Solid Rock Research Articles

Tectonics of rock loosening: geological data and physics of the process

Block-granular geological objects and rock volumetric mobility indicators are described. The mechanisms of structural and material reworking of rocks are considered in relation to the formation of a discrete tectonic structure of rocks and changes in the shapes of the geological bodies, which take place without rupturing the rock surfaces bounding these bodies and provide for the volumetric tectonic flow of solid rocks. Based on the study of natural objects and their comparison with the theoretical and experimental data on solid mechanics and geomechanics, it is suggested that one of the triggers for the volumetric disintegration of rock masses is rock fatigue damage (a fundamental phenomenon of solid-state physics). The disintegrated rocks behave according to the laws of mechanics of granular materials and mesomechanics. This study is of both theoretical and pragmatic importance as it contributes to the understanding of the regional geological features and provides new knowledge on the formation of crystalline protrusions known among the main hydrocarbon reservoirs within the basements of various geologic structures.

Fluid flow modeling in solid rock fractures

This paper considers the solution of the problem of modeling fluid flows occurring while filling solid rock fractures with fluid under pressure. For the mathematical modeling of the solid rock, real data of the rock core sample density was used, obtained in the imaging process of Synchrotron radiation X-ray tomographic microscopy. A calculation method of computational grid cell effective volume, which takes into account rock permeability parameter and is based on tomographic data, is described. To simulate the fluid behavior the modified finite volume method, widely used in hydrodynamics, was applied. Its modification is described for calculating the medium with a variable permeability. The results of numerical experiments are presented.

Dehydration at subduction zones and the geochemistry of slab fluids

Subducting oceanic slabs undergo metamorphic dehydration with the increase of temperature and pressure during subduction. Dehydration is an essential step for element recycling, and slab fluids are critical agents for mediating slab-mantle interaction. Dehydration is mainly controlled by the thermal structure of subduction zones and the stability of hydrous minerals. At fore-arc depths, slab dehydration produces aqueous fluid with dissolved salts such as NaCl. As subduction proceeds deeper, the content of silicate components increases. At sub-arc and post-arc depths, a hydrous silicate melt is likely to form, or a supercritical fluid could arise from complete miscibility between silicates and H2O. The partitioning of elements between slab fluid and the residual solid rock is controlled by the type of fluid, and generally it is the supercritical fluid that is the most capable of mobilizing trace elements, being an effective carrier even for high field strength elements. Understanding the chemistry of slab fluids relies on sophisticated integration of experiments, theoretical computation and investigation of natural rock samples. This contribution focuses on the content and speciation of key volatiles, including carbon, nitrogen and sulfur, in slab fluids as well as important fluid properties such as oxygen fugacity and acidity. The properties of slab fluids show complicated variation under the control of mineral assemblages and T-P conditions. Slab fluids at great depths of subductions have been inferred to be modestly alkaline and not necessarily very oxidizing as often assumed. Further progress in the research of slab dehydration and the chemistry and properties of slab fluids demands urgently the development of innovative experimental and computational technology including in situ analytical methods at high T-P.

Research and Evaluation of a New Autogenic Acid System Suitable for Acid Fracturing of a High-Temperature Reservoir.

An organic ester p-nitrobenzyl acetate (PNBA) was synthesized and used to establish a kind of autogenic acid system through the hydrolysis of ester to acetic acid in situ. The autogenic acid system can form a homogeneous solution by adding an organic solvent. The autogenic acid system possesses the desired characteristic in which hydrolysis can generate a small amount of acetic acid below 120 °C and a large amount of acid above 140 °C in 2 h. The acid-generated ability at different time and temperature was studied in detail. The dissolution of solid calcium carbonate and carbonate rocks by the autogenic acid system was investigated. The autogenic acid displayed lower dissolution ability on a carbonate rock and weak corrosion of a N80 steel sheet at 150 °C. The autogenic acid is especially suitable for acid fracturing and dissolution of rocks in a high-temperature carbonate reservoir.

Quantifying the buffering of oceanic oxygen isotopes at ancient midocean ridges

Abstract. To quantify the intensity of oceanic oxygen isotope buffering through hydrothermal alteration of the oceanic crust, a 2D hydrothermal circulation model was coupled with a 2D reactive transport model of oxygen isotopes. The coupled model calculates steady-state distributions of temperature, water flow and oxygen isotopes of solid rock and porewater given the physicochemical conditions of oceanic crust alteration and seawater δ18O. Using the present-day seawater δ18O under plausible modern alteration conditions, the model yields δ18O profiles for solid rock and porewater and fluxes of heat, water and 18O that are consistent with modern observations, confirming the model's validity. The model was then run with different assumed seawater δ18O values to evaluate oxygen isotopic buffering at the midocean ridges. The buffering intensity shown by the model is significantly weaker than previously assumed, and calculated δ18O profiles of oceanic crust are consistently relatively insensitive to seawater δ18O. These results are attributed to the fact that isotope exchange at shallow depths does not reach equilibrium due to the relatively low temperatures, and 18O supply via spreading solid rocks overwhelms that through water flow at deeper depths. Further model simulations under plausible alteration conditions during the Precambrian showed essentially the same results. Therefore, δ18O records of ophiolites that are invariant at different Earth ages can be explained by the relative insensitivity of oceanic rocks to seawater δ18O and do not require constant seawater δ18O through time.

Influence of biotic and abiotic factors of seagrass Posidonia oceanica recruitment: Identifying suitable microsites

The period between seed germination and successful seedling establishment is considered the most vulnerable phase for plant development. To better predict recruitment patterns within plant communities, it is essential to identify the abiotic constrains and biotic interactions that allow for the colonization of substrates by plant species. We evaluated which combination of factors are associated with successful survival and development of seedlings of the seagrass Posidonia oceanica in order to identify the most important microsite features acting together on recruitment success. Our results show that P. oceanica seedlings are rather specific in their environmental requirements during their first 18 months of life, when their development and survival are favored in microsites of consolidated substratum (solid rock, and to a lesser extent P. oceanica matte) covered by macroalgae (mainly crustose algae) and located in sheltered locations (with energy flux values not exceeding 7 × 105 kg s−2 m s−1). After this phase, their probability of surviving becomes more independent from external conditions.

Rock salt structure GdO epitaxial thin film with a high ferromagnetic Curie temperature

GdO with unusual valence of Gd2+ (4f75d1) has been known as the only gas phase so far. In this study, we report on the growth of solid phase rock salt structure GdO epitaxial thin films. The GdO thin film was an n-type semiconductor with the bandgap of 0.1 eV. The ferromagnetic Curie temperature (TC) was as high as 276 K, which was much higher than that of archetypal ferromagnetic rare earth monoxide EuO (TC = 69 K). TC increased slightly with electron doping similar to non-stoichiometric EuO1−δ, while decreased significantly with La doping probably caused by the magnetic dilution effect due to substitution of Gd with divalent La.

Testing the rocks loosening process by undercutting anchors

Abstract The method of unconventional solid rock loosening with undercutting anchors and the literature analysis of the problem are presented. The tests and test results of the rocks loosening process with a fixed undercutting anchor are described. The tests were carried out within the RODEST project, OPUS 10 competition No. 2015/19/B/ST10/02817, financed by the National Science Centre. Numerical modeling process as well as a series of laboratory and in situ tests were carried out. The test stand equipment and methodology for the in situ tests are presented. The tests were conducted in four mines, which allowed to obtain and determine the following characteristics: loosening force as a function of anchoring depth (for a given type of rock), the range of rock loosening in a function of anchoring depth (for a given type of rock), and loosened rock volume as a function of anchoring depth (for a given type of rock). The in situ test results are compared with the concrete capacity design (CCD) model used for the calculation of anchor load capacity in concrete.

Assessment of the Supply Chain under Uncertainty: The Case of Lithium

Modeling the global markets is complicated due to the existence of uncertainty in the information available. In addition, the lithium supply chain presents a complex network due to interconnections that it presents and the interdependencies among its elements. This complex supply chain has one large market, electric vehicles (EVs). EV production is increasing the global demand for lithium; in terms of the lithium supply chain, an EV requires lithium-ion batteries, and lithium-ion batteries require lithium carbonate and lithium hydroxide. Realistically, the mass balance in the global lithium supply chain involves more elements and more markets, and together with the assortment of databases in the literature, make the modeling through deterministic models difficult. Modeling the global supply chain under uncertainty could facilitate an assessment of the lithium supply chain between production and demand, and therefore could help to determine the distribution of materials for identifying the variables with the highest importance in an undersupply scenario. In the literature, deterministic models are commonly used to model the lithium supply chain but do not simultaneously consider the variation of data among databases for the lithium supply chain. This study performs stochastic modeling of the lithium supply chain by combining a material flow analysis with an uncertainty analysis and global sensitivity analysis. The combination of these methods evaluates an undersupply scenario. The stochastic model simulations allow a comparison between the known demand and the supply calculated under uncertainty, in order to identify the most important variables affecting lithium distribution. The dynamic simulations show that the most probable scenario is one where supply does not cover the increasing demand, and the stochastic modeling classifies the variables by their importance and sensibility. In conclusion, the most important variables in a scenario of EV undersupply are the lithium hydroxide produced from lithium carbonate, the lithium hydroxide produced from solid rock, and the production of traditional batteries. The global sensitivity analysis indicates that the critical variables which affect the uncertainty in EV production change with time.

Powdered rock versus solid rock comparisons in particle‐induced X‐ray emission measurements for planetary geochemical exploration

Grain size is an important consideration in the determination of the bulk chemistry of Martian rocks and unconsolidated materials in situ by the alpha particle X‐ray spectrometer (APXS), deployed on the NASA‐led Mars Science Laboratory mission. We used 2.5 MeV protons to emulate the particle‐induced X‐ray emission (PIXE) branch (5 MeV alphas) of the APXS. Seven polished rock slabs (igneous and sedimentary), ranging from fine‐ to coarse‐grained, were analyzed by PIXE in their original form, then milled to powders and pressed into pellets for further analysis. The summed area (160 mm2) over 10 interrogated regions on each slab is comparable to the area interrogated on the APXS; analysis of two pellets per rock, each using a 16 mm2 region, was found to be appropriate. The mean pellet/slab concentration ratio for Na, Mg, Al, Si, K, Ca, and Fe was close to 1.0 for fine‐grained samples, but changed by ±10% for the coarser cases. The variability among PIXE concentration values across the 10 rock regions increased monotonically with coarseness in the rock slabs. Comparison of overall PIXE concentrations with values measured by borate‐fusion WDXRF provides further quantitative support to the direct comparison of pellet and slab PIXE concentrations. This work affirms the use of the APXS on fine‐grained Martian materials but recommends larger interrogation areas (including rastering) when analyzing coarser‐grained materials. It also demonstrates that the presence of relatively large mineral grains (phenocrysts) or rock/mineral fragments within fine‐grained materials can contribute to greater error for specific elements associated with those phenocrysts/fragments.

Substantiation of laboratory facilities set to study physico-mechanical properties of coal-gas-moisture composites

Intensive development of coal deposits along with introduction of advanced high-performance machinery leads to higher number of fire- and explosion-hazardous events induced by gas dynamic phenomena at mines. Mass media regularly inform on tragic events concerning the combustible gas explosions and loss of lives at collieries in Russia and abroad. The main subject is development of a composite on the basis of solid coal and rock particles, gasses (methane, hydrogen) and moisture, prone to penetrate into mechanisms, initiating catastrophic dynamic processes in course of mining operations. The present research objective is foundation of a laboratory base to develop coal-gas-moisture composites in the form of coal cores, experimental investigation into their physico-mechanical properties. The special stand for development and investigation into coal-gas-moisture composites was designed. The relationships of variations in physico-mechanical properties of cores versus pressure were obtained experimentally on various materials (coal, limestone, graphite, etc) at the new-designed stand. The long-flame coal of different coarseness were used to establish specific variations in temperature, deformation of briquetted mass, its density under increase in pressure up to 200 MPa. It is demonstrated that temperature of a coal briquette increases by maximum 14 °C under atmosphere pressure and 10 °C in vacuum. The test stand allows physical modeling of coal and rocks with account for their material composition. The scientific novelty involves development of composites simulating mineral coal and rocks under prescribed physical and mechanical conditions.

Interpretation of Oxygen Isotopes in Phanerozoic Ophiolites and Sedimentary Rocks

AbstractTwo reactive transport models were developed to integrally simulate fluxes of oxygen isotopes from hydrothermal alteration of oceanic crust and weathering of continental rocks for a better understanding of the regulation of oxygen isotopes in the ocean. The hydrothermal alteration model consists of three boxes to represent pillow basalt, sheeted dike, and gabbro sections and simulates the steady‐state δ18O of solid rocks and porewaters in three individual sections along the spreading direction. The continental weathering model similarly calculates steady‐state δ18O profiles along the uplift direction. The two models were run in concert to simulate the evolution of seawater δ18O during the Phanerozoic, reflecting the relevant forcing factors to the corresponding parameter values of the models as functions of time. The seawater δ18O was calculated to have evolved from less than −5‰ in the early Paleozoic to between −2 and 0‰ for the Mesozoic and Cenozoic, as a result of declines in atmospheric CO2 and land area of igneous and high‐grade metamorphic rocks. The transition of seawater δ18O is similar to the δ18O trend that is commonly recorded in authigenic sedimentary rocks such as carbonates and cherts. The simultaneously simulated δ18O values for altered continental and oceanic rocks are decoupled from seawater δ18O because of kinetic inhibition and solid‐rock buffering at respective low and high temperatures and are similar to the shale and ophiolite δ18O records. Overall consistency between the simulation and observations supports the dynamic behavior of oceanic δ18O over the Phanerozoic eon.

Expansion of application range of pneumatic hammers with adjustable impact effect

The author reviews briefly existing machines for trenchless laying of underground utilities and vertical driving of steel elements in soil. For a pneumatic hammer with ring and inertia valves for driving different diameter pipes, arrangement and operating principles are described. Powerful longitudinal forces generated by shocks ensure destruction of solid rocks or compaction of soil in the zone of hole-making. These forces can be used in implementation of other technologies as well. For instance, maintenance and rehabilitation of oil well centrifugal pumps, which requires complete disassembling of the machine. For taking of many parts (impellers and guide vanes) out of a hole (a pipe), a pneumatic hammer with piston weight of 40 kg was tested. Another application area of pneumatic hammers can be stimulation of caking material unloading from railway cars using a vibropercussion plant driven by pneumatic puncher. Replacement of the latter by a pneumatic hammer of the same size and performance can enhance efficiency of the process.

The effectiveness of granular chalk use for growing winter wheat on grey forest soil

The research aims to establish the eff ectiveness of granular chalk use produced by «Slavuta-Calcium» Ltd. under growing Poliska–90 winter wheat variety, changing the physicochemical properties of grey forest soil and the wheat productivity. It also aims to establish optimal dosis of «Slavuta-Calcium» granular chalk as the meliorant and mineral fertilizer for grey forest soil in the system of winter wheat fertilization. In the temporary fi eld studies, various doses of nutrients N60–90–120P30–45–60K60–90–120 combined with «Slavuta–Calcium» granular chalk in a dose of Ca230–460–690 kg/ha of the active substance were studied against the background of secondary plowing of rotation products – soybean biomass that averaged 2.34 t/ha. Granular chalk is a modern complex highly eff ective meliorant with the content of Ca – 37.7 and Mg – 0.2 %, the mass fraction of carbonates (CaCO3 + MgCO3) makes at least 95 %. It is characterized by a high level of solubility when interacting with moisture in soil. It has a form of white granules, the mass fraction of 4.0–6.0 mm in size granules makes not less than 90 % and the one of 1.0 mm in size makes less than 5 %. Reactivity – 97 %. The granular chalk is advisable to apply on acidic soils, as a highly concentrated calcium-magnesium fertilizer, with the former as the dominant fertilizer, to optimize the physicochemical properties of the soil, as well as the plant nutrition system, in particular, increasing the availability of an element for assimilation by plants and as long-term ameliorants. The eff ectiveness of the use of mineral fertilizers, in particular acidic nitrogen on highly and medium acidic soils, after chemical reclamation is increased by 30–50 %, and slightly acidic by 15–20 %. The increase in productivity of crops from the combined eff ects of nutrients and chalk granulated is usually higher than when separately applied. The eff ectiveness of the integrated action of these elements is manifested in the growth of plant productivity and the quality of the resulting products, as well as the optimization of physical chemical properties and soil buff ering in the long term. In order to optimize the physicochemical properties of the arable layer of gray forest soil and the productive nutrition of agricultural crops, winter wheat, in particular, biogenic elements should be used in doses N60-90-120P30-45- 60K60-90-120 with granulated chalk «Slavuta-Calcium» in doses of Ca230-460-690 kg/ha of active substance. Granulated chalk obtained as a result of industrial grinding of solid sedimentary carbonate rocks of natural origin, subsequently under the infl uence of the granulation process of the starting material contains Ca and Mg carbonates of at least 95 %, dense granules which facilitates convenient mechanized application, as well as chalk suitable for accurate metered application on the quest map. Key words: granular chalk, gray forest soil, chemical reclamation, crop productivity.

Slipping on till

Ice Sheets How do glaciers flow over the ground underlying them? We know that friction, ice stream velocity, and water pressure at the ice bed all matter, but we still do not know how to represent the process over both hard beds (which are solid rock) and soft ones (composed of unconsolidated erosion products called till). Zoet and Iverson present experimental results describing how glacial ice moves over watersaturated till (see the Perspective by Minchew and Joughin). These observations should help to solve the long-standing problem of constructing a generalized slip law that combines the processes of hard-bedded sliding and bed deformation. Science , this issue p. [76][1]; see also p. [29][2] [1]: /lookup/doi/10.1126/science.aaz1183 [2]: /lookup/doi/10.1126/science.abb3566

Zeolites derived from natural minerals: Solid rock and volcanic ash

Zeolites derived from natural minerals: Solid rock and volcanic ash

Mineralogical and geochemical characteristics of hydrocarbon-bleached rocks in Baiyanggou mud volcanoes, Xinjiang, NW China

A total of 11 rock samples were systematically collected along the main flow of geofluids running on the slope of the Baiyanggou mud volcanic system and analyzed for their mineralogical and chemical compositions as well as for iron species using XRD, XRF and Mössbauer spectroscopy, respectively. The analytical results clearly indicated spatial variations for most geochemical parameters caused by redox fluctuation processes around the Baiyanggou mud volcanic system. Close to the mud volcanic craters, the bleached greyish rocks mainly contained ferrous iron in chlorite and muscovite (para-Fe2+) with some portion of ferric hydroxide and ferric iron in clay minerals (para-Fe3+), suggesting a strong reducing environment. Further away from the craters, the relative contents of reducing iron species (Fe2+) in the rocks gradually decreased. The reddish rocks did not appear to be greatly influenced by erupting geofluid and contained relatively high contents of para-Fe3+ and ferric iron in hematite (hem-Fe3+). A redox front occurred at a certain distance from the active mud volcanic craters, in which sharp changes of iron-bearing minerals could be tracked. The reducing and weakly alkaline medium contributed to the precipitation of secondary carbonate minerals such as calcite and siderite. Geofluids composed of brackish waters, gases and oils tended to migrate through sandy veins in a clay sequence, faults and fracture networks with relatively high porosity and permeability. Iron speciation of the solid rocks in the seepage areas could therefore be considered a potential indicator for the migration of reducing geofluids including hydrocarbons located underground.

Applications of Electrical Resistivity Surveys in Solving Selected Geotechnical and Environmental Problems

Standard test methods may not be suitable or sufficient for determining the geotechnical conditions of a structure’s subsoil and the effects of the designed structures on the environment. Geophysical test methods, validated with other methods, may prove useful. In recent years they have found many new applications in engineering practice, both geotechnical and environmental. The advantages of geophysical methods include the non-destructive and non-invasive nature of the tests, their low costs and quick results, as well as compatibility with different materials, including soils, solid rocks, wastes and anthropogenic formations. The paper presents the analysis of laboratory and field investigations including research in a modified oedometer, resistivity chamber, electrical resistivity tomography (ERT) and resistivity cone penetration test (RCPT). Laboratory tests allowed for the assessment of the degree of saturation and porosity of sandy and clayey soils. The tests were carried out on saturated and unsaturated soil samples and allowed for the determination of some relationships between electrical conductivity and porosity. The proposed equations were used to assess parameters in in situ studies using RCPT tests and showed good agreement with reference values based on undisturbed soil samples. ERT tests confirmed the usefulness of electrical measurements in the quality assurance of subsoil and hydrotechnical structures. The tests showed weakening zones in the levee body, discontinuity of the vertical sealing system on the modernized section of the embankment, and location of the top of clay deposits.

A single Rayleigh mode may exist with multiple values of phase-velocity at one frequency

SUMMARYOther than commonly assumed in seismology, the phase velocity of Rayleigh waves is not necessarily a single-valued function of frequency. In fact, a single Rayleigh mode can exist with three different values of phase velocity at one frequency. We demonstrate this for the first higher mode on a realistic shallow seismic structure of a homogeneous layer of unconsolidated sediments on top of a half-space of solid rock (LOH). In the case of LOH a significant contrast to the half-space is required to produce the phenomenon. In a simpler structure of a homogeneous layer with fixed (rigid) bottom (LFB) the phenomenon exists for values of Poisson’s ratio between 0.19 and 0.5 and is most pronounced for P-wave velocity being three times S-wave velocity (Poisson’s ratio of 0.4375). A pavement-like structure (PAV) of two layers on top of a half-space produces the multivaluedness for the fundamental mode. Programs for the computation of synthetic dispersion curves are prone to trouble in such cases. Many of them use mode-follower algorithms which loose track of the dispersion curve and miss the multivalued section. We show results for well established programs. Their inability to properly handle these cases might be one reason why the phenomenon of multivaluedness went unnoticed in seismological Rayleigh wave research for so long. For the very same reason methods of dispersion analysis must fail if they imply wave number kl(ω) for the lth Rayleigh mode to be a single-valued function of frequency ω. This applies in particular to deconvolution methods like phase-matched filters. We demonstrate that a slant-stack analysis fails in the multivalued section, while a Fourier–Bessel transformation captures the complete Rayleigh-wave signal. Waves of finite bandwidth in the multivalued section propagate with positive group-velocity and negative phase-velocity. Their eigenfunctions appear conventional and contain no conspicuous feature.

Investigation of the cosmic ray angular distribution and the East–West effect near the top of Etna volcano with the MEV telescope

An experimental investigation of cosmic muons has been carried out with the Muography of Etna Volcano (MEV) tracking telescope, installed at an altitude of about 3100 m a.s.l. in front of the North-East Etna crater. The analysis of a statistically significant data sample ($$\sim 10^7$$ events), taken during a period of approximately 2 months, has been carried out to investigate the angular distribution of cosmic muons originating both from the open sky side and from a large solid rock thickness (Etna side). Due to the geographical orientation of the MEV telescope, anisotropies caused by the East–West effect could also be observed, extracting the asymmetry factor in small steps of the zenithal angle.