The African-Antarctic sector of the Southern Ocean is the least studied part of the World Ocean, the structure and evolution of the tectonosphere of which remains debatable. The complex history of the development of the region under study, accompanied by manifestations of intense magmatic and tectonic activity, has contributed to the formation of a number of large underwater ridges and rises. Identifying the features of the deep structure of the tectonosphere on the basis of the analysis of geophysical information and understanding the geodynamic nature of the morphostructures of the studied region is an urgent problem of marine geophysics and geodynamics. Structural analysis of the anomalous gravitational and magnetic fields of the studied region was carried out. Zoning scheme by the anomalous fields as well as a generalized scheme are constructed. The results of the sestudiesmadeit possible to identify heterogeneous blocks of the lithosphere, which for medon different spreading ridges and are separated by submarine rises.

As a result of generalization of geophysical studies, petro-paleomagnetic and structural-geomorphological analyses, as well as thermodynamic modeling, some features of ore formation in the hydrothermal system of Cape Fiolent (southwestern Crimea) under island arc conditions were revealed. It has been established that the main transformations of rocks of the Middle Jurassic igneous complex of Cape Fiolent occurred under the influence of hydrothermal fluids during the introduction of felsic intrusions during 168–140 Ma. The zones contain sulfide mineralization, the main minerals of which are pyrite, sphalerite, pyrrhotite, galena, chalcopyrite and arsenic pyrite. In the central parts of the hydrothermal alteration zone, massive sulfides are strongly weathered; these zones contain many secondary sulfates. In the marginal parts of hypergenic limonite, yellow-brown goethite prevails in the oxidation zone, yellow jarosite in the center, which is probably due to the large amount of pyrite in the center of the system, which gave more sulfuric acid during oxidation. The presence of native sulfur in the section testifies to the mixing of the acidified hydrothermal solution with seawater. Complex petro-paleomagnetic and magnetometric studies have shown that contact changes and transformation of the contrasting basalt-rhyolite formation occurred along the NNW-trending faults.

Abstract—The features of potential fields characterizing the Islas Orcadas and Meteor undersea rises located in the South Atlantic are considered. The rises are located at approximately the same distance to the west and to the east from the axis of the southern segment of the Mid-Atlantic Ridge. Density modeling along the profiles intersecting the rises was carried out. The analysis of potential fields and the results of density modeling shows a generally similar structure of the crust and lithosphere of the Islas Orcadas Rise and the Meteor Rise, which supports the common nature of their formation as a result of the splitting of the lithosphere of the small Agulhas plate due to kinematic restructuring, which led to the extinction of the Agulhas Ridge and formation of the southern segment of the Mid-Atlantic Ridge. However, some features in the density structure of these rises, both along their north-south trend where the influence of hot spots on the heating of the mantle is particularly evident, and along the conjugate profiles, indicate an asymmetric structure of the rises during the initial stage of their formation.

The tectonosphere and formation conditions of the Mozambique Ridge are considered. The Mozambique Ridge is located in the southwestern part of the Indian Ocean between the Natal and the Mozambique Mesozoic Basins. The way how the ridge formed remains debatable. The anomalous structure of the crust of the Mozambique Ridge can be explained either by underplaying - thickening of the oceanic crust from below due to magmatism, or by stretching and thinning of the continental crust. Based on gravitational and magnetic field anomalies, seismotomography and other geological and geophysical information, density modeling was carried out along four profiles. Physical modeling determined the conditions of formation of the Mozambique Ridge. It formed due to the splitting of the African-Antarctic continent, the presence of structural heterogeneities in the lithosphere of the African continent and the influence of the Karoo plume.

The results of density modeling of the tectonosphere structure in the Antarctic sector of the South Atlantic Ocean are presented. The modeling was carried out along the profiles stretching from the Falkland Plateau to the Mozambique Ridge and crossing a series of submarine rises and ridges separated by deep-sea basins. Studies show that the crust of this region has a heterogeneous structure and the crust underlying the rises is of a different structure, indicating different origins of the respective rises.

The tectonic zoning of the African-Antarctic sector of the Southern Ocean was carried out on the basis of cluster analysis of a large volume of heterogeneous geophysical and geological data. It is known that the degree of geological and geophysical exploration of this part of the ocean by marine surveys and drilling remains extremely low. The results of such an analysis make it possible in areas with weak geophysical knowledge to quickly draw up tectonic zoning schemes based on regional geophysical data that are freely available throughout the entire territory of the world ocean and use them as a basis for further interpretation. The following materials were used as input data or classification features: ocean floor topography, gravity anomalies in free air and in the Bouger reduction, ∆Ta anomalous magnetic field model, ocean floor age, geoid height data, and the SL2013sv seismotomography model. «K-means» algorithms and the «Gaussian mixtures» method used for clustering. Based on the results of the application of these algorithms, cluster models of the study region were obtained, in which the selected classes fully reflect the main tectonic elements.

Издание включает теоретическую часть курса «Геологическая интерпретация гравитационных и магнитных аномалий», читаемого магистрантам геофизического профиля. Пособие предназначено для студентов геофизиков и специалистов, интересующихся интерпретацией гравитационного и магнитного полей при решении широкого круга геологических задач.

The the southwestern part of the Indian Ocean, where the Mozambique and Madagascar ridges are located was studied. The ideas about the tectonic structure of these ridges are still under debate. The anomalous structure of the crust of these ridges can be explained either by underplating (thickening of the oceanic crust from below due to magmatism), or by stretching and thinning of the continental crust. Based on the data on anomalous gravitational and magnetic fields, seismotomography, and other geological and geophysical information, density modeling was performed along four profiles, which revealed differences in the crustal structure and evolution of the Mozambique and Madagascar ridges.

Магматические образования в Крыму изучаются геологами более ста лет. Эти исследования совершаются преимущественно методом натурных наблюдений, которые не могут дать ответ на многие важные вопросы о строении и генезисе этих образований. Магматические тела имеют высокие значения намагниченности, по сравнению с вмещающими породами, что является физическими предпосылками для применения магниторазведки. Статья посвящена анализу новых данных высокоточной площадной магнитной съемки масштаба 1:10000, выполненной на периферийной части Качинского антиклинория Крыма в районе реки Бодрак у села Трудолюбовка в комплексе с палеомагнитными исследованиями интрузий средней юры J2bd. Авторы по площадным магнитным данным показывают вариант площадного картирования сложнодислоцированного интрузивного комплекса и дополняют свои исследования построением магнитных моделей геологического разреза с учетом данных остаточной намагниченности, значения которой получены по данным отобранной палеомагнитной коллекции. Полученные результаты позволяют по-новому рассмотреть пространственно-временные соотношения интрузий бодракской свиты и вмещающих их горных пород на исследуемой территории. Magmatic formations in Crimea have been studied by geologists for over a hundred years. These studies are carried out mainly by the method of field observations, which cannot answer many important questions about the structure and genesis of these formations. Magmatic bodies have high magnetization values in comparison with containing rocks, which is the physical prerequisite for use of magnetic prospecting. This article focuses on the analysis of new high-precision areal magnetic survey data at a scale of 1:10000, performed on peripheral part of the Kachinsky anticlinorium in Crimea, near to the Bodrak river and Trudolubovka village, in a complex with paleomagnetic studies of the Middle Jurassic J2bd intrusions. The authors, using magnetic data, show a variant of areal mapping of a complexly deployed intrusive complex and supplement their studies with magnetic modeling of a geological section. Magnetic modeling was carried out taking into account a remanent magnetization data, which values were obtained from data of selected paleomagnetic collection. The results allow us to re-examine the spatiotemporal relationships between intrusions of the Bodrak formation and rocks enclosing them in the study area.

Summary This paper is dedicated to research on structural position of magmatic formations in the area of educational and research site of Geological Faculty, LomonosovMoscow State University, located in the Bakhchisaraidistrict in Crimea.In this area, magmatic formations are represented in all their diversity. There is no consensus about the form of intrusions occurrences.In different years, the same arrays of igneous rocks were considered as diapirs, stocks, laccoliths, and plate bodies.Petrophysical measurements on“Bodrak formation”outcrops near theTrudolubovka village, showed that intrusive bodies have a high contrast in magnetic susceptibility.It creates prerequisites for mapping dikes and intrusions hidden under a thin layer ofsame age volcanogenic-sedimentary rocks. To understand the depths and geometry of intrusive bodies near mount Kremennaya, the authors performed a two-dimensional magnetic modeling of magmatic bodiesstructural positions. It showed high variability of models using only induced magnetization. The authors demonstrated that using of paleomagnetic data and determination of thermo-residual magnetization vectordirection will make it possible to determinemore reliably the structural position of magmatic bodies, which is important for explanation of magmatismin the region.

Summary The article is devoted to the results of the interpretation of data of high-precision magnetic surveys conducted on most of the archaeological site of Jankent from 2011 to 2018. According to the results of the interpretation of magnetic data, it was possible to classify local anomalies and associate them with various types of archaeological objects. By the linear negative anomalies (-5 -20) nT extended in the submeridional and sublatitudinal directions fragments of the internal layout of the hillfort were traced. By the results of the analysis of various transformations of the anomalous magnetic field and the solution of the inverse problem, conclusions were made about the localization of the sources of anomalies in the depth range from 0.6 meters to 1.4 meters. Magnetic modeling allows us to conclude that sources of intense magnetic anomalies are likely to be foci or furnaces. The results will be verified by archaeologists in the course of further research.

Summary The report examines the prospects for the development of a new scientific direction in Russia -AGROGEOPHYSICS. The analysis of foreign experience of application of geophysics for agricultural tasks is given. It is noted that the most widespread were various modifications of methods of electrical prospecting. According to the results of the research carried out by the authors, great prospects of magneto-prospecting and georadiolocation are shown in combination with electrical prospecting in solving soil and agroecological problems.

Summary The report discusses the results of the interpretation of regional and detailed magnetic and gravitational fields within the Ladoga electrical conductivity anomaly. The constructed density and magnetic models allow for a new understanding of the geological and tectonic structure of the area. The connection of the region of increased resistance with areas of high density and magnetization at depths of 25–30 km. Interpretation of detailed gravity material along the profile of the Vyborg - Suoyarvi in the upper part of the section has established the presence of complex Cup-like structure, which agrees well with regional models.

Summary This paper reviews the specifics of the magnetic methods in its application and its particular effectiveness in the exploration for intrusive rocks deposits (mainly with diorite and dactic compound — usually/ potentially a good source of gravel raw materials) using the case studies collected at the foothills in the Southern part of the Crimea peninsula. The combination of detailed magneto-prospecting methods used includes land high-precision measurements of a magnetic susceptibility on rock outcrops and on core samples taken from the exploration wells. Such approach not only allowed to contour the intrusive bodies, but, for some cases, successfully calculate the potential volume of the raw material deposits. This article also presents the comparison example of the mineral stock calculation based on the contours derived from the magnetic field data versus the drilling data. The high cost-efficiency of a detailed high-precision magnetic exploration is demonstrated in the article in its particular application for finding and delineating of the intrusive granodiorite and diorite bodies. Such high efficiency can also be achieved in a broader application of the magnetometric method when searching for shallow accumulations of raw gravel materials of diorite and dacitic composition with high magnetic properties contrast.

На территории Александровского городища, которое является памятником мощинской культуры, выполнены электротомографические, магнитометрические и георадиолокацион-ные исследования . Проведена высокоточная тахеометрическая съемка, которая зафиксиро-вала состояние поверхности памятника в 2014 г. Установлено, что площадка городища и ва-лы сделаны из принесенного грунта, который имеет повышенную магнитную восприимчи-вость. Средняя мощность отсыпанного грунта составляет около 1.2 м. Судя по высоким удельным сопротивлениям, основная масса грунта состоит из песка. Углубления рвов были незначительные и вероятно не превышали 50 см. Наблюдается сходимость результатов гео-радарной съемки с результатами бурения. Установлено, что нижние слои лежат практически горизонтально, а в верхнем слое песков отмечены наибольшие изменения мощности. По геофизическим данным установлено, что верхняя часть разреза Александровского городища состоит из трех слоев: песчаной отсыпки, слоя песка перемешанного с суглинком и гумуси-рованного культурного слоя.

Summary Today, evolution of material and element base of the geophysical equipment and fast implementation of unmanned aerial vehicles in everyday lifegives possibility of creation of magnetometric complex based on the UAV, capable to make meeting modern quality requirements aeromagnetic shooting in automatic mode.For development of the optimum scheme of the device carrier of the magnetometric equipment, within the project ordered the Ministry of Education and Science of the Russian Federation of 16.10.2014 (the project 2014-14-579-0156-002 code) on development of hardware complex for aero magnetic shooting on the basis of the UAV has executed studying of distortion of magnetic field of already developed and actively applied UAV “Geoskan-201”. During researchboth influence of manifestation in constant magnetic field of ferromagnetic elements of design of the UAV and influence of working power and navigation systems at flight emulation was studied.

Summary The complex geophysical researches conducted on the Naransky area, have shown the high importance of detailed magnetic shootings in the scales 1:25000 and 1:1000 allowing makingmuch more exact geological tectonic maps, important at evaluation stage of ore occurences of chromites. Density and magnetic modeling, taking into account geoelectric model allows to solve problems of identification of chromite bodies of difficult configuration and to adjust available forecast geological constructions by searches of chromite ores of the Naransky ophiolitic complex.