Geological Cross-sections Research Articles

Assessment of Relative Tectonics Activity Zones in Masila Oil Field, Yemen

Masila oil field, a part of rift graben basin (Sayun-Masila basin), Yemen, is affected by several tectonic events since Pre-Cambrian period. The present study makes an effort to assess the relative tectonic activity in this oil field. Several geomorphic indices, lineaments, and depth structural anomalies were generated as thematic maps using remotely sensed data, wells data, and existing geological and seismic data in a GIS platform. The thematic maps were converted into a grid format, classified into different categories based on their relative importance, and integrated using the GIS integration tool. The final map, generated by the integration of thematic maps, was categorized into five relative tectonic zones, namely very high relative tectonic zone (9.2%), high relative tectonic zone (10.6%), moderate relative tectonic zone (30%), low relative tectonic zone (36%), and very low relative tectonic zone (14.2%). The surface lineament anomalies and subsurface geological cross-section were subsequently used to validate the derived results. The results obtained through this approach may be helpful for exploring resources, such as hydrocarbons, and predicting hazards. The study highlights the advantage of using different datasets from various sources and their overlay in a GIS platform for assessing relative tectonic activity.

Using Reference Springs to Describe Expected Flow, Temperature, and Chemistry Conditions for Geologically Related Groups of Springs

ABSTRACT Reference springs can result in improved conceptual models of groundwater flow and an expanded understanding of the temporal variations in flow, temperature, and chemistry that may be expected for related springs. The reference spring concept is patterned off of the common practice of establishing reference sites to establish benchmark ecological conditions. We use the term “reference spring” to indicate a spring that is minimally disturbed and representative of a geologically related group of springs. Seven reference springs were selected from six previously defined groups that represent over 400 springs in Wisconsin, United States. Geologic cross-sections were constructed for each reference spring site, and springs were monitored for flow, spring-water temperature, and chemistry for up to 4 years, revealing new relationships within and between groups. Examples include: a range of temperature conditions that can be related to the depth of groundwater circulation for springs discharging from layered bedrock uplands, and differences in thermal patterns and specific conductance that can be related to the permeability and solubility of surficial glacial deposits for springs emanating from uneven glacial terrain. The results suggest that establishing reference springs may be a useful approach in other regions where geologically related groups of spring have been identified.

The multistage structural development of the Upper Weichselian Jasmund Glacitectonic Complex (Rügen, NE Germany)

Glacitectonic deformation in the Quaternary caused the tectonic framework of large-scale folds and displaced thrust sheets of Maastrichtian (Upper Cretaceous) chalk and Pleistocene glacial deposits in the southwestern Baltic Sea area. A wide spectrum of methods has been compiled to unravel the structural evolution of the Jasmund Glacitectonic Complex. The analyses of digital elevation models (DEM) suggest a division into two structural sub-complexes – a northern part with morphological ridges striking NW–SE and a southern part with SW–NE trending ridges. Geological cross sections from the eastern coast (southern sub-complex) were constructed and restored using the software Move™ and the complementary module 2D Kinematic Modelling™. The final geometric model of the southern sub-complex shows a small-scale fold-and-thrust belt. It includes three different orders of architectural surfaces (see PEDERSEN, 2014): erosional surfaces and the decollement (1st order), thrust faults (2nd order), and beds outlining hanging-wall anticlines as well as footwall synclines (3rd order). Thrust faults of the southern structural sub-complex are mainly inclined towards south, which indicates a local glacier push from the S/SE. The glacitectonic structures have a surface expression in form of sub-parallel ridges and elongated valleys in between. Geomorphological mapping and detailed landform analyses together with the structural investigations provide an insight into the chronology of sub-complexes formation. The northern part of the glacitectonic complex is suggested to have been formed before the southern one, considering the partly truncated northerly ridges and their superimposition by the southern sub-complex. Although there is a high number of scientific publications on the glacitectonic evolution of Jasmund, these presented models often lack a consistent theory for the development integrating all parts of the 100 km2 large complex. Therefore, the combination of all results leads to a more self-consistent genetic model for the entire Jasmund Glacitectonic Complex.

Geodynamic model and tectono-structural framework of the Bengal Basin and its surroundings

ABSTRACT We present a brief, but precise description of the geodynamic evolution, and tectono-structural framework of the Bengal Basin. The tectonic map (Main Map) at 1:12,50,000 scale should be considered as a first attempt to provide a more comprehensive and accurate geotectonic cartography of the entire region, with respect to the available maps in the published literatures, and in the light of scientific advances in geodynamics, tectonics and structures reached in the last decades plus new geological field works carried out in some key sectors of the Bengal Basin. The tectonic map of the Bengal Basin improves the knowledge of the geometry of the basin boundary, tectonic settings and relevant structures, and its relation to the collision of the Indian and the Burmese plates. Three schematic geological cross-sections illustrate the tectonic architecture of the basin in depth as well as surroundings. The latest understanding of the present-day geodynamics would help to develop advanced kinematic and dynamic modelling of the Bengal Basin in relation to the pre- and post-collisional stages of the Indian Plate.

Analysis of geothermic parameters of oil-and gas deposits of the central part of the Dnieper-Donets depression

Distribution of geothermic parameters in the central part of the DDD in the joint of Lokhvitsa and Izyum blocks has been considered in the paper. Geothermic gradient and heat flow have been calculated according to the results of measurements conducted directly in the process of drilling.It has been found that geothermic gradient varies both with depth and area even within the limits of one deposit. Comparison with geologic cross-section shows that the leaps of gradient are connected with crossing of stratigraphic (and lithologic) borders and the changes of temperature are noticed while crossing the roof of hydrocarbon deposits predominantly in the Lower Carboniferous. In most cases they are positive. In the Devonian volcanogenic-sedimentary stratum in considerable cases negative leaps appear as well. For calculation of heat flow (HF) only the measurements were used conducted in the deep holes crossing hydrocarbon deposits. Two modes of HF distribution are fixed in many deposits that differ by 5—10 units possibly explainable by hydrogeologic isolation of different blocks of the same deposit. The leaps of gradient and fluctuations of HF values may be produced by diffluence of hydrothermal solution in porous layers of sedimentary stratum. In the Machekha gas deposit a coincidence is fixed for the depth of gradient growth and the depth of registration of hydrogeologic inversion and a zone of anomalously high pressure in the stratum.Comparison with a map of HF, plotted by the results of temperature measurements in the wells with established heat regime demonstrates overall coincidence of HF distribution.The margin of the Lokhvitsa and Izyum blocks is a zone of changes of many physical characteristics of the basement and shows itself in the majority of geophysical fields. In the HF map it is marked out with the increase of average values in the northern and southern sides of the DDD and with their decrease in its central part. While increased values of HF are distributed both in the west and in the east of DDD, then the similar negative anomalies are represented only in this zone.

Geophysical characterization of the Northwest Geysers geothermal field, California

The Clear Lake Volcanic Field in northern California is the youngest and northern-most part of a long-lived volcanic system that has produced recent (~10 ka) eruptions. Adjacent to the Clear Lake Volcanic Field is the world's largest energy producing geothermal field, The Geysers. The hottest part of The Geyser's geothermal field is in the northwest where temperatures reach ~400 °C at 3 km depth. Low permeability, high thermal gradients, and low steam saturation prescribed development of an enhanced geothermal system (EGS) in the Northwest Geysers to increase energy producing capacity. Though the Northwest Geysers is known to be the hottest part of the field, geophysical methods have failed to adequately image any inferred heat source. This project aims to image the heat source of the Northwest Geysers using newly collected gravity and magnetotelluric (MT) measurements. Gravity data were jointly modeled with existing magnetic data along a two-dimensional profile aligned with an existing geologic cross-section. The key feature of the potential field model is a low-density, low-susceptibility body at 5 km depth (bmsl) under the EGS. MT data were modeled in three-dimensions to characterize subsurface resistivity structure, where the upper 3 km of the resistivity model agrees well with existing data. Lithologic and steam saturation are estimated from modeled resistivity values using existing geophysical data. Below 3 km depth (bmsl), the resistivity model images a possible young intrusion under the EGS. A possible zone of partial melt (<5%) below 7 km depth (bmsl) in the northwestern part of the field is also imaged which extends northeast towards the main part of the Clear Lake Volcanic Field.

Finding Oil Is Really Hard, Making Money Even Harder

As ExxonMobil announced discovery after discovery offshore Guyana, it sounded easy. Beginning with the Liza-1 discovery well, the giant oil company announced 16 successful exploration wells. There were four or five successful wells per year from 2017 through 2019, ending with news of its 16th find in January—pushing its estimated oil in the ground to 8 billion bbl. For those who found the oil, the evidence they used to pick those drilling targets was hardly clear cut, and it took more than 90 years to get to that point. “In retrospect it wasn’t obvious, and that was why it took so long,” said Maria Guedez, exploration manager for Guyana and Suriname for ExxonMobil. While a timeline of the Guyana project includes “initiated oil and gas exploration activities in Guyana in 2008,” the story ExxonMobil presented at the recent AAPG SuperBasins 2020 conference covered exploration starts and stops going back to 1928 by the company’s predecessor, Standard Oil Co. One slide showed a typewritten report from the 1930s noting the test wells were “salted,” giving the impression of a rich reservoir, even though “there is no evidence of oil.” But ExxonMobil and other oil companies kept coming back. There were dry holes in the 1970s off nearby Suriname—the eastern extension of the play. They saw some positive signs, but the source rock was judged to be not mature enough to fill the conventional oil deposits needed to justify development. Finally, in the 1990s ExxonMobil geoscientists looking for new exploration opportunities used what had been learned, plus advanced seismic imaging, a better understanding of the movements of tectonic plates, and some simple analysis to outline a plan that ultimately led to the discovery. Guedez showed a picture of a simple chart evaluating the pros and cons of the basin with handwritten notes, and a geologic cross section in which a geologist hand-counted layers in shallow and deep waters to identify the elements of a productive play. “New data and technologies often trigger key insights, but you need to ask the right questions,” Guedez said. “Sometimes you don’t need massive amounts of data to make a difference.” Executing the concept required developing the ability to drill wells in water 8,000 ft deep and high resolution to seismic that allowed interpreters to see the subtle signs of hydrocarbon-rich stratigraphic traps. “The places where you have structure, it was hard [to spot anomalies]. Stratigraphic traps are normally just really difficult to explore. It was going to be difficult to hit without having some sort of high-resolution 3D seismic,” Guedez said. These anomalies are never easy to spot, but she said that compared to her experience in offshore Africa, signs of traps off Guyana were “remarkably subtle.” So far, they have hit on 89% of the wells drilled. “Once the eyes of the team got fine-tuned to that, they did a good job spotting them,” Guedez said.

Evaluation of complex site effects through experimental methods and numerical modelling: The case history of Arquata del Tronto, central Italy

This work deals with the experimental and numerical evaluation of the local seismic response of Arquata del Tronto area (Marche Region, central Italy), severely struck by the Mw 6.0 August 24th, 2016 earthquake. Arquata main village rises on elongated WNW-ESE-trending ridge of the central Apennines thrust-belt (central Italy), at elevations about 170 m higher than the underlying alluvial valleys where Borgo and San Francesco hamlets are built on. Despite their proximity (less than 500 m), Arquata del Tronto, Borgo and San Francesco reported a different damage distribution after the August 2016 mainshock, suggesting that the seismic response of the area may be controlled by site effects. In order to explore this hypothesis, we evaluated the 2D numerical local seismic response along four representative geological cross-sections passing through Arquata del Tronto, San Francesco and Borgo. Additional 1D analyses were carried out at strategic points along the cross-sections in order to explore the 2D physical phenomena governing the local response. The satisfactory agreement between numerical amplification functions in linear range and experimental amplification functions obtained by the Generalized Inversion Technique (GIT) applied to a large number of aftershocks confirms the substantial reliability of the subsoil models. Numerical analyses representative of the 2016 mainshock were carried out and processed in terms of peak and key ground motion parameters. A comparison with the damage induced by the 2016 mainshock was finally undertaken substantially justifying the observed pattern. This study provides general implications about site response and seismic microzonation in sites characterized by similar complex geological and morphological settings.

In-situ LA-ICP-MS trace element and oxygen isotope signatures of magnetite from the Yamansu deposit, NW China, and their significance

The Yamansu iron deposit is hosted in submarine volcanic rocks in the Aqishan–Yamansu belt of Eastern Tianshan, NW China. A geological cross-section for the Carboniferous strata in the ore district shows that ore bodies in the Yamansu deposit are hosted in andesitic crystal tuff of the third cycle of the Carboniferous Yamansu Formation. This indicates an association between mineralization and volcanism. The orebodies are strata bound and lensoid and generally share the occurrence state of the host rocks. Magnetite mineralization mainly occurs asbreccia ores, ores in the mineralized volcanic rocks, massive ores, and sulfide-rich ores according to their structures and sequences of formation. Trace element compositions of magnetite from various types of ores were determined by LA-ICP-MS. The dataset indicates thatdifferent types of magnetite havedistinct trace element contents correlated to their formation environments. Magnetite crystals from breccia ores have high Ti, Ni, V, Cr, and Co and low Si, Al, Ca, and Mg contents, indicating crystallization from a volcanic magmatic eruption, which is consistent with field evidence of coexisting altered volcanic breccia. Magnetite crystals from ores in the mineralized volcanic rocks have moderate Ti, Ni, V, Cr, and Co contents. In contrast, magnetite from massive ores and sulfide-rich ores have low concentrations of Ti, Cr, Ni, and V, high concentrations of Si, Al, Ca, and Mg, and evidence of hydrothermal magnetite. In-situ magnetite compositions imply a magmatic-hydrothermal process. Although δ18O values for magnetite grains fromYamansu vary (+ 1.3 to + 7.0‰), they all plot in the range field of volcanic iron deposits, and they also record a magmatic-hydrothermal process. The compositions of Yamansu magnetites are interpreted as controlled mainly by temperature, fluid, host rock buffering, oxygen fugacity, and sulfur fugacity. The metallogenic conditions of the Yamansu deposit changed from high temperature and low oxygen fugacity to low temperature and high oxygen fugacity. However, more fluid-rock reactions and higher sulfur fugacity were involved during the deposition of massive ores and sulfide-rich ores.

The role of orogen-transversal tectonic structures on the “syn” and “post” depositional evolution of a foredeep succession: The case of the Cervarola Sandstones Formation, Miocene, Northern Apennines, Italy

In collisional belts, foredeep turbidites are tracers of the evolution of the orogenic wedge. Syn-depositional tectonics affects the sedimentary facies distribution of the turbidite deposits, while post-depositional tectonics generates the major structures that deform the foredeep basins. The Aquitanian to Burdigalian Cervarola turbiditic succession is one of the main Oligo-Miocene foredeep units that characterize the northwestern portion of the Northern Apennines. The reconstructed syn and post depositional evolution of the Cervarola succession reveals that orogen-transversal tectonic structures strongly and persistently controlled this turbiditic succession, from the time turbidites were infilling the foredeep basin (Aquitanian-Burdigalian) to the time this foredeep deposits became a major and complex thrust sheet of the Northern Apennines orogenic wedge (post-Burdigalian-Present). The syn-depositional history of the Cervarola turbiditic succession has been defined through a detailed facies analysis that has allowed the basin morphology to be accurately constrained. Then, the post-depositional history has been addressed to define the multi-scale deformations preserved in the Cervarola succession through the following approaches: 1) analysis of published geological maps, 2) detailed field mapping, 3) construction of geological cross sections across the major folds, 4) analysis of meso-scale structures and 5) analysis of a seismic reflection profile.The study has outlined that the foredeep basin morphology was tectonically controlled and segmented by compressive structures transversal to the NW-SE basin elongation. The same structures were also present during the post-depositional compressive phases that built up the orogenic wedge and they have been even reactivated in the latest extensional events that have dismembered the mountain range.These orogeny-transversal and long-lasting (~23Myrs) lineaments cross-cut the entire tectonic stacking of the Northern Apennines, affecting tectonic units which suffered different amount of translation during the mountain building, making the reconstruction of the geological evolution possible only with an integrated approach as performed in this work.

Database on seismic response of instrumented flood control levees

We present a database documenting the seismic response of seven instrumented flood control levee segments in Japan. The database includes (1) maps and cross-sections showing levee geometry and instrument layouts; (2) ground motion time series, and (where available) piezometric recordings; (3) reported field performance from post-earthquake reconnaissance (i.e. permanent displacements, other evidence of ground failure); and (4) geotechnical data, including geologic cross-sections, stratigraphy, penetration resistance, and shear wave velocity ( VS) profiles. The data are complete with respect to these attributes for three sites, with geotechnical data and field performance data missing for two and four sites, respectively. The database contains 150 recordings from 25 events and can be accessed through DOI: 10.21222/C2TC95. Ground motions were processed using standard procedures for Next Generation Attenuation projects. We present example data for a segment damaged by the M9.1 2011 Tohoku-oki earthquake, which includes ground motion and pore water pressure measurements.

Temperature and pressure corrections applied to rock thermal conductivity: impact on subsurface temperature prognosis and heat-flow determination in geothermal exploration

Precise knowledge of the subsurface thermal field plays a key role in the assessment of geothermal targets. Unfortunately, deep underground temperature data is generally scarce and a matter of research. To achieve first estimates for subsurface temperatures, steady-state conductive thermal modeling is commonly applied. Thereby the rock thermal conductivity is an essential parameter, which is usually determined under ambient laboratory conditions. To arrive with in situ thermal conductivity, the ambient values need to be corrected for in situ temperature and pressure. In this paper, we apply different conversion functions for the correction of thermal conductivity and study the impact on the resultant temperature and heat flow prognoses for a synthetic, upper crustal sedimentary and a magmatic scenario along 2-D geological cross sections. Application of the correction functions results in maximum temperature prognosis uncertainties of about 8 °C and 55 °C at 2 km depth and at 8 km depth, respectively. The effect positively correlates with the magnitude of the basal heat flow used in modeling. In contrast to the heat flow determined at depth, the resulting surface heat flow is only minor affected by the different correction functions applied. In addition, the modeled temperature at depth is strongly dependent on the type and sequence of application of the pressure and temperature correction equations.

Investigation of the Norcia basin (Central Italy) through ambient vibration measurements and geological surveys

During the 2016–2017, a seismic sequence struck the Central Italy, involving four regions (Umbria, Marche, Abruzzo and Lazio) and causing important damages and victims in inhabited areas such as Norcia and Amatrice towns. The strongest event of the seismic sequence was a Mw 6.5 event with epicenter at about 5 km far from the Norcia area, which is an intermontane basin prone to ground motion amplification. The historical town of Norcia and the surrounding hamlets were recently investigated by the microzonation activity, but information on the geometry and velocity are still partial considering the entire basin. Indeed, past studies aimed at reconstructing the elastic and geometrical properties focusing mainly on the northern part of the basin. Specifically in this paper, we integrated seismic and geological data to get a better knowledge of the properties of the Quaternary Norcia basin. A geological survey was carried out to provide a geological map and three geological cross-sections. We analyzed new seismic ambient vibrations data, collected by single-seismic stations, to infer the distribution of resonant frequency (f0) for the entire basin. We used passive arrays of seismic stations to better define the velocity profiles of the area. In the northern part of the basin, two 2D arrays with elliptical-like shapes were deployed showing strong discrepancies of the elastic soil properties in proximity of Norcia town. We found shear-wave velocities of the near-surface profile of about 300–400 and 500–800 m/s in presence of palustrine and alluvial fan deposits, respectively. Further, the values of f0 are abruptly varying from 0.5 Hz in the SW sector of Norcia village up to 2 Hz in its NE sector. Ambient vibration data reveal less pronounced variation of f0 in the southern part of the basin, with resonant values that are almost in the range 1–1.3 Hz. In the southern sector, a 1D array was arranged along a 5-km line and was analyzed by means of seismic noise cross-correlation analysis suggesting the presence of a deeper seismic contrast. The integration of geophysical and geological results has allowed to infer insights on the subsurface geometry of the basin.

Effects of earthquakes on the discharge of groundwater systems: The case of the 2016 seismic sequence in the Central Apennines, Italy

The 2016–2017 seismic sequence in Central Italy caused the reactivation of a complex NNW-SSE trending, WSW-dipping normal fault system associated with relevant coseismic ruptures. The seismic sequence significantly affected the groundwater circulation hosted in limestone aquifers. Based on the data available in May 2019, this work aims to contribute to understanding how the reactivation of the seismogenic faults has influenced the hydrological system of the upper Nera River basin. It appears that the seismic sequence changed the recession processes of the Nera River. Post-seismic recession curves are described by straight lines (non-darcian flow), while the pre-seismic ones follow the exponential function (darcian flow). After the earthquake, the system empties (i.e., the storage decreases) at a faster rate than before; this effect persists after more than two years from the 2016 earthquake. According to some geological cross-sections, the analysis of coseismic deformations and recession curves, a presumable increase in aquifer permeability seems to be the main factor affecting the post-earthquake river discharge. If the non-darcian recession process continues in the future, the river flow will be more variable than in the past, causing significant problems to water-using productive activities. This because, during prolonged drought periods, the fast decrease of the dynamic water storage would produce discharges lower than in the past. The results here reported can contribute to the understanding of the medium-long term evolution of this particular hydrological system as well as of other similar ones and could be useful to better managing the groundwater resources.

Using of GIS on field geology studies; An application on central-southern of Eskişehir

Technological developments on Geographical Information Systems (GIS) make possible to use its applications on all departments of earth sciences. GIS based drill-hole data, lithological and structural maps are used integrated with field geolgy investigations in this study. The area where is bordered Batıkent-Yukarı Söğütönü districts on northwest and Vadişehir-Ihlamurkent districts on southeast is defined as study area. 44 water wells drilled by State Hydraulic Works (DSİ) are located in various points of Eskişehir region were transformed to GIS base. Geological cross-sections which were designed by drill-hole lithology are point out a disconformity zones between Paleogene and Neogene according to principle of lateral continuity. Neotechtonic researches on study area Show thah right lateral strike slip shear zone dominates the region structurally. Searching these structural traces on the field and representing new field evidances by using GIS on the regions where there is no consensus stratigraphicly are the main purposes of the study. Geological map of the region where lies between Çankaya and Karapınar districts without consensus stratigrapichly was made by field observations on Miocene units. The other surface evidances include dilation fractures, strike-slip faults are support the idea which is suggested for Eskişehir region as right lateral strike-slip shear zone.

New data on the Paleogene lithostratigraphic units’ distribution in the Avren Step south of Varna and Beloslav Lakes based on borehole data and seismic profiles’ interpretation

The present article aims to provide new data on the spatial distribution and lithological features of the Paleogene lithostratigraphic units in the Avren Step, which is a part of the Moesian Platform in Eastern Bulgaria. On the basis of primary lithological data derived from 81 boreholes’ sections and lithostratigraphic interpretation of five seismic profiles, six formal Paleogene lithostratigraphic units were recognized. They are as follows: the Komarevo Fm. (Thanetian), the Beloslav Fm. (Ypresian), the Dikilitash Fm. (Ypresian), the Aladan Fm. (Ypresian), the Avren Fm. (uppermost Ypresian–Priabonian), and the Ruslar Fm. (Oligocene). Their spatial distribution and relationships in the northern part of the studied area are visualized by drawing up of five geological cross-sections, while the deep geological structure of the southern part is shown by lithostratigraphic interpretation of the five seismic profiles. Four of the units (the Beloslav, Dikilitash, Aladan and Ruslar Formations) demonstrate almost constant lithology throughout the whole studied area with some variations in their thickness. The Komarevo Formation, and especially the Avren Formation, show considerable lithologic and thickness variability.

A new view to the spatial distribution of the Paleogene lithostratigraphic units in the Goren Chiflik Horst based on borehole data

The present article aims to provide new data on the spatial distribution and lithological features of the Paleogene lithostratigraphic units in the Goren Chiflik Horst, which is part of the Moesian Platform in Eastern Bulgaria. Eight formal Paleogene lithostratigraphic units were recognized on the basis of primary lithological data derived from 29 borehole sections. They are as follows: the Komarevo Fm. (Thanetian), the Beloslav Fm. (Ypresian), the Dikilitash Fm. (Ypresian), the Aladan Fm. (Ypresian), the Avren Fm. (uppermost Ypresian–lowermost Priabonian), the Dvoynitsa Fm. (Lutetian), the Dolni Chiflik Mb. of the Avren Fm. (Bartonian–Priabonian), and the Ruslar Fm. (Oligocene). Their spatial distribution and relationships are visualized by drawing up 11 geological cross-sections. Additional data on their lithology, thickness, boundaries and age are also given.

Gravity-magnetic model of the Kolomyia paleovalley for the Nadvirna―Otyniya―Ivano-Frankivsk geotravers

The purpose of the work is development of a complex seismic-density-magnetic model of the geological cross-section for the geotraverse SG-1 (67) (Nadvirna―Otynia―Ivano-Frankivsk) and appreciation of oil and gas bearing perspectives in the Kolomyia Paleovalley. The research methodology is based on the analysis of anomalous gravity and magnetic fields and the creation of density and magnetic models of geological cross-section. Local anomalies are defined by methods of transformations. Modeling of the geological cross-section structure is performed by methods of solving direct and inverse problems of gravity and magnetic survey, which implemented the ideas of the criteria approach to creating optimal models of geological environments that are consistent with the observed geophysical fields and do not conflict with the data of drilling and seismic survey. The reliability of interpreting gravimagnetic data method is achieved by geological subordination: the condition of maximum application of seismic survey and geological and tectonic maps. The conceptual density model and magnetic model of the geological environment along the seism-geological profile of CG-I (67) was developed. The distribution of densities and magnetization of rocks in sedimentary cover and basement blocks to a depth of 20 km is detailed. As a result of modeling within certain stratigraphic complexes, zones with anomalous in density and magnetization of rocks were defined. The decompression zones, which are within positive structures, are identified as perspective ones. It is also confirmed that there is a high probability of deep intrusions that are predicted from materials of seismic survey within the limits of the hidden tectonic zone and reaching the bottom of sedimentary cover. The analysis of morphology of gravity and magnetic anomalies and gravimagnetic modeling allowed clarifying the geological structure of the Kolomyia Paleovalley cross-section and to appreciate oil and gas perspectives of its separate areas.

Geological conditions of suffosion processes development and their acitivity at Sal-Don neotectonic upland (Rostov NPP area)

Suffusion processes and their influence on the stability of the Rostov NPP site are investigated. Geological, tectonic, geomorphological, hydrogeological conditions, as well as anthropogenic factors affect the development and intensification of suffusion. These conditions and factors include the following: predominance of Pliocene and Quaternary sands in the geological cross-section; the presence of clay aquiclude underlying sandy deposits; natural seasonal and human-induced fluctuations of the water level in the Tsimlyansk reservoir; as well as pumping of groundwater. The buried relief in the shape of a slope dissected by erosional gullies are also of great importance. These erosional depressions are probably channels, along which sand is removed to the Tsimlyansk water reservoir. It is suffusion that may be the reason of surface subsidence that causes deformation of ground basements and inclinations of some engineering structures at NPP. Recent tectonic conditions control the formation of active zones and fracturing in the mantle deposits favoring percolation of surface water. Suffusion amplified by tectonic and technogenic factors results in the subsidence of soil basement in some places at the NPP site, displacement of reference marks, and inclination of engineering structures.

Building a three dimensional model of the active Plio-Quaternary basin of Argostoli (Cephalonia Island, Greece): An integrated geophysical and geological approach

This work is a multidisciplinary approach from geological and geophysical surveys to build a 3D geological model of Argostoli Basin (Cephalonia Island, Greece) aiming to be used for computational 3D simulation of seismic motion. Cephalonia Island is located at the north-western end of the Aegean subduction frontal thrust that is linked to the dextral Cephalonia Transform Fault (west of Cephalonia) where the seismic hazard is high in terms of earthquake frequency and magnitude. The Plio-Quaternary Koutavos-Argostoli basin site was selected within the French Research Agency PIA SINAPS@ project (www.institut-seism.fr/projets/sinaps/ - last accessed on November 25th 2019) to host a vertical accelerometer array. The long-term goal is to validate three-dimensional nonlinear numerical simulation codes to assess the site-specific amplification and nonlinearity. Herein the geological and geophysical surveys carried out from 2011 to 2017 are presented and in particular the complementary investigations that led to the identification of the main stratigraphic units and their structures. In addition, coral debris sampled from the vertical array deep borehole cores were used for 230Th/234U measurements, which confirmed the Pleistocene age of the Koutavos basin. The characterization of the three-dimensional structure of the stratigraphic units was achieved by coupling geological cross-sections (i.e., depth geometry) and geophysical surveys based of surface wave analysis.