Investigation of Magneto-/Radio-Metric Behavior in Order to Identify an Estimator Model Using K-Means Clustering and Artificial Neural Network (ANN) (Iron Ore Deposit, Yazd, IRAN)

The study area is located near Toot village in the Yazd province of Iran, which is considered in terms of its iron mineralization potential. In this area, due to radioactivity, radiometric surveys were performed in a part of the area where magnetometric studies have also been performed. According to geological studies, the presence of magnetic anomalies can have a complex relationship with the intensity of radioactivity of radioactive elements. Using the K-means clustering method, the centers of the clusters were calculated with and without considering the coordinates of radiometric points. Finally, the behavior of the two variables of magnetic field strength and radioactivity of radioactive elements relative to each other was studied, and a mathematical relationship was presented to analyze the behavior of these two variables relative to each other. On the other hand, the increasing and then decreasing behavior of the intensity of the Earth’s magnetic field relative to the intensity of radioactivity of radioactive elements shows that it is possible to generalize the results of magnetometric surveys to radiometry without radiometric re-sampling in this region and neighboring areas. For this purpose, using the general regression neural network and backpropagation neural network (BPNN) methods, radiometric data were estimated with very good accuracy. The general regression neural network (GRNN) method, with more precision in estimation, was used as a model for estimating the radiation intensity of radioactive elements in other neighboring areas

Geology, geochemistry and gold-ore potential assessment within Akimov ore-bearing zone (the Altai Territory)

The article considers the geological setting of ore-bearing zone. Geochemical zoning of secondary dispersion haloes within Akimov ore-bearing zone was analyzed. Based on analytical data, distribution of gold mineralization trace-elements was examined. Geochemical associations were identified, analyzed and geometrized. The structure of abnormal geochemical field associated with gold-silver mineralization was determined. Three promising areas for exploration activities were identified

Geochemical and Hydrothermal Alteration Patterns of the Abrisham-Rud Porphyry Copper District, Semnan Province, Iran

In this study, the zonality method has been used to separate geochemical anomalies and to calculate erosional levels in the regional scale for porphyry-Cu deposit, Abrisham-Rud (Semnan province, East of Iran). In geochemical maps of multiplicative haloes, the co-existence of both the supra-ore elements and sub-ore elements local maxima implied blind mineralization in the northwest of the study area. Moreover, considering the calculated zonality indices and two previously presented geochemical models, E and NW of the study have been introduced as ZDM and BM, respectively. For comparison, the geological layer has been created by combining rock units, faults, and alterations utilizing the K-nearest neighbor (KNN) algorithm. The rock units and faults have been identified from the geological map; moreover, alterations have been detected by using remote sensing and ASTER images. In the geological layer map related to E of the study area, many parts have been detected as high potential areas; in addition, both geochemical and geological layer maps only confirmed each other at the south of this area and suggested this part as high potential mineralization. Therefore, high potential areas in the geological layer map could be related to the mineralization or not. Due to the incapability of the geological layer in identifying erosional levels, mineralogy investigation could be used to recognize this level; however, because of the high cost, mineralogy is not recommended for application on a regional scale. The findings demonstrated that the zonality method has successfully distinguished geochemical anomalies including BM and ZDM without dependent on alteration and was able to predict erosional levels. Therefore, this method is more powerful than the geological layer

Geostatistical and Remote Sensing Studies to Identify High Metallogenic Potential Regions in the Kivi Area of Iran

The Kivi area in the East Azerbaijan Province of Iran is one of the country’s highest-potential regions for metal element exploration. The primary goal herein was to process the data obtained from geochemical, geostatistical, and remote sensing tools (in the form of stream sediment samples and satellite images) to identify metallic mineralization anomalies in the region. After correcting the raw stream sediment geochemical data, single-variable statistical processing was performed, and Ti and Zn were identified as the elements with the highest degree of contrast. The relationship among these elements was further investigated using correlation and hierarchical clustering analyses. Principal component analysis was then applied to determine the principal components related to these elements, which were subsequently plotted on a regional geological map. Elements related to Ti and Zn were identified using threshold limits of anomalous samples determined via linear discriminant analysis. Lithological units and alteration patterns were detected through remote sensing investigations on Landsat-8 images. Stream sediment geochemical and remote sensing survey results identified anomalous areas of Ti and Zn in the eastern part of the study region. Our results indicate that Ti and Zn are good pathfinder elements for further exploratory investigation in this area

Estimating gold-ore mineralization potential within Topolninsk ore field (Gorny Altai)

Based on the results of ore and near-ore metasomatite composition analysis, the factors and indicators of gold-ore mineralization potential were proposed. Integration of the obtained data made it possible to outline magmatic, structural, and lithological factors, as well as direct and indirect indicators of gold-ore mineralization. Applying multidimensional analysis inherent to geochemical data, the spatial structure was investigated, as well as the potential mineralization was identified. Based on the developed and newly-identified mineralization, small (up to medium-sized) mineable gold-ore deposits in skarns characterized by complex geological setting was identified

Petrological Features of the Burlakski and Nizhne-Derbinsk Mafic-Ultramafic Plutons (East Sayan Mountains, Siberia, Russia)

The Nizhne-Derbinsk mafic-ultramafic complex is located between the Central Asian Orogenic Belt and the Siberian Craton and, is associated with the Ballyk fault. The largest, spatially related to each other, plutons in the central part of the complex are the Burlakski and Nizhne-Derbinsk. Rocks in the main units of these plutons are divided into three groups: peridotites (ultramafic), pyroxenites (sub-ultramafic), and gabbroic rocks (mafic). The ultramafic and sub-ultramafic cumulate series are devoid of plagioclase and contain <3 vol. % chromian spinel. The Fo content of olivine in the sub-ultramafic cumulates from both plutons ranges from Fo79 to Fo86. The En content [= Mg/(Mg + Fe + Ca) × 100 atomic ratio] of clinopyroxenes and orthopyroxenes varies from 46-56, and 63-80, respectively. Plagioclase corresponds to labradorite with An contents between 55 and 57. Hornblende is compositionally similar to pargasite. The sequence of change of rock units corresponds to the paragenesis: olivine − olivine + clinopyroxene (orthopyroxene) − clinopyroxene + orthopyroxene - clinopyroxene + orthopyroxene + plagioclase - orthopyroxene. Petrographic, mineralogical, and mineral chemical features of the Burlakski and Nizhne-Derbinsk plutons suggest that the diversity of the material composition of these plutons is due to the processes of magmatic differentiation in deep-seated conditions. Estimates of crystallization pressures and temperatures of the Burlakski and Nizhne-Derbinsk plutons suggest that they crystallized at high pressures ≥ 10kb and temperatures ranging from 1000-1400 °C. Mineralogical and petrological features suggest that the mafic-ultramafic cumulates were derived from a high-Mg basaltic magma. The presence of magmatic hornblende and hydrous mineral assemblages within the ultramafic cumulates indicates that the parental melts had been enriched in dissolved volatile constituents. Taking into account the age of the gabbronorites of the Burlakski pluton (~490 ± 11.8 Ma), the magmatism likely occurred during the Ordovician collision stage of the evolution of the Central Asian Fold Belt

Geochemical criterions for identifying reservoirs and predicting their petroleum potential (Vankor field)

The relevance of research is caused by the necessity to develop new approaches to assessment of petroleum potential of terrigenous sediments based on the study of metals geochemistry in the processes of the imposed epigenesis. The aim of the research is to determine the regularities of chemical elements redistribution in the processes occurring in the oil-water-rock system; based on lithogeochemical data to develop a methodology for evaluating the reservoir rock properties and nature of saturation of reservoirs. The material and methods. The study is based on the data on distribution of U, K, Ca, Ti, Cr, Fe, Mn, Rb, Sr, Ba, Zr the superimposed epigenesis areas of Jurassic-Cretaceous oil and gas deposits selected by the authors. The distribution patterns of these elements were studied in combination with lithological, mineralogical and petrographic studies of core and cuttings of exploratory wells drilled in the area of the Vankor field. The content of U in rocks was determined by delayed neutron, the contents of some elements (K, Ca, Ti, Cr, Fe, Mn, Rb, Sr, Ba, Zr) were defined on the express x-ray fluorescence analyzer INNOV-X50 with external control analyses by ICP MS. Characteristics of the newly formed minerals composition were studied using scanning electron microscope TESCAN VEGA 3 SBU. The results. It was determined that in the studied sediments uranium is a detecting element of the areas of improved reservoir characterized by abnormally low concentrations. The authors have revealed a significant redistribution of some chemical elements associated with hydrocarbon formation and determined the geochemical zonality. The regularities of chemical elements distribution allow predicting petroleum potential of terrigenous sediments section. Within the study area, the selected intervals are productive deposits recommended for testing

Ore mineralogy of Sokhatiny gold deposit (Northeast Asia, Russia)

Актуальность исследования обусловлена необходимостью расширения минерально-сырьевой базы действующих золотодобывающих предприятий Восточной Якутии и Магаданской области. Цель: изучение минералогии руд Сохатиного золоторудного месторождения и установление последовательности минералообразования. Методы: топоминералогическое картирование руд и метасоматитов; изучение прозрачных, прозрачно-полированных и полированных шлифов (Carl Zeiss Axio Imager.A2m.); сканирующая электронная микроскопия с локальным энергодисперсионным анализом (TESCAN VEGA 3 SBU с ЭДС OXFORD X-Max 50); рентгенодифракционный анализ (Rigaku Ultima IV), массспектрометрический с индуктивно связанной плазмой анализ, геофизические (каппаметрия). Результаты. Установлено, что гипогенная золоторудная минерализация на месторождении Сохатиное представлена жильно-прожилковыми телами кварц-карбонат-сульфидного состава, приуроченными к зонам мезотермальных метасоматитов пропилит-березитового ряда. Минерализация развивается на сопряжении пологопадающих надвиговых зон и крутопадающих поперечных разрывов. Вмещающая среда представлена метаморфитами фации зеленых сланцев: амфибол-биотитполевошпатовыми и мусковит-кварцевыми сланцами, подвергшимися процессам пропилитизации. В результате проведенных исследований изучен минералогический состав руд и метасоматитов, определена последовательность рудоотложения; проведено морфологическое описание самородного золота; выявлены новые минералы (аркубисит, селеноаркубисит, висмутин, сервеллеит, матильдит, шапбахит, науманнит, клаусталит, гессит), не описанные на Сохатином месторождении ранее. Отложение рудных минералов шло в три ступени, которым соответствуют следующие минеральные ассоциации: 1) кварцкарбонат-барит-пиритовая; 2) золото-полиметаллическая; 3) золото-висмут-теллуридная. Концентрация золота возрастает от ранних парагенезисов к поздним. В гипергенных условиях вдоль рудных зон сформировались линейные коры выветривания глинистого состава с максимальными концентрациями золота. Золото в окисленных рудах более высокопробное, в значительной степени очищенное от примесей серебра и других элементов.The relevance of the study is caused by the need to expand the mineral resource base of operating gold mining enterprises in Eastern Yakutia and the Magadan region. The main aim: to study the material composition of the ores of the Sokhatiny gold ore deposit and to establish the sequence of mineral formation. The methods: topomineralogical mapping of ores and metasomatites; study of transparent, transparent-polished and polished thin sections; scanning electron microscopy (TESCAN VEGA 3 SBU OXFORD X-Max 50); X-ray diffraction analysis (Rigaku Ultima IV), ICP-MS, geophysical (kappametry). Results. It was established that the gold ore mineralization at the Sokhatiny deposit has a hydrothermal-metasomatic and hypergenic genesis. In the first case, vein-veinlet bodies of a quartz-carbonate-sulfide composition were formed, confined to the zones of circum-ore beresitization rocks. In the second, there was a transformation of the products of the hydrothermal-metasomatic stage under the influence of exogenous factors. The metasomatic processes in the field are manifested in the form of areal propylization and beresitization of the host metamorphic shale rock. As a result of mineralogical and mineralografic research methods, the material composition of ores was studied in detail and the sequence of ore deposition was determined; a morphological description of native gold was carried out; new minerals were identified that were not previously described at the Sokhatiny deposit. The deposition of ore minerals went in three stages, which correspond to the following mineral associations: 1) quartz-calcite-barite-pyrite; 2) gold-polymetallic; 3) gold-bismuth-telluride. Based on the names, it follows that increased concentrations of gold are confined to later steps. In oxidized ores, native gold is also noted, which in its morphological parameters does not differ from primary one. The oxidation zone is characterized by low levels of addition of silver and other elements in gold, due to chemical dissolution in surface conditions

Mineral-geochemical zonality of golden-bearing weathering crust of the Tom-Yaya interfluve

Актуальность. Коры выветривания Томь-Яйского междуречья могут быть объектами промышленной добычи золота. В Томь-Яйском междуречье коры выветривания широко распространены, установлена их золотоносность, но строение, минеральный состав и геохимические особенности изучены недостаточно. Цель: выявить минерально-геохимическую зональность кор выветривания Томь-Яйского междуречья для решения вопросов генезиса и разработки критериев прогнозирования их золотоносности. Объект: коры выветривания по породам палеозойского фундамента Томь-Яйского междуречья. Методы. Кристалломорфологические особенности золота и минералов-спутников, парагенетические ассоциации минералов изучались микроскопически под бинокуляром, в отраженном свете, химический состав минералов - методом ИСП-масс-спектрометрии, на рентгено-флюоресцентном микроскопе HORIBA Scientific XGT-7200, сканирующем электронном микроскопе TESCAN VEGA 3 SBU с ЭДС OXFORD X-Max 50. Сокращенный химический состав продуктов выветривания определялся методом ИСП-масс-спектрометрии. Минеральный состав пелитовой фракции определялся методом рентгенофазового количественного анализа на дифрактометре D8 Advance фирмы Bruker. Проведен сокращенный гранулометрический анализ продуктов выветривания разных зон профиля. Результаты. В Томь-Яйском междуречье установлены остаточные и переотложенные коры выветривания. Продукты выветривания представлены песчано-алевритовым, глинистым и щебнисто-дресвяным материалом, с преобладанием песчаной и алеврито-глинистой составляющей. Установлен состав и распределение по разрезу глинистых минералов, карбонатов, пирита, золота и других минералов. Состав остаточных кор выветривания монтмориллонит-гидрослюдисто-каолинитовый. В строении полного профиля выделяются зоны: 1) дезинтеграции, 2) гидратации и 3) гидролиза. Дана минерально-геохимическая характеристика выделенных зон. На основании сокращенного химического анализа рассчитаны основные геохимические модули.The relevance. Weathering crusts of the Tom-Yaya interfluve can be the objects of commercial gold mining. Weathering crusts are widespread in the Tom-Yaya interfluve, their gold content was established, but the structure, mineral composition and geochemical features have not been studied enough. The main aim of the research is to identify mineral and geochemical zonation of weathering crusts of the Tom-Yaya interfluve to solve the genesis issues and develop the criteria for predicting their gold content. Object: weathering crusts on the rocks of the Paleozoic basement of the Tom-Yaya interfluve. Methods. Crystal morphological features of gold and satellite minerals, paragenetic associations with ore and vein minerals were analyzed microscopically under a binocular, in reflected light, chemical composition of minerals was studied by inductively coupled plasmaatomic emission mass spectrometry (ICP-AES/MS), X-ray fluorescence microscope HORIBA Scientific XGT-7200, on a scanning electron microscope TESCAN VEGA 3 SBU with EMF OXFORD X-Max 50. Reduced chemical composition of weathering products was determined by inductively coupled plasma-atomic emission mass spectrometry. Mineral composition of pelite fraction was determined by X-ray diffraction analysis using a D8 Advance diffractometer from Bruker. The authors have carried out the reduced particle size analysis of weathering products in different zones of the profile. Results. The authors identified the residual and redeposited weathering crusts in the Tom-Yaya interfluve. The weathering products are sandy-silty, clayey and gravelly-aggregate, with a predominance of sandy and silty-clayey constituents. The authors determined the composition and distribution of section clay minerals, carbonates, pyrite, gold and other minerals. Residual weathering crusts have montmorillonite-hydromica-kaolinite composition. In the structure of the complete profile, the following zones: 1) disintegration, 2) hydration and 3) hydrolysis, are distinguished. The mineral-geochemical characteristics of the isolated zones are given. Based on the abbreviated chemical analysis, the main geochemical modules were calculated

Geochemical criterions for identifying reservoirs and predicting their petroleum potential (Vankor field)

Актуальность исследований обусловлена необходимостью разработки новых подходов к оценке нефтегазоносности терригенных отложений, основанных на изучении геохимии металлов в процессах наложенного эпигенеза. Цель работы: установить закономерности перераспределения химических элементов в результате процессов, происходящих в системе «нефть-вода-порода»; на основе литогеохимических данных разработать методику оценки коллекторских свойств пород и характера насыщенности коллекторов. Материал и методы исследования. В основу работы положены данные по распределению U, K, Ca, Ti, Cr, Fe, Mn, Rb, Sr, Ba, Zr в выделенных авторами зонах наложенного эпигенеза юрско-меловых нефтегазоносных отложений. Закономерности распределения данных элементов изучались в комплексе с литологическими и минералого-петрографическими исследованиями по керну и шламу поисковых и разведочных скважин, пробуренных в районе Ванкорского месторождения. Содержания U в породах определялись методом запаздывающих нейтронов (2330 проб керна и шлама), содержания ряда элементов (K, Ca, Ti, Cr, Fe, Mn, Rb, Sr, Ba, Zr) - на экспрессном рентгенфлуоресцентном энергодисперсионном анализаторе INNOV-X50 (396 проб керна) с внешним контролем анализов методом ICP MS. Особенности состава новообразованных минералов изучались с использованием сканирующего электронного микроскопа TESCAN VEGA 3 SBU. Результаты. Установлено, что в изучаемых отложениях уран является индикаторным элементом зон высокопористых пород-коллекторов, характеризующихся аномально низкими его концентрациями. Выявлено закономерное перераспределение ряда химических элементов, связанное с формированием залежей углеводородов, что позволяет осуществлять прогноз нефтегазоносности разреза терригенных отложений на основе литолого-геохимических данных. В пределах изученной территории выделены интервалы продуктивных отложений, рекомендуемые к испытаниям.The relevance of research is caused by the necessity to develop new approaches to assessment of petroleum potential of terrigenous sediments based on the study of metals geochemistry in the processes of the imposed epigenesis. The aim of the research is to determine the regularities of chemical elements redistribution in the processes occurring in the oil-water-rock system; based on lithogeochemical data to develop a methodology for evaluating the reservoir rock properties and nature of saturation of reservoirs. The material and methods. The study is based on the data on distribution of U, K, Ca, Ti, Cr, Fe, Mn, Rb, Sr, Ba, Zr the superimposed epigenesis areas of Jurassic-Cretaceous oil and gas deposits selected by the authors. The distribution patterns of these elements were studied in combination with lithological, mineralogical and petrographic studies of core and cuttings of exploratory wells drilled in the area of the Vankor field. The content of U in rocks was determined by delayed neutron, the contents of some elements (K, Ca, Ti, Cr, Fe, Mn, Rb, Sr, Ba, Zr) were defined on the express x-ray fluorescence analyzer INNOV-X50 with external control analyses by ICP MS. Characteristics of the newly formed minerals composition were studied using scanning electron microscope TESCAN VEGA 3 SBU. The results. It was determined that in the studied sediments uranium is a detecting element of the areas of improved reservoir characterized by abnormally low concentrations. The authors have revealed a significant redistribution of some chemical elements associated with hydrocarbon formation and determined the geochemical zonality. The regularities of chemical elements distribution allow predicting petroleum potential of terrigenous sediments section. Within the study area, the selected intervals are productive deposits recommended for testing