Study Of Geological Structure Research Articles

Structural and geomorphological regional studies of the Kryvyi Rih-Kremenchuk suture zone using remote data

The economy of Ukraine is raw material and depends on the prices of raw materials on world markets. The five largest iron ore producing countries accounted for 86% of its world production in 2020. China, with 41% of world production, was in first place, Ukraine was in seventh place, ahead of Canada and the USA. In terms of raw iron ore reserves, our country is also in seventh place. The largest reserves of iron ore in Ukraine are concentrated in deposits of the the Kryvyi Rih-Kremenchuk zone. The article deals with a set of structural, geomorphological and aerospace geological studies to identify the relative neotectonic activity of the blocks of the Kryvyi Rih-Kremenchuk suture zone, within which the predictive structures promising for the search for ore minerals are identified. A fundamentally new geologic and tectonic model of the Kryvyi Rih-Kremenchuk suture zone has been built, which is confirmed by the analysis of geophysical fields, structural, geomorphological and aerospace data. Because of our studies, it is proposed to pay attention to the object highlighted by our research - the Zhovtorichenska syncline area within the Ternovska depression of the Kryvyi Rih-Kremenchuk zone.

Seismic Exploration Methods for Structural Studies and for Active Fault Characterization: A Review

In this paper, seismic exploration methods are reviewed with a particular emphasis on the use of the reflection seismology to investigate the subsurface structures and characterize active faults. The paper provides a descriptive overview, intended for a non-specialist audience, of the methods and of their recent developments aimed at improving the resolution, accuracy, and computational efficiency of seismic imaging. Techniques such as seismic ray tomography, full-waveform inversion and pre-stack depth migration are briefly introduced, highlighting their potential applications in structural geology studies. The main seismic attributes that have become increasingly important in the interpretation of faults and fractures are also presented, along with some examples of application. Finally, some case studies of active fault characterization are discussed. From these examples, the crucial role played nowadays by the seismic exploration methods for structural studies and for active fault characterization is evident.

Larsemann Hills: Geomorphometric modeling and mapping

Geomorphometric modeling is widely used in geosciences. However, geomorphometric modeling and mapping of Antarctic oases has not been performed so far. This article presents the first results of our work on geomorphometric modeling and mapping of the Larsemann Hills obtained in the frameworks of the 68th Russian Antarctic Expedition in January–April 2023. As input data, we used a fragment of the Reference Elevation Model of Antarctica (REMA). From the extracted and edited digital elevation model, we derived digital models and maps of the following 17 morphometric variables: slope, aspect, horizontal curvature, vertical curvature, mean curvature, Gaussian curvature, minimal curvature, maximal curvature, unsphericity curvature, difference curvature, vertical excess curvature, horizontal excess curvature, ring curvature, accumulation curvature, catchment area, topographic index, and stream power index. We also conducted a field geomorphometric interpretation work to provide correct physical geographic, geological, and geomorphological interpretations of morphometric maps. In the fieldwork, we carried out 54 foot routes with the total length of about 422 km. During the routes, we collected 150 rock samples for further petrological and mineralogical analyses as well as three-dimensional modeling of the samples. Derived morphometric maps can be useful for structural geological and process-oriented hydrological studies. The ultimate goal of the ongoing work is to create a large-scale geomorphometric atlas of Antarctic oases and other ice-free Antarctic territories.

A Comparative Analysis of Lineaments Extracted from Landsat 8 OLI & ASTER-GDEM Data, in Talmakent Area, Western High Atlas, Morocco

Structural mapping by remote sensing is an essential component to completing the geological mapping of the Talmaknet region. It allows us to understand the regional tectonics of the southernmost segment of the Hercynian of Western Morocco, exploiting Geographic Information Systems (GIS) and satellite imagery processing techniques in order to obtain a good lineament discrimination. To this end, the approach adopted was based on preliminary processing of Landsat 8 OLI satellite imagery combined with a morpho-structural shading analysis technique, using the Digital Elevation Model (DEM), and applying several techniques of image enhancement and directional filters to the different treatments to improve the visibility of the linear structures in the images.Given the interesting number of fractions collected, a statistical and directional study was carried out on the synthetic maps to show the distribution and orientation of the lineaments. This analysis indicates a dominant NE-SW oriented geological fracturing, which agrees with the existing geological data in the area, confirming the effectiveness of GIS and remote sensing techniques in structural geology studies, especially to have a detailed mapping of the linear structures in the study area.

Identification of Volcanic Geothermal Systems Based on Integrated Study of Volcanostratigraphy, Structural Geology, and Fluid Geochemistry in Southern Ngada Field, Indonesia

Southern Ngada is one of the areas that shows occurrence of volcanic geothermal potential in East Nusa Tenggara. The spreading volcanoes in the study area raised a hypothesis that the Southern Ngada Geothermal Field consists of several geothermal systems. The spreading volcanoes showed the presence of at least three volcanoes and manifestation clusters, which are Nage, Keli-Bena, and Wolo Puti Clusters. This research aimed to identify the number, type, and characteristics of geothermal systems in Southern Ngada Geothermal Field. The identification is conducted through the integration of geomorphology, volcanostratigraphy, structural geology, and geochemistry of fluid manifestation. The determination of geothermal system in Southern Ngada Geothermal Field is important to identify the field characteristics and reduce exploration risks. The Southern Ngada Field constitutes of the pre-caldera, post-caldera, and recent volcanism products. The study area is intensively deformed through strike slip faults and resembled Riedel Shear patterns. Fluid manifestation geochemistry in the study area showed various type of waters, which consists of Cl-SO4, SO4, and SO4-HCO3 waters with meteoric water mixing. The solfatara is associated with active magmatic gases due to boiling of reservoir beneath cinder cones. The fluid mixing processes are explained furthermore in Schoeller diagram plot. The integration of analyses showed the presence of Nage, Keli-Bena, and Wolo Puti Geothermal Systems with each different volcanostratigraphy, structural setting, and fluid mixing processes. The Nage System is associated with inferred heat source beneath the Nage Caldera and eastern part master and antithetic fault. The Keli-Bena System is associated with inferred heat source beneath Bena Crater and western antithetic fault. The Wolo Puti System is associated with inferred heat source beneath cinder cone volcanoes and northern extensional structures.

Carbonate rocks in northern of West Jiwo Hills Bayat: The indication of thrust belt development in southern Central Java

Bayat, Klaten, Central Java, is one of three locations in Java with complete types of rocks exposed at the earth’s surface. All those rocks are scattered over a short distance in Bayat, revealing past processes of rock deformation (folding, fracturing, and faulting) and present-day processes of rock weathering and erosion. In this study, we present how clastic carbonate rock of the Oyo Formation at northern Jiwo Hills could be separated about ±15 km northern from its platforms as an indication of thrust fault growth. This study uses aerial photography for photogrammetry (drones) combined with structural geology and microfossil analyses (to know the exact formation) from the outcrop observation. Recent studies have certified that drones are one reliable observation tool in various aspects with better resolution, especially in structural geology studies. Aerial photogrammetry is very well done to see the exact condition of a wide area combined with high resolution on an outcrop scale. The result shows that the carbonate rocks are from Oyo Formation (N9–N11) with the Middle Neritic bathymetric zone. The structural geology phenomenon kinematically indicates the impact of the transpressional movement called flower structure. Based on subsurface interpretation, the authors hypothesize this area was the product of an imbrication thrust stack uplifted basement as the result of the thrust fault rather than horst or paleo-basement high.

Exciting opportunities in planetary structural geology and tectonics: An early career perspective

The outer shells of solid planetary bodies have been all subject to deformation during their history. The nature and style of deformation strictly depends on the evolution of each planetary body. Earth’s lithospheric style of deformation is related to plate tectonics, but it turns out to be a unique case in our Solar System. How can we study the tectonics of other planetary bodies? How and why do planetary lithospheres deform, and what are the implications of these processes? These are the driving questions for investigations of modern planetary structural geology. The improvement in technology, machine learning analyses, and quality and quantity of planetary space mission data give us the chance to deepen our grasp in planetary surface deformation. The lack of micro-to-local scale information that is so crucial in Earth structural geology studies has driven planetary structural geology to advance pioneering methods to study crustal deformation. Conversely, the study of old deformed surfaces such as those of Mercury, the Moon and Mars will deepen our grasp on the early evolution of Earth tectonics.

Effect of engineering geological properties on dam type selection of the Qadis Khordak Dam, Afghanistan

This paper deals with engineering geological properties of Qadis Khordak dam site in Northwest Afghanistan. This study is based on on-site and laboratory tests, surface discontinuity surveying, drilled borehole and permeability test of dam foundation. The engineering geological properties at the dam site were studied in order to evaluate geotechnical characteristics of rock masses at dam foundation, geotechnical properties of alluvium at dam axis, reservoir and borrow materials. The structural geological studies also carried out due to stability and safety of dam on their abutments reservoir and seismicity. Existence of a fault, high permeable zone at dam foundation and the thickness of alluvium at dam axis, are the most engineering geological issues that cause change on dam type selection. In the feasibility phase, the dam type was chosen as the concrete face rock-fill dam, because of state of engineering geological properties of dam site. However, in the design phase dam type has been changed as a rock-fill with a clay core.

Гравиметрические исследования на научном полигоне «Мыс Шульца»

Gravity measurements with different kind of absolute gravimeters and spring gravimeters were started at the Marine Experimental Observatory Shults Cape of Il'ichev Oceanological Institute, Far East Branch of Russian Academy of Sciences from 2010 year. Simultaneously, on the polygone, located in the South of Primorie, started the geodetic measurements by GNSS methods for determination of the coordinates and study of gravimetric points’ displacements. Gravimetric measurements are used to solve structural and monitoring tasks. Planned and high-altitude geodetic measurements are necessary for the correct interpretation of gravimetric results and obtaining reduced gravity values. Complex measurements with absolute and relative gravimeters are used to test the metrological characteristics of relative gravimeters such as SCINTREX and GPhone. As a result of the analysis of tidal variations of gravity, corrections to the absolute data were obtained. Carrying out measurements at different altitudes using absolute gravimeters of the GABLM-M type made it possible to reduce the values of gravity and compare experimental and theoretical estimates. The results are used in structural geological studies in Primorie. The second task of the research was to determine the level of time variations of gravity, 3D displacements of the earth's surface and determine their nature. According to measure-ments in the period 2010–2020, the effects associated with the Japanese earthquake of 11.03.2011 with a magnitude of M = 9,0 were investigated. At a distance of 1000 km from the epicenter, the mag-nitude of post-seismic subsidence for the period 2012–2020 was 22 m, gravity increased by 6 microgal. According to the shape of the attenuation curve of vertical displacements, a model was selected and an estimate of Maxwell's time (T = 3 years) was obtained. Within the framework of a two-layer model, the viscosity of the earth's crust lower part – the asthenosphere on the edge of the continent – was determined.

Применение методов геоинформатики для изучения и оценивания риска последствий землетрясений

The struggle of mankind against the consequences of strong and catastrophic earthquakes has been going on throughout its history, and so far, success in this field is rather modest. This is due to the complexity and inaccessibility of objects for studying deep geological processes that lead to defor-mation and destruction of the Earth's crust, in which seismicity is manifested. Earthquake risk assess-ment for earthquake mitigation is one of the most important issues for a country where such natural disasters can occur. Tectonic and structural-geological studies using modern space remote sensing tools and their integration with spatial data in a geographic information system (GIS) environment are becoming increasingly popular among scientists. Ruptures and associated surface deformation due to ground shaking can be observed with remote sensing data. The use of remote sensing methods to rec-ognize the displacement of faults was carried out in Isfahan (Iran). Based on the obtained data, a map of seismic activity was compiled with field checks and laboratory data analysis. Thus, the purpose of the article is to show the possibilities of geoinformatics for the study of earthquakes. This will increase resilience to future earthquakes, especially for those historic buildings and bridges that are over 400 years old.

Tonian and Cryogenian 40Ar/39Ar hornblende and muscovite ages for the São Gabriel Terrane, Dom Feliciano Belt, southern Brazil

Geochronological 40Ar/39Ar investigations in the São Gabriel Terrane, Dom Feliciano Belt, Brazil, associated with previous structural geology and geochronology studies, allow for a better understanding of Neoproterozoic events in this region. The Sanga da Cachoeira Complex and metasedimentary rocks of Arroio Marmeleiro Complex (U–Pb provenance age > 1.5 Ga) show 40Ar/39Ar spectra with no successful plateau age, attributed to the alteration or excess 40Ar. Tonian (ca. 729 ± 9 Ma) 40Ar/39Ar hornblende age of metadiorites of the Cambaí Complex (U–Pb protolith age ca. 750 Ma) is interpreted to register the age of an early structure in this unit, where hornblende is a mineral of the composite banding fabric formed by remnants of original bedding, locally preserved, and added by metamorphic recrystallization. A cooling rate of at least 5°C/Ma is suggested for the Cambaí Complex, from its crystallization to its metamorphic event. The Cryogenian (<690 ± 8 Ma) 40Ar/39Ar hornblende and muscovite ages belonging to the Imbicuí Complex (protolith age ca. 869 Ma) whose ages are related to the late structure formed by a short and intense activity of the Cerro Branco Shear Zone, which experienced a rapid cooling of 12°C/Ma. The ages from the rocks belonging to such a diverse tectonic setting, including continental and intraoceanic island arc, oceanic crust low‐K amphibolites and meta‐harzburgites, and metasediments, presenting similar nature and fabric orientation, indicate that major tectonic‐magmatic–metamorphic activity was responsible for the accretion of these lithotectonic units that gave rise to the São Gabriel Terrane in southern Brazil.

Historical memory of the geology of Antioquia: Emil Grosse and The Carboniferous Tertiary of Antioquia

The Carboniferous Tertiary of Antioquia (TCA), published by Dr. Jakob Emil Grosse in 1926, is one of the most influential scien­tific results of the Ordinance 16 of 1918 of the Honorable Departmental Assembly of Antioquia. The work began with the main objective of quantifying the coal reserves of Antioquia, and showing their surface extension on a scale of 1:50 000, in a region that includes the Arma river to the Puente de Occidente and from the western side of the Cauca River to the Romeral lineament and the plains of Ovejas. As a result, extensive work comprising petrological, structural, and economic geology studies was published in a manuscript published in Spanish and German, plus four attached maps, including coal, gold, silver, kaolin, and carbonate mines, among others. In the present work, the four TCA maps were digitized at a scale of 1:50 000 with Bessel 1841 datum and created a unified file in .kml format, which can be used directly in field trips, via Google Earth on cell phones, tablets, or computers. The metadata associates the information in the TCA with the Servicio Geológico Colombiano for the year 2015. In addition, 480 thin sections were scanned, which were donated by Dr. Grosse to the Escuela Nacional de Minas and today are in the Museum of Geosciences of the Faculty of Mines of the Universidad Nacional de Colombia. The geospatial information contained in each thin section was interpreted and georeferenced, obtaining, as a result, a list with north and west geographic coordinates, in degrees, minutes, and seconds. This unpublished information is available in the supplementary material of this article. Finally, nine field trips were made to the places referenced in 23 photographs of the TCA between 1920 and 1923 to take their current equivalent and thus carry out a multi-temporal analysis of the TCA.

On backflow associated with oceanic and continental subduction

SUMMARY A popular idea is that accretion of sediment at a subduction zone commonly leads to the formation of a subduction channel, which is envisioned as a narrow zone located above a subducting plate and filled with vigorously circulating accreted sediment and exotic blocks. The circulation can be viewed as a forced convection, with downward flow in the lower part of the channel due to entrainment by the subducting plate, and a ‘backflow’ in the upper part of the channel. The backflow is often cited as an explanation for the exhumation of high-pressure/low-temperature metamorphic rocks from depths of 30 to 50 km. Previous analyses of this problem have mainly focused on the restricted case where the walls bounding the flow are artificially held fixed and rigid. A key question is if this configuration can be sustained on a geologically relevant timescale. We address this question using a coupled pair of corner flows. The pro-corner accounts for accretion and deformation directly above the subducting plate, and the retro-corner corresponds to a deformable region in the overlying plate. The two corners share a medial boundary, which is fully coupled but is otherwise free to rotate and deform. Our results indicate that the maintenance of a stable circulating flow in a narrow pro-corner (<15°) requires an unusually large viscosity ratio, μretro/μpro > 103. For lower viscosity ratios, the medial boundary would rotate rearwards, converting the initially narrow pro-corner into an obtuse geometry. For a stable narrow corner, we show that the backflow within the corner is caused by downward convergence of the incoming flow and an associated downward increase in dynamic pressure, which reaches a maximum at the corner point. The total pressure is thus expected to be much greater than predicted using a lithostatic gradient, which means that estimates of depth from metamorphic pressure would have to be adjusted accordingly. In addition, we show that the velocity fields associated with a forced corner flow and a buoyancy-assisted channel flow are nearly identical. As such, structural geology studies are not sufficient to distinguish between these two processes.

The Late Jurassic extensional event in the Yanshan fold and thrust belt (North China): New insights from an integrated study of structural geology, geophysics, and geochemistry of the Siganding granitic pluton

The Yanshan fold and thrust belt (YFTB) was built up by multiple contractional events, namely the “Yanshan Movement”, which was traditionally subdivided into the “Yanshan-A” and “Yanshan-B”. In contrast with the better constraint on “Yanshan-B” (ca.140 Ma), the timing of “Yanshan-A” is still in dispute. The Middle Jurassic contraction (172–160 Ma) was widely accepted, however, whether this contraction can last into 150 Ma is still unclear. In this article, to clarify the Late Jurassic tectonic regime in the YFTB, a multidisciplinary study, including structural geology, Anisotropy of Magnetic Susceptibility (AMS), gravity modeling, geochronology, and geochemistry, has been carried out to investigate the emplacement mechanism of the Siganding pluton (ca. 161–157 Ma) in the northern Beijing area. The magma was predominantly derived from the Precambrian continental lower crust. The magnetic foliations are pluton margin-parallel and outward dipping, resembling the fabric pattern of magmatic dome. The NE-SW striking magnetic lineations and NW-SE linear feeder zones revealed by gravity modeling indicate that the emplacement of the Siganding pluton was controlled by a weak NE-SW crustal stretching interpreted as a regional tectonic extension. Considering that the Late Jurassic (164–153 Ma) NE-SW oriented extension structures are not only documented in the YFTB, but also the entire eastern NCC, hereby we propose that the “Yanshan-A” is constrained at 172–164 Ma, instead of a wide range from the Middle Jurassic to Late Jurassic (172–150 Ma) as argued by previous workers. The extension could be ascribed to the oblique subduction of the Izanagi plate.

Structural control on badland slope evolution: A case study from the southern Apennines (Italy)

This work focuses on a multi-method study of badlands exposed in two different areas of southern Italy. Results of both geomorphological and structural geological studies are obtained by combining field and laboratory analyses of the badlands affecting Plio-Quaternary silty-clays of southern Italy. Results are discussed in terms of deformation mechanisms and badland formation and evolution. Results highlight the role played by pre-existing structural heterogeneities, such as high-angle faults and joints, on both gravitational processes and water circulation. The aforementioned heterogeneities are due to specific tectonic stress regimes, and are interpreted in light of their genetic nature, kinematics, attitude, geometry, relative timing of formation, and aerial distribution. Results of this work are summarized in a four-stage conceptual model characterized by specific genetic mechanisms. The conceptual model includes representative sketches aimed at assessing the time-dependant evolution of the badlands. A profound link between structural geology and geormophological processes is therefore envisioned for the badlands of southern Italy.

Provenance of Middle Jurassic sequences in the Northern Qiangtang: implications for Mesozoic exhumation of the Central Tibetan Mountain Range

ABSTRACT The exhumation history of the Central Tibetan Mountain Range (CTMR) in the Qiangtang terrane is important for establishing the boundary conditions prior to the India-Asia collision. Previous studies suggest that the CTMR is a significant provenance for Jurassic sediments in the Qiangtang terrane. The Middle Jurassic sediments north of the CTMR provide crucial information to constrain the timing of exhumation in the source area. Here we present detailed stratigraphic sections and detrital zircon U-Pb geochronology in the northern Qiangtang basin. Sedimentary facies analyses indicate that the Early-Middle Jurassic Quemoco Formation is mainly deposited in the deltaic system and carbonate-platform environment. Upsection, the Middle Jurassic Xiali Formation was deposited in a prodelta environment. Combined analyses of palaeocurrent indicators, conglomerate clast composition and U-Pb age spectra suggest that the CTMR is the main provenance for the Quemoco and Xialai formations; while the Triassic southern Qiangtang strata and Jinsha suture are the secondary source areas. The changes in the specific position of detrital zircon U-Pb age peaks around 500 Ma indicate evolving source terranes. Detrital zircon U-Pb geochronological data from the base of the Quemoco Formation and top of the Xiali Formation constrain the conservative maximum depositional ages to be 174.8 ± 1.0 and 161.7 ± 2.3 Ma, respectively. Combined with previous geochronology data, structural geology, and provenance studies across the Qiangtang terrane, the CTMR experienced rapid exhumation during Middle Jurassic and Late Cretaceous and slow exhumation since Eocene. The Jurassic uplift and exhumation of the CTMR were accompanied by the uplift of the southern Qiangtang terrane. The deformation and exhumation history is in favour of the hypothesis that plateau growth in the south-central Qiangtang terrane initiated during the Mesozoic, which is an important initial condition to quantify Cenozoic growth of the Tibetan Plateau.

Evolution of the Mesozoic Yuljeon Basin in South Korea and its tectonic implication

The Mesozoic Yuljeon Basin (YB) is a small scale non–marine sedimentary basin in the northeastern part of the Gyeonggi Massif in the Korean Peninsula. The YB consists of two lithostratigraphic units, the Munamdong and Yuljeon formations. Based on an integrated study of stratigraphy, structural geology, geochronology, and geochemistry, major episodes of the YB have been investigated. In the late Triassic (after 227 Ma), the YB was formed in a tectonic setting, wherein crust was extended and uplifted, which resulted in deposition of the Munamdong Formation. In the latest early Jurassic (circa 180 Ma), the Yuljeon Formation was deposited in association with volcanic activity in a continental magmatic arc setting. On entering the middle Jurassic (circa 174 Ma), extension in the YB stopped and then basin inversion occurred due to contractional deformation. The middle Jurassic thermal pulse in the area generated various scale igneous rocks and induced hydrothermal circulations, which created suitable conditions for fault activity with help of fluid pressure. This study demonstrates that the YB formed with sedimentation in a post–collisional extensional setting related to the Songrim Orogeny, and then it was enlarged with volcanic–related sedimentation in a continental arc setting related to the Daebo Orogeny, and lastly it was followed by basin inversion with arc magmatism in the same continental arc setting, reflecting the temporal and spatial changes in regional tectonics. Moreover, the general provenance characteristics for the early Mesozoic strata in the eastern North China Block, Gyeonggi Massif of South Korea, and southwest Japan, can be geochronologically correlated. The sedimentary rocks record the distinctive tectonothermal histories of East Asia such as the middle Paleoproterozoic orogens in the eastern North China Block, the Permo–Triassic continental collision between North and South China Blocks, and the subduction of Paleo–Pacific plate during the Mesozoic.

Anisotropy of Full and Partial Anhysteretic Remanence Across Different Rock Types: 2—Coercivity Dependence of Remanence Anisotropy

AbstractMagnetic fabrics are powerful tools in structural geology and tectonic studies, because they provide a fast and efficient measurement of mineral alignment, which helps interpret a rock's (de)formation history. The magnetic fabric of remanence‐carrying minerals provides useful information when these grains record different deformation stages than the bulk minerals in a rock. When rocks contain several subpopulations of remanence‐carrying minerals, each of these potentially displays a distinct fabric. This can lead to complex remanence anisotropies, being a superposition of all subpopulations' individual anisotropies. Characterization of partial remanence anisotropies has been used to investigate changes in fabric with grain size. However, most studies still report one bulk remanence anisotropy tensor per sample, and it remains to be determined how commonly different populations of remanence‐carrying grains reflect different subfabrics. Based on a large sample collection including 93 specimens from different lithologies, we have investigated the coercivity dependence of anisotropy of (partial) anhysteretic remanent magnetization A(p)ARM. We find that the principal directions, degree, and shape of A(p)ARM are generally dependent on the coercivity window used to impart the anhysteretic remanent magnetizations (ARMs). Depending on the carrier minerals and their fabrics, ARM anisotropy can either increase or decrease when the ARMs are applied over larger coercivity windows. Additionally, the coercivity fraction that dominates the ARM anisotropy is not always the coercivity fraction that acquires the strongest mean ARM. This illustrates the complexity of characterizing remanence anisotropy, and highlights the importance of carefully choosing experimental parameters in A(p)ARM determination for both magnetic fabric and anisotropy correction studies.

Application of Remote Sensing in Mapping Hydrothermal Alteration Zones and Geological Structures as Areas of Economic Mineralization in Mwitika-Makongo Area, SE Kenya

Remote sensing investigations combined with Geographical investigation systems (GIS) have become more important for the study of geological mineralization and structural geology like lineaments. Automatic extraction of lineaments from satellite imagery help in giving an overview of the tectonic events in the study area. The main objective of the study was to map hydrothermally altered rocks and geological structures that may be associated with mineral deposits in Mwitika-Makongo area. The study involves the use of Landsat- 8/OLI image. The satellite images were classified using ENVI 5.3 and ArcGIS 10.5. PCI geomatics 2016 was used for extraction of lineaments while Rose diagram was generated using Rockworks 16. Different remote sensing techniques, such as colour composite, band ratio and principal component analysis were applied to identify geological units and features related to economic mineralization. Colour composite band combination (5, 6, 7) showed hydrothermally altered geological units as blue. Band ratio combination (4/2, 6/7, 6/5) showed the areas that were hydrothermally altered as blue. Lineament mapping was done using PCA, with the first three PCs having the highest percentage of Eigenvalues. A lineament density map showed higher values in Makongo hill followed by Kalima Kathei hill. The structural trend from the rose diagram is in the NE direction. The results of image analysis and lineament extraction show that the economic minerals like iron ore are located in areas of hydrothermal alterations where intrusive rocks like Pyroxenite were found. Keywords: Colour composite, Geographical investigation systems, Landsat- 8/OLI, Lineaments, Principal component analysis, hydrothermally altered. DOI : 10.7176/JEES/9-11-03 Publication date: November 30 th 2019

Neotectonics of the Pleistocene deposits in the northeast of Taman peninsula, the southern Asov sea region

Studies in paleomagnetism, structural geology, and paleontology (mammals, molluscs, palynology) in the coastal sections of the Taman Peninsula north-eastern part (2017–18) resulted in definition of three sedimentary members. The sandy and clayey lower member (I) formed at 2.1–1.7 Ma. It contains a normally magnetised zone within deposits of reversed polarity correlated to the Olduvai Subchron and the Matuyama Chron.
 The middle member (II) is composed of the basal pebbles overlain by sands. The reversely magnetised deposits hosting the Sinyaya Balka site, the type locality of the Tamanian faunal complex, is correlated to the basal bed of the middle member II. The overlying sands are normally magnetised (Jaramillo Subchron) in the lower part and show reverse polarity (late Matuyama Chron) in the upper part. The member II is dated in the range of 1.3–0.78 Ma.
 The silty upper member (III) represents Middle-Late Pleistocene. The dissimilar displacement degree of the members reflect developmental stages of the Quaternary deformation.
 The member I is characterised by dip angles up to 70° is fragmented by faults into blocks. The member II filled the relief of the eroded surface of the Member I and also displaced by faults. The faulting separated the bone-bearing body of the Taman faunal complex as a rock land-slide. The attitude of the member III outline an anticline with a gentle south-western and a steeper north-eastern limbs eroded by land-slides and marine abrasion. During its entire life the anticline was affected by mud volcanism. The anticline continues its development at the present stage.