Rock Bodies Research Articles

P 20. Stimulus-dependent behavioural disorder in patients with ANT-DBS for Epilepsy

Deep brain stimulation (DBS) targeting the anterior nucleus of the thalamus (ANT) is as an effective and safe treatment option for patients with resistant epilepsy. A SANTE Study reported that there was a gradual improvement in selected neuropsychological test results in patient with DBS in ANT. Among those improvements there were reported a number of psychiatric adverse affects. However little is studied about immediate neuropsychological effects of DBS in ANT. Recently demonstrated Voges B. et. al (2015) a stimulus- and voltage-dependent effect interrupting sleep and leading to the occurrence of neuropsychiatric symptoms (npS) (e.g. depression, mood instability, disturbed sleep) during ATN-DBS. We here present one patient with a voltage-independent developing of npS during ANT-DBS. The 45-year-old right-handed female patient with mental retardation with autistic spectrum disorder presented with focal not lesional refractory epilepsy. The average seizure frequency was 6.1 per day with a range of 1 to 16 seizures daily. After failure of 13 AED“s, a DBS-ANT was initiated at the age of 44. Follow up simultaneous EEG- video recording from 26 surface electrode contacts after beginning to stimulate with standard parameters (unipolar cyclic (1min ON/5min OFF) stimulation with 5 V stimulation amplitude, 120 Hz stimulation frequency and a pulse width of 90 μs) there were seen a directly dependence of neuropsychiatric symptoms (stereotypical movements with sitting down, torso wiggling (Body rocking) with or without singing) and impulse onset. In video-EEG monitoring we determined, that the duration of npS was also the same as impulse lasts. A clinical response to stimulation was 84 %. We improve adverse effects changing the programming settings: the amplitude was gradually reduced to two volts, the stimulation frequency 120 Hz and a pulse width of 90 μs where the same. Actual case report devoted to immediate complex behavioural disorder, which does not fulfil criteria for a complex focal seizure, and is strongly associated with unipolar bilateral stimulation of ANT. The actual clinical presentation of the DBS induced behavioural disorder semiologically coincide with the term “stereotypic movement disorder”. We hypothesize that impaired function of ARAS lead to reduced behavioural suppression of impulse mediated behaviour in the patient with mental retardation. We analysed her video-EEG before she was being stimulated and noticed, that she already had a typical body movement (body rocking) but much less frequently. Obviously a DBS of ANT had had a strong influence on behavioural disorder of our patient and was reversible after adjusting the stimulation parameters.

Multifield Coupling Mechanism of Unloading Deformation and Fracture of Composite Coal-Rock

The deformation and fracture evolution of coal and rock under unloading are prone to sudden instability or dynamic damage. To solve the problem, this paper combines interdisciplinary theories such as damage mechanics and electromagnetic field theory. The mathematical model of multiphysics coupling during loading and unloading of composite coal-rock is deduced. In addition, numerical simulations along with experimental verification are carried out to study multi-physical field variation and coupling mechanisms. The composite coal-rock deforms and ruptures under unloading, and the brittle failure of the rock body becomes more sudden when the confining pressure is unloaded. Macroscopically, many microcracks are generated and expanded during the loading and unloading of composite coal-rock. Microscopically, the internal old molecular chains are broken to form new molecular chains by the force. Simulation results show that, during the loading and unloading process, the three physical fields of the composite coal-rock all change regularly. During the unloading of coal and rock, there is a transition period in which the temperature increases sharply and reaches the maximum. Then, the temperature decreases due to the gradual decrease of its bearing capacity. Besides, the electromagnetic field is strongest on the surface of the coal body, and its propagation in the air decays exponentially. There are small fluctuations that appear at the junction of the coal body and the air. The experimental results show that the internal infrared radiation temperature of the composite coal-rock decreases during the initial stage of loading and unloading due to the discharge of internal gas. In the first stage of “loading and unloading,” it increases with the increase in stress, and the temperature suddenly increases in a short time after unloading. The electromagnetic radiation fluctuates in small amplitudes at the initial stage. When the stress is about to reach the peak, the electromagnetic radiation intensity increases and reaches the peak suddenly. Then, the coal-rock ruptures, the stress decreases, and the electromagnetic radiation weakens. The experiment and simulation results are consistent. The multiphysics coupling model is used to study the characteristics of coal and rock unloading under complex conditions, providing a theoretical basis and new method for the prediction and forecast of coal and rock mining dynamic disasters.

A highly dynamic hot hydrothermal system in the subduction environment: Geochemistry and geochronology of jadeitite and associated rocks of the Sierra del Convento mélange (eastern Cuba)

A U-Pb zircon date of ∼113 Ma revealed that a variety of jadeitites and related omphacitite, chloritite and albite-rich rocks from the subduction-related Sierra del Convento block-in-serpentinite-matrix mélange (eastern Cuba) formed nearly synchronously with MORB metabasite-derived anatectic trondhjemitic liquids at high-temperature and pressure in a hot subduction environment. Field, petrologic and geochemical data indicate hydrothermal/metasomatic processes triggered by juvenile fluids likely evolved from the crystallizing hydrous trondhjemitic melts. These fluids, variably mixed with sediment-derived fluids and channelized along fractures in the supra-slab mantle, precipitated relatively pure jadeitite with geochemical patterns depleted in REE and HFSE and epidote-rich jadeitite with LILE- (notably Ba) enriched compositions with respect to N-MORB. The crystallization of jadeitite veins was accompanied by formation of chloritite blackwalls at the vein-ultramafic rock contact and omphacititic patches at the outer parts of the veins, denoting wall rock-fluid interactions. Further pervasive flow of external fluid within the rock bodies triggered modal and cryptic (geochemical) metasomatic transformation of earlier jadeitite, producing mica-rich jadeitite and albite-epidote (-chlorite) rocks. Altogether these rocks document a discrete episode of massive flow of fluid in the supra-slab mantle roughly coeval with hydrous melting of subducted MORB metabasite.

Contrasting metamorphic and post-metamorphic evolutions within the Algyő basement high (Tisza Mega-unit, SE Hungary). Consequences for structural history

AbstractThe Algyő High (AH) is an elevated crystalline block in southeastern Hungary covered by thick Neogene sediments. Although productive hydrocarbon reservoirs are found in these Neogene sequences, numerous fractured reservoirs also occur in the pre-Neogene basement of the Pannonian Basin. Based on these analogies, the rock body of the AH might also play a key role in fluid storage and migration; however, its structure and therefore the reservoir potential is little known. Based on a comprehensive petrologic study in conjunction with analysis of the spatial position of the major lithologies, the AH is considered to have been assembled from blocks with different petrographic features and metamorphic history. The most common lithologies of garnet-kyanite gneiss and mica schist associated with garnetiferous amphibolite are dominant in the northwestern and southeastern parts of the AH. The first regional amphibolite facies metamorphism of the gneiss and mica schist was overprinted by a contact metamorphic (metasomatic) event during decompression in the stability field of kyanite. Garnet-bearing amphibolite experienced amphibolite facies peak conditions comparable with the host gneiss. Regarding the similarities in petrologic features, the northwestern and southeastern parts of the area represent disaggregated blocks of the same rock body. The central part of the AH area is characterized by an epidote gneiss-dominated block metamorphosed along with a greenschist-facies retrograde pathway as well as a chlorite schist-dominated block formed by greenschist-facies progressive metamorphism. The independent evolution of these two blocks is further confirmed by the presence of a propylitic overprint in the chlorite schists. The different metamorphic blocks of the northwestern, southeastern and central parts of the AH probably became juxtaposed along post-metamorphic normal faults developed due to extensional processes. The supposed brittle structural boundaries between the blocks could have provided hydrocarbon migration pathways from the adjacent over-pressured sub-basins, or could even represent suitable reservoirs.

Mechanical and energy characteristics of coal–rock composite sample with different height ratios: a numerical study based on particle flow code

To explore the differences in mechanical and energy evolution characteristics of coal–rock composite samples with different coal–rock height ratios, uniaxial compression tests of coal–rock composite samples with height ratios ranging from 4:1 to 1:4 were conducted by PFC software. A total of 7 PFC models were built and calculated. Results show that the smaller coal–rock height ratios lead to the higher elastic modulus and higher peak strength, both following exponential relationships with coal–rock height ratios, while the peak strain decreases linearly with the decrease of coal–rock height ratios. When the coal–rock height ratios decrease from 4:1 to 1:3, the fragmentation degree of coal body decreases gradually, and the failure modes are mainly of “V” type. And when the ratio is reduced to 1:4, failure mode is no longer of “V” type, the degree of coal body breaking becomes larger, and the part of rock body in the composites is also damaged. With the decrease of coal–rock height ratios, number of acoustic emission events of the composites increase first and then decrease. And U, $$U_{e}$$ and $$U_{d}$$ at different coal–rock height ratios exhibited similar trends, all of which increase slowly first, fast afterwards and very sharply at the peak stress points. At the peak stress point, the values of total input energy ( $$U_{A}$$ ) and dissipative energy ( $$U_{A} {d}$$ ) decrease firstly then increase as the coal-rock height ratios decreases and the value of elastic strain energy ( $$U_{A} {e}$$ ) decrease as coal-rock height ratios decreases. While the decrease of both $$U_{A}$$ and $$U_{A} {d}$$ are larger than $$U_{A} {e}$$ . These results can provide a useful reference for safe and efficient exploitation of coal resources.

Creating Cloud-Fracture Network by Flow-induced Microfracturing in Superhot Geothermal Environments

Superhot geothermal environments with temperatures of approximately 400–500 °C at depths of approximately 2–4 km are attracting attention as new kind of geothermal resource. In order to effectively exploit the superhot geothermal resource through the creation of enhanced geothermal systems (superhot EGSs), hydraulic fracturing is a promising technique. Laboratory-scale hydraulic fracturing experiments of granite have recently demonstrated the formation of a dense network of permeable fractures throughout the entire rock body, referred to as a cloud-fracture network, at or near the supercritical temperature for water. Although the process has been presumed to involve continuous infiltration of low-viscosity water into preexisting microfractures followed by creation and merger of the subsequent fractures, a plausible criterion for cloud-fracture network formation is yet to be clarified. The applicability of the Griffith failure criterion is supported by hydraulic fracturing experiments with acoustic emission measurements of granite at 400 °C under true triaxial stress and at 450 °C under conventional triaxial stress. The present study provides, for the first time, a theoretical basis required to establish the procedure for hydraulic fracturing in the superhot EGS.

Az Alföld metamorf aljzata: a köztes tömegtől a tarka mozaikig

A hozzáférhető fúrómaganyag mennyiségének növekedésével, valamint a kőzettani módszerek fejlődésével párhuzamosan az elmúlt évtizedekben alapvetően megváltozott a modellünk az Alföld metamorf képződményekből álló medencealjzatáról. A korábbi egyveretű, statikus aljzat kép helyét egy nagyon eltérő metamorf fejlődéstörténetű egységekből álló, tarka mozaik vette át. Ez a kőzettani sokszínűség az 1960-as évekig feltételezett merev, „köztes tömeg” elképzeléssel szemben a variszkuszi orogenezis óta a szerkezeti mozgásokban aktív szerepet játszó metamorf litoszféra dinamikájának eredményeként alakulhatott ki. Dolgozatunkban nyolc aljzati mintaterületen mutatjuk be a felépítő fő metamorf képződményeket, azok evolúcióját, valamint térbeli kapcsolatrendszerüket. A vizsgált területek Jánoshalma, Kiskunhalas-Tázlár, Szank, Csólyospálos-Kömpöc, Szeghalom, Mezősas-Furta, Dorozsma és Algyő. A kőzetblokkok térbeli helyzetének rekonstrukciója során a részletes petrológiai elemzés mellett négy esetben lyukgeofizikai információt is integráltunk a modellekbe.
 Az eredmények alapján az Alföld metamorf aljzatát a vizsgált területeken különböző szerkezeti mintázatok jellemzik. Kiskunhalason alsó szerkezeti helyzetű ortogneisz-domináns egység fölött széles, különböző kiindulási kőzettípusok deformációjával keletkezett milonitzóna, majd azt követően kis metamorf fokú fillit következik. Az eltérő fejlődésű egységeket elválasztó képlékeny nyírási zóna lapos szögű, közel északi dőlésű. A Szank, a Szeghalom, valamint a Mezősas-Furta területeket három, eltérő metamorf P-T (nyomás-hőmérséklet) fejlődést mutató egység építi fel, melyeket töréses deformációval jellemzett kataklázit zónák választanak el egymástól. Ezek a DNy-i dőlésű nyírási zónák feltételezhetően az alpi takarórendszer valamely egységéhez tartoznak. Szintén kréta korú feltolódásként értelmezzük a Dorozsma területen felismert aljzati blokkokat elválasztó széles kataklázit zónát. Itt, valamint a szomszédos Algyő területen ezt a felépítést felülírják a medence harmadidőszaki keletkezésével szinkron metamorf magkomplexum kialakulásához köthető szerkezetek. Mindezek komplex eredményeként jelenleg inkompatibilis metamorf fejlődésű egységek alkotják az Alföld déli részének metamorf aljzatát.
 A különböző mintaterületeken azonosított szerkezeti mintázatok megfelelő alapot biztosítanak az Alföld metamorf aljzatának litosztratigráfiai újragondolása során is. Így az egyes, litológiailag önmagukban is rendkívül heterogén egységeket (komplexumokat) célszerű ezen mintázatok alapján definiálni és lehatárolni.

BRUCS: a new system for classifying and naming mappable rock units

A new scheme is introduced for classifying and naming mappable rock bodies that lack primary stratification. In recognition of their distinctive geological characteristics, these ‘nonstratiform’ bodies are defined and classified according to their 3D form, spatial distribution and genetic relationships, in two hierarchical (parent–child) chains: one for intrusions and one for tectonometamorphic units. Geologically complex units, encompassing bodies of different genetic classes, are classified in a third chain reserved specifically for ‘mixed-class’ units. The new classification scheme is offered as an alternative to existing recommendations in the International Stratigraphic Guide and North American Stratigraphic Code, in which nonstratiform bodies are recognized and defined primarily by their lithological character. BRUCS (the BGS Rock Unit Classification System ) combines the three new parent–child chains for nonstratiform units with the well-established chain for stratiform units (bed–member–formation–group–supergroup) to create a flexible, practical and effective solution for classifying and naming all mappable rock bodies. The taxonomic rigour of BRUCS means that the considerable capabilities of modern digital systems for managing and communicating mapping data can be exploited fully.

A three-dimensional matching localization algorithm based on helix triangular pyramid array

On the eve of the occurrence of geological hazards, part of the rock and soil body begins to burst, rub, and fracture, generating infrasound signals propagating outward. 3D advanced positioning of the landslide has remained unsolved, which is important for disaster prevention. Through the Fourier transform and Hankel transform of the wave equation in cylindrical coordinates, this work established a three-dimensional axisymmetric sound field model based on normal waves, and designed a 4-element helix triangular pyramid array with vertical and horizontal sampling capabilities. Based on this, the three-dimensional matching localization algorithm of infrasound for geological hazards is proposed. Applying the algorithm to the infrasound signal localization of rock and soil layers, it was found that the helix triangular pyramid array can achieve accurate estimation of depth and distance with a smaller number of array elements than the traditional array, and may overcome the azimuth symmetry ambiguity. This study shows the application prospects of this method for predicting geohazards position several hours in advance.

Tectonic Setting of the Kenya Rift in the Nakuru Area, Based on Geophysical Prospecting

In this paper, we present results of tectonic and geophysical investigations in the Kenya Rift valley, in the Nakuru area. We compiled a detailed geological map of the area based on published earlier works, well data and satellite imagery. The map was then integrated with original fieldwork and cross sections were constructed. In key areas, we then performed geophysical survey using Electrical Resistivity Tomography (ERT), Hybrid Source Audio MagnetoTelluric (HSAMT), and single station passive seismic measurements (HVSR). In the study area, a volcano-sedimentary succession of the Neogene-Quaternary age characterized by basalts, trachytes, pyroclastic rocks, and tephra with intercalated lacustrine and fluvial deposits crops out. Faulting linked with rift development is evident and occurs throughout the area crosscutting all rock units. We show a rotation of the extension in this portion of the Kenya rift with the NE–SW extension direction of a Neogene-Middle Pleistocene age, followed by the E–W extension direction of an Upper Pleistocene-Present age. Geophysical investigations allowed to outline main lithostratigraphic units and tectonic features at depth and were also useful to infer main cataclasites and fractured rock bodies, the primary paths for water flow in rocks. These investigations are integrated in a larger EU H2020 Programme aimed to produce a geological and hydrogeological model of the area to develop a sustainable water management system.

Subcratonic and tectonic evolution of pyroxenite and eclogite with lamellar inclusions in garnet, Western Gneiss Region, Norway

Abstract Oriented lamellar inclusions of pyroxene and rutile in mantle garnet often serve as evidence for majoritic and titaniferous precursor garnets, respectively. We investigated ten new such microstructure-bearing samples from six orogenic peridotite bodies in SW Norway, which originated in the E Greenland mantle lithosphere, petrologically and thermobarometrically. All pyroxenite (nine) and eclogite (one) samples have large (mainly porphyroclastic) garnet containing silicate and oxide inclusions with shape-preferred orientation relationship. These inclusions vary—dependent on their size—systematically in shape (acicular to subprismatic), width (∼50 μm to submicron size), spacing (several 100 to ∼10 μm) and phase (pyroxene to Ti-oxide ± pyroxene). Smaller inclusions can fill the space between larger inclusions, which support the idea of consecutive generations. The larger, early formed lamellae occur least frequent and are most poorly preserved. A younger generation of other inclusions decorates healed cracks cutting across cores but not rims of garnet. These inclusions comprise oxides, silicates, carbonates (aragonite, calcite, magnesite) and fluid components (N2, CO2, H2O). The older, homogeneously distributed inclusions comply texturally and stoichiometrically with an origin by exsolution from excess Si- and Ti-bearing garnet. Their microstructural systematic variation demonstrates a similar early evolution of pyroxenite and eclogite. The younger inclusions in planar structures are ascribed to a metasomatic environment that affected the subcratonic lithosphere. The microstructure-bearing garnets equilibrated at ∼3.7 GPa (840 °C) and ∼3.0 GPa (710 °C), at a cratonic geotherm related to 37–38 mW m−2 surface heat flow. Some associated porphyroclastic grains of Mg-rich pyroxene have exsolution lamellae of Ca-rich pyroxene and vice versa that indicate a preceding cooling event. Projected isobaric cooling paths intersect isopleths for excess Si in garnet at ∼1550 °C, if an internally consistent thermodynamic data set in the system Na2O–CaO–MgO–Al2O3–SiO2 (NCMAS) is applied (or ∼1600 °C if using CMAS). This temperature may confine the crystallisation of the unexsolved garnets at 100–120 km depths of the E Greenland subcratonic lithosphere. Tectonism is indicated in coastal and hinterland samples by porphyroclastic orthopyroxene with Al2O3 concentrations showing W-shaped profiles. Cores of associated large (>200 μm) recrystallised grains have low Al2O3 contents (0.18–0.23 wt.%). Both characteristics typify relatively short intracrystalline Al diffusion lengths and a prograde metamorphism into the diamond stability field. We assign this event to subduction during the Scandian orogeny. Porphyroclastic orthopyroxene in other samples shows U-shaped Al2O3 concentration profiles paired with long Al diffusion lengths (several 100 μm) that exceed the radius of recrystallised grains. Their cores contain high Al2O3 contents (0.65–1.16 wt.%), consistent with a diffusional overprint that obliterated prograde and peak metamorphic records. Unlike Al2O3, the CaO content in porphyroclastic orthopyroxene cores is uniform suggesting that early exhumation was subparallel to Ca isopleths in pressure–temperature space. The depth of sample origin implies that rock bodies of Scandian ultra-high pressure metamorphism occur in nearly the entire area betweenNordfjord and Storfjord and from the coast towards ∼100 km in the hinterland, i.e. in a region much larger than anticipated from crustal eclogite.

Investigation of groundwater table under rock slope by using electrical resistivity imaging at Sri Jaya, Pahang, Malaysia

Over the years, rock slope will undergo the natural phenomenon of weathering, leading to the weakening of strength and physical properties of the slope material. In Malaysia, one of the causes of the weathering of rock is due to the presence of water, which can form groundwater table in the subsurface of rock slopes. The weathering of rock material in slopes can have significant effect on the stability. In Sri Jaya, Pahang, a large body of rock is exposed in cut slope, where different weathering grade was observed on the surface. The study aims to investigate the groundwater table under the rock slope surface and determine the extent of weathering of the rock slope. For that purpose, the electrical resistivity imaging (ERI) was chosen as a geophysical method to map the subsurface condition of the slope. Resistivity values from the survey were interpreted based on established work that correlates weathering condition of rock material with resistivity value. Different zones of weathering grade and groundwater were determined based from the profile.

Discrete Element Simulation Analysis of the Bending and Toppling Failure Mechanisms of High Rock Slopes

The high rock slope situated in the Southwest stope of Taiping Mining, Inner Mongolia, is subject to dumping failure due to its instability. The dumping body rock layer of this stope shows obvious bending and lowering of the head. The overturning angle of the rock strata can reach 46°, and tension dislocation along the rock joint can be observed in exposed sections and at the bedding and lithologic interface. The sliding surface also displays a broken line morphology. Through evaluation of regional rock integrity parameters and rock soft and hard parameters, rock-mass strength based on Hoek Brown strength estimation criteria can be developed. Based on the discrete element method, the geological model of layered excavation of the thin layer slope can be constructed. Combined with indoor and outdoor assessments, the characteristics of toppling deformation of the thin layer open-air slope can be studied and summarized. In this study, simulation analysis showed that under first excavation conditions, a crack-, dump-, and antislip zone was formed. The rock in the crack zone formed a “<”-shaped fracture along the slope surface that was squeezed towards the bottom of the slope. In the lower dumping area, the deflection angle gradually increased with excavation, and the deformation range and levels in the antislip area increased with excavation. Following the third excavation, the antisliding zone disappeared and the toppling line changed from a broken line to a straight line. In the final state, the slope collapsed as a whole, with the collapse of the dumping body penetrating the top to the foot of the slope.

Tunneling in heterogeneous rock masses with a block-in-matrix fabric

Heterogeneous rock masses composed of strong rock blocks embedded in a weaker matrix belong to complex formations and are often referred to as bimrocks (block-in-matrix-rocks). Due to the high spatial, dimensional, geo-hydrological and lithological variability of such rock bodies, a common geotechnical engineering design practice is not to consider the presence of the blocks and assign the strength and deformability properties of the weaker matrix to the whole rock mass. However, over the last decades, several case histories and many relevant studies on bimrocks have demonstrated that neglecting the presence of the blocks can produce wrong forecasts, which often lead to serious technical problems and severe economic repercussions during the construction of engineering works on and in these complex formations.The aim of this study is to investigate the stability of a deep circular tunnel excavated in a heterogeneous rock mass with a chaotic block-in-matrix fabric. In order to determine how the presence of rock inclusions may influence the overall behavior of the bimrock during the excavation, different Volumetric Block Proportions (VBPs) are used. To take the inherent spatial and dimensional variability of the blocks into account, many heterogeneous tunnel configurations are generated for each VBP considered by means of a stochastic approach. The analyses are performed using the Finite Element code RS2.Moreover, in order to highlight potential inaccuracies caused by neglecting the presence of the blocks at the design stage, simplified approaches commonly used by geopractitioners, which assume bimrocks to be homogeneous equivalent geomaterials, are also applied by way of comparison.

Osmium isotopic constraints on sulphide formation in the epithermal environment of magmatic-hydrothermal mineral deposits

In the magmatic-hydrothermal environment, fluids with similar metal concentrations and sources may yield contrasting mineral assemblages in successive stages of sulphide mineralization. These differences are linked to the physico-chemical conditions of the mineralizing fluids (e.g., T, pH, fS2, fO2) acquired during their interaction with country rocks and/or by mixing with groundwater. Here, we integrate petrography and osmium (Os) isotope (187Os/188Os) sulphide geochemistry, and discuss novel constraints on magmatic fluid-rock interaction and magmatic fluid-groundwater mixing that are deemed to govern sulphide deposition in magmatic-hydrothermal systems. We studied pyrite (FeS2) and enargite (Cu3AsS4) from the porphyry-related polymetallic Cerro de Pasco (14.54–14.41 Ma) and Colquijirca (10.83–10.56 Ma) epithermal deposits in the Central Andes, Peru. Sulphide mineralization is genetically associated with Miocene magmatism and includes breccia and replacement bodies of carbonate country rocks, and veins cutting the magmatic and sedimentary country rocks.At both deposits, pyrite is followed by enargite in the paragenesis. Pyrite has a radiogenic initial 187Os/188Os isotopic composition (187Os/188Osi-pyrite or Osi-pyrite = 0.80 to 1.45). Enargite (I) enclosing pyrite or filling in cracks in pyrite also has a radiogenic initial 187Os/188Os isotopic composition (Osi-enargite I = 0.56 to 1.24). Conversely, enargite (II) that formed on irregular surfaces on earlier pyrite has an unradiogenic 187Os/188Os isotopic composition (Osi-enargite II = 0.13 to 0.17). Our data show that the paragenetic evolution from pyrite to enargite records a sharp change in the osmium isotope composition within these sulphides.Pyrite and enargite (I) record radiogenic initial 187Os/188Os isotopic compositions, indicating interaction of magmatic hydrothermal fluids with the sedimentary country rocks. However, the unradiogenic initial 187Os/188Os isotopic composition of enargite (II) suggests that magmatic fluids with a mantle-like 187Os/188Os signature ascended from parental magmatic chambers to the epithermal environment without incorporation of crustal Os via fluid-rock interaction or mixing with groundwater. This difference may be due to the country rocks being altered during previous stages, with the radiogenic crustal Os signature being flushed by earlier magmatic pulses. Our findings imply that ore metals (i.e., Cu, Au) are magma-derived, whereas the Os isotopic composition of pyrite and some enargite in epithermal deposits may capture the signature of the interaction of magmatic fluids with country rock lithologies (e.g., the Eifelian black shale in the study area) and/or groundwater. Thus, the isotopic composition of the siderophile and chalcophile trace element Os in sulphides may act as a tracer of metal source, and degree of wall-rock interaction.

Dense seismic arrays deny a massive magma chamber beneath the Taipei metropolis, Taiwan

Several recent studies suggest that the Tatun Volcano Group (TVG) in the Taipei metropolis of Taiwan is still active with a mappable magma chamber beneath it. Here we report new seismic evidence from dense seismic arrays in northern Taiwan to refute the presence of a massive magma chamber. We investigated two near Taipei earthquakes with focal depths of ~ 140 km. We found that all the waveforms exhibited distinct S waves even when they traversed across the previously postulated magma chamber. Instead, the S-wave shadows found in the previous study may result from seismic waves traveling through a magma diapir above the subducting Philippine Sea Plate offshore northern Taiwan. Moreover, we found the P-wave delay increased with hypocentral distance when the seismic waves propagated through the footwall (west side) of the Shanchiao fault, regardless of whether they traversed across the postulated magma chamber. Our study results also indicate no abnormal attenuation when seismic rays traversed across the postulated magma chamber. Furthermore, the average {Q}_{P}/{Q}_{S} ratio around the TVG is less than 1, which implies that scattering attenuation is dominant. We conclude that a highly fractured rock body is beneath the TVG with a tiny fraction of magma instead of a massive magma chamber. Without sufficient magma supply, the TVG may stay dormant (except for small phreatic eruptions).

Петрогеохимическая характеристика мафит-ультрамафитовых пород южной части Марункеуского блока (Полярный Урал)

In the Polar Urals, in the Central and Western tectonic zones, small bodies of mafic-ultramafic rocks are widespread. Their age, petrographic and geochemical features are poorly studied. The paper presents the results of petrographic and petro-geochemical study of muscovite-albite-epidote-amphibole and pyroxene-amphibole-chlorite rocks of the southern part of the Marunkeu block of the Polar Urals, localized in the Middle Riphean sediments of the Nyarovey series and presumably belonging to the Ampelshor complex (O1-2). The primary composition of metamorphites corresponded to high-magnesian, low-titanic, low-alumina, and potassium-sodium tholeiitic hornblende gabbro-dolerites (dolerites) and peridotites formed either from primary magmas melted at the level of the spinel facies from the depleted mantle under the influence of an aqueous fluid, or by intra-chamber differentiation. In terms of the contents of rare and rare-earth elements, they differ from continental riftogenic formations (in particular, dolerites of the Orangyugan-Lemva complex) and are close to the tholeiites of the ensimatic island arcs.

Distribution peculiarities of basic ore components in Goshgarchay porphyrous copper deposit (lesser Caucasus, Azerbaijan)

Formulation of the problem. Large size and great reserves, as well as the possibility to apply rational methods of metals extraction predetermined the increasing interest to the copper-porphyry deposits. Today, they are the main raw material based on Cu, Mo, accompanying metals all over the world. The value of these deposits lie in the fact that they are in located in geologically well-studied regions. However, their ores in basic and associated components have relatively small content of Cu, Mo, Au, Ag, Bi, Re, Se, Te, spreading in large area. The purpose of the article. The main objective of the research is to study distribution peculiarities of basic ore components of Goshgarchay deposits, to detect geochemical features and behaviour of elements in the process of sedimentation by developing geochemical criteria of the search and the prognosis of hidden mineralization. Methods. The author studied the distribution problem of basic ore components of copper-porphyry mineralization, carried out field investigations (field researches), documented and tested underground mine working and core samples of over seventy well bores. When choosing the type of analysis, a special attention was paid to the sensitivity and exactness of the determination method. Analytical work was conducted according to the definition of chemical elements. The following types of analytical methods were used: chemical, atomic-absorption, spectral-chemical, etc. The analytical data were processed by the method of mathematical statistics. Results. As follows from the analysis of the above-mentioned results, the elements flaccid for hydrothermal solutions (Cr, Ni, V, Co, Mn, Ti) keep their independence in all groups of rocks. Their grouping is probably associated with the process of crystallized differentiation of magma. The elements Cu, Pb, Zn, Ag and partly Mo, don’t have specific place. Their presence is likely associated with the degree of rocks susceptibility, hydrothermal interaction being the source of these elements. In various types of ores and mineral associations the definition of elemental impurities is different. Their amount increases the amount (quantity) of clarke and coefficient of concentration a thousand times. Three different mineral associations coexist in the ore body: 1-primary sulphide-chalcopyrite and bornite-chalcopyrite ore. 2-oxidized ore and zone of secondary enrichment. 3-primary sulphide ore, significantly enriched in copper. Scientific novelty. Based on existing analytical data, the author studied distribution of basic ore and admixture components (gangue) and basic sulphide minerals. The concentration in series of elemental impurities were detailed in ore-bearing rocks of copper-porphyry deposits of Goshgarchay. The primary geochemical zonality was revealed in the distribution of basic ore-containing components in the ore body of copper-porphyry deposits of Goshgarchay ore field. Practical significance. The revealed peculiarities of the distribution of basic ore components in the ore body and host rocks (wallrock), the factors contributing to the accumulation of indicated elemental impurities can be used as geochemical criteria for the prognosis of copper-porphyry mineralization , supporting the effective directions of the research.

Space‐Time Evolution Laws of Zonal Disintegration in Deep Underground Caves Based on Coordination Deformation between the Bolt Body and Surrounding Rock

Zonal disintegration refers to the special phenomenon whereby fractured zones and intact zones appear alternately in deep‐buried surrounding rocks under high stress conditions, which are different from that of the shallow rock mass. Because the divisional rupture law in engineering practice is closely related to the force characteristics of the bolt body, this paper analyzed stress distribution rules of the same bolt body at different times and that of different bolt bodies at the same time in the case of zonal disintegration based on coordination deformation between the bolt body and surrounding rock. The nonlinear rheological mechanics model of rock mass on the elastic‐plastic interface under the maximum support pressure was established. It puts forward the theoretical calculation formula about the mechanics criterion and breakdown moment of the zonal disintegration. Using the mechanics model of interaction between a bolt and the surrounding rock, the distribution locations along the bolt body of the anchor neutral points and its maximum axial forces were discussed with the multiple theoretical neutral points. Furthermore, the location and width of each fracture zone were back analyzed. The results show that the rock mass on the elastic‐plastic interface of the surrounding rock has a significant creep effect after the excavation of the deep underground cave. While maximum deviator stress of the rock mass is more than its long‐term strength, the rock mass will fracture along a radial direction and come into the fractured zone. The multiple redistribution of the surrounding rock stress will generate alternate distribution phenomena of the fractured zone and intact zone. Meanwhile, the distribution regularity of the peaks and troughs interval of the displacement of surrounding rock leads to multiple neutral points along the anchor length direction. The computed results of zonal disintegration through the back analysis can reflect the actual space‐time evolution laws of zonal disintegration in deep underground caves.

Metamorphism of the Dizi Series Rocks (the Greater Caucasus): Petrography, Mineralogy and Evolution of Metamorphic Assemblages

The Dizi Series is exposed within the Southern Slope zone of the Greater Caucasus, in the core of the Svaneti anticlinorium. It is mainly composed of terrigenous, volcanogenic and carbonate rocks faunistically dated from the Devonian to the Triassic inclusive. Regional and contact metamorphism of the Dizi Series rocks was studied. It is stated that the degree of regional metamorphism corresponds to the chlorite-sericite subfacies of the greenschist facies, occurring at a temperature of 300–350°C and a pressure of 1.5–2.3 kbar. As a result of the action of the Middle Jurassic intrusive rock bodies, the regionally metamorphosed rocks of the Dizi Series underwent contact metamorphism. Three zones of contact metamorphism were distinguished corresponding to albite-epidote-hornfels, andalusite-biotite-muscovite-chlorite-hornfels and andalusite-biotite-muscovite-hornfels subfacies. Contact metamorphism took place at a significantly higher temperature and lower pressure than the preceding regional metamorphism. The maximum temperature of the contact metamorphism reached ≈ 570°С, while pressure varied within the range of ≈ 0.3–0.8 kbar. The evolution of rock associations of regional and contact metamorphism of the Dizi Series was studied. The fields of facies and subfacies of regional and contact metamorphism are shown in the Ps-T diagram. Three age populations of zircons were identified using U-Pb LA-ICP-MS dating of the diorite-porphyrite intrusion in the Dizi Series: Zrn1 (ca. 2200 Ma) and Zrn2 (458 ± 29 Ma) that were captured by the diorite-porphyrite magma from the ancient magmatic and metamorphic rocks of the crystalline basement, and Zrn3 (166.5 ± 4.6 Ma) that corresponds to the age of diorite-porphyrite crystallization.