Tectonic Displacement Research Articles

The Neoproterozoic Mozambique Belt in the Gol Mountains (N Tanzania): Structural Analysis of Amphibolite and Granulite‐Facies Nappe Tectonites From a Crustal Orogenic Channel

AbstractA structural analysis of the Gol Mountains of North Tanzania is presented in which we identify and characterize a sheet‐like deformation‐localization zone of regional scale. Syn‐metamorphic rock‐deformation within the localization zone gave rise to widespread tectonite development under high‐T in lower‐mid crustal realms. Regional foliations and mineral/stretching lineations, and associated non‐coaxial mineral petrofabrics can be correlated with ductile flow shear planes. At the macro‐scale these structures are genetically connected with tangential movement zones involving large a‐type and sheath folds, thrusts and ductile shear zones, and hydrothermal quartz megaveins plastically deformed. The dimension of the area affected by this structural style is c. 30 km across the Mozambique Belt and >50 km parallel to it. The associated tectonic displacements likely attained several tens of km in the context of an overall W‐directed tectonic vergence transversal to the Mozambique Belt orogenic trend. It is interpreted as a segment of a mid‐lower crustal orogenic channel active during late Ediacaran amalgamation of the Congo‐Tanzania Archean Craton (and its discontinuous fringe of Paleoproterozoic and Mesoproterozoic orogens) with the amalgamated arcs and terranes of the Arabian‐Nubian Shield.

Distinguishing fault offset from climatically modulated channel deflections: Insights from the Pearblossom slip-rate site, Mojave section of the San Andreas fault, California, USA

Fault slip histories are essential for understanding seismic hazard and regional fault system development but fundamentally depend on identifying, dating, and reconstructing displaced markers. Here, we use a case study of the Pearblossom site along the Mojave section of the San Andreas fault in California (USA) to show how pulses of sediment aggradation during wet periods can complicate such reconstructions by producing “imposter offsets”—landforms that develop with an initial deflection that is easily misread as tectonic displacement caused by fault slip. Specifically, we document two channels on the downstream side of the fault: a subtle one that we interpret to have been beheaded and displaced 24–49 m from a source channel on the upstream side of the fault, and a second and more prominent one that we interpret as an imposter offset of 36–88 m. Using optically stimulated luminescence dating, we determine that the source channel incised between 1.44 ± 0.43 ka and 1.27 ± 0.18 ka with a subsequent phase of alluvial fan aggradation at ~0.6 ka, when the channel with the imposter offset formed. Because the pulse of fan deposition coincides temporally with a wet period in Southern California precipitation records, we attribute formation of the imposter offset and the alluvial fan into which it incised to climatically modulated deposition at the site. Comparing precipitation records with charcoal ages compiled from multiple Mojave Desert region locations suggests that other slip-rate sites may be similarly affected. Although climatic effects can complicate slip-rate studies, we show that the morphology and upstream position of the deflected channel can indicate whether a site likely records useful information about fault slip.

Assessment of coastal and mangrove vulnerability in the Andaman Island, Indian Ocean

Coastal regions are highly susceptible to the effects of global warming, including rising atmospheric and sea surface temperatures, increased cyclone frequency, and sea level rise. Thus, it is imperative to examine coastal vulnerability to minimize the impact of multiple hazards and protect coastal resources, such as mangroves. Particularly in India studying the vulnerability of coastal zones of Andaman and Nicobar Islands which fall in seismic zone V is critical for conservation efforts. We conducted a vulnerability analysis of coastal zones impacted by the 2004 earthquake, causing varying degrees of ground upliftment and subsidence. We compared coastal vulnerability among sites that experienced uplift, no change, and subsidence (the southern portion). Our analysis utilized the Coastal and Mangrove Vulnerability Index (CVI and MVI) to measure and compare vulnerability in six zones distributed along uplift and subsidence gradient. High-resolution satellite imagery including WorldView-2, 3, and GeoEye-1 from year 2022 are utilized on this study. The CVI and MVI offers a good way to measure and compare vulnerabilities across sites and offer insights for better management. The CVI and MVI results indicate that approximately 34% of coastal grids and over 23% of mangrove grids across all zones are highly to extremely highly vulnerable. Subsided zones were found to be more vulnerable than uplifted zones. These findings suggest that large-scale natural disturbances such as tectonic displacement have the potential to impact coastal vegetation and mangrove cover can become even more vulnerable. In conclusion, our study emphasizes the importance of vulnerability analyses in coastal regions, especially in areas prone to seismic activity. Our findings have direct implications for conservation and restoration efforts and underscore the need for continued monitoring and mitigation efforts to safeguard coastal resources for long-term sustainability.

Reconstruction of the deformation history of an active fault: implications from the Atera Fault, Central Japan

Atera Fault clay gouges were collected for age dating near Kawaue, Nakatsugawa City, Central Japan, and the results integrated within its complex geological history. The results form an internally consistent data set constrained by extensive geochronological data (AFTA, ZFTA, CHIME) and support the application of gouge dating in constraining timing of brittle deformation in Central Japan. The Atera illite age data complete recently obtained limited illite fault gouge age data from underground exposure in the Toki Granite; the new illite age data are identical within error. The age of the heterogenous welded tuff breccia zone (Atera 1) ranges from 40.6 ± 1.0 Ma to 60.0 ± 1.4 Ma, whereas ages of the fault core gouge sample (Atera 2) range from 41.8 ± 1.0 Ma to 52.7 ± 1.2 Ma. The finest < 0.1 µm fraction of the fault breccia and fault core gouge yield ages around 41 Ma, identical within error. The new illite age data indicate brittle faulting and a following geothermal event occurring in the Paleogene–Eocene, similar to the nearby Toki Granite area and confirm they were both synchronous with a post-intrusive pluton exhumation. The Atera Fault illite age data provide additional insights into an integrated, regional-scale record of the tectonic displacement of Central Japan and might be influenced by large-scale tectonic processes such as the Emperor sea mount kink around 55 to 46 Ma with fault initiation around 50 Ma and brittle fault cessation or reactivation around 40 Ma in the Eocene.Graphical

ПОЛЯ НАПРУЖЕНЬ ТА ГЕОЛОГІЧНА СТРУКТУРА ЗАХІДНОГО ЗАМИКАННЯ ГОРЛІВСЬКОЇ АНТИКЛІНАЛІ ДОНБАСУ ЧАСТИНА 2. ПОЛЯ НАПРУЖЕНЬ І ДЕФОРМАЦІЙ

Background. In tectonophysical studies, particular importance is placed on the mechanism of formation of large complex deformation structural elements, and the Horlivka anticline of the Donets Basin serves as such an example. Its importance lies not only in its complex structural composition and development mechanism but also in its potential impact on safe and efficient coal mining. This study aims to analyse the geological structure, stress and strain fields of the western closure of the Horlivka anticline that could be useful in forecasting geological factors for coal mining operations. Methods. The paleostress analysis was performed on the collected fault orientation and kinematic data using Gushchenko's kinematic method based on the analysis of tectonic displacement vectors along slickensides. Mesoregional stress field characteristics were reconstructed by statistical processing of local stereographic solutions. The relative age chronology and staging of tectonic stresses were studied using the stress monitoring method. The characteristics of the principal axes of the total strain field were processed using the GEOS software. Results. Mesoregional stress field is characterised by a subhorizontal NW–SE-oriented maximum principal stress axis and a subhorizontal NE–SW-oriented minimum principal stress axis. This stress regime is classified as a strike-slip regime and is the youngest one (Alpine orogeny) for the Donets Basin. The evolution of tectonic loading conditions of the studied structure is characterised by a deformation series of six stress regimes from the oldest (normal) to the youngest (strike-slip). Stretching axis of the strain ellipsoid is oriented NW and N–S, and shortening axis is oriented NE, nearly orthogonal to the anticline axis. Strike- and oblique-slip faulting regimes of the total strain field were determined for most of the study area, and the deformation has occurred under shear conditions, as indicated by the Lode–Nadai coefficient. Conclusions. A structural pattern of deformation elements, including a conjugate strike-slip fault system of the shear zone, a dome-shaped fold, and longitudinal thrusts in its limbs, may be interpreted as a single pattern of structural paragenesis developed by right-lateral displacements along the longitudinal strike-slip fault system within the Horlivka anticline paraxial part. Fragments of mutual symmetry between the stress and strain fields can be taken as evidence of their genetic relationship.

Tectonic Displacements of the Nansen Basin Sedimentary Cover: Causes and Consequences

Tectonic Displacements of the Nansen Basin Sedimentary Cover: Causes and Consequences

The Charnwood Terrane revisited: an integrated petrogenetic and petrophysical model for crustal structure in southern Britain

We based an integrated petrological and petrophysical model for the Ediacaran crust of southern Britain on a review of the c. 570–550 Ma Charnian volcano-sedimentary complex. The latter was emplaced in a magmatic rift wedge within the juvenile continental crust of the c. 720–600 Ma Marches Terrane, a subduction magmatic domain formed at the margin of the Gondwana palaeocontinent. The Charnian magmatic arc is characterized by primitive island arc tholeiite to more evolved calc-alkaline compositions. The inversion of aeromagnetic potential field data and petrophysical modelling reveals details of the internal structure of the Charnian Domain, including a median rift, superimposed annular structures and partitioning lineaments. The modelling suggests that the arc foundation could incorporate magnetite-rich cumulates, which may explain the anomalous geophysical properties, including crustal thickness, rigidity and buoyancy. There is no evidence for significant tectonic displacement between the Charnian Domain and its Marches Terrane host. Instead, the domain likely occupies a wedge-shaped arc/marginal rift basin complex, propagated from a neighbouring ocean into the Gondwana margin. Contemporaneous volcanic rift successions in the Welsh Borderland and Wales of the 570–550 Ma Charnian magmatic phase developed in coeval ensialic rifts within less strongly extended Marches Terrane lithosphere. A comparable diversity of subduction-related magmatism is found in the Neogene–recent Hikurangi destructive margin of New Zealand, providing a plausible analogue for Charnian magmatism. Supplementary material: Supplementary Publication 1 (borehole geophysical log correlation; petrophysical data table; unannotated geophysical maps and sections) and Supplementary Publication 2 (geochemistry analytical conditions and data table) are available at https://doi.org/10.6084/m9.figshare.c.6805248

Spatio‐Temporal Variations in Sediment Delivery as a Response to Rapid Quaternary Climate Change in the Lake Malawi Rift, East Africa

AbstractThe interplay of rapid climate change and tectonics drives landscape development, sediment routing, and deposition in early‐stage continental rift systems. The Lake Malawi Rift, in the Western Branch of the East African Rift, is an archetype of a juvenile rift and an ideal natural laboratory for evaluating lacustrine source‐to‐sink systems on orbital or shorter timescales. We examine the interplay of these processes over the past 140 kyr using observations from nested seismic reflection data sets tied to scientific drill cores, which calibrate numerical forward models of this closed sedimentary system. Fault slip rates measured from seismic data drive tectonic displacements in the model. Satellite‐derived precipitation maps constrain modern precipitation and are scaled to previous hydrologic balance studies to reconstruct past climates. Our model reproduces known sediment thicknesses across the rift and accounts for 96% of the estimated siliciclastic sediment deposited over the past 140 kyr. The results demonstrate that the onset of arid climate conditions (140–95 kyr BP) causes extreme drainage adjustments downstream and the formation of mega‐catchments that flow axially into a shallow restricted paleo‐lake. Sedimentation rates during this time are twice the present values due to increased sediment focusing via these axial systems into a much smaller, hydrologically closed lake. As the climate became wetter (95–50 kyr BP), the lake rapidly expanded, decreasing both erosion and sedimentation rates across the rift. This closed‐loop approach allows us to evaluate the role of high‐frequency climate change in modulating basin physiography as well as sediment fluxes in juvenile rift systems.

Geology and sulphide geochemistry of the Ni-Cu-Co mineralisation of the Espedalen Complex, Norway: Constraints for the distribution of magmatic sulphides within a variably deformed anorthosite suite

The Espedalen Complex is located in the eastern portion of the Jotun–Valdres Nappe Complex, south-central Norway and comprises three main suites (jotunite-charnockite-augengneiss; main anorthosite–ultramafite–norite; and gabbronorite suites) formed between 1520 and 1500 Ma. The anorthosite-ultramafite-norite suite hosts Ni-Cu-Co mineralisations grouped as: i) ‘primary sulphides’ referring to undeformed occurrences with magmatic textures; ii) ‘deformed sulphides’ which include dismembered ore bodies; and iii) ‘remobilised sulphides’ which comprise thin sulphide veinlets indicating remobilisation. The ‘primary sulphides’ characterise the deposits of Dalen, Megrund, Trona, Veslegruva and Melgard, whereas the ‘deformed sulphides’ characterise the deposits of Stormyra, Storgruva, Andreasberg, Niccoline, Gråhøa, Jørstad and Grimstjønna. The largest mineralisations are the Dalen and Stormyra deposits, which host 5.3 Mt @ 0.29% Ni, 0.12% Cu and 0.02% Co, and 1.01 Mt @ 1.09% Ni, 0.48% Cu and 0.04% Co, respectively. This study provides the first systematic characterisation of the different Ni-Cu-Co mineralisations from the Espedalen Complex.Primary sulphides are typically hosted by medium-grained poikilitic olivine-orthopyroxenite, whereas deformed sulphides are hosted within shear zones, commonly within anorthosites. Primary and deformed occurrences comprise disseminated, net-textured and massive sulphides. The disseminated and semi-massive to massive sulphide ores from different localities comprise pyrrhotite and pentlandite with minor chalcopyrite. Post-magmatic sulphide alteration and recrystallisation (notably at Stormyra Deposit) are marked by variable (5 to 30%) development of pyrite, which replaces pyrrhotite-dominated masses. The remobilised sulphide assemblages are associated with retrograde silicates (e.g., chlorite and talc). Overall, primary and deformed sulphides can be divided into three main compositional groups based on metal tenors and the concentration of platinum-group elements (PGE): (i) Stormyra, Andreasberg (both deformed) and Megrund (primary) have the highest Ni and Cu tenors (7 to 8.5% and 3 to 3.5%, respectively) and no IPGE (Ir-group PGE) depletion relative to PPGE (Pt-group PGE); (ii) Dalen, Trona, Melgard (primary), Jørstad, Gråhøa and Grimstjønna (deformed) are similar regarding PGE distribution but have lower Ni and Cu tenors (4 to 5.5% and 1.6 to 3%, respectively); and (iii) Niccoline, Storgruva (deformed) and Veslegruva (primary) have comparable Ni and Cu tenors to group (ii), but are IPGE-depleted relative to PPGE (i.e. fractionated PGE distribution). The tenors vary from 0.3 to 2% Ni and 0.25 to 1.5% Cu in remobilised sulphides. Variations in metal tenors are interpreted to reflect a combination of different, but invariably PGE-depleted, parental magmas and variable R-factor regimes (R-factor varying from 350 to 700) during ore formation. The parental magmas can be modelled as the product of 15% mantle melting followed by approximately 2% crystallisation with sulphide removal, which lead to a PGE-depleted nature. Redistribution of sulphides during deformation of the Espedalen Complex seems to have taken place at large and small scales. Large-scale tectonic displacement has no major geochemical impact, whereas local remobilisation yielded sulphide veinlets with low metal tenors. We support that assessing if other geological domains, previously assigned to the Jotun-Valdres Nappe, are correlated or not with the Espedalen Complex is essential for further expanding this prospective area as these terrains could represent potential targets for Ni-Cu-Co deposits.

Topographic Response to Horizontal Advection in Normal Fault‐Bound Mountain Ranges

AbstractTectonic displacements consist of vertical uplift or subsidence, and horizontal advection. We consider the effects of tectonic advection on mountain range topography, surface drainage patterns and drainage divides. Through numerically modeling a normal fault and uplifted footwall, we find that advection promotes the elongation of catchments and reduction in outlet spacing at mountain fronts. We demonstrate an erosional disequilibrium associated with the advection‐induced transfer of mass from the proximal mountain front toward the distal mountain front. Our modeling also demonstrates the development of an erosion rate disequilibrium around fixed geomorphic features such as drainage divides, that we deem characteristic of advection. In our model, steady‐state is achieved when the divide migration occurs at the same rate as advection; advection moves topography away from the fault, meaning drainage migration becomes a mechanism for balancing advection. Topographic observations in a mountain range bound by a low angle normal fault, the Sierra la Laguna (Mexico), are consistent with our modeling results when advection is included. These observations reveal a strong influence of advection on the development of the Sierra la Laguna's topography and suggest the main drainage divide is migrating toward the fault to counterbalance advection. Tectonic advection exerts a significant control on erosion rate distribution, topographic and drainage patterns and the stability of drainage divides. This work also highlights that the Gilbert metrics and across‐divide χ disequilibrium cannot always be interpreted in terms of growing or shrinking catchments in settings with a large advection component of tectonic displacement.

Tectonic evolution of the Yangsan Fault, SE-Korea, by gravity field interpretation

SUMMARY To estimate the tectonic displacement history of the Yangsan Fault (YSF) in the Cretaceous Gyeongsang Basin (GB), SE-Korea, gravity field measurements were implemented and interpreted. A total of 8000 ground-measured gravity data were compiled and deployed to calculate the Bouguer and residual gravity field. The residual field shows that the mean value in the southern segment of the YSF is very similar to that of the northern segment, meanwhile that of the central segmentation is significantly lower than those of the other segmentations. This implies that the crustal structure and petrophysical properties of the central segment differ significantly from those of the other segments. Applying dip curvature analysis to enhance the image of the residual gravity field, we find that (1) the Gaum fault system (GF) in the western and middle part of the GB extends up to the YSF, where A-type granite outcrops are observed. (2) The middle- and eastern segments of the GF that formed before tectonic motion of the YSF are revealed in turn in areas east of the YSF, which were now covered by the younger sedimentary basin. (3) The middle segment of the GF which occupies between the YSF and the Yeonil tectonic line (YTL) has been displaced approximately 25 km southward from the main GF trace. (4) The easternmost segment is revealed buried in the eastern side of the YTL, which is displaced southward about 18 km from the main GF trace. Comparing all the available geoscientific data sets, we conclude that the right-lateral tectonic movement of the YSF, and the deeply buried middle segment of the GF remained stationary, while the most eastern segment of the GF is reversely moved to the north through left-lateral strike movement of the YTL.

Tectonic advection of contacts enhances landscape transience

AbstractContrasts in bedrock erodibility have been shown to drive landscape transience, but it is unclear whether horizontal tectonic displacements would enhance such effects. Furthermore, one might expect these factors to coexist, as tectonic convergence helps to create rock strength contrasts in settings like the Himalayas. How do landscapes respond when contacts separating units are raised vertically and shifted horizontally by tectonics? To evaluate such questions, we use landscape evolution models to simulate the exposure of a weak unit in a landscape equilibrated to a strong unit. We explore different simulations varying factors like weak unit erodibility, diffusivity, contact dip, and topographic advection rate. In these simulations, we assess the migration of the main drainage divide as well as changes in channel steepness and topographic relief within the strong unit. Our model results show that the horizontal movement of a contact does enhance drainage divide migration and increases in channel steepness, especially when the contact migrates along rivers with low drainage areas. Across all simulations, however, increases in topographic relief are minimal and temporary. Unexpected behaviors emerge in our simulations in which the mass balance of topography is influenced by horizontal tectonic displacements. For example, the exposure of the weak unit causes a gradual decline in the steepness of the strong unit. We interpret such behaviors to be artifacts related to the fixed boundaries of our domain and likely unrepresentative of natural landscapes. Instead, we focus on simulations where advection does not influence the mass balance of topography. These models show that the horizontal movement of contacts can enhance landscape transience, but this transience is marked by features one can use as diagnostic characteristics. Detecting such characteristics in natural landscapes featuring tectonic convergence would be difficult, however, due to the natural coincidence of factors such as faulting, folding, and landslides.

Выражение Марковско-Ичерской зоны дислокаций Непско-Батуобинской антеклизы в геологическом строении района Дулисьминского НГКМ

In the Nepa-Botuoba anteclise of the Siberian Platform, the Sosninsky swell-like fold-thrust structure is described that was formed, presumably, since the Late Devonian – Early Carboniferous under conditions of episodic displaying of significant tangential stresses from the southeast – i.e. from the structural heterogeneity of the Baikal-Patom highlands, which has formed in the Late Riphean. The effect of shear deformations occurred also. It is shown that tectonic displacements that were recognized along thick plastic layers of salt, caused a significant difference in the geological structure of the deformed lower-middle (supra-salt and saline) and undeformed lower (sub-salt) structural complexes of the Dulisma oil and gas condensate field.

Distribution of landforms and buried sedimentary deposits during the growth of the Aceh River delta (Sumatra, Indonesia)

ABSTRACT Fluvial and coastal landforms are indicative of landscape river delta evolution over time and provide clues for understanding coastal adjustments to sea-level and fluvial dynamics fluctuations, tectonic displacements, and extreme waves. We have mapped the surface and sub-surface footprints of fluvial and coastal geomorphological features in the Aceh River delta, northern Sumatra, using imagery dataset, vertical facies logging and helicopter electromagnetic surveys. The result is a geomorphological map at the scale of 1:75.000 which outlines the main features of the deltaic plain, including rivers, tidal and buried channels, fluvial levees, beach ridges, swales, tidal flats and lagoons. We compare their spatial distribution to the geometry of buried sediment bodies, revealed by boreholes and resistivity maps. Buried channel belts and floodplain deposits document the former locations of the distributary channels of the Aceh River. Coastal-parallel beach ridges evidence 7–8 km of asymmetric delta progradation since the mid-Holocene sea-level high stand.

Empirical predictive models for fling step and displacement response spectra based on the NESS database

The characterization of the fling-step represents a challenging task due to the shortage of near-source records with permanent tectonic displacement and the limitation in retrieving the fling-amplitude from accelerometric waveforms. In recent years, innovative ground-motion processing techniques have been developed for a more accurate estimation of both fling-displacements and spectral displacements in contrast to traditional bandpass filtering, although their application is still unusual. In this paper, we exploit the newly released dataset of the Near-Source Strong-motion records (NESS2) uniformly processed with the extended BASeline COrrection technique (eBASCO), against which we propose: (1) a new empirically-based ground motion model (GMM) for the prediction of the fling-step, and (2) an adjustment factor of the spectral displacements predicted by a reference GMM to account for the contribution of the fling-step at long periods. Such models are in agreement with observations and existing GMMs, and thus could be advantageously employed in seismic hazard analyses.

On Pole Position: Causes of Dispersion of the Paleomagnetic Poles Behind Apparent Polar Wander Paths

AbstractPaleomagnetic poles used to compute apparent polar wander paths (APWPs) are strongly dispersed, which was recently shown to cause a large fraction (&gt;50%) of these poles to be statistically distinct from the APWP to which they contributed, suggesting that current statistical approaches overestimate paleomagnetic resolution. Here, we analyze why coeval paleopoles are so dispersed, using the paleopoles behind the most recent global APWP and a compilation of paleomagnetic data obtained from &lt;10 Ma volcanic rocks (PSV10). We find that paleopoles derived from sedimentary rocks, or from data sets underrepresenting paleosecular variation (PSV), are more dispersed and more frequently displaced. We show that paleopoles based on a smaller number of paleomagnetic sites are more dispersed than poles based on larger data sets, revealing that the degree to which PSV is averaged is an important contributor to the pole dispersion. We identify as a fundamental problem, however, that the number of sites used to calculate a paleopole, and thus the dispersion of coeval paleopoles, is essentially arbitrary. We therefore explore a different approach in which reference poles of APWPs are calculated from site‐level data instead of paleopoles, thereby assigning larger weight to larger data sets. We introduce a bootstrap‐based method for comparing a collection of paleomagnetic data with a reference data set on the same hierarchical level, whereby the uncertainty is weighted against the number of paleomagnetic sites. Finally, our study highlights that demonstrating smaller tectonic displacements requires larger paleomagnetic data sets, and that such data sets can strongly improve future APWPs.

Uplift of the Tibetan Plateau: How to Accurately Compute the Hydrological Load Effect?

AbstractThe uplift state of the Tibetan Plateau (TP) is determined by tectonic displacement and hydrological load displacement. However, it is unknown how much the load effect contributes to the uplift of the plateau. Typically, the vertical displacement due to the mass load is calculated based on the Gravity Recovery and Climate Experiment (GRACE) data and the spherical harmonic analysis method. However, because the GRACE data are truncated at lower harmonic degrees and tectonic mass changes are contained in the GRACE‐derived mass changes, the validity of using GRACE data to estimate the load displacement of the TP is questionable and needs further discussion. This study presents a reasonable approach to computing the loading effect by considering the global hydrological mass budget (seawater, lake, glacier, river, snow, soil water, canopy water, and groundwater). The TP's mean vertical load displacement rate we obtained is 0.15 mm/yr, contributing to 16 percent of the average TP uplift rate. Comparing the hydrologically computed load displacements and the GRACE‐derived load displacements indicates that the GRACE‐derived displacement differs significantly from the real hydrological load displacement. That is, we found that the GRACE‐derived load effect cannot be applied to correct the Global Positioning System (GPS) displacement, but the one computed with hydrological data works well. We claim that the load displacement effect for any GPS station should be calculated by Green's function method based on global hydrological data. Finally, we present a distribution map of the valid load vertical displacement of the TP and the load displacement correction for all the collected GPS stations.

地盤変動を考慮した沿岸域の海面水位上昇量の分析方法

地盤変動を考慮した沿岸域の海面水位上昇量の分析方法

Создание карты разломов Центрально-Камышового мегантиклинория Западно-Сахалинских гор по данным космических съемок

The network of fault zones caused by vertical and horizontal tectonic displacements blocks of Earth’s crust relative to each other is clearly visible on the Earth’s surface in images obtained from satellite surveys. Many researchers distinguish linear and annular structures among the faults. Lineaments in satellite images are detected as rectilinear objects with a certain spectral brightness. The initial data for the experimental research includes images from the Landsat-8 satellite and SRTM data. The lineament analysis of satellite images and SRTM data of the Central-Kamyshovy meganticlinorium of the West Sakhalin Mountains was carried out using the functionality of the LEFA software package using the developed decryption technology. The obtained results were processed using the QGIS program tools. Statistical processing of Sakhalin lineaments was carried out on the basis of researching distribution directions of linear segments set of vector strokes data and lineaments data. The map of disjunctive disturbances of the Central-Kamyshovy meganticlinorium of Western Sakhalin Mountains on a scale 1:500 000 was compiled by basis of data obtained. The analysis of SRTM model with the help of LEFA toolkit made it possible to identify zones where discontinuous disturbances of the Earth’s crust are located. As a result of analysis, West Sakhalin fault and many other faults of a rank below 2 were identified. Fault zones are mapped on scale of 1:500 000. It was revealed that 15.3 % of all earthquakes in this area were timed to the Krasnopolsky fault, including in the zone within 1 km from the fault—70 %, 1–2 km—19 %, 2–3 km—9 %, more than 3 km—2 %. The results of work will be useful in choosing places for construction of industrial facilities, as well as for seismic zoning of territory.

Field evidence suggests that the Palaeoproterozoic Gowganda Formation in Canada is non-glacial in origin

Abstract During more than a century since its original identification, the Gowganda Formation in Ontario (Canada) has gradually been reinterpreted from representing mainly subglacial tillites to secondary gravity flow and glaciomarine deposits. The main pieces of geological evidence advanced in favour of glaciation in recent articles are outsized clasts that have been interpreted as dropstones and patches of diamictites in a single small-sized area at Cobalt which is still interpreted as displaying subglacial basal tillites. The present research considers field evidence in the Gowganda Formation in the light of more recent work on gravity flows linked to tectonics. Detailed studies have demonstrated that the clasts which are interpreted to be dropstones rarely penetrate laminae and are commonly draped by sediments the appearance of which is similar to lonestones in gravity flows. The “subglacial area” at Cobalt displays evidence of tectonics and gravity flows, which can be traced from the underlying bedrock, and then further in the overlying sequence of diamictites and rhythmites. The sum of geological features displays appearances at odds with a primary glaciogenic origin, and there is no unequivocal evidence present of glaciation. The data indicate deposition by non-glaciogenic gravity flows, including cohesive debris flows for the more compact units, probably triggered by tectonic displacements.