor, displacement, and deformation of the bedding cataclastic rock slope containing multi-muddy interlayers under the different conditions of number of muddy interlayers n, inclination angle θ, cohesion c, and angle of internal friction φ. Moreover, the deformation failure mechanism and stability of bedding cataclastic rock slope containing multi-muddy interlayers were revealed. The results showed that, as n increased, the maximum horizontal displacement of the slope increased, the factor of safety decreased, and the key influence on the stability of the slope was the muddy interlayers through the toe of the slope. As θ increased, the horizontal displacement of the slope first increased, then decreased, and then increased again, the safety factor first decreased, then increased, and then decreased again, and the stability of the upright laminar slope was slightly larger than that of the horizontal laminar slope. When the slope angle β was 45°, with the increase in θ, the failure mechanism of the slope manifested as a compression-shear failure, traction-sliding failure, traction-sliding-bending-shear failure, flexural deformation, and bending-buckling-collapse failure in sequence. As c increased, the slope evolved from traction-sliding failure to traction-sliding-bending-shear failure; the stability of the slope increased as c and φ increased.

Development mechanism of metamorphic fractured reservoirs in the Bozhong area, Bohai Bay Basin: Implications from tectonic and magmatic hydrothermal activities

The BZ19-6 condensate gas field is the largest metamorphic gas field of the Bohai Bay Basin in China and contains typical fractured reservoirs within the inner parts of an Archean metamorphic buried hill. However, the mechanisms driving its creation and evolution are not well explored. Based on core and sidewall samples, thin sections, X-ray diffraction (XRD) analysis, U–Pb age dating, fluid inclusions, and imaging logging and seismic data, the lithologies, mineral contents and reservoir characteristics of the inner parts of a metamorphic buried hill were evaluated and then the main factors controlling the fractured reservoir were further explored in the Bozhong area. The results show that the lithology mainly includes granitic gneiss, cataclastic rocks and Mesozoic intrusions, among which the granitic gneiss is widely distributed and contains a large number of light-colored minerals. The reservoir spaces are mainly composed of tectonic fractures (TFs), cleavage fractures (CFs), introduced fractures (IFs) and dissolved pores (DPs). Numerous tectonic fractures provide the main reservoir spaces and can be divided into two groups, namely those with nearly WE- and NS-oriented strikes, which are closely related to the stress fields produced by Indosinian and Yanshan movements, respectively. IFs and DPs were developed by magmatic activities, which occurred during the Mesozoic, while magmatic hydrothermal fluid had an obvious negative impact on reservoir quality, resulting in fracture fillings with minerals such as ankerite and calcite. In this study area, reservoir spaces underwent various changes, from creation to development and from filling to dissolution. Finally, we proposed an integrated reservoir model to describe the distribution and evolution of high-quality reservoirs. This study explores the formation mechanisms of fractured reservoirs within metamorphic rocks and makes practical contributions to oil and gas exploration of buried hills.

Experimental study on strength and failure characteristics of sandstone rock mass with complex cataclastic structure using 3D printing models

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.

A novel, spongy mesoporous hybrid bio-adsorbents derived from agricultural waste for highly selective thorium recovery

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.

Influencing factors, deformation mechanism and failure process prediction for reservoir rock landslides: Tanjiahe landslide, three gorges reservoir area

Compared with terrestrial rock landslides, reservoir rock landslides are also affected by the rise and fall of the reservoir water level, and these landslides are more threatening. High-speed debris flows may form once they lose stability, and once they enter the water a surge is formed. This endangers the safe operation of reservoirs. This study explored the deformation characteristics and influencing factors of the Tanjiahe reservoir rock landslide in the Three Gorges Reservoir using field investigations, GPS surface displacement monitoring, and groundwater level monitoring. The discrete element system MatDEM was used to simulate failure motion, and predict the hazard area affected by the Tanjiahe landslide. The results show that within the reservoir water variation section (145–175 m), the Tanjiahe landslide mass was composed of surface soil (156–175 m) with low permeability and deep cataclastic rock (145–156 m) with high permeability. Due to the difference in permeability between the deep and surface layers, the response of landslide deformation to water level rise is not obvious. The high-level (175 m) operation of the reservoir and the decline in the reservoir water level (175–145 m) are key factors affecting the landslide deformation. Rainfall had a positive effect on landslide deformation. Under their combined action, the stability of the front gentle anti-sliding section of the landslide decreases, and the displacement of the middle and rear steeper sliding section increases under the driving force, which may lead to slope failure. The simulation results show that the upper part of the Tanjiahe landslide slides first and pushes the lower part to move, which is a typical of thrust load-caused failure. The speed of the sliding mass has three stages: rapid rise, rapid decline, and slow decline. The higher the slope angle, the higher the acceleration of the sliding mass in the direction parallel to the slope surface, the higher the speed peak value and the faster the sliding mass speed reaches the peak value. During the failure process, energy is transferred between sliding mass through collisions. Landslides can easily lead to debris flow. The maximum height of the first wave generated when the debris flow entered the water is 5.95 m, and the wave height that propagated to the opposite bank is 3.09 m. The landslide-induced waves propagated along the reservoir area for 30 km.

Petrogenesis and geodynamic implications of the Late Cretaceous granitoids in Puerto Libertad, Sonora, México: Insights into geochemical signatures of adakites, adakitic affinity and calc-alkaline rocks in NW Mexico

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.

Brittle cataclastic process of fault rocks based on a large-displacement direct shear model realized with DEM

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.

Structural Characteristics of Regenerated Roof and Distribution Law of Overburden Porosity in Downward Mining of a Bifurcated Coal Seam

During downward mining of a bifurcated coal seam, the roof of the lower coal seam is relatively broken and difficult to control due to the mining influence of the upper coal seam. Roof accidents occur frequently during mining of the lower coal seam, reducing mining efficiency. How to ensure safe and efficient mining of the lower coal seam is a significant issue. In this paper, overlying strata migration and fracture characteristics of the lower coal seam, the structure and stability of the regenerated roof, and porosity and permeability characteristics of the overlying strata under the mining influence of the upper coal seam are studied by using similar simulation tests. Results show that the overburden structure of the lower coal seam is altered due to the mining influence of the upper coal seam, and the regenerated roof of the lower coal seam is divided into three structural types from top to bottom, namely: intact rock mass+block fracture rock mass+loose rock mass (type I structure); intact rock mass+block fracture rock mass+loose rock mass+cataclastic rock mass (type II structure); and intact rock mass+block fracture rock mass+loose rock mass+cataclastic rock mass+slab-rent rock mass (type III structure). The stability of each type of rock mass structure is evaluated, and the stability of three types of rock mass structures is III > II > I. The overburden porosity and slurry permeability coefficient are relatively large at the cutting hole and stopping line. The porosity of the caving zone within 70 m of the cut hole and stopping line is greater than 5%, and the permeability coefficient is greater than 0.1 m/s. Based on differences in the surrounding rock porosity and permeability characteristics, the grouting difficulty of overburden is divided into three types of areas: extremely easy grouting areas, easy grouting areas, and difficult grouting areas. The results of this paper can provide reference for the stability evaluation of the regenerated roof and the selection of grouting treatment parameters for the broken roof under similar conditions.

Natural Radionuclide Levels and Radiological Hazards of Khour Abalea Mineralized Pegmatites, Southeastern Desert, Egypt

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.

Drill core structural analysis and extensional-contractional controls on the sulfide mineralization at the Ambrosia Sul zinc deposit, Vazante group, Western São Francisco craton, Brazil

The Ambrósia Sul Zn-(Pb) sulfide deposit is located in the southern section of the Vazante Group, which is the border area between the Brasília belt and the southwestern edge of the São Francisco craton. This region is characterized by a typical karst environment in a tropical climate that is commonly represented by the intense development of thick and uneven soil cover, which hinders structural geologic mapping. A survey with oriented core samples allowed a full structural investigation and description of structures such as faults, fractures, veins, bedding, folds, foliations, and lineations. The structural analysis suggests an extensional phase with down block in the west, during which normal faults and high-angle veins were generated, followed by a contractional phase associated with the reactivation of bedding planes, the nucleation of reverse faults and low-angle veins, and east-vergent folding. The zinc sulfide ore bodies are preferentially hosted in high-angle veins and in cataclastic rocks generated during the extension. Low-angle veins, rarely mineralized with Zn, cut the high-angle veins, suggesting that the mineralization event lasted even during the tectonic inversion phase. The regional context indicates that the Ambrósia Sul deposit formed in the bulge region of the foreland basin and that it was affected first by an extensional phase during its nucleation and subsequently by a compressive phase with the advancement of thrusting in the Brasília belt to the east.

Physical and chemical processes of Abu Rusheid cataclastic rocks for recovering niobium, zirconium, and uranium compounds

Physical and chemical processes of Abu Rusheid cataclastic rocks for recovering niobium, zirconium, and uranium compounds

Influence of the microstructure and roughness of weakness planes on the strength anisotropy of a foliated clay-rich fault gouge

Cataclastic rocks, as clay-rich fault gouges, are commonly present in brittle rock masses when fault zones appear during geological engineering projects. Highly deformed rocks that are of poor mechanical quality can lead to technical, safety, and economic problems in rock engineering. The aim of this study is to characterise the resistant behaviour of a highly deformed clay-rich gouge >40 m wide with a marked tectonic fabric that indicates strength anisotropy. We present the results of consolidated-undrained (CU) triaxial tests that were performed at low confining pressures (50, 150, and 300 kPa) on several sets of foliated gouge specimens with four different orientations in the tectonic fabric. Specimens were collected from the encapsulated rock cores of two research boreholes drilled through the Alhama de Murcia Fault (AMF), a main regional fault located in SE Spain. The strain–stress relationships and failure modes were established, indicating that the gouge behaves as hard soil or very soft rock. The test results were adjusted at each orientation using the non-linear Hoek and Brown criteria by considering the fault gouge as an intact material or as a tectonised rockmass. Here, we use the Geological Strength Index (GSI) as an indicator of the rockmass strength that depends on the direction of the tectonic fabric. However, the results from specimens with tectonic fabric that is oriented most favourably for failure were not the weakest in terms of rock strength. Such an anomalous result could be the result of asymmetry in the roughness of the weakness planes that is related to the original gouge microstructure characterised by the strong reorientation of clays in an S-C′ like tectonic fabric.Our results will be useful for practical applications that are related to the stability of slopes and/or shallow underground excavations in brittle fault zones, and provide an inexpensive and easy way to preliminarily evaluate the anisotropic behaviour of this type of brittle fault zones for future engineering projects.

Adsorption of uranium (VI) from acidic leach liquor using Amberlite IRA-400 impregnated with amines

Amberlite IRA 400 was impregnated with N, N’, N’-Tetramethylethylenediamine (ATMEDA) as well as N-Methyl benzyl amine (AMBA) and examined for uranium uptake efficiency from sulfate medium. The potential of the studied adsorbents for uranium uptake was evaluated at different conditions; the effect of aqueous uranium concentration, contact time, pH value, temperature variation, amount of added adsorbent and matrix competitive ions. The implication of adsorption isotherms for (Amberlite IRA 400), (AMBA) and (ATMEDA) revealed that the results correlate with the Langmuir isotherm model with 90.90, 181.81 and 196.07 mg/g as theoretical capacity. Uranium adsorption kinetics was studied using Lagergren pseudo-firrst order, pseudo-second-order, Elovich and intra-particle diffusion models. Studied kinetics revealed that the process corresponds to the pseudo-second-order model. Optimum conditions were applied for uranium (VI) recovery from sulfate leach liquor of cataclastic rocks, Abu-Rusheid, south Eastern Desert, Egypt. The final uranium precipitate was characterized using ICP-OES, XRF and EDX.

Stability Analysis and Reliability Evaluation in Cataclastic Loose Rock Mass Blocks

Cataclastic rock masses with multiple failure modes and mechanisms are critical geological problems in the construction of rock slopes. Cataclastic rock masses are widely distributed in slopes of a hydropower project located on Lancang River, which is located in Tibet, China. In this study, the potentially unstable block of the slope is divided into key block and secondary key block based on the key block theory, and the system reliability evaluation theory is introduced. The method for quantitatively analyzing the rock mass stability of cataclastic slopes with sliding failure is established. Then, the spatial distribution of cataclastic rock masses and discontinuities in several rock slopes of a hydropower project are determined using traditional geological surveying and 3D laser scanning. At last, combining the BATE 2.0 software and the stereographic projection of the vector, the proposed method is applied to the study area. The results show that the main failure mode of the studied slope is wedge failure, and the system reliability is 1.69. With the increase in the instability probability of the key block, the increase in the instability probability of the system block is obvious, which reflects the controlling effect of the key block on the stability of the system block. The calculated system instability probability is slightly larger than the key block instability probability.

INFLUENCE OF REGIONAL TRANSCURRENT FAULT SYSTEMS ON MINERALIZATION IN THE NIGERIA PAN-AFRICAN PROVINCE

Regional fault systems evolve as a result of crustal movements of massive scale trailing for hundreds to thousands of kilometers across land and sea. Impact of these large-scale geologic structures within such provinces have resulted in the development of primary and secondary conduits, serving as pathways for the movement of mineralizing fluids. Such effects lead to ore deposit formations. The Nigerian regional fault systems trending NE-SW include the Anka-Zuru and Kalangai-Zungeru-Ifewara faults which traverse the entire western half of Nigeria, evident within the Neoproterozoic supracrustal low to medium grade metasediments. They are marked by series of discontinuous quartzite ridges, mylonites, sheared and cataclastic rocks of discrete bodies. Gold and rare-metal mineralization however, evolved within associated hydrothermal fluids that exploited the conduits and precipitated within and associated subsidiaries. This paper looks at these regional faults as they act as the primary plumbing systems and as points of economic mineralization. Concentrated mineralizing fluids enriched by valuable elements, ions and metals are thus dispersed into various lithological and/or structural units through multiple subsidiary fractures/faults within the Basement Complex of Nigeria.

A novel method for extractive spectrophotometric determination of uranium by Azur II dye in some geological samples.

ABSTRACT 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.