The Posht-e-Badam block is situated in the central part of the Central-East Iranian Microcontinent (CEIM), as part of the larger Alpine‒Himalayan orogenic system. Eocene volcanic rocks of the Posht-e-Badam block present very good exposures in the Saghand (Khoshumi Mountain), Allahabad and Chapedony areas (Yazd province, Central Iran). These Eocene volcanic rocks are basic to acidic in composition (SiO2 = 48.9 to 63.4 wt
The spatial distribution of sediment source areas and paleodrainage evolution of the Ciscaucasian Foredeep’s Neogene‒Quaternary deposits have remained contentious. Here, we resolve this debate through systematic analysis of the Upper Miocene Lysogorskaya Formation’s alluvial facies, which constrain provenance terranes via integrated paleocurrent direction (PCD) compositional data and stratigraphic position. Comprehensive representative paleocurrent datasets (n = 70) were acquired from the formation’s spectacular exposures in two deeply incised river valleys of two biggest Terek’s tributaries: The Baksan River section near village Islamey and the Cherek River section near village Aushiger (Kabardino-Balkarian Republic). These continuous, vertically-oriented outcrops display the complete stratigraphic architecture, featuring five main conglomerate units separated by minor erosional remnants of floodplain deposits. Systematic evaluation of six distinct sedimentary structure types within the formation demonstrates a predominant northeastward paleocurrent direction during alluvial deposition. This directional trend unequivocally identifies the sediment source area as the southwestern, axial zone of the Central Caucasus, directly opposing the paleoflow. The conglomerates’ composition, featuring crystalline rock fragments intermingled with sedimentary lithologies and granitoid clasts, provides definitive evidence for syn-depositional exposure of the Central Caucasus crystalline core through orogenic uplift during this period. The observed unconformities, with their north‒east-directed dips, record tectonic uplift along the south‒west margin of the depositional basin during the Miocene‒Quaternary. That uplifted zone simultaneously acted as a sediment source for the basin, as indicated by angular discordances between the Lysogorskaya Formation and the underlying/overlying sedimentary units. These findings collectively with polymictic contain and pebble-boulder dimension of alluvium establish the crystalline highlands of Central Caucasus in the south‒west as the principal sediment provenance while documenting active tectonic uplift in the Late Miocene foredeep setting.
Our analysis of the paleontological data allowed us to assess the chronology and characteristics of the formation of the Caucasian land mass and the emergence of its mountainous relief. It has been established that the origin of the Caucasian land mass occurred in the Oligocene. The studied fossil records of Caucasian land mass biota showed that it is reliably recorded in sediments beginning from the Late Oligocene. Data from the Late Middle and Early Late Miocene (13–8 Ma) bears evidence of dissected relief and the existence of altitudinal zonation. In the Late Pliocene and Early Pleistocene (3.6–1.5 Ma), the Caucasian land mass acquired the characteristics of its modern relief.
The article examines the Late Miocene deposits of the Western Ciscaucasia, represented by the Gaverdov (Belaya River) and Armavir (Kuban River) formations. Based on field and laboratory studies conducted by the authors in 2024–2025 and earlier studies, which Provided new stratigraphic, lithological, and paleontological data, as well as U–Pb dating of detrital zircon, their stratigraphic features and provenances are compared. These results allowed us (i) to refine the chronology of the geological development of the Greater Caucasus folded structure; (ii) to identify evidence of exposure of its crystalline core in the Late Miocene; (iii) to investigate the influence of neotectonic uplifts on the formation of continental sedimentary strata and the dynamics of core exposure. Our data refine and complement the thermochronology and lithostratigraphy of the study region.
Our study of the structure of Ciscaucasian local foredeeps, and in particular the study of molasses, allowed us to clarify the history of the most recent orogeny in the Greater Caucasus. The asynchronous appearance of boulder–pebble alluvium in Ciscaucasian foredeeps, corresponding to different segments of the mountain system, recorded the onset of the formation of the Caucasus mountain relief and enabled us to identify the stages of its segmental uplift: (i) pre-Sarmatian, formation of the Caucasus land mass; (ii) Sarmatian‒Cimmerian, slow collisional orogeny and formation of mid-mountain topography; (iii) Pliocene‒Quaternary, Late-collisional acceleration of uplift and formation of high-mountain topography. The crystalline core of the orogen was exposed in the Central Caucasus region during the Late Sarmatian‒Maeotian. Our study examines the role of large transverse fault zones in Caucasian orogeny and presents new structural, geomorphological, and tectonophysical data on the structure of the Pshekha–Adler and Terek–Aragvi fault zones. We have identified the Terek–Aragvi transeverse fault zone for the first time in the structure of the Greater Caucasus. In the Ciscaucasus and Transcaucasia, the identified fault zones delimit local piedmont troughs and control the distribution of the Maeotian, Pontian, Akchagylian, and Apsheronian marine basins. This article provides a data review and presents the results of study of the structure, recent kinematics, and stress-strain state of the Pshekha–Adler and Terek–Aragvi transverse fault zones.
The author studied the history of the development of the recent uplift of the Greater Caucasus. There are two stages of its development: (I) the formation of relatively low‒altitude deformational uplifts and (II) the subsequent rapid rise, which led to the transformation of these uplifts into a current high-altitude structure. Stage (I) had different duration and intensity in different segments of the Greater Caucasus. Stage (II), which appeared in the entire Greater Caucasus except for its northwestern segment (the Northwestern Caucasus), began in the Pliocene and developed with acceleration. Stage (I) began in the Oligocene with the emergence of lowland in the central segment of the Greater Caucasus. The eastern part of the central segment (the Central Caucasus) reached middle-mountain altitudes by the end of the Sarmatian epoch (Tortonian), and erosion and transportation of fragments of the Paleozoic basement rocks began in the Maeotian (7.6–6.1 Ma). In the western part of the central segment of the Greater Caucasus (the Western Caucasus), basement erosion has also been recorded since the Maeotian, but the altitudes of the Western Caucasus remained on the low-mountain level until the middle of the Pliocene. As a result of the subsequent rise of stage (II), the Central Caucasus has reached the maximum height for the Greater Caucasus (up to 5200 m), while the Western Caucasus is 1000 m lower. In the eastern segment of the Greater Caucasus (the Eastern Caucasus), the beginning of stage (I) is recorded in the Middle Miocene ( 20 Ma), but the uplift of the Eastern Caucasus remained low-mountain until stage (II), during which, especially in the Quarternary, the Eastern Caucasus rose faster than the Central Caucasus, reaching the average height of the summit surface almost 4000 m. The first signs of exhumation of the Northwestern Caucasus are dated to 10–8 Ma. At the end of the Miocene, this segment underwent deformation, which led to uplift up to 1400 m high. Ongoing deformation combined with advanced erosion had kept the summit surface at heights of 1000 m. There are no signs of uplift of the stage (II) type in the Northwestern Caucasus. The intensive uplift of the central segment of the Greater Caucasus is due to the thickening of its crust as a result of the under-thrusting of the continental crust of the edge of the Scythian Plate under the segment in the Late Paleozoic. In other segments of the Caucasus, the edge of the Scythian Plate was probably sub-oceanic, and its subduction did not affect the intensity of uplift. The consequences of the thickening of the crust of the Central Caucasus were: (i) its uplift in the Cimmerian epoch, which led to the erosion of the Lower-Middle Jurassic cover, (ii) the reduced thickness of subsequent marine sediments, (iii) the early occurrence and relatively high altitudes of the stage (I) uplift. The intensification of upward movements in stage (II) may be due to the penetration of a decompressed sub-lithospheric flow from the African superplume under the Central Caucasus. Later, this flow spread under the Western and Eastern Caucasus, causing their accelerated uplift.
The article presents the results of study and substantiating the age (SHRIMP II, LA-ICP-MS) of Paleo- and Mesoproterozoic sedimentary and volcanosedimentary complexes of the Ulutau Terrane to west of Central Kazakhstan. Paleoproterozoic formations are represented by quartzites and schists of the Kumola Formation with a maximum sedimentation age 2.03 Ga. These formations, including the terrigenous strata of the Chuy–Kendyktas and Issyk-Kul terranes, mark the oldest stage of accumulation of mature sedimentary strata in the western part of the Central Asian belt, associated with the opening of rift basins within the Nuna Supercontinent during the post-collisional stretching stage. The Mesoproterozoic formations include the bimodal volcanic-sedimentary association of the Zhiide series ( 1326–1367 Ma), which is associated with the Ectasian stage of rift magmatism that accompanied the breakup of the Nuna supercontinent. The data obtained suggest that in the Paleo- and Mesoproterozoic, the Ulutau Terrane, the Tarim Craton, and the Yangtze Craton had a similar evolution related to intraplate tectonomagmatic processes in the western and northwestern parts of the Nuna Supercontinent.
The article discusses the structural and tectonic features of the Riphean–Vendian section of the Kama-Belsky Trough. It is shown that its formation is determined by the layered-block (up to a depth of 3500 m) and block (at a depth of more than 3500 m) geofiltration structure of the Proterozoic section. Based on an analysis of the lithological composition of the deposits of the Kama-Belsky Trough, the following were identified: (i) regionally developed lateral conductive strata, (ii) low-permeability strata with subordinate development of reservoirs, and (iii) subvertical permeable zones. Moreover, well-defined potentially lateral conductive strata have been identified in the Riphean (Rotkovsky, Tukaevsky, and Leonidovsky formations) and Vendian (Baikibashevsky (Kykvinsky) formation) deposits. Based on the results of laboratory studies of 1600 core samples, a range-based assessment of the filtration and capacity properties of the most typical lithotypes of Proterozoic rocks was performed. A comprehensive assessment of the filtration and capacity properties of rocks was conducted, including (i) empirical dependences, (ii) the fractional lithological composition of objects, and (iii) the analysis of lithotypes taking into account the layered-ordered and layered-disordered structures. To carry out modeling of migration-accumulation processes in the factor-range formulation, expert parameters of permeability for various lithotypes of rocks are introduced. The assessment of the weighted average permeability and the comparison of the calculation results are carried out on the basis of the sections of individual wells with the subsequent generalization for the territorial zones of the Kama-Belsky trough. As an example, the calculation of the permeability range of geofiltration elements for a model of layered-ordered and layered-disordered lithological structure of the formation based on the data from the Arlansky-7000 well is presented.
Tectonophysical zoning of active faults according to the level of Coulomb stresses for the Altai‒Western Sayan region has been performed. The source of stress data is earthquake focal mechanisms and a modified algorithm for cataclastic analysis of discontinuous faults, implemented in the new computer program STRESSseism_v.3.0. Based stress reconstruction results, the kinematic types of regional faults and angles of their dip in the upper crust (5‒15 km) have been refined. Five zones have been identified with fault systems having a high level of Coulomb stresses with the length of hazardous fault sections exceeding 50‒70 km. The result is considered a deterministic long-term prediction of the preparation zones for strong earthquakes with magnitudes Mw ≥ 6.5‒7.0 and possibly higher.
The studies of the structural-formational zones of the paleoceanic sector of the Southern Urals were conducted. The formation sequence of mesostructural parageneses was established, allowing us to reconstruct the structural evolution of the region and develop a new model based on the metamorphic features of the East Ural megazone, in which the megazone is part of the Magnitogorsk island-arc system. The Magnitogorsk island arc is partially ensialic and partially is ensimatic. In the structural evolution of the paleoceanic sector of the Southern Urals during Middle-Late Paleozoic collisional events, deformation stages D1 and D2 were identified. The first stage of deformation, D1, was expressed in the formation of west-vergent isoclinal folds in the west of the Magnitogorsk megazone and east-vergent folds in its east. In the East Ural megazone, southeast- and west–southwest-vergent folds formed during the D1 stage. The D1 stage marked the oblique sinistral collision of the Magnitogorsk island arc with the margin of the Baltica paleocontinent at the end of the Devonian. As a result of deformations occurring under sinistral transpression, a bivergent “palm tree” structure formed in the Southern Urals during the D1 stage, with the formation of west-vergent F1 folds (in the Aktau–Tanalyk zone) and east-vergent folds (in the eastern West Magnitogorsk and East Magnitogorsk zones), as well as southeast- and west–southwest-vergent folds (within the East Ural megazone). The second stage of deformation, D2, was associated with the Late Paleozoic Ural intercontinental collision at the end of the Middle Carboniferous–Permian. Stage D2 marked the completion of the Main Ural Fault zone and the formation of northwest-vergent F2 folds in the Aktau–Tanalyk zone. Stage D2 includes the formation of west- and northwest-vergent folds in the East Mugodzhar megazone and all structures of the Trans-Ural megazone. The formation of Late, predominantly sinistral strike-slip folds with steeply dipping hinges corresponded to the stage of postcollisional strike-slip movements that completed the structural and geodynamic evolution of the Ural Paleoocean.
The Paleogene back-arc basin tectonic evolution of NW Iran is closely related to the tectonic activities in the Lesser Caucasus and neighboring region. During this period, the region experienced significant tectonic, magmatic and metamorphic activities, including the formation of ortho-amphibolites. Amphibolites from NW Iran are located between three main suture zones: (i) the Sevan-Akera suture zone in Armenia, (ii) the Bitlis-Zagros suture zone in Türkiye, and (iii) the Zagros suture zone in Iran. They are spatially associated with various magmatic intrusions of the Shahjahan batholith. These amphibolites have an igneous protolith, primarily consisting of plagioclase and hornblende as the main mineral phases, along with rutile and opaque minerals as accessory phases. Based on whole rock, major, and trace element geochemistry, the protolith of the amphibolites formed from a sub-alkaline basalt to andesite basalt magma with tholeiitic affinity. This magma originated from high partial melting (more than 10
The Neybaz Metamorphic Core Complex (NMCC), situated in the West Central Iranian Microcontinent, is a high-grade metamorphic zone composed of diverse lithologies ranging from Precambrian to Cenozoic in age. It has undergone multiple deformation phases, evidenced by tight isoclinal, overturned, and recumbent folds, boudins, fold interference patterns, and significant variation in fold geometry. The region displays signs of both compressional and extensional tectonics: intense folding and thrusting reflect contraction, while boudinage indicates extension. Shear-related fabrics such as sigma- and delta-structures and sheath folds further suggest concurrent shearing. Quantitative fold analysis reveals an average shortening of 72.43
The Kohat-Potwar fold-and-thrust belt in Pakistan extends over 250 km along the Himalayan fold-thrust system. The Potwar fold-and-thrust belt is bounded by the Main Boundary Thrust (MBT) to the north, the Kalabagh fault to the west, the Jhelum fault to the east, and the Salt Range thrust to the south. The Kohat fold-and-thrust belt, part of the sub-Himalaya in northwestern Pakistan, formed due to the Indian‒Eurasian plate collision. In our study the inverted structures in the Kohat-Potwar fold-and-thrust belt through structural restoration, were identified and analyzed. Using 2D MOVETM (2018.1) software, two seismic lines from the Potwar area and two seismic lines from the Kohat area were restored, incorporating 2D seismic data with pre-stack depth migration, subsurface geological data, and structural modeling. The analysis reveals that the Indian‒Eurasian collision caused significant uplift, driven by tectonic inversion and basement rock push, leading to back thrusts, fault-propagation folds, and pop-up structures. Seismic section restoration highlights the unfolding of the footwall block, identifying null points and revealing positive inversion during the Late Jurassic in the Potwar area and the Late Permian in the Kohat area. Reactivated normal faults from these periods were confirmed through back restoration techniques. This research enhances understanding of the tectonic processes in the region and provides a geological framework for future hydrocarbon exploration.
The Du Toit–Andrew Bain–Marion–Prince Edward transform fault system separates two parts of the Southwest Indian Ridge that differ in structure and development. The change in extension direction significantly affected the structure of the transform faults, when in the period 69–52 Ma it was successively undergone to transtension and transpression, forming multiple bends in its fault zones. A physical modeling was used to identify the conditions of structural changes and the evolution of the transform fault during this period. It was experimentally shown that a complex structural pattern could only have formed under certain combined conditions, the most important of which are (i) the obliquity of the transform fault system to the extension direction, (ii) the length of the fault segments, and (iii) the ratio of the fault segment length to the spreading segment length. The experimental results suggest the evolution of fault zone bends as a transtensional duplex, which is confirmed by the long existence of the structure and its self-development. Almost identical results were obtained under transpressional conditions, in which the multitransform system gradually turns into a single oblique transform fault influenced by a gradual decrease in the length of intertransform spreading segments. The possible formation of intertransform ridges observed within the Andrew Bain Fault Zone, which remained as a result of the rotation of lithospheric blocks, was shown in two experimental series. Sharp structural and kinematic changes in the fault zone may be the result of a major regional tectonic reorganization during the India-Eurasia collision.
The March 28, 2025 Mandalay Earthquake, with a magnitude Mw = 7.7 and its epicenter near the city of Mandalay, occurred within the zone of the major N‒S-trending active right-lateral Sagaing Fault. The earthquake generated a seismic rupture zone that extended mainly southward from the epicenter along this fault. Using radar interferometry and subpixel correlation of satellite imagery, the authors determined the parameters of the rupture zone. Its length is 460 km, with right-lateral displacement reaching the maximum observed amplitude of 5.8 m. Given the hypocentral depth of 10 km, the seismic ruptures can be considered the surface expression of the earthquake source. The Sagaing Fault is associated with the ophiolite belt of Myanmar, which represents relicts of the Mesotethys paleocean, displaced by Cenozoic tectonic movements. In northern Myanmar, where the Mandalay earthquake occurred, the ophiolite belt functions as the magmatic component of the submeridional northern segment of the Sunda island arc, beneath which the Indian Plate is subducting in the north-northeast direction. While the subduction surface is gently dipping near the front of the Sunda Plate, it experiences steep subduction further to the east. The Sagaing Fault lies above the eastern flank of the region of steep subduction of the Indian Plate. Beneath the region lies a mantle plume that reduces lithospheric thickness and causes softening of the lower crust. We suggest that the increased extent of the rupture zone of the Mandalay earthquake is due to the plasticity of the ophiolitic substrate, which facilitates rock slip, while the shallow depth of the hypocenter is related to the softening of the lower crust and upper mantle under the influence of the mantle plume. The significance of these factors is confirmed by comparing the Mandalay earthquake with the strongest earthquakes in Eastern Anatolia over the past 80 years, which occurred under similar tectonic conditions. These factors should be taken into account when assessing seismic impacts of major earthquakes.
In this article, we constructed a numerical model of the stress state of the Earth’s crust of the We-stern Tien Shan microplate to use as additional parameter for machine learning. An alternative to the deep learning models could be a neural network based on the Kolmogorov–Arnold general approximation theorem (KAN). What distinguishes a KAN from existing machine learning networks is its interpretability, i.e., the ability to explain the “logic” of the model’s operation and high accuracy in complex physical processes. In contrast to conventional networks, a KAN requires only one or two layers to obtain a solution to the problem, which significantly reduces computing power. Using the KAN algorithm, we have constructed for the first time a neural network for classification and regression applied to the medium-term earthquake prediction in the Western Tien Shan microplate. The results obtained allowed us to predict the locations of possible earthquakes with a magnitude of 5 > M < 6 in environs of the city Tashkent (the capital of the Republic of Uzbekistan). The performed retrospective analysis of strong earthquakes that occurred in 2024 within the West Tien Shan microplate showed that the developed model predicts the locations of earthquakes with a magnitude of M < 6 with an accuracy of geographic coordinates of ±0.1° N, ±0.1° E and a magnitude of ΔM = ±0.4.
Based on results of structural studies using the structural–paragenetic and cataclastic methods of disjunctive deformation analysis of the Altai‒Sayan and Western Sayan region that formed the Altai‒Sayan fold region, a complex structure of the stress field of the neotectonic stage was revealed. The lateral structural heterogeneities of the region determibe sihnificant variations in the stress field with the prevalence of a general shear deformation setting. In the study region, the submeridional direction of maximum horizontal compression is most clearly expressed. The manifestation of compression transversely and longitudinally to local and regional structures in which the orientation of the Paleozoic structural plan significally dominate, was also established. We consider the reason for the complex tectonics and geodynamics of the Altai‒Sayan fold region is in the activation of the Paleozoic disjunctive structures of the Alpine stage.
The article presents the results of structural studies in the areas of distribution of fold structural complexes that formed the main structural-formational zones of the paleocontinental sector of the Southern Urals. The sequence of formation of mesostructural parageneses of these complexes is considered, and the Middle-Late Paleozoic structural evolution of the study region is determined. Structural evidence of the previously assumed existence of the united Sakmara‒Kraka allochthon is obtained. The three stages of deformation, which are distinguished in the Hercynian deformation history of the Southern Urals region, are established. At the first stage of deformation (D1), the formation of F1 folds of southeastern and (rarely, northwestern) vergence occurred. Stage D1 is associated with the oblique left-lateral collision of the Magnitogorsk island arc with the margin of the Baltica paleocontinent. The second stage of deformation (D2) is marked by the formation of F2 folds and associated thrusts of western and southwestern vergence. Stage D2 is associated with the movement of the Sakmara‒Kraka allochthon in the western direction. At the third stage of deformation (D3), the formation of F3 folds and cofold thrusts of eastern and northeastern vergence occurred. Stage D3 is due to the processes of back thrusting, which occurred under conditions of sublatitudinal compression directed from east to west, when the package of allochthonous plates did not shift to the west. At the final stage of deformation, left-lateral folds with steeply dipping hinges were formed, which corresponds to postcollisional strike-slip movements. That stage completed the main phase of structural evolution of the Southern Urals region.
Selecting the most appropriate method to determine the relationship between mineralization and fractures in tectonized deposits is the main goal of many exploratory studies. In the present approach, 2D and 3D modeling of surveyed faults at the variety of levels performed to study the relationship with mineralization, qualitatively and quantitatively. The Emarat Pb‒Zn deposit located in the Markazi Province (Iran) explored by underground tunnels at the various elevation levels with a total length of 11 000 m, is our case study. To achieve the purpose we studied a complete statistical status of the faults (i); 2D strike-and-dip map with rose-diagram and 2D grid-based map were drawn (ii); 3D strike-and-dip diagram and solid model of the faults from the various levels were drawn (iii); the different mathematical algorithms applied in geosciences, were analyzed (iv); a stratified iso-grade map of total Pb‒Zn for the different levels was produced (v). The qualitative comparison of 2D grid-based maps and iso-grade maps for each level peer to peer, shows that in general, at the various levels orientation of mineral deposit follows the faults frequency but this factor has not much effect on the deposit grade. The linear determination coefficient between the faults frequency and deposit grade at the different levels obtained 0.4 on average, equaling to “medium” correlation. The results of the quantitative correlation at various levels, confirm the results of the qualitative correlation. The results of performed research are useful to find lost veins or layer of the deposit during the exploitation operation.
