scholarly journals FORECASTING GEOCHEMICAL PREREQUISITES FOR DETECTING THE PORPHYROUS SYSTEM IN THE KOMSOMOLSK REGION OF KHABAROVSK REGION

2021 ◽  
pp. 126-130
Author(s):  
INNA VLADIMIROVNA BUCHKO ◽  
◽  
IVAN ALEXANDROVICH YATSENKO ◽  

The information on the results of geological exploration work to identify the porphyry system in the Komsomolsk region of the Khabarovsk Territory is given. It is shown that copper-molybdenum-porphyry mineralization is associated with the type of porphyry deposits by a porphyry stock surrounded by fields of hydrothermal-metasomatic alteration. The possibilities of the object of the gold-rare metal type are substantiated.

Author(s):  
С.Г. Парада

Статья посвящена выявлению особенностей геологического строения и минерагении Танадон-Сангутидон-Казбекского района проявлений медно-порфировых минерализаций Центральной части Большого Кавказа и оценке соответствия геологических обстановок оруденения современным моделям рудно-магматических систем медно-порфирового типа. Актуальность работы определяется необходимостью разработки научно-методической основы прогнозирования и поисков скрытого оруденения. Цель исследования.Выявить особенности геологии и минерагении Танадон-Сангутидон-Казбекского рудного района и установить соответствие обстановок оруденения современным моделям рудно-магматических систем медно-порфирового типа. Методы. Сравнительно-геологический и металлогенический анализ на основе современных геоинформационных технологий в среде программного комплекса ArcGIS. Результаты. Установлено, что рудно-магматические системы исследуемого района соответствуют геолого-структурной позиции медно-порфировых месторождений. Изученный район объединяет группу медно-порфировых рудно-магматических систем, связанных с малыми гранитоидными интрузиями теплинского плиоцен-плейстоценового комплекса. Здесь также отмечаются рудопроявления вольфрама, мышьяка, золота, сурьмы и др., составляющие единый генетический ряд, в котором медно-порфировое оруденение занимает вполне определенную позицию, – приурочено к порфировой фазе новейшего интрузивного магматизма. Сопоставление обстановок проявления позднекайнозойского оруденения и его характеристик в пределах изученных рудоносных площадей с основными элементами типовой модели медно-порфировой системы позволяет рассматривать Сангутидонский, Теплинский и Танадонский рудные узлы как выражение надстраивающих друг друга по вертикали частей единой рудно-магматической системы медно-порфирового ти­па. Продук­тивная на медно-порфировое оруденение новейшая гранит-гранодиоритовая формация Большого Кавка­за образовалась в условиях повторноорогенного режима активизации региона и наложена на его гетерогенный субстрат. Последний в пределах изучаемого района характеризуется двухэтажным стро­ением и состоит из нижне-среднеюрского вулканогенно-осадочного комплекса чехла и доюрского основания, в котором главную роль иг­рают докембрий – нижне-среднепалеозойские метаморфические тол­щи кристаллического фундамента Большого Кавказа, прорванные пале­озойскими гранитоидами Главного хребта. Состав поздненеогеновых гранитоидов находится в зависимости от состава субстрата, как на глубинных уровнях его анатектического плавления, так и на путях подъема образованных при этом магм. В этой связи повышенная основность гранитоидов полифазного теплинского комплекса, сформированных в гипабиссальных и субвулканических условиях, обусловлена более высокой по сравнению с соседними блоками степенью мафичности субстрата исследуемого района, включающего ряд базальтоидных или близких к ним по составу толщ The article is devoted to the identification of the features of the geological structure and mineralogy of the Tanadon-Sangutidon-Kazbek district of the manifestations of copper-porphyry mineralization in the Central part of the Greater Caucasus and the assessment of the correspondence of the geological conditions of mineralization to modern models of ore-magmatic systems of the copper-porphyry type. The relevanceis determined by the need to develop a scientific and methodological basis for forecasting and searching for hidden mineralization. Aim. To identify the features of the geology and mineralogy of the Tanadon-Sangutidon-Kazbek ore region and to establish the correspondence of the mineralization conditions to modern models of ore-magmatic systems of the copper-porphyry type. Methods.Comparative geological and metallogenic analysis based on modern geoinformation technologies in the environment of the ArcGIS software package. Results. It is established that the ore-magmatic systems of the studied area correspond to the geological and structural position of copper-porphyry deposits. The studied area unites a group of copper-porphyry ore-magmatic systems associated with small granitoid intrusions of the Teplinsky Pliocene-Pleistocene complex. There are also ore occurrences of tungsten, arsenic, gold, antimony, etc., which make up a single genetic series, in which copper-porphyry mineralization occupies a well - defined position-it is timed to the porphyry phase of the latest intrusive magmatism. The comparison of the conditions of the Late Cenozoic mineralization and its characteristics within the studied ore-bearing areas with the main elements of the typical model of the copper-porphyry system allows us to consider the Sangutidon, Teplinsky and Tanadon ore nodes as an expression of the parts of a single ore-magmatic system of the copper-porphyry type superstructuring each other vertically. The newest granite-granodiorite formation of the Greater Caucasus, which is productive for copper-porphyry mineralization, was formed under the conditions of a repeated-rhogenic regime of activation of the region and superimposed on its heterogeneous substrate. The latter within the studied area is characterized by a two-story structure and consists of the Lower-Middle Jurassic volcanogenic-sedimentary complex of the cover and the Pre - Jurassic base, in which the main role is played by the Precambrian-Lower-Middle Paleozoic metamorphic strata of the crystalline basement of the Greater Caucasus, broken by Paleozoic granitoids of the Main Ridge. The composition of Late Neogene granitoids depends on the composition of the substrate, both at the deep levels of its anatectic melting, and on the ascent paths of the magmas formed during this process. In this regard, the increased basicity of granitoids of the polyphase Teplinsky complex formed under hypabyssal and subvolcanic conditions is due to a higher degree of maficity of the substrate of the studied area, which includes a number of basaltoid or similar strata in composition, compared to neighboring blocks.


Author(s):  
Pan Qu ◽  
Wubin Yang ◽  
Hecai Niu ◽  
Ningbo Li ◽  
Dan Wu

Porphyry deposits are the main source for global Cu and Mo production. The generation of hydrous silicate magmas and subsequent separation of volatile-rich magmatic fluids with hydrothermal alteration are significant processes leading to the formation of porphyry deposits. However, a specific understanding of these processes has been limited by a lack of direct mineralogical records in the evolving magmatic-hydrothermal system. In this paper, we present an integrated textural and geochemical investigation on apatite from the giant Daheishan porphyry Mo deposit in NE China, illustrating that apatite can be a potential recorder of the magmatic-hydrothermal evolution of porphyry systems. Apatite from the ore-forming porphyry displays distinctive core-rim textures, with melt inclusions in the resorption cores (Type-A1) and co-existing of melt and fluid inclusions in the euhedral rims (Type-A2), indicating a magmatic-hydrothermal origin of apatite. This is also supported by both chemical and isotopic compositions obtained by in situ analyses using laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS) and LA-multi collector-ICP-MS. The late Type-A2 apatite is relatively enriched in incompatible elements, such as rare earth elements (REE) and Th, but slightly depleted in fluid-mobile elements such as Na and S, compared to the early Type-A1 apatite. Relatively homogeneous (87Sr/86Sr)i ratios (0.70436−0.70504) of the Type-A1 and Type-A2 apatites indicate that they were formed in a relatively closed system without detectable contamination. Meanwhile, some apatite in the wall rock (biotite granodiorite) shows characteristics of secondary altered textures, resulting from the intensive alteration by hydrothermal fluids exsolved from the porphyry system. Apatite trapped in mineral phenocrysts of the wall rock is usually unaltered (Type-B1 apatite), with clear oscillatory growth zones in cathodoluminescence (CL) images. In contrast, the intergranular apatite is commonly altered (Type-B2 apatite), with chaotic zoning in CL images, abundant micro-fractures and secondary fluid inclusions. Compositionally, the Type-B2 apatite shows notable tetrad REE patterns, relatively lower light-REE and S contents, and elevated 147Sm/144Nd ratios compared to the Type-B1 apatite. LA-ICP-MS U-Pb dating yields a lower intercept age of 171.4 ± 2.3 Ma for Type-B2, which is consistent with the age of 171.5 ± 2.4 Ma for Type-A2, but is notably younger than the Type-B1 apatite (175.5 ± 1.3 Ma). It is suggested that the Type-B2 apatite has been significantly reset by hydrothermal fluids exsolved from the porphyry system. Therefore, we conclude that the textures and geochemistry of apatite in porphyry systems can be used as a potential proxy for recording fluid exsolution and hydrothermal alteration processes.


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