Guide des sports

Dombar type sections

Dombar type sections

Dombarovsky type sections are typical for areas confined to paleoriferous zones with the predominant development of basic basalts of homogeneous and contrasting formations with a negligible role (fractions of a percent) of acidic components. The sections have the following appearance (from bottom to top): 1) basalts of a homogeneous formation, represented by products of submarine outpourings of pillow lavas, dolerites, hyaloclastites with siliceous interlayers; thickness of the stratum is more than 1 km; 2) transitional to a contrasting formation, characterized by a variety of facies, including glassy small-ball and drip lavas, hyaloclastites, plagioporphyritic basalts, dolerites, siliceous rocks, especially widely developed in the upper reaches There are often extrusive domes of liparitic dacites and dacites, accompanied by a small volume of pyroclastic material; thickness of the thickness is about 500 m; 3) basaltoids of contrasting formation — dolerites and basalts of various facies with a thickness of 1-1.5 km or more.

The pyrite ore deposits are confined to the transitional stratum located on the border of basalts of homogeneous and contrasting formations, as well as to the upper stratum of the section of the contrasting formation, which is similar to it in facies characteristics.

Uchalinsk-Sibai type sections (type B) are typical of ore regions located in the inner and outer zones of paleooxtapular arcs. Volcanites of contrasting formations are deposited here on homogeneous basalts. Acidic constituents are present in small amounts and lie inside the basaltoid section, but generally tend to the upper parts of it. The section of acid volcanites, as shown by comparing data for a number of areas, is characterized by specific features in each case. The common features are the participation in its structure of lava and pyroclastic facies, corresponding to individual phases of volcanic activity, forming strata with a thickness from the first hundred meters to 1 km, composed of lava domes and products of their destruction, alternating with lava flows and layers of pyroclastic emissions. The boundaries of volcanites belonging to different eruption phases are often marked by horizons of eroded rocks. In some cases, separate flows of basaltoids are associated with them. The erosion is most pronounced in the upper part of the section of acidic volcanites, on the border with the overlapping strata of basalts. The stratified rock bundles are represented by rhythmically alternating volcanomicts, siliceous sediments, and pyroclasts.

According to the quantitative ratio of acidic and basic rocks, with which ore deposits are spatially and temporally associated, two subtypes of sections are distinguished, in which acidic rocks: 1) they play a very insignificant role, being represented by low-power (from the first tens to hundreds of meters) formations with separate inflations with a capacity of up to 300 m (Uchalinsky subtype); 2) they form large domes with core parts with a capacity of 1 km or more (Sibai subtype).

The position of pyrite ore deposits in acidic and volcanic sections is determined by their localization at one or more levels. Located at the same level, they are represented by a set of Stratified bodies lying in the layered horizon of the upper part of the section of the contrasting formation. Sometimes the deposits are located in the range almost from the base to the roof of the liparite stratum, representing a set of stratified bodies, as if strung onto a single channel oriented but normal to the stratification. The total thickness of the mineralized part of the section is several hundred meters (Sibayskoye deposit in the Urals).

In some ore fields, pyrite deposits confined to the upper part of the acid volcanite section form powerful compact ore bodies. So, at the Uchalinsky deposit, the ore body lies at the top of the liparite-dacite section, forming a small domed structure. The flanks of the deposit, represented by layered ores of low capacity, are confined to bundles of volcanomictic rocks crowning a section of acidic volcanites overlain by volcanoids. Powerful inflations of the ore body are performed by local depressions developed on the surface of the liparite-dacite dome. Another level of mineralization, located several hundred meters below the first, coincides with the boundary of two phases of liparite-dacite volcanism, marked by the development of intermittent basalt flows.

Finally, in a number of areas, mineralization is manifested on three levels: in the upper part of the section of the lower basalt horizon, in the depression structures of the paleosurface of the basalt horizon, and on the trench of andesite dacites overlying it with liparite dacites. The total capacity of the ore-bearing part of the section ranges from 150 to 500 m, sometimes up to 1000 m. Апостиль и легализация документов — ключевые процедуры для признания украинских бумаг за рубежом с компанией ust group киев более 10 лет успешно помогает клиентам ставить апостиль на справку о несудимости, свидетельства о рождении, браке и дипломы. Мы также организуем консульскую легализацию для стран, не входящих в Гаагскую конвенцию, и предлагаем услуги профессионального бюро переводов. Специалисты компании берут на себя общение с государственными органами, что экономит ваше время и нервы.