Search

• SW Cameroon Atlantic Coast displays a peculiar evolution compared to classic ones. • We document the landscape various response to active tectonics in SW Cameroon Atlantic Coast. • We highlight the CVL and fault reactivation controls on tectonic setting and landscape. • We bring out the preeminent endogen forcing controls on Edea–Eseka Region. • The present study enables to update neotectonic evidences in Edea–Eseka Region. Complex geology and tectonics of the SW Cameroon Atlantic Coast are responsible for the present-day landscapes of the Edea – Eseka Region (EER). The EER is tectonically active and shows differential tectonic uplift, contrasting relief, variations in erosion rates, in river incision, and in channel gradient. Drainage system divides are dynamic features of a landscape that migrate over time during the development of river networks. To study the neotectonic variability in this region, we investigate the drainage river system and the topographic expression of active regional tectonics across the EER. From the Digital elevation model (DEM, 30 m pixel resolution) using Geographic Information System (GIS) interpretive techniques, we extracted eleven morphometric parameters of thirty-two main drainage basins which were combined with Analytical Hierarchy Process (AHP) method. The inter-relationships between these indices grouped into four categories such as watershed geometry, relief characteristics, drainage texture analysis and regional tilting/uplift; can determine the influence of regional tectonic activity in the shape development of drainage basins. The results of the landscape analysis reveal significant variations of the morphometric parameters within the study area indicate a strong tectonic control. From the AHP values, the area is subdivided into high (∼25 %), moderate (∼43.75 %), and low (∼31.25 %) regional tectonic classes. The spatial distribution of different AHP classes shows a gradational pattern from coast to hinterland, suggesting a gradual decrease (from west to east) in the neotectonic activity in the EER drainage basin systems. The moderate-to-high neotectonic activity (∼68.75 %), demonstrates the complexity of the EER unstable tectonic character due to lithospheric mantle dynamism/asthenospheric upwelling as well as the Cameroon Volcanic Line (CVL) activity. [ABSTRACT FROM AUTHOR]

Based on comprehensive analysis of geological, geochemical, and paleotectonic settings, the conditions for the formation of Neoproterozoic oil and gas source rocks of the Earth are analyzed. A brief review of oil and gas fields in Eastern Siberia, China, the Middle East, Africa, and Australia is given, with Riphean and Vendian terrigenous and carbonate source rock. An overview of the oil and gas bearing basins of the world and a stratigraphic reference of the Neoproterozoic strata discovered within them, containing proven and suspected oil and gas source rocks, are given.The formation of Neoproterozoic oil and gas source rocks is analyzed in a complex way: simultaneously from the point of view of paleotectonics, paleogeographic and paleoclimatic conditions, paleobiological diversity and geochemical conditions. As part of paleotectonic analysis, the results of plate tectonic reconstructions for the Neoproterozoic stage are presented in accordance with one of the most currently relevant geodynamic models. Paleogeographic events and paleoclimatic conditions are described in the context of the specifics of the formation settings of carbonate-terrigenous oil and gas source rocks. In particular, the reasons for the accumulation of sediments enriched with organic carbon in the interglacial epochs of the Neoproterozoic and possible mechanisms for maintaining conditions favorable for their accumulation are considered. The conditions for the accumulation of oil and gas source rocks are also linked to global paleobiological pre-Phanerozoic events, and the analysis of the geochemical data of rocks makes it possible to characterize and correlate Neoproterozoic oil and gas source rocks on a global scale. On the basis of such a comprehensive assessment, a conclusion was made about fundamentally similar geological conditions for the formation of Neoproterozoic oil and gas source rocks in oil and gas bearing basins.

In this work, the influence of various cosmic factors (gravitational influence of the Moon and the Sun, solar activity, the Earth’s rotation) on mud volcanic activity was analyzed for the first time. The analysis was carried out mainly on the example of mud volcanoes in Azerbaijan, for which there is the largest and most complete catalog of eruptions (431 events over almost 210 years). It has been found that the activity of mud volcanoes can increase after syzygial tides, when the Earth is in line with the Moon and the Sun (their tidal forces are summed up in this case). The response of mud volcanoes to the tidal influence of the Moon is delayed by 5–10 days. It is also found that the number of mud volcanic eruptions is distributed unevenly throughout the year with maximums in March–June and September–October. The presence of these maximums may be due to a change in the distance between the Sun and the Earth and variations in solar tidal forces during the periods of perihelion and aphelion. At the same time, the response of mud volcanoes to the tidal influence of the Sun is delayed by several months and is quite strongly extended in time. It was revealed that there are fluctuations in mud volcanic activity with a period of 14–20 years, which do not coincide with the cycles of solar activity (with periods of 11 and 22 years), although some researchers talk about a connection between solar and mud volcanic activity. It is possible that the indicated fluctuations in mud volcanic activity are related to the main harmonic of the Earth’s nutation (18.6 years). It is shown that the maximum number of mud volcanoes on the Earth falls on the latitudinal belts of 30–45° N and 10–15° N (about 22 and 46 % of the total number of volcanoes, respectively). In the southern hemisphere, the largest number of volcanoes (about 3 % of their total number) is located within the boundaries of 5–10° S.

We use morphometric and geomorphic approaches in order to evaluate the relative active tectonic index (IAT) of the SW Cameroon Atlantic Coast, including the active Cameroon Volcanic Line (CVL). We determine the linear, areal, relief morphometric parameters and geomorphic indices of 53 drainage basins from the Digital Elevation Model (DEM, 30 m) using Geographic Information System (GIS) interpretive techniques coupled with available geological and field data. The results of the landscape analysis reveal significant variations of the morphometric parameters and geomorphic indices within the study area. The linear (~ 67.92%), areal (~ 94.34%), and relief (~ 86.84%) morphometric parameters, as well as the geomorphic indices (~ 84.91%), indicate a strong structural control. The longitudinal river and normalized stream profiles display complex, stepped, and uneven shapes with knickpoints (Kps). These results highlight the dominance of the tectonic control over the lithological variations and differential erosion. From the IAT values, the area is subdivided into very high (~ 18.87%), high (~ 54.72%), moderate (~ 22.64%), and low (~ 3.77%) tectonic classes. The high-to-very high tectonic activity (~ 73.59%) proves that the SW Cameroon Atlantic Coast is tectonically unstable due to mantle dynamism, CVL activity, and differential erosion. [ABSTRACT FROM AUTHOR]

The Pamir salient is a key part of the Himalayan–Tibetan Plateau orogenic system and has undergone intense tectonic deformation during the India–Asian collision. Delineating the Cenozoic kinematics and geodynamics of the Pamir salient requires a comprehensive understanding of the active arcuate structures along its frontal margin, from the perspective of the multi-spatiotemporal evolution of deformation patterns. Here, we reviewed the deformation rates of the major structures at different timescales, reanalyzed the published Global Positioning System velocities, and examined the present-day seismicity to constrain the kinematics of the Pamir salient since the Late Cenozoic. Integrated with the crustal evolution history during the Middle–Late Cenozoic and the deep structure, we proposed a new model to explain the multi-stage kinematics and associated geodynamics of the Pamir salient. During ∼37–24 Ma, the initial Pamir salient moved northward via radial thrusting that rotated the basins on both sides, which was driven by the continuous compression of the Indian slab after the breakoff of its oceanic part. During ∼23–12 Ma, the gravitational collapse of the Central and South Pamir crusts, which was induced by the breakoff of the continental part of the Indian slab, triggered the extension within the Pamir and foreland-ward movement of the upper crust. The upper crustal materials moved in varying directions due to the differential strength of the foreland areas, transforming the crustal kinematics from radial thrusting into a combination of radial thrusting and transfer faulting. Since the coupling of the Indian and Pamir slabs at ∼12–11 Ma, the deformation propagation towards the forelands accelerated, after which the kinematics of the Pamir salient exhibited asymmetric radial thrusting that has been sustained until the present. The asymmetric radial thrusting was likely driven by the compressive stress effect of the lithospheric basal shear generated by the underthrusting of the cratonic Indian lithosphere, which further led to the rollback of the Pamir slab and the consequent migratory extension in the South Pamir.

Copper‐gold magmatic‐hydrothermal systems dominate in the Chibougamau area of the Neoarchean Abitibi subprovince (greenstone belt) of the Superior Province (craton), whereas orogenic gold mineralization is more common in the rest of the Abitibi. Understanding differences in metal endowment within the Abitibi greenstone belt requires insights into the geodynamic evolution of the Chibougamau area. This was addressed by imaging the crust using seismic reflection profiling acquired as part of the Metal Earth project. Seismic reflection sections display shallowly south‐dipping reflectors located within the upper crust (e.g., a possible deep continuation of the Barlow fault) and a northward‐dipping midcrust imbricated with older crust (Opatica subprovince) to the north. Multiple reflectors characterize the upper part of the midcrust, interpreted as faults superimposed on a major lithological boundary. These structures likely formed during terrane accretion prior to craton stabilization. Combining the new seismic data with known stratigraphic, structural, and magmatic records, we propose that the study area was initially a normal (i.e., thick) Archean oceanic crust that formed at or before 2.80 Ga and that evolved through terrane imbrication at 2.73–2.70 Ga. Shortening caused rapid burial, devolatilization, and partial melting of hydrated mafic rocks to produce tonalite magmas that may have mixed with mantle‐derived melts to produce the diorite‐tonalite suite associated with observed Cu‐Au magmatic‐hydrothermal mineralization. Key Points: A seismic reflection survey of the Chibougamau area, Abitibi greenstone belt, is performed by the Metal Earth projectThe Metal Earth and Lithoprobe seismic surveys reveal that the northern part of the Abitibi greenstone belt has a consistent architectureThe Chibougamau area is an Archean oceanic crust evolved through terrane imbrication and not through plume activity and subduction processes [ABSTRACT FROM AUTHOR]

The early Archean represents an important eon in the evolution of the earth's continental crust and could provide insights into the nature of geodynamic processes that operated during that period. The Singhbhum Craton from the Indian Shield is the only major archive of Palaeo-Mesoarchean geological processes. The Palaeoarchean granitoids from the Keonjhar area of Singhbhum Craton are potassic granites and granodiorites of calc-alkaline affinity. Their age and elemental concentrations resemble the low Al2O3 granites reported from the Eastern Pilbara Craton of Australia. The geochemical systematics of these granitoids suggests their derivation due to crustal reworking involving partial melting of a tonalitic source, possibly older metamorphic tonalitic gneiss (OMTG). The OMTG could have been derived due to the melting of an enriched basaltic source at the base of an oceanic plateau. In the second stage, the resultant underplating at crustal levels caused the reworking that led to intracrustal melting and differentiation of OMTG to form potassic granites, similar to that of Keonjhar pluton. Consolidating the evidences from the available geochemical and isotopic studies with our own data and correlating them with the geophysical evidences, we interpret that the Keonjhar granitoids are the product of intracrustal melting in an oceanic plateau setting. [ABSTRACT FROM AUTHOR]

Currently, the load on railway tracks is increasing due to the increase in freight traffic. Accordingly, more and more serious requirements are being imposed on the reliability of the roadbed, which means that studies of methods for monitoring the integrity of the railway roadbed are relevant. The article provides a mathematical substantiation of the possibility of using seismoelectric and phasemetric methods of geoelectric control of the roadbed of railway tracks in order to identify defects and deformations at an early stage of their occurrence. The methods of laboratory modeling of the natural–technical system “railway track” are considered in order to assess the prospects of using the presented methods. The results of laboratory studies are presented, which have shown their high efficiency in registering a weak useful electrical signal caused by seismoacoustic effects against the background of high-level external industrial and natural interference. In the course of laboratory modeling, it was found that on the amplitude spectra of the output electrical signals of the investigated geological medium in the presence of an elastic harmonic action with a frequency of 70 Hz, the frequency of a harmonic electrical signal with a frequency of 40 Hz is observed. In laboratory modeling, phase images were obtained for the receiving line when simulating the process of sinking the soil base of the railway bed, confirming the presence of a transient process that causes a shift in the initial phase of the signal Δφ = 40° by ~45° (Δφ’ = 85°), which allows detection of the initial stage of failure formation.

In this paper, the authors consider the issue of processing the data of electromagnetic pulses (EMPs) recorded in mine workings and their interpretation. The Sami fault (Russia, the Murmansk region) was chosen as the object of the research. A number of experiments, including measuring the EMP level along the fault and the analysis of the results, were performed by the authors. The paper also presents a previously unconsidered method of transition from geological concepts to electro-technical ones, the aim of which is to identify the dependences of the amplitude of electromagnetic field anomalies on the parameters of active tectonic disturbances. The authors assumed the dependence of the amplitude of anomalies on the geological parameters of the rock mass and the thickness of the tectonic disturbance.

В работе представлены аспекты основных методов геодинамических исследований на территории Азербайджана. Представлена история развития GPS-сети. В результате полученных данных за 2015-2016 гг. было выявлено, что существующее распределение скоростей способствует накоплению напряжений различной величины вдоль Главного Кавказского надвига, что может сказываться на сейсмическом режиме исследуемого региона.

Recent deformation processes taking place in real time are analyzed on the basis of data on fault zones which were collected by long-term detailed geodetic survey studies with application of field methods and satellite monitoring.A new category of recent crustal movements is described and termed as parametrically induced tectonic strain in fault zones. It is shown that in the fault zones located in seismically active and aseismic regions, super intensive displacements of the crust (5 to 7 cm per year, i.e. (5 to 7)·10–5 per year) occur due to very small external impacts of natural or technogenic / industrial origin.The spatial discreteness of anomalous deformation processes is established along the strike of the regional Rechitsky fault in the Pripyat basin. It is concluded that recent anomalous activity of the fault zones needs to be taken into account in defining regional regularities of geodynamic processes on the basis of real-time measurements.The paper presents results of analyses of data collected by long-term (20 to 50 years) geodetic surveys in highly seismically active regions of Kopetdag, Kamchatka and California. It is evidenced by instrumental geodetic measurements of recent vertical and horizontal displacements in fault zones that deformations are ‘paradoxically’ deviating from the inherited movements of the past geological periods.In terms of the recent geodynamics, the ‘paradoxes’ of high and low strain velocities are related to a reliable empirical fact of the presence of extremely high local velocities of deformations in the fault zones (about 10–5 per year and above), which take place at the background of slow regional deformations which velocities are lower by the order of 2 to 3. Very low average annual velocities of horizontal deformation are recorded in the seismic regions of Kopetdag and Kamchatka and in the San Andreas fault zone; they amount to only 3 to 5 amplitudes of the earth tidal deformations per year.A ‘fault-block’ dilemma is stated for the recent geodynamics of faults in view of interpretations of monitoring results. The matter is that either a block is an active element generating anomalous recent deformation and a fault is a ‘passive’ element, or a fault zone itself is a source of anomalous displacements and blocks are passive elements, i.e. host medium. ‘Paradoxes’ of high and low strain velocities are explainable under the concept that the anomalous recent geodynamics is caused by parametric excitation of deformation processes in fault zones in conditions of a quasi-static regime of loading.Based on empirical data, it is revealed that recent deformation processes migrate in fault zones both in space and time. Two types of waves, ‘inter-fault’ and ‘intra-fault’, are described. A phenomenological model of auto-wave deformation processes is proposed; the model is consistent with monitoring data. A definition of ‘pseudo-wave’ is introduced. Arrangements to establish a system for monitoring deformation auto-waves are described.When applied to geological deformation monitoring, new measurement technologies are associated with result identification problems, including ‘ratios of uncertainty’ such as ‘anomaly’s dimensions – density of monitoring stations’ and ‘anomaly’s duration – details of measurements in time’. It is shown that the RSA interferometry method does not provide for an unambiguous determination of ground surface displacement vectors.

Сегодня все больше внимания уделяется сейсмотектонике, так как от решения ее вопроса зависит, в частности, достоверность карт СР (сейсмическое районирование) сейсмоактивных регионов. В данной статье рассматривается сейсмотектоника Азербайджана.

Geomorphological and environmental modifications that originate the dredging of carbonated mud in Cayo Moa bay were analyzed. Bathymetric data of different dates (1972, 2001 and 2010) were compared to evaluate the geomorphological changes in the bottom of the bay; also were determined elements as Fe, Ca, K, Al and Si in sediment samples. The Ratio Matching method was applied to determine the predominant orientation of the flows and their possible nexus with the background transformations. It was verified that dredging transforms the sedimentation medium into its geometry, the available sedimentary load and the energy involved in the sedimentation process. From the ecological point of view, dredging in the Cayo Moa bay of has contributed to the deterioration of life forms, impacting the marine environment through the increase of suspended and dissolved solids, changes in the morphology of the bottom, erosive and sedimentary dynamics and the loss of natural structure and floristic biodiversity in areas affected by extraction. [ABSTRACT FROM AUTHOR]

The results of monitoring radon emanations in the territory of Gorno-Altaisk due to seismic activity and their influence on human health are considered. It is shown that the level of activity of subsoil radon in the vicinity of the fault zone in the territory of Gorno-Altaisk exceeds such a level recorded in Moscow by 3-4 times. There is ambiguity in the behavior of radon as a precursor of a seismic event. Some radon anomalies are synchronous with moments of earthquakes and others correspond to quiet periods. The radon activity is more closely associated with the earthquakes localized in the aftershock zone of the Chuya earthquake. This is assumed to be caused by the network of fluid-conducting channels within the active fault between this region and the observation station. [ABSTRACT FROM AUTHOR]

The study was carried out by applying the Hooke’s physical law – to describe the relationship of the horizontal strains and geodynamic stresses of the Earth-crust. Experimental studies were carried out in the territory of the geodynamic polygon of the Ignalina Nuclear Power Plant. New data of geodynamic stress changes that are significantly related with the tectonic structure of the territory were obtained. After the analysis and generalization of results obtained, the change of tectonic stresses in the surroundings of the geodynamic ground of the Ignalina Nuclear Power Plant and its connections with tectonic structure were determined. The conclusion is drawn that Hooke’s law, by describing the relations between horizontal strains of the Earth-crust and geodynamic stresses, may be used practically and applied for estimating the regularities of the geodynamic stress change.

The article describes modeling procedure and calculation of wave fields in microseismicity monitoring in anisotropic medium. The research findings are intended for testing of processing algorithms for data of seismic observations in underground mining. [ABSTRACT FROM AUTHOR]

The article describes engineering decisions on equipment for acquisition of microseismicity data, that improve information content of microseismic monitoring of geodynamic processes in underground hard mineral mining. [ABSTRACT FROM AUTHOR]

The programme Ansys was applied to model the horizontal movements and the change of tectonic stresses of the Earth crust according to the data of geodetic measuring by the finite element method. Experimental studies were carried out in the territory of the geodynamic polygon of the Ignalina Nuclear Power Plant. The detailed results of parameters of horizontal deformations have been obtained; the new indices of tectonic stress increases - the most important stress increases were calculated and their directions established. On the basis of the study results and their analysis, the conclusion was drawn that the programme Ansys may be applied to model horizontal movements of the Earth crust. The merit of application of this programme, in comparison with usual widely-applied methods of geodetic researches, is not only that it is possible to detail the dispersion of the Earth crust deformations, but also to obtain a new information about the change of tectonic stresses. Article in Lithuanian Žemės plutos horizontaliųjų judesių tyrimas Ansys programa Santrauka. Žemės plutos horizontaliesiems judesiams ir tektoninių įtampų kaitai modeliuoti pagal geodezinių matavimų duomenis baigtinių elementų metodu taikyta Ansys programa. Eksperimentiniai tyrimai atlikti Ignalinos atominės elektrinės geodinaminio poligono teritorijoje. Gauti detalūs horizontaliųjų deformacijų parametrai bei apskaičiuoti nauji tektoninių įtampų prieaugių rodikliai – svarbiausieji įtempimų prieaugiai, nustatytos jų kryptys. Remiantis tyrimo rezultatais bei jų analizės duomenimis, daroma išvada, kad horizontaliesiems Žemės plutos judesiams modeliuoti gali būti taikoma Ansys programa. Šios programos taikymo privalumas, palyginti su įprastiniais plačiai taikomais geodezinių tyrimų būdais, yra ne tik tai, kad galima detalizuoti Žemės plutos deformacijų sklaidą, bet ir gauti naujos informacijos apie tektoninių įtampų kaitą. Raktažodžiai: baigtinių elementų metodas, GPS, geodinaminiai procesai, tektoninės įtampos, Žemės plutos deformacijos.

The study was performed with intent to apply the inverse Hook’ law – to describe connections between horizontal deformations of the Earth-crust and geodynamic stresses; tensor methods of stress estimation were based theoretically and experimental calculations were carried out in the territory of the Ignalina Nuclear Power Plant region. New data of the study of geodynamic stress change that are significantly related to a tectonic structure of the territory were obtained. Having analysed and generalised the results of calculation according to geodetic surveys, a tectonic activity in the surroundings of the graben Drūkšiai was established. The conclusion is drawn that the inverse Hook’ law, by describing the connections between horizontal movements of the Earth-crust and geodynamic stresses, may be used practically and applied for estimating the regularities of the geodynamic stress change. Article in Lithuanian Geodinaminių žemės plutos įtampų pokyčiai Ignalinos atominės elektrinės regione Santrauka. Tyrimas atliktas siekiant pritaikyti atvirkštinį Huko fizinį dėsnį horizontaliųjų Žemės plutos deformacijų bei geodinaminių įtampų s ąsajoms aprašyti, teoriškai pagrįsta tenzorinė įtampų įvertinimo metodika bei atlikti eksperimentiniai žemės plutos įtampų Ignalinos atominės elektrinės regiono teritorijoje skaičiavimai. Gauti nauji geodinaminių įtampų pokyčių duomenys, kurie akivaizdžiai yra susiję su teritorijos tektonine sandara. Išanalizavus skaičiavimo pagal geodezinių matavimų duomenis rezultatus ir apibendrinus, nustatytas tektoninis aktyvumas Drūkšių grabeno aplinkoje. Daroma išvada, kad atvirkštinis Huko dėsnis, nusakant horizontaliųjų Žemės plutos judesių bei geodinaminių įtampų sąsajas, gali būti taikomas praktiškai bei įvertinant geodinaminių įtampų pokyčių dėsningumus. Raktažodžiai: GPS, geodinaminiai procesai, tektoninės įtampos, Žemės plutos deformacijos.

The landscapes of eastern Georgia (Caucasus) are increasingly exposed to anthropogenic impacts and are replaced by natural-anthropogenic or completely transformed landscapes. These processes can be observed worldwide, though with different intensity. The underlying causes include the construction of hydro energy facilities, uncontrollable (illegal) felling of trees, pasture overload, and so on, which inevitably have a serious impact on the environment and cause frequent and increasingly intensive geodynamic processes such as erosions, landslides and mudflows. These processes are facilitated by steep slopes composed of less steady Jurassic shale, sandstone and partly by cretaceous sediments and heavy precipitation (1 600 - 1 800 mm/year in north-eastern part, Lagodekhi). The study of the impacts of particular anthropogenic factors on Eastern Georgian landscapes made it possible to design a model of the region -- a landscape-ecological map showing ecological factors characteristic of a particular landscape zone and highlighting ecologically hazardous areas. [ABSTRACT FROM AUTHOR]

Abstract: The Ningshan Granitoid Batholith (NGB) is located in the middle segment of the South Qinling Belt (SQB) section of the Qinling orogenic belt, in Shaanxi Province, China, and consists of the Laocheng, Yanzhiba and Lanbandeng intrusions. The Laocheng intrusion is dominated by quartz diorites, granodiorites and monzogranites, with the Yanzhiba intrusion being granodiorite dominated, and the Lanbandeng intrusion predominantly consisting of two-mica monzogranites. LA–ICP–MS zircon U–Pb isotopic dating indicates that the NGB formed during two distinct episodes of magmatism, with an earlier episode at 222–216Ma and a later episode at ∼210Ma. Whole-rock geochemistry and geochronology data have allowed us to divide the NGB into three groups, with Group #1 rocks consisting of Laocheng intrusion quartz diorites and granodiorites, and Yanzhiba intrusion granodiorites that were produced in the early magmatic episode. Group #1 samples have high-K calc-alkaline compositions, and are characterized by high Mg# values, high Sr, Cr, and Ni concentrations, and high (La/Yb)N and Sr/Y ratios, but low Yb and Y concentrations, implying that these rocks were formed from a mixed magma derived from melting of Neoproterozoic crustal basaltic rocks and magmas sourced from a region of depleted mantle. Group #2 rocks are composed of the mid-K calc-alkaline monzogranites in the Laocheng intrusion that were formed in the later magmatic episode, and are characterized by lower Mg# values, and lower Cr, Ni, and Co concentrations than the Group #1 samples, but with high Sr concentrations and (La/Yb)N and Sr/Y ratios, low Y and Yb concentrations, negligible Eu anomalies, and a significant range in zircon ε Hf(t) values. The highest zircon ε Hf(t) values of the Group #2 samples plot close to the depleted mantle evolutionary line, indicating that these rocks were derived from a mixed magma with both crustal- and mantle-derived components. Group #3 samples consist of high-K calc-alkaline two-mica monzogranites of the Lanbandeng intrusion that were formed during the later magmatic episode. These rocks are characterized by high SiO2, Al2O3, and K2O concentrations, with low MgO and Sr concentrations, low (La/Yb)N and Sr/Y ratios, Nb, Ta, P and Ti depletions, and significantly negative Eu anomalies, implying that the magmas from which these rocks formed were derived from partial melting of sedimentary rocks and minor amount of basalt. The early magmatic episode associated with formation of the NGB occurred in a continental arc environment at 222–216Ma, with ∼210Ma magmatism during a geodynamic transition from syn-collisional to post-collisional tectonics across the SQB. [Copyright &y& Elsevier]

The collision of earth's crustal plates is modeled mathematically based on a numerical solution of the equations of deformable solid mechanics using a finite element method with the MSC software. The interaction of the plates with each other and with the mantle is described by the solution of the contact problem with an unknown contact boundary between the solids considered. The mantle material is assumed to be ideal elastic-plastic with the Huber-Mises yield surface, and the properties of the plate material are described using an elastic-plastic model with the Drucker-Prager parabolic yield function which takes into account fracture in the tensile stress region. The results of the mathematical modeling show that the surface profiles of the plates in the region of their collision are consistent, both qualitatively and quantitatively, to the surface topography observed in nature under similar conditions. [ABSTRACT FROM AUTHOR]

Global geodynamic processes have a significant influence on the tempo of human society development and can cause the complete devastation of large areas of the Earth and mass mortality in a number of catastrophic cases. Technogenous factors can sometimes trigger geodynamic events. The potential consequences of natural and technogenous disasters became apparent during the catastrophe on the Deepwater Horizon platform on April 20, 2010. This paper takes a brief look at some aspects of this disaster. The possibilities of preventing the similar events in the future are discussed here. For this purpose, the development of a geodynamics information system (IS-Geodynamics) based on a network of global (subglobal) monitoring of the Earth's hydrogeodeformation (HGD) field, is suggested. [ABSTRACT FROM AUTHOR]

The aim of this paper is to give an overview of important historical results and review current knowledge of the Earth's core, as well as to discuss prospects for seismological studies of the core. Although the properties of the core of the Earth can only be determined indirectly, there has been considerable progress in elucidating its structure. The iron-rich core is dense but has lower P-wave speed than the mantle above; the solid inner core has fewer light constituents than the fluid outer core. The density contrast at the inner-core boundary is too large for just a phase transition. The fluid outer core is well stirred by the convective flows associated with the generation of the geodynamo and is expected to have a nearly adiabatic profile. Only inside the tangent cylinder defined by the presence of the inner core might there be some seismic heterogeneity in the bulk of the outer core. Some variability along the underside of the core - mantle boundary due to selective separation of lighter material is suggested by some observations. By comparison, the inner core is rather complex with heterogeneous and anisotropic structures that appear to have hemispherical differences. Significant attenuation occurs just below the inner-core boundary, probably due to a mushy zone associated with the growth of the inner core. A variety of seismic observations help to define inner-core structures, but it is important to take account of the influence of the complex structure at the base of the mantle. A slightly different zone has been suggested around the centre of the Earth, although it is difficult to get good control on this region. [ABSTRACT FROM AUTHOR]

The dynamic processes within the Earth leave their record in geophysical and geochemical variation about the general stratification with depth. A snapshot of current structure is provided by geophysical evidence, whereas geochemical information provides a perspective over the age of the Earth. The combination of information on the distribution of heterogeneity from geophysical and geochemical sources provides enhanced insight into likely geodynamic processes. A variety of techniques can be used to examine crustal structure, but the major source of information on seismic heterogeneity within the Earth comes from tomographic studies, exploiting surface waves for the lithosphere and body waves for the bulk Earth. A powerful tool for examining the character of mantle heterogeneity is the comparison of images of bulk-sound and shear-wave speed extracted in a single inversion, since this isolates the dependencies on the elastic moduli. Such studies are particularly effective when a common path coverage is achieved for P and S as, for example, when common source and receiver pairs are extracted for arrival times of the phases. The relative behaviour of the bulk-sound and shear-wave speeds allows the definition of heterogeneity regimes. For subduction zones, a large part of the imaged structure comes from S-wave speed variations. The narrow segments of fast wave speeds in the lower mantle, in the depth range 900 - 1500 km, are dominated by S variations, with very little bulk-sound contribution, so images of P-wave speed are controlled by shear-wave variability. Deep in the mantle, there are many features with high seismic-wave speed without an obvious association with subduction in the last 100 million years, which suggests long-lived preservation of components of the geodynamic cycle. The base of the Earth's mantle is a complex zone with widespread indications of heterogeneity on many scales, discontinuities of variable character, and shear-wave anisotropy. Discordance between P- and S-wave speed anomalies suggests the presence of chemical heterogeneity rather than just the effect of temperature. [ABSTRACT FROM AUTHOR]

Abstract: The Carpathian–Pannonian Region contains Neogene to Quaternary magmatic rocks of highly diverse composition (calc-alkaline, shoshonitic and mafic alkalic) that were generated in response to complex microplate tectonics including subduction followed by roll-back, collision, subducted slab break-off, rotations and extension. Major element, trace element and isotopic geochemical data of representative parental lavas and mantle xenoliths suggests that subduction components were preserved in the mantle following the cessation of subduction, and were reactivated by asthenosphere uprise via subduction roll-back, slab detachment, slab-break-off or slab-tearing. Changes in the composition of the mantle through time are evident in the geochemistry, supporting established geodynamic models. Magmatism occurred in a back-arc setting in the Western Carpathians and Pannonian Basin (Western Segment), producing felsic volcaniclastic rocks between 21 to 18 Ma ago, followed by younger felsic and intermediate calc-alkaline lavas (18–8 Ma) and finished with alkalic-mafic basaltic volcanism (10–0.1 Ma). Volcanic rocks become younger in this segment towards the north. Geochemical data for the felsic and calc-alkaline rocks suggest a decrease in the subduction component through time and a change in source from a crustal one, through a mixed crustal/mantle source to a mantle source. Block rotation, subducted roll-back and continental collision triggered partial melting by either delamination and/or asthenosphere upwelling that also generated the younger alkalic-mafic magmatism. In the westernmost East Carpathians (Central Segment) calc-alkaline volcanism was simultaneously spread across ca. 100 km in several lineaments, parallel or perpendicular to the plane of continental collision, from 15 to 9 Ma. Geochemical studies indicate a heterogeneous mantle toward the back-arc with a larger degree of fluid-induced metasomatism, source enrichment and assimilation on moving north-eastward toward the presumed trench. Subduction-related roll-back may have triggered melting, although there may have been a role for back-arc extension and asthenosphere uprise related to slab break-off. Calc-alkaline and adakite-like magmas were erupted in the Apuseni Mountains volcanic area (Interior Segment) from15–9 Ma, without any apparent relationship with the coeval roll-back processes in the front of the orogen. Magmatic activity ended with OIB-like alkali basaltic (2.5 Ma) and shoshonitic magmatism (1.6 Ma). Lithosphere breakup may have been an important process during extreme block rotations (∼60°) between 14 and 12 Ma, leading to decompressional melting of the lithospheric and asthenospheric sources. Eruption of alkali basalts suggests decompressional melting of an OIB-source asthenosphere. Mixing of asthenospheric melts with melts from the metasomatized lithosphere along an east–west reactivated fault-system could be responsible for the generation of shoshonitic magmas during transtension and attenuation of the lithosphere. Voluminous calc-alkaline magmatism occurred in the Cãlimani-Gurghiu-Harghita volcanic area (South-eastern Segment) between 10 and 3.5 Ma. Activity continued south-eastwards into the South Harghita area, in which activity started (ca. 3.0–0.03 Ma, with contemporaneous eruption of calc-alkaline (some with adakite-like characteristics), shoshonitic and alkali basaltic magmas from 2 to 0.3 Ma. Along arc magma generation was related to progressive break-off of the subducted slab and asthenosphere uprise. For South Harghita, decompressional melting of an OIB-like asthenospheric mantle (producing alkali basalt magmas) coupled with fluid-dominated melting close to the subducted slab (generating adakite-like magmas) and mixing between slab-derived melts and asthenospheric melts (generating shoshonites) is suggested. Break-off and tearing of the subducted slab at shallow levels required explaining this situation. [Copyright &y& Elsevier]

Abstract: Metallogenic provinces in Europe range in age from the Archaean to the Neogene. Deposit types include porphyry copper and epithermal Cu–Au, volcanic-hosted massive sulphide (VMS), orogenic gold, Fe-oxide–Cu–Au, anorthosite Fe–Ti-oxide and sediment-hosted base-metal deposits. Most of them formed during short-lived magmatic events in a wide range of tectonic settings; many can be related to specific tectonic processes such as subduction, hinge retreat, accretion of island arcs, continental collision, lithosphere delamination or slab tear. In contrast, most sediment-hosted deposits in Europe evolved in extensional, continental settings over significant periods of time. In Europe, as elsewhere, ore formation is an integral part of the geodynamic evolution of the Earth''s crust and mantle. Many tectonic settings create conditions conducive to the generation of water-rich magma, but the generation of ore deposits appears to be restricted to locations and short periods of change in temperature and stress, imposed by transitory plate motions. Crustal influence is evident in the strong structural controls on the location and morphology of many ore deposits in Europe. Crustal-scale fault–fracture systems, many involving strike-slip elements, have provided the fabric for major plumbing systems. Rapid uplift, as in metamorphic core complexes, and hydraulic fracturing can generate or focus magmatic–hydrothermal fluid flow that may be active for time spans significantly less than a million years. Once a hydrologically stable flow is established, ore formation is strongly dependent on the steep temperature and pressure gradients experienced by the fluid, particularly within the upper crust. In Europe, significant fracture porosity deep in the crystalline basement (∼1%) is not only important for magmatic–hydrothermal systems, but allows brines to circulate down through sedimentary basins and then episodically upward, expelled seismically to produce sediment-hosted base-metal deposits and Kupferschiefer copper deposits. Emerging research, stimulated by GEODE, can improve the predicting power of numerical simulations of ore-forming processes and help discover the presence of orebodies beneath barren overburden. [Copyright &y& Elsevier]

The geometric and electric parameters of rock mass in the north-eastern section of the Baikal proving ground are determined. The methods are proposed for processing and interpreting the data of long-term measurements of active electromagnetic monitoring. The basic regularities of change in the electric parameters of time series are revealed. The sensitivity diagram is plotted for direct current monitoring. Development of geodynamic processes is explained with allowance for geoelectric structure of the proving ground. [ABSTRACT FROM AUTHOR]

In the Carpathian–Pannonian region in Neogene times, westward-dipping subduction in a land-locked basin caused collision of two lithospheric blocks (Alcapa and Tisia) with the southeastern border of the European plate. Calc-alkaline and alkaline magmatism was closely related to subduction, rollback, collision and extension. From the spatial distribution of the magmatic activity, four segments can be defined: Western Segment (magmatism occurring on the Alcapa block), Central Segment (magmatism occurring on both Alcapa and the Tisia blocks), South-Eastern Segment and Interior Segment (both on the Tisia block).Most calc-alkaline magmatism in the region resulted from melting of a heterogeneous asthenospheric mantle source modified by addition of fluids and sediment. Assimilation and fractionation processes at shallow crustal levels occurred in most of the segments, strongly masking the deeper source processes. Long-term subduction, rollback and/or delamination led to contamination of the asthenosphere beneath the Western Segment. Here, large-volume partial melts of the contaminated mantle caused underplating and crustal anatexis, leading to mixing of mantle-derived calc-alkaline magmas with crustal melts. In the Central Segment, calc-alkaline magmas were formed by subduction and rollback, followed by back-arc extension and slab breakoff. A variable mantle source is indicated in the back-arc setting and larger amount of fluid-induced metasomatism, source enrichment and assimilation nearer to the trench. In the Interior Segment, evolution from typical calc-alkaline magmas to adakite-like ones was related to extension due to fast rotations and transtensional tectonics. Here, calc-alkaline magmas formed by decompression melting of a heterogeneous crust–mantle lithosphere, while adakite-like melts resulted from fliud-dominated melting of the lithosphere. Along the South-Eastern Segment, slab breakoff was responsible for the generation of typical calc-alkaline magmas, but in the extreme south of the segment, shallow level tearing of the slab followed breakoff. Strike–slip tectonics allowed the rise of hot asthenosphere and generation of adakite-like magmas, via slab-melting, along the torn edge of the East European Plate. Alkalic basaltic volcanism with an OIB-like asthenosphere source followed the calc-alkaline stage (Western Segment), or was contemporaneous with it (South-Eastern and Interior Segments) mainly in response to local extensional tectonics. [Copyright &y& Elsevier]

Models for Superior Province greenstone belt development have changed over the last 30 years from ensimatic, generally autochthonous models to suspect allochthonous terrane models based on the plate tectonic paradigm. Models intermediate between these end-members such as autochthonous terrane models have not been prominent. Within the Superior Province, there is a secular variation from early ca. 3 Ga platformal assemblages with overlying rift-related komatiite–tholeiite units representing breakup of ca. 3 Ga continental fragments to late (ca. 2.7 Ga) pull-apart basins. Autochthonous terranes should demonstrate some sort of logical order such as that described above, whereas allochthonous terranes will be largely oceanic in character and should be essentially random in their occurrence rather than exhibiting secular order. In the face of this situation, this paper reviews evidence from throughout the Superior Province that suggests many, but not all greenstone assemblages developed autochthonously or parautochthonously. The earliest greenstone assemblages in the Superior Province are generally quartzite and carbonate-bearing platform sequences in the North Caribou terrane and the Marmion terrane deposited unconformably upon granitoid or greenstone basement. The evidence for autochthonous/parautochthonous development includes the presence of unconformities between Keewatin type greenstone units such as: (1) basal unconformities between ca. 3 Ga granitoid or volcanic basement and slightly younger platformal assemblages; (2) between ca. 2.9 Ga platformal assemblages and younger platformal and Andean arc assemblages. Stratigraphic patterns such as adjacent greenstone belt assemblages representing sharply differing geodynamic settings with some indication of palinspastic order or progression in the northern, central and southern Superior Province are considered suggestive of orderly, autochthonous progression from platforms through rifting of continental fragments and late assembly during the Kenoran orogeny. Petrogenetic data indicating involvement of older granitoid crust in genesis of greenstone assemblages of a variety of ages throughout the Superior Province suggests the presence of older basement, implying autochthonous or parautochthonous development of many assemblages. Younger greenstone assemblages in the Abitibi–Wawa subprovince and the North Caribou terrane contain xenocrystic zircons similar in age to stratigraphically underlying greenstone assemblages. This pattern has been interpreted to represent autochthonous greenstone development. The current above enumerated evidence for autochthonous development of greenstone assemblages is generally indirect; few actual unconformities between Keewatin type greenstone assemblages have been recognized in the Superior Province. To aid in future recognition of unconformities in Keewatin type greenstone assemblages, examples of unconformities of varying degrees of subtlety in Archean sequences are reviewed. Archean unconformities ranging from sharp angular discordances in the northern Superior Province to subtle stratigraphic patterns, to weathering-related geochemical mobilization along inter-formational contacts are described. These styles of unconformity in Archean sequences suggest previously unrecognized major disconformities and unconformities may well exist between Keewatin type assemblages in the Superior Province generally and the Abitibi–Wawa subprovince specifically. The most important disconformity suggested in the Abitibi–Wawa subprovince is between the ca. 2726 Ma Deloro and the ca. 2708 Ma Tisdale assemblages. The presence of unconformities and disconformities coupled with the indirect lines of evidence cited above suggest an ‘autochthonous’ origin for many Superior Province greenstone belts. This ‘autochthonous’ origin involves either autochthonous or parautochthonous evolution of assemblages at least in part in place. That is, development of ca. 3 Ga platform sequences in selected locales followed by in place evolution of a succession of plume, oceanic and arc assemblages culminating in late pull-apart basin sequences. Implications of the autochthonous model for greenstone belts of the Superior Province, particularly the Abitibi–Wawa subprovince, include the future ability to recognize unconformity bounded sequences, potentially improving regional scale correlation. [Copyright &y& Elsevier]

Currently, the load on railway tracks is increasing due to the increase in freight traffic. Accordingly, more and more serious requirements are being imposed on the reliability of the roadbed, which means that studies of methods for monitoring the integrity of the railway roadbed are relevant. The article provides a mathematical substantiation of the possibility of using seismoelectric and phasemetric methods of geoelectric control of the roadbed of railway tracks in order to identify defects and deformations at an early stage of their occurrence. The methods of laboratory modeling of the natural–technical system "railway track" are considered in order to assess the prospects of using the presented methods. The results of laboratory studies are presented, which have shown their high efficiency in registering a weak useful electrical signal caused by seismoacoustic effects against the background of high-level external industrial and natural interference. In the course of laboratory modeling, it was found that on the amplitude spectra of the output electrical signals of the investigated geological medium in the presence of an elastic harmonic action with a frequency of 70 Hz, the frequency of a harmonic electrical signal with a frequency of 40 Hz is observed. In laboratory modeling, phase images were obtained for the receiving line when simulating the process of sinking the soil base of the railway bed, confirming the presence of a transient process that causes a shift in the initial phase of the signal Δφ = 40° by ~45° (Δφ' = 85°), which allows detection of the initial stage of failure formation. [ABSTRACT FROM AUTHOR]