Anticlinal Folds Research Articles

Active Tectonics and Paleoseismicity of the Eastern Issyk-Kul Basin (Kyrgyzstan, Tien Shan)

Abstract—The Malyi Orgochor, Orgochor, Birbash, Sukhoi Ridge, Ichketosma, and Tosma uplifts in the eastern Issyk-Kul basin are fault-related anticlinal folds composed of Neogene and Quaternary sediments involved in tectonic movements. The folds have asymmetric transversal profiles, with low-angle southern limbs and steep northern limbs cut by segments of the South Issyk-Kul and Karkara reverse faults reactivated in the late Quaternary. The location and geometry of the two faults, which both show reverse and left-lateral strike slip components, correspond to neotectonic propagation of deformation from the Terskey-Ala-Too Range over almost the whole eastern Issyk-Kul basin. Judging by primary and secondary coseismic surface deformation in the area, the South Issyk-Kul and Karkara faults repeatedly generated large earthquakes (M ≥ 7, I ≥ 9) in the Late Pleistocene and Holocene. According to trenching results, the historical earthquakes that occurred in the first and 10–11th centuries accommodated motions on the South Issyk-Kul fault. The new seismotectonic and paleoseismicity data from the eastern Issyk-Kul basin provide updates to its seismic potential.

GEOLOGICAL STRUCTURE OF A SEGMENT IN THE CHORNA TYSA RIVER BASIN (UKRAINIAN CARPATHIANS), A HIGH-POTENTIAL SITE FOR RECREATION AND TOURISM

The segment has a rather complex geological structure. The Svydovets massif is characterized by a complex division of structural overthrust sheets – Dukliansky, Porkuletsky and Chornohirsky overthrusts. The northern part of the site is located in the Slavsko-Verkhovynsky subzone of the Krosno zone. The Dukliansky overthrust represents Svydivets and Blyznytsia subzones, the Porkuletsky overthrust represents the Luzhansky subzone, and Chornohirsky – Yalovychorsky or Hoverliansky subzones. Each overthrust sheet shows the presence of ridgelike anticlinal folds that are deformed by thrusts and faults in fold parts. The Krosno zone is blocked by the thrusts of the Dukliansky and Chornohirsky overthrust sheets. A significant area within the study segment is occupied by the Inner Gorgans (near the water divide), which are confined to the raised base of the Silesian sheet, where the Gorgan folds were formed. The main morphostructural element is the massive Bratkivsky ridge, whose structure is dominated by resistant rocks of the Paleocene and Eocene, in particular the sandstones of the Yamna and Vyhodsky suites. The territory of the Chorna Tysa basin upper part is located in a seismic zone where resonant earthquakes of magnitude 4-6 periodically occur. Slow tectonic movements in this area are +1.5 –2.0 mm per year. Apart from analyzing the geological structure of the Chorna Tysa basin segment, which is a promising area for recreation and touristic development, this paper aims to outline the possibilities of using the geological structure and relief to develop educational forms of tourism, including geotourism. It is most often the geological structure (tectonics, diversity of rocks, long history of geological development, formation of mountain relief, etc.) that creates attractive sites – picturesque landscapes, outcrops of rocks, peaks, relict landforms, waterfalls, gregots, i.e., massive rock stream accumulation, and others). It can thus be concluded that the geological structure is crucial in forming promising tourism and recreation proposals and in the development of prospective infrastructure. Therefore, it is imperative to keep in mind the geological structure and landforms, when planning the development of recreation and tourism. Key words: geological structure (tectonics and lithology); landform, recreation and tourism; geotourism; geotourism attractions; Chorna Tysa; Ukrainian Carpathians.

Regularities of variability of methane content in the coal layers of the Western Donbass

The article considers the factors that contribute to the accumulation and preservation of methane in the coal seams of the Western Donbass. Mines of the district develop lower and middle carbon bituminous coal. It is characterized by a low degree of catagenetic transformations, increased collector properties. Regional regularities of change of methane bearing capacity of coal seams and content of free methane in them are established. In tectonic terms, the area is a monoclinal with domed and brachyform local structures associated with rupture. Methane-bearing anomalies, in turn, are associated with the vaults of such structures, both anticlinal and synclinal types. When bending into the anticlinal fold, the fracture of the rocks increases in the upper part of the formation, which increases their filtration rates. Roof rocks are characterized by high permeability and this leads to degassing of the anticline fold. During the formation of synclines, fractured zones are formed in the bottom of the coal seams and the screen for methane migration becomes directly the coal seam, which contributes to the preservation of methane in such structures. As a result, local synclines mostly have positive methane and free methane content and local anticline bends are mostly negative. It is established that the methane reservoirs in the study area are coal seams, argillites and siltstones with high reservoir properties, which are located in the vaults of plicative structures. The established patterns will improve reliability of the forecast of methane accumulations within coal deposits Keywords: methane bearing capacity, local folding, syncline structures, free methane, reservoir properties.

Западная часть Терско-Каспийского прогиба как зона разгрузки глубинных флюидных систем

The article describes the mechanisms of formation of the Terek and Sunzha anticlinoria as the main zones of oil and gas accumulation. An assumption is made about the formation of high-amplitude anticlinal folds in the Upper Cretaceous deposits as a result of vertical migration of high-pressure fluids along deep faults with a breakthrough of their upper horizons of the sedimentary cover into the late orogenic phases of folding. The main prerequisites for the deep genesis of oil and gas are listed – a pronounced unevenness in the distribution of hydrocarbon accumulations, abnormal pressure, hydrochemical anomalies.

On the stratigraphy and tectonics of Zilair synclinorium of the Urals

The purpose of the work was to study the tectonic structure of the Zilair synclinorium of the Western slope of the southern Urals, which is important both from the general scientific point of view and for the needs of oil and gas prospecting of the territory. The main method of research was a detailed study of the stratigraphy of key sites with the search for conodonts in siliceous rocks. We also used data from seismic profiling of the territory. Result of work. The Zilair synclinorium of the southern Urals is an asymmetrically different facies structure; its Western and Eastern wings are composed of deposits belonging to different facies zones – the shelf (neritic) in the West and the continental slope and rise (bathyal) in the East. In the axial zone of the synclinorium, among the Famennian graywacke deposits of the Zilair series, several sites composed of cherts are known. It was believed, that the cherts are of Silurian age and are the klippes of a very large overthrust belonging to the ophiolite association. According to occurences of conodonts, we have established that all these cherts have Devonian, mainly Frasnian age. They are not klippes of an overthrust, but the central parts of the anticlinal folds, complicated by steep thrusts. According to our data, the real overthrust with a great horizontal amplitude is Pokrovsky, where two facial zones come into an abrupt contact without any transition between them.

Geophysical implications for the exploration of concealed orogenic gold deposits: A case study in the Sandy Lake and Favourable Lake Archean greenstone belts, Superior Province, Ontario, Canada

Since 2000, gold discovery rates have not reflected the record levels of exploration expenditure, with those discoveries that are made being predominantly in areas of post-mineral cover. Hence, gold exploration has been increasingly focused on concealed exploration targets where geophysics takes on an increasingly important role in the exploration process.Archean orogenic gold deposits are attractive exploration targets that represent a major proportion of global gold resources. Orogenic gold deposits consistently form late during the tectonic and structural evolution of their host terranes, normally during a transition from compressional to transpressional tectonic stress regimes. Thus, for target generation, the late timing of gold mineralization within the structural history of a prospective orogenic belt is crucial, as it means that current geological maps and sections reflect the geometry of the gold deposits at the time of formation unless there has been subsequent orogeny. Lithological contacts between granitic intrusions and volcano-sedimentary greenstone sequences, as well as between volcanic and sedimentary sequences, are important rheological and geochemical trap sites. Lithosphere-scale faults and dilational jogs in second-order faults act as ore-fluid conduits with anticlinal folds as structural traps for ore-fluid infiltration and gold deposition given suitable host rocks and fluid seals.Geophysical exploration for concealed orogenic gold deposits is challenging due to normally subtle petrophysical contrasts between the gold lodes and their host rocks. Most greenstone-hosted lode-gold deposits do not contain strong conductors as they normally contain <5 vol% of disseminated arsenopyrite and pyrite, which are poor conductors, and rarely contain significant quantities of strong conductors such as pyrrhotite. However, pyrrhotite may be a component of rock sequences such as sulfidic shales or cherts adjacent to the orogenic gold lodes. It is proposed that the combination of HTEM and magnetic surveys be used to explore for concealed orogenic gold deposits, using the Favourable Lake and Sandy Lake greenstone belts in the Superior Province, Canada, as a case study. AIP Cole-Cole time-constants, combined with magnetic and EM data, can efficiently detect disseminated pyrite/magnetite at shallow depths, indicating their potential use as vectoring tools for concealed Archean orogenic gold deposits.

Morphological features of ore reserves of the Novo-Uchaly vms deposit (Southern Urals)

Background. The Novo-Uchaly copper-zinc VMS deposit in the Southern Urals (54°10΄54˝N and 59°20΄45˝E) is represented by a steeply dipping lens of Eifelian volcanics (rhyodacites and basalts), which are crumpled into a strongly compressed anticlinal fold. The ore deposit is blind and localised at the convergence of felsic (bottom) and mafic (top) rocks. The deposit is located at depths of 550 m (in the northern part) and 1050 m (in the southern part). The deposit thickness reaches 186 m. The length along the strike and along the dip equals 1250 m and 900 m, respectively. The ore body is intruded by gabbro-diorite and gabbro-diabase dikes. The main ore minerals are pyrite, sphalerite and chalcopyrite, as well as non-metallic minerals, such as quartz, barite and calcite. Unlike most of the Ural VMS deposits, this deposit is the zinc subtype (Zn &gt;&gt; Cu). The ores are predominantly massive and solid sulphide, being banded or brecciated in some parts. The main elements extracted are copper, zinc and sulphur, but gold, silver, cadmium, indium, cobalt, nickel, selenium and tellurium are also obtained.Aim. To clarify the morphology of the ore deposit, to study the ore mineral composition of the upper horizons of its northern part and to determine the underlying reasons for the complex lenticular structure of the sulphide reserve.Materials and methods. In the period 2017—2019, employees of the Institute of Ore Deposits, Petrography, Mineralogy and Biochemistry of the Russian Academy of Sciences (IGEM RAS) together with geologists of the Uchaly Mining and Processing Plant carried out a geological and mineralogical mapping of the deposit in the course of exploration works.Results. The ore contours and mineral composition of the northern part of the ore body were significantly clarified. A series of dikes of variable morphology was identified. A comparison was made of the results with current theories about the structure of the ore deposit. Detailed geological sections were determined and illustrate the complex lenticular structure of the ore deposit complicated by pinch and swell areas. The deposit was formed by processes of dynamic metamorphism.Conclusion. The geological and mineralogical structure of the deposit determined in the study enabled us to propose a schematic reconstruction of the conditions leading to the formation of its folded structure. The findings will help to re-assess the reserves and improve the system of operational exploration and delineation.

Geological structure and tectonic evolution of the Ukrainian sector of the Black Sea

The entire Ukrainian sector of the Black Sea, which occupies its northernmost part, was studied with the interpretation of the post-1990 seismic reflection data along seismic lines having a total length of some 30 000 km. In the northern Black Sea relatively low extension of the continental crust occurred in Albian-Cenomanian times and did not cause formation of deep (sub)-oceanic basins. Rift faults formed three major rift basins. One of the ENE-WSW oriented rift basins occupied areas of the present-day Karkinit Through, Krylov-Zmiiny Uplift, Gubkin Ridge and Sulina Depression within the Odessa Shelf. Another ENE-WSW oriented basin included areas of the present-day Tetyaev High, Sorokin Trough, Crimea Mountains and Marine Continuation of the Crimean Folds. The NW-SE oriented major rift basin occupied areas of the present-day Andrusov Ridge, Eastern Black Sea Basin, Shatskiy High and Euxinian Graben. Passive, thermal (post-rift) subsidence lasted in Turonian—Middle Eocene times and occurred in marine basins with a water depth that did not exceed a few hundred meters. A strong regional compression at the end of the Middle Eocene interrupted the post-rift (thermal) subsidence of rift basins, strongly deformed the sedimentary cover and formed a large NW-SE oriented landmass. This onshore terrain occupied the central and southern parts of the Odessa Shelf and the Crimean Peninsula, and deep-water area, including the Euxinian Graben, Marine Continuation of the Crimean Folds, Sorokin Trough, Tetyaev High, Andrusov Ridge, Shatskiy High and Eastern Black Sea Basin. Up to 5 km of sediments were eroded during the time of the existence of the emerged onshore terrain. Two subsequent S—N compressional events occurred at the end of the Late Miocene and invoked folding and thrusting of the sedimentary sequences in the originally ENE-WSW Cretaceous rift basins mainly. Anticlinal structures on the Odessa Shelf underwent additional growth and numerous new anticline folds were generated on the margins of the Western Black Sea Basin, including the Sorokin Trough and Marine Continuation of Crimean Folds. During both Late Miocene compressional events broad landmasses arose across the northern Black Sea region. These onshore terrains ran in a roughly E-W direction and occupied the present-day shallow shelves and northern part of the current deep water as well as almost the whole Crimea Peninsula. Like the Late Eocene landmass, the Late Miocene onshore terrains were evidently a source of sediments into marine basins that surrounded them. The first Late Miocene compression probably coincided in time with the Messinian Salinity Crisis and it was apparently accompanied by a sharp fall of the sea level. Prior to the second Late Miocene compressional event the sea level had risen sufficiently that a considerable part of the Odessa Shelf and other parts of the middle Pontian landmass were covered, at least periodically, by a shallow sea. The present-day deep-water part of the study area began to subside rapidly in the Pliocene. The mechanical response to this rapid subsidence appears to have reactivated normal faulting of the previously inverted south-dipping rift faults along the coast of the Crimean Mountains and in the eastern part of the Euxinian Graben during the Pleistocene and possibly Holocene. The very rapid subsidence and lack of sedimentary supply led to sub-oceanic water depth in the Western and Eastern Black Sea basins that had previously developed as relatively shallow seas.

Seismic Deformations in the Archeological Monuments of Mugkala and Mugtepa (Fergana Depression, Uzbekistan)

The article provides data on the geological, tectonic, and seismological situation of the region. Results of archeoseismological field studies of the ancient fortress and castle of Mugkala and Mugtepa in the Fergana Valley (Namangan region, Uzbekistan) are considered. At the archeological sites, we revealed such characteristic destruction and damage as wedges, inclinations, shaking, sagging, and extend through cracks and interbrick cracks in city walls, confirming their seismogenic origin. Similar seismic deformations can be considered as evidence of the high local seismic oscillation intensity. It was noted that seismic shocks propagated along the sublatitudinal axis. Both the Mugtepa and Mugkala archeological sites are located between the North Fergana Fault and North Fergana flexural-fracture zone. The seismicity of the research area is associated with the development of the Kasansay group of young Quaternary anticlinal folds. A new residence on Mugtepa could have been built by new kings of the Fergana Valley at the end 1st century BCE, which was destroyed in the 1st century CE by a strong earthquake with a local seismic intensity of IL = VIII–IX (MSK-64 scale). The residence of the Turkic Khaganate could have been built by new kings of Fergana Valley in a new location. Mugkala could also have been destroyed by a strong earthquake with a seismic intensity of IL = VIII–IX (MSK-64 scale) at the end of the 8th century CE. This earthquake caused the various deformations described in the paper.

Geology, Tectonics and Stratigraphy of the Construction Site of the New Bushehr NPP Units in the Islamic Republic of Iran as Part of Recent Geotechnical Studies

Southern Iran in the area of Zagros and the borders of the Arabian and Eurasian plates is a seismically active territory in which large industrial facilities are located, including Bushehr NPP. In this regard the relevance of studying modern geodynamics and geology of the region is understandable. The geological structure of the territory after engineering surveys of 1974-2001 no longer seemed questionable. However, after completion of engineering surveys for new NPP units in 2015, new views on some positions on seismotectonics, and later on the geology of the area, appeared. The article provides information about the geology, tectonics and stratigraphy of the region and the research area, including not covered earlier in domestic reporting materials and scientific articles, and also considered the possible reasons for the appearance of other interpretations regarding seismotectonics and geology of the area where the NPP site is located. A brief analysis of the research results, both previously completed and completed relatively recently, is presented. An additional argument is considered in favor of the presence of fault zones within the Bushehr anticline proposed by Iranian researchers. In particular, the Khark-Mish fault supposed by them may be part of the buried ancient anticlinal fold before the position of its axis changes in the modern period as a result of neotectonic processes common to the region as a whole. The geology and tectonics of the Bushehr anticline are compared with similar structures on Fr. Hark and the nearest islands. Updated information on the stratigraphy of individual geological formations of the region and the research area is also provided. In spite of the reasoned justification of various positions on the geology and tectonics of the region, it seems necessary to conduct a number of additional special direct and indirect studies aimed at ensuring the safety of the Bushehr NPPs under construction and operating.

Compressional origin of the Aegean Orogeny, Greece

The Aegean Sea area is thought to be an actively extending back-arc region, north of the present day Hellenic volcanic arc and north-dipping subduction zone in the Eastern Mediterranean. The area shows extensive normal faulting, ductile ‘extensional’ shear zones and extensional S-C fabrics throughout the islands that have previously been related to regional Aegean extension associated with slab rollback on the Hellenic Subduction Zone. In this paper, we question this interpretation, and suggest the Cenozoic geodynamic evolution of the Aegean region is associated with a Late Cretaceous–Eocene NE-dipping subduction zone that was responsible for continent-continent collision between Eurasia and Adria-Apulia/Cyclades. Exhumation of eclogite and blueschist facies rocks in the Cyclades and kyanite-sillimanite grade gneisses in the Naxos core complex have pressures that are far greater than could be accounted for purely by lithospheric extension and isostatic uplift. We identify four stages of crustal shortening that affected the region prior to regional lithospheric extension, herein called the Aegean Orogeny. This orogeny followed a classic Wilson cycle from early ophiolite obduction (ca. 74 Ma) onto a previously passive continental margin, to attempted crustal subduction with HP eclogite and blueschist facies metamorphism (ca. 54–45 ​Ma), through crustal thickening and regional kyanite – sillimanite grade Barrovian-type metamorphism (ca. 22–14 ​Ma), to orogenic collapse (<14 ​Ma). At least three periods of ‘extensional’ fabrics relate to: (1) Exhumation of blueschists and eclogite facies rocks showing tight-isoclinal folds and top-NE, base-SW fabrics, recording return flow along a subduction channel in a compressional tectonic setting (ca. 50–35 ​Ma). (2) Extensional fabrics within the core complexes formed by exhumation of kyanite- and sillimanite gneisses showing thrust-related fabrics at the base and ‘extensional’ fabrics along the top (ca. 18.5–14 ​Ma). (3) Regional ductile-brittle ‘extensional’ fabrics and low-angle normal faulting related to the North Cycladic Detachment (NCD) and the South(West) Cycladic Detachment (WCD) during regional extension along the flanks of a major NW–SE anticlinal fold along the middle of the Cyclades. Major low-angle normal faults and ductile shear zones show symmetry about the area, with the NE chain of islands (Andros, Tinos, Mykonos, Ikaria) exposing the NE-dipping NCD with consistent top-NE ductile fabrics along 200 ​km of strike. In contrast, from the Greek mainland (Attica) along the SE chain of islands (Kea, Kythnos, Serifos) a SW-dipping low-angle normal fault and ductile shear zone, the WCD is inferred for at least 100 ​km along strike. Islands in the middle of the Cyclades show deeper structural levels including kyanite- and sillimanite-grade metamorphic core complexes (Naxos, Paros) as well as Variscan basement rocks (Naxos, Ios). The overall structure is an ~100 ​km wavelength NW–SE trending dome with low-angle extensional faults along each flank, dipping away from the anticline axis to the NE and SW. Many individual islands show post-extensional large-scale folding of the low-angle normal faults around the domes (Naxos, Paros, Ios, Sifnos) indicating a post-Miocene late phase of E–W shortening.

Geological model Construction for Yamama Formation at Faihaa Oil Field- South of Iraq

A construction of a 3D geological model of Yamama Formation to explain the distribution of petrophysical properties (shale volume, effective porosity and hydrocarbon saturation) by using Petrel software. Five wells were selected in order to build structural and petrophysical models based on interpretation of well logs and petrophysical properties. Yamama reservoir is divided into four main units (YA, YB, YC, and YD), YA is divided into five secondary reservoir units (YA1, YA2, YA3, YA4, and YA5), YB is divided into two secondary reservoir units (YB1 and YB2), YC is divided into two secondary reservoir units (YC1 and YC2) and YD is divided into three secondary reservoir units (YD1, YD2, and YD3). Structural model showed Faihaa oil field represented by anticlinal fold with double plunging. Petrophysical models (shale volume, effective porosity and hydrocarbon saturation) constructed for each subunit of Yamama reservoir using sequential Gaussian simulation executed with Petrel software. According to data analyzes and the results from modeling, the subunits for both YB and YB are good reservoir units regarding its good petrophysical properties (high effective porosity and high hydrocarbon saturation) and considered as the most important productive units in Yamama Formation

Tectonic development of Nahr Umr oil field southeastern Iraq: inferences from seismic reflection and borehole data

Nahr Umr oil field is located in the southernmost of Mesopotamian foreland basin, southeast Iraq. Even though it is one of the largest and most important oil fields in south Iraq, the time sequence of its tectonic development is still equivocal. Therefore, pre-acquired two-dimensional seismic reflection profiles of total length 47.65 km, time and depth structure maps, well logs information, and calculated porosity distribution surfaces of Zubair and Mishrif formations were gathered to build a simplified tectonic development model. The suggested tectonic sequence model indicated that Nahr Umr oil field was formed during Late Cretaceous-Miocene synchronous to the dominant compressional stresses due to convergent plate boundaries, Arabian and Eurasian. These stresses of northeast-southwest direction formed the field anticline fold and affected the post-Cretaceous stratigraphic sequences. The stratigraphic sequence flexure is associated with fractures and faults, particularly in the axial zone. The fractured zones produced high porosity areas which played as pathways to move the Infra-Cambrian salts, upward. The salts stopped underneath Dammam formation of the Eocene-Miocene age because of either salt depletion or overburden weight. The Middle and Late Miocene-Recent time may show subtle anticline combined with few faults, but no free surface expressions.

Structural evolution and exhumation of the Yulong dome: Constraints on middle crustal flow in southeastern Tibetan Plateau in response to the India-Eurasia collision

It is generally accepted that lateral rigid block extrusion of the Sundaland block in southeastern Tibetan plateau accommodated the India-Eurasia collision. Recent studies, however, revealed that channel flow of low-viscosity middle to lower crust can explain outward growth of the Tibetan plateau. Controversies continue as to which of these processes is most significant and how the crustal mass flew if happened in response to the India-Eurasia collision. In this contribution, we focus on characterizing the Cenozoic ductile deformation of the Yulong complex beyond the eastern Himalayan Syntaxis. Detailed structural, microstructural, fabrics and thermo-chronological studies demonstrate that the Yulong complex constitutes an anticlinal dome structure. Three stages of structural deformation, i.e., D1-a pure shear-dominated deformation, D2-a simple shear-dominated progressive deformation and D3-a superposition deformation, contributed to the formation and exhumation of the dome structure. The main stage of exhumation of the Yulong dome occurred in Oligocene-Miocene (34-8 Ma). The core part experienced fast cooling from ~425 °C at ca. 11–12 Ma to ~110 °C at ca. 8–9 Ma with cooling rate of 105–109 °C/Ma. However, the limb experienced relatively slow cooling, with cooling rate of 10.8 °C/Ma from 33.5 Ma to 16 Ma. Such a cooling pattern (earlier, slower in the limbs and later, faster in the core) is interpreted as the result of exhumation by anticlinal folding. Structural analysis reveals that the doming was coeval with bedding-parallel shearing of the Yulong complex. We show, from the present study, that Oligo-Miocene crustal flow occurred along subhorizontal shear zones throughout the middle to lower crust in eastern and southeastern Tibetan Plateau. Top-to-the south or southeast subhorizontal shearing during doming possibly resulted from combined effects of southward gravitational sliding of rigid upper crust and northward flow of viscous lower crust relative to the middle-upper crust.

ROLE OF TECTONIC REGIME IN THE DEVELOPMENT OF CONCEDIMENTAL DEPOSITS OF CHOCRATIC ANTICLINE FOLD

In the article based on the data of the field studies for 2008-2013, the sequence of tectonic movements in the formation of the Chocratic anticlinical fold is justified on the basis of a facial analysis. The Kerch Peninsula is a unique region where both anthropogenic and subaerial deposits of shelf and marine formations are widely represented. Of particular interest is located in the north-eastern part of the peninsula of Lake Chocrac with the anticline structure of the same name, which is part of the system of folds of the Lychagin shaft. Using the methodology of reconstruction of geological events and geological and structural analysis of Quaternary sediment, condimentary deposits of the Chocratic anticline fold were identified for the first time, the sequence of terrace formation and the impact of tectonic movements on its formation were shown. It was shown that the formation of sediments of the Karangad period on the north-eastern shore of Lake Chocratic differs from the formation of other sediments of that time on the Crimean Peninsula.Features of lithologic-facial composition of the Chocratic anticline fold require a comprehensive approach to their study to more accurately reflect the conditions of sedimentation and geological processes associated with formation fluids. It is well known that formation fluids are responsible for the "clay" tectonics, which are widely distributed on the territory of the Kerch Peninsula and the nearby Kerch shelf.The authors conclude that the tectonic movements that formed the Chocratic anticline occurred from the end of the early quarantine to the time when the leveling surface appeared.

ГОЛОВНІ ЧИННИКИ ФОРМУВАННЯ ТА АКТИВІЗАЦІЇ ГРАВІТАЦІЙНИХ ПРОЦЕСІВ У МЕЖАХ КИЇВСЬКОГО ПРИДНІПРОВ'Я

Integrated assessment and analyses of gravitational geological processes impact on the technogene objects is based on a systematic approach to the analysis of the geological environment; creation of geological, mathematical and spatial models of the geological environment, development of analytical tools. The complex application of geological and geomorphological methods (structural-morphometric analysis, comparative tectonics and structural analysis), remote sensing data and GIS technologies made it possible to identify the relationship between the processes of geomorphogenesis and tectogenesis within the Middle Dnieper area, identify the causes of gravitational geological processes, and build a series of spatial models. These models describe the impact of geomorphological and tectonic processes on the natural hazards. Based on the analysis of structural and morphometric indices, the tectonic structures, which are most elevated in relief, were recorded. Using the residual relief map, located above the baseline surfaces of the respective orders, structural zones are highlighted, reflecting the relationship of tectonic and erosion and reservoir erosion processes. Digital models of base surfaces and residual topography are aimed at the detection of local structures and the study of slope processes of the territory. Neotectonic movements of not only local but also regional character were allowed to follow. The residual relief outlines the positive forms of relief confined to anticlinal folds, which refer to the positive anomalies of gravity.

The Jackalope gas hydrate system in the northeastern Gulf of Mexico

Abstract We present a new gas hydrate system, Jackalope, in the US Gulf of Mexico ~110 km from the Louisiana coast primarily in Mississippi Canyon (MC) Blocks 127 and 128. Jackalope is a relatively shallow prospect (~1650 m water depth) and is associated with a submarine channel-levee depositional system. Several kilometers below the seafloor, an extended sub-circular salt ridge rooted into the allochthonous salt canopy creates a system of faulted anticlinal folds. Accordingly, the distribution of bottom simulating reflections mapped at ~250–300 m below seafloor (mbsf) is structurally controlled, indicating that gas tends to accumulate above the hinge of the salt ridge in sand-dominated turbidites. The Jackalope system is not a single accumulation; it comprises two primary prospects (Saint Petersburg and Columbus) and several secondary prospects. The primary prospects are defined based on seismic data by peak-leading reflections and phase reversals at the base of the gas hydrate stability zone: a strong peak-leading amplitude above it changes to trough-leading amplitude below. We interpret strong peak-leading amplitudes as gas hydrate in sand-rich intervals, which is confirmed by resistivity and gamma ray logs at the margin of the Saint Petersburg prospect. Continuous gas-water contacts below the primary prospects characterize them as permeable three-component reservoirs comprising gas hydrate above gas, and gas above water. Both prospects are located at ~230–300 mbsf occupying a total area of ~5.9 km2. Low and high estimates of in place gas at standard pressure and temperature conditions in the primary prospects range between 1.5 and 10.6 BCM. These characteristics define Jackalope as a promising, cost- and time-efficient gas hydrate system for further drilling exploration. Moreover, Jackalope demonstrates there is potential for new discoveries in the US Gulf of Mexico in particular due to expanding public 3D seismic and well log datasets.

A 3-D structural model of the Saddle Mountains, Yakima Fold Province, Washington, USA: Implications for Late Tertiary tectonic evolution of the Columbia River Flood Basalt Province

The Yakima Fold Province (YFP) is a series of asymmetric, north-verging anticlines in the Columbia River Flood Basalt Province of south-central Washington. Ridges represent anticlinal folds produced by tectonically active thrust faults, and their proximity to the Hanford nuclear facility has motivated many studies on the timing and extent of Quaternary deformation within the folds; however, multiple generations of faults and folds in the region have recorded a history of deformation spanning ~50 Ma. In this work, we utilize ~44 km of seismic profiles, structural orientation measurements collected in the field, USGS geologic maps, and stratigraphic information collected from 13 well logs to investigate the subsurface structure of the Saddle Mountains in the northern section of the YFP. We developed a three-dimensional structural model of the mountain range and estimated displacement and strain accommodated by faulting and folding. Our resulting model requires a multi-stage deformational sequence, and indicates that ~1800 m of uplift is generated by two parallel listric faults, soling into décollements at ~4 and ~8 km depth. Patterns of displacement and orientations of strain suggest that the deeper fault is older and that it may reflect a history of clockwise rotation, making the YFP the shortening counterpart to the extensional northern Basin and Range. The model presented has implications for understanding deformation in flood basalt provinces more broadly, and the methodology can be applied to interpret multi-stage deformation and reactivation histories of long-lived fault systems.

Structural modeling of the Alam EL-Bueib Formation in the jade oil field, Western Desert, Egypt

The Jade oil field is located in the Matruh Basin in the northern portion of the Western Desert, Egypt. The region is one of the most productive areas for hydrocarbons in Egypt. The main producing reservoir in the area is the Cretaceous Alam-El Bueib Formation. The main goal of the present study was done through construction structural model using Petrel™ Schlumberger software by integrating thirty 2D seismic sections with eight digital well logs. Two-way time and depth structure maps were achieved, besides the geological cross section. Seismic and well log data are used to identify and correlate the four sandstone units of the Alam EL-Bueib Formation, AEB-3A, AEB-3D, AEB-3E and AEB-3G, where only the AEB-3D to 3G sandstones are hydrocarbon-bearing in the Jade oil field. The Alam EL-Bueib Formation in the Jade oil field structure dips slightly to the northwest as part of an anticlinal fold bounded by a northeast-southwest striking reversed fault, the main tectonic element of the study area. This fault was caused by compressional forces during the Syrian arc movement in Late Cretaceous. The area east of the main fault shows antithetic Riedel-shear faults (75° to the main fault) and a corresponding narrow graben to the south of the study area. The hydrocarbon-bearing Alam EL-Bueib Formation of the Jade oil field revealed the main trapping style following the tectonic evolution during Late Cretaceous. It so provides an excellent strategy in the well explored basins in the western Desert of Egypt.

InSAR and seismic analyses of the 2014–15 earthquake sequence near Bushkan, Iran: shallow faulting in the core of an anticline fold

InSAR and seismic analyses of the 2014–15 earthquake sequence near Bushkan, Iran: shallow faulting in the core of an anticline fold