Nickel anomalies and gold-quartz mineralization in dunite-harzburgite massifs of the Pervomaisko-Verkhoturinskaya area, Central Urals

2021 ◽  
pp. 90-98
Author(s):  
Andrey Motov ◽  
Yury Malakh ◽  
Ilya Voropaev

Along with some gold-quartz deposits hosted by dunite-harzburgite massifs elsewhere in the Urals, elevated Ni concentrations were revealed within the ore field of the Anna gold-(sulfide)-quartz deposit localized in weathered oxidized dunites and harzburgites of the Pervomaisky complex (συO2p) in the Pervomaisko-Verkhoturie district of the Central Urals. The spatial association of Au and Ni concentrations in dunites-harzburgites may be attributed to a partial inheritance of Ni-controlling tectonic dislocations by those hosting gold mineralization. Therefore, the combination of halos of Ni and Au concentrations in dunite-harzburgite massifs is a favorable indicator of areas prospective for discovery of goldquartz mineralization.

2021 ◽  
pp. 4-18
Author(s):  
ANATOLY IVANOV ◽  
YURI AGEEV ◽  
ALEXANDER MEZENTSEV ◽  
BASIL MOLOCHNY ◽  
VICTOR KONKIN

New data is provided on gold mineralization in the southern Baikal-Patom metallogenic province, Ikibzyakskoye ore field, located in Pravo-Mamakansky deep fault zone separating Patom fold area from Baikal-Vitim volcanic-plutonic belt. For the first time, the metallogenic province was found to comprise granitoid-hosted ore vein-stringer zones with high-grade economic gold sulfide-quartz mineralization. This mineralization is localized within fault shistosity zones manifesting intense beresitization and listvenitization (in metabasite xenoliths).


2013 ◽  
Vol 828 ◽  
pp. 1-10
Author(s):  
Adilkhan Baibatsha ◽  
Kulyash Dyussembayeva ◽  
Aimkhan Kassenova

The gold-sulfide deposit Southern Ashaly is localized in carbonaceous terrigenous formation (black shale strata) of the middle carboniferous (Bukon suite, which is the ore-hosting for super large deposit Bakyrchik). The Southern Ashaly is at the exploration stage and according to preliminary estimates of the expected resources belongs to a large deposit in scale. Ore gold mineralization of such level as Southern Ashaly in southwestern Kalba is found for the first time and gives hope for the discovery of such objects in the Boko Vassilyevskoye ore field. Ore-hosting at the field Southern Ashaly is carbonaceous terrigenous formation of the middle carboniferous, with no visible signs of volcanic formations. But, it was revealed, at microscopic research by us, paragenetic relation of the gold mineralization with small intrusions of plagiogranites and zones of plagiogranite porphyry dykes and found volcano-sedimentary rocks (aleuritic tuffsandstone, tuff breccia) which have undergone hydrothermal-metasomatic changes. The vein-disseminated gold-sulfide mineralization is associated with beresitizated plagiogranites and plagigranite-porphyries and hydrothermally altered tuff sandstones, tuff breccia and carbonaceous shales. Southern Ashaly unlike Bakyrchik deposit which contains invisible gold in sulfides, all the gold is concentrated in the pyrite mainly in the form of micro-sized (1-5 µm or less) in arsenopyrite is noted rarely.


2021 ◽  
Author(s):  
Quentin Masurel ◽  
Paul Morley ◽  
Nicolas Thébaud ◽  
Helen McFarlane

Abstract The ~15-Moz Ahafo South gold camp is located in southwest Ghana, the world’s premier Paleoproterozoic gold subprovince. Major orogenic gold deposits in the camp include Subika, Apensu, Awonsu, and Amoma. These deposits occur along an ~15-km strike length of the Kenyase-Yamfo shear zone, a major tectonostratigraphic boundary juxtaposing metamorphosed volcano-plutonic rocks of the Sefwi belt against metamorphosed volcano-sedimentary rocks of the Sunyani-Comoé basin. In this study, we document the geologic setting, structural geometry, and rheological architecture of the Ahafo South gold deposits based on the integration of field mapping, diamond drill core logging, 3-D geologic modeling, and the geologic interpretation of aeromagnetic data. At the camp scale, the Awonsu, Apensu, and Amoma deposits lie along strike from one another and share similar hanging-wall plutonic rocks and footwall volcano-sedimentary rocks. In contrast, the Subika gold deposit is hosted entirely in hanging-wall plutonic rocks. Steeper-dipping segments (e.g., Apensu, Awonsu, Subika) and right-hand flexures (e.g., Amoma, Apensu) in the Kenyase-Yamfo shear zone and subsidiary structures appear to have represented sites of enhanced damage and fluid flux (i.e., restraining bends). All gold deposits occur within structural domains bounded by discontinuous, low-displacement, sinistral N-striking tear faults oblique to the orogen-parallel Kenyase-Yamfo shear zone. At the deposit scale, ore-related hydrothermal alteration is zoned, with distal chlorite-sericite grading into proximal silica-albite-Fe-carbonate mineral assemblages. Alteration halos are restricted to narrow selvages around quartz-carbonate vein arrays in multiple stacked ore shoots at Subika, whereas these halos extend 30 to 100 m away from the ore zones at Apensu and Awonsu. There is a clear spatial association between shallow-dipping mafic dikes, mafic chonoliths, shear zones, and economic gold mineralization. The abundance of mafic dikes and chonoliths within intermediate to felsic hanging-wall plutonic host rocks provided rheological heterogeneity that favored the formation of enhanced fracture permeability, promoting the tapping of ore fluid(s). Our interpretation is that these stacked shallow-dipping mafic dike arrays also acted as aquitards, impeding upward fluid flow within the wider intrusive rock mass until a failure threshold was episodically reached due to fluid overpressure, resulting in transient fracture-controlled upward propagation of the ore-fluid(s). Our results indicate that high-grade ore shoots at Ahafo South form part of vertically extensive fluid conduit systems that are primarily controlled by the rheological architecture of the rock mass.


2019 ◽  
Vol 20 (2) ◽  
pp. 174-183
Author(s):  
Hani E. Sharafeldin ◽  
Alexander A. Vercheba

Banded ferruginous-siliceous formations (FSF) are confined to the Precambrian basement of the Arabian-Nubian Shield within the central part of the Eastern Desert of Egypt. Gold mineralization is spatially associated with banded ferruginous quartzite, representing one of the most ancient manifestations of gold ore. The Precambrian rocks are combined into deposits complex of the Neoproterozoic Pan-African megacycle of the territory development. Banded iron-silicate rocks occur in sedimentary-volcanogenic rocks that were formed in the subduction trough zones, and are represented by metamorphosed ferruginous quartzites, jaspilites and schists. FSF show tectonic dislocations, shear cracks, and fracture cracks made by gold-quartz-sulphide mineralization. Promising for the identification of gold-bearing mineralization in the rocks of the FSF can be iron-silicate deposits with the occurrence of epigenetic hydrothermal activity as a result of activation of the submarine volcanism of the tholeiitic type.


2015 ◽  
Vol 7 (1) ◽  
pp. 61
Author(s):  
Seang Sirisokha ◽  
Lucas Donny Setijadji ◽  
I Wayan Warmada

Western Java is a part of the Sunda Banda magmatic belt. This belt is well known to be host for several gold deposits in Indonesia, the distribution of 107 Au occurrences in this area was examined in terms of spatial association with various geological phenomena. The goal of this project is to use GIS to conduct weights of evidence (WofE) model for gold mineralization in West Java, Indonesia. A Geographic Information System (GIS) is a computer system for capturing, storing, querying, analyzing, and displaying geospatial data and weight of evidence method is one of the most important datadriven methods for mapping in GIS. The method is a probability based on technique for mapping mineral potential using the spatial distribution of known mineral occurrences. Therefore this method is very useful for gold potential mapping. There are six evidences maps such as NE–SW lineaments NW–SE Lineament, host rocks, heat sources, clay alteration and limonitic alteration, have been combined using a weights of evidence model to predict gold potential in West Java. The best predictive map generated by this method defines 21.62% (9902 km) of study area as favourable zones for gold mineralization further exploration work. It predicts correctly 74 (92.5%) of the 80 model deposits and predicts correctly 26 (96.35%) of the 27 validation deposits, has 6 main 2 prospective target for future exploration are located in Bayah Dome, southern mountain, Honjie Igneous Complex and Bogor zone, Purwakarta. Bayah Dome is highest potential area for gold deposit like Gunung Pongor, Cikidang, Cirotan, Ciawitali, Cikotok destricts and other deposits. The potential area of Au occurrences in research area is associated with NE–SW and NW–SE structure/ lineaments, dominated surrounding the Tertiary intrusive rock unit and hosted in Miocene to Pleistocene lithology rock unit.


2021 ◽  
Author(s):  
A.V. Snachev ◽  
◽  
A.V. Kolomoets ◽  
M.A. Rassomakhin ◽  
V.I. Snachev ◽  
...  

The article discusses the geological structure of the Baikal deposit, located within the Kumak ore field and confined to the black shale of the Bredy Formation (C1bd). It has been established that the gold mineralization within the occurrence is confined mainly to the members of quartz-mica-tourmaline metasomatically altered carbonaceous shales. Gold is noted here in intergrowth with tourmaline. In terms of their chemical composition, tourmalines belong to dravite and foitite and are close to those of orogenic gold and gold-sulfide deposits. The close intergrowth of thin needle- like tourmaline and gold indicates the synchrony of their formation and allows the manifestation of Baikal deposit to be attributed to the quartz-tourmaline formation.


Author(s):  
Д.Б. Давыденко ◽  
С.Г. Парада

Приведены результаты металлогенического анализа новых данных, полученных в ходе проведения геолого-поисковых и региональных геофизических работ на территории Донецкого бассейна, представляющего центральный фрагмент Днепрово-Донецкой рифтогенной системы. По результатам металлогенического анализа и математической обработки геофизических данных, включающих оригинальную технологию объектно-ориентированной фильтрации, установлены полихронность и полигенность золотого оруденения, соответствующие полиэтапному развитию Донецкого авлакогена. В составе золотоносных руд вычленяются два основных типа: 1) крупнообъемные зоны и залежи золото-сульфидно-прожилково-вкрапленной минерализации в песчанико-сланцевых углеродистых толщах, относящихся к осадочно-(метаморфогенно)-гидротермальному генетическому классу, связанные с литогенезом и метаморфизмом каменноугольных углеродистых отложений на доорогенном этапе развития авлакогена (Бобриковское и др. месторождения) 2) эпитермальные кварцевые жилы и локальные жильно-прожилковые зоны золото-серебряно-полиметаллической минерализации, связанные с развитием вулкано-плутонических аппаратов центрального типа на этапе мезозойской тектоно-магматической активизации авлакогена, выделяемые по геофизическим данным (Керчикское и др. рудопроявления). Отнесение к осадочно-(метаморфогенно)-гидротермальному генетическому классу золотоносных минерализаций бобриковского типа обосновано особенностями локализации, размещения и вещественного состава руд, а также особенностями геологического строения Донбасса, свойственными классическим рудным районам с подобным типом оруденения в углеродисто-терригенных (черносланцевых) формациях: внутриконтинентальная позиция складчатых структур и отсутствие гранитоидного магматизма, отчетливо выраженная асимметрия складчато-разрывных структур, сочетание углеродисто-терригенных и карбонатных формаций различной степени их постседиментационного преобразования, наличие стратифицированной сульфидной минерализации. Выделение мезозойских вулкано-плутонических структур центрального типа, с которыми связана эпитермальная золотоносная минерализация керчикского типа, основано на выявлении изометричных положительных аномалий магнитного поля, сопряженных с изометричными отрицательными аномалиями гравитационного поля, а также выходами магматических пород. Выявленные в Западном Донбассе к настоящему времени золотоносные руды бобриковского типа представляют собой объекты ранней доорогенной минерализации золото-сульфидно-прожилково-вкрапленного типа в углеродисто-терригенных комплексах. Выявленные в Восточном Донбассе к настоящему времени золото-серебряно-полиметаллические руды керчикского типа представляют собой позднепродуктивную стадию, связанную с регенерацией и перераспределением доорогенных золотоносных минерализаций на этапе мезозойской тектоно-магматической активизации The results of a metallogenic analysis of new data obtained during geological exploration and regional geophysical work in the Donets basin, which is the central fragment of the Dnieper-Donetsk riftogenic system, are presented. According to the results of metallogenic analysis and mathematical processing of geophysical data, including the original technology of object-oriented filtering, the polychronism and polygenicity of gold mineralization is established, corresponding to the poly-phased development of Donetsk aulacogen. In the composition of gold ores, two main types are distinguished: 1) large-volume zones and stratiform deposits of gold-sulfide-vein-disseminated mineralization in sandy-shale carbon strata, belonging to sedimentary (metamorphic) -hydrothermal genetic class, associated with lithogenesis and metamorphism of stony-carbon metamorphism at the preorogenic stage of development of aulacogen (Bobrikovskoye and other deposits) 2) epithermal quartz veins and local vein-vein zones of gold-silver-polymetallic mineralization associated with the development of central-type volcanic-plutonic apparatuses at the stage of Mesozoic tectonic-magmatic activation of aulacogen, identified according to geophysical data (Kerchik and other ore occurrences). The assignment to the sedimentary (metamorphogenic) -hydrothermal genetic class of Bobrikovsky type gold-bearing mineralizations is justified by the features of localization, distribution and material composition of the ores, as well as the peculiarities of the geological structure of the Donbass, characteristic of classical ore regions with a similar type of mineralization in carbon-terrigenous (black shale) formations the position of folded structures and the absence of granitoid magmatism, a pronounced asymmetry of folded-discontinuous structures, with the carbon-terrigenous and carbonate formations of varying degrees of their post-sedimentation transformation, the presence of stratified sulfide mineralization. The isolation of the Mesozoic volcanic-plutonic structures of the central type, which are associated with the zythermal gold-bearing mineralization of the Kerchik type, is based on the detection of isometric positive anomalies of the magnetic field, coupled with isometric negative anomalies of the gravitational field, as well as the outputs of igneous rocks. Gold-bearing ores of the Bobrikov type identified in the Western Donbass to date are objects of early pre -ogenic mineralization of a gold-sulfide-vein-disseminated type in carbon-terrigenous complexes. The gold-silver-polymetallic ores of the Kerchik type discovered in the East Donbass to date represent a late-productive stage associated with the regeneration and redistribution of pre -ogenic gold-bearing mineralizations at the stage of Mesozoic tectonic-magmatic activation


2021 ◽  
pp. 28-35
Author(s):  
Sergei MILYAEV

The formation conditions and characteristics of secondary dispersion haloes in the gold-bearing weathering crust of a gold-sulfide-quartz deposit are considered. The fraction < 0,1mm is demonstrated to be preferable for lithochemical prospecting for the Vasilkovskoe type gold mineralization. The secondary dispersion haloes of gold, identified based on analyses of this fraction, are characterized by the maximum size and productivity.


Author(s):  
V. A. Stepanov ◽  
◽  
V. Ye. Kungurova ◽  
I. A. Koidan ◽  
◽  
...  

The article describes the ore bearance of three stages of reflected activation of the Kamchatka middle massif: Late Cretaceous, Eocene, and Miocene. In the first stage, gold mineralization of the gold-quartz and gold-sulfide-quartz formations was formed; in the second - sulfide platinoid-copper-nickel; in the third - gold-copper-molybdenum-porphyry. The relationship of gold, sulfide platinoid-copper-nickel and gold-copper-molybdenum-porphyry mineralization with certain igneous rock complexes - (Kola, Dukuk and Lavkin) is shown. The mining of nickel, copper from the Shanuch deposit and gold from placers has been noted.


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