Methods of prospecting - Geology. Forecasting and search for mineral deposits

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The exploratory works are carried out with the purpose of revealing mineral deposits of industrial type within known and potential ore fields and basins. The entire complex of minerals, possible in the given territory, is taken into account. The scale of work is determined by the size of ore zeros, deposits and the complexity of the geological structure of the area (from 1: 25000 to 1: 5000). The search is carried out on a geological basis of this scale using various search methods. As a result of the search, manifestations of minerals should be identified that deserve evaluation statements.

The search methodology is determined by the geological, landscape and geographical and economic conditions of the prospective areas. The main factors in determining the system of search operations are the nature of geological and geophysical anomalies that can be created by the expected objects of searches [VV Aristov, 1975]: geological, mineralogical, geophysical, geochemical. The search is carried out by geological, geophysical, schlich, clastic-boulder, thermobarogeochemical, geochemical methods with the use of surface mines and wells. A systematic sampling is performed. Usually, searches are performed in several ways. Under the system of search operations is understood a set of main and auxiliary complexes of search methods with which you can find the desired object.

VV Aristov, the basis for prospecting works is the grouping of mineral deposits based on the nature of the anomalies they create:

/ group includes deposits that create distinct geological and indistinct mineralogical, geochemical and geophysical anomalies.

It includes deposits of piezo-optical raw materials, mica, graphite, magnesite, coals, refractories, ceramic raw materials, building materials

II group includes deposits that create distinct geological, mineralogical and geochemical anomalies. These include gold placers, platinoids, cassiterite, ilmenite, tantalite-columbite, deposits of limonite, siderite, manganese ores, silicate nickel ores, phosphorites, sulfur, salts, fluorite, asbestos, talc, corundum, low-temperature deposits of lead and zinc, copper, antimony and mercury.

Group III includes deposits that create distinct geological and simple geophysical anomalies that can be identified by one of the geophysical methods. This group includes deposits of manganese ores, chromites, uranium, boron, stone and brown coals.

IV group includes deposits that create distinct complex geophysical anomalies, the identification of which requires the use of several geophysical methods. These include deposits of bauxite, rich iron ore KMA.

The V group includes deposits that create distinct geological, mineralogical, geochemical and geophysical anomalies - buried alluvial placers of gold, platinum, cassiterite, tantalite-columbite, endogenous deposits of nickel, copper, lead and zinc, tin, tungsten, molybdenum, beryllium, rare earths, niobium, tantalum, gold, platinum, silver.

For example, for objects of the first group of deposits, the system of prospecting works includes the main set of methods - geological, mining and drilling; auxiliary complex of methods - mineralogical, geochemical, geophysical. The presence of not distinct anomalies for this group of manifestations determines the application of mining drilling methods in the discovery of geological anomalies that are most promising for the detection of ore occurrences. The use of geophysical methods is used to decipher geological structures, and geochemical studies usually do not give positive results due to indistinctly manifested anomalies associated with bodies of minerals. Only improved expensive geophysical and geochemical methods sometimes allow us to detect weak and indistinct anomalies created by such objects.

For the manifestations of the second group of deposits, the main set of methods includes geological, mineralogical, geochemical, mountain-drilling, and auxiliary - geophysical. The identification of distinct mineralogical, geochemical anomalies with schist and lithochemical, hydrochemical or atmo chemical methods allows drastically reducing the areas of prospecting and limiting the volume of mining operations.

For the objects of the third group of deposits, the recommended system of prospecting works contains geological, one of geophysical methods, mining and drilling, and auxiliary methods - other geophysical, geochemical and mineralogical methods. The detection of one of the geophysical methods of anomalies localizes the process of conducting search operations and thereby increases their effectiveness.

The presence of distinct and complex geophysical anomalies for the objects of the fourth group of deposits requires the application of several geophysical methods. Therefore, the system of prospecting works will include: the main methods of search - a complex of geophysical methods, geological, mining and drilling, and auxiliary - mineralogical and geochemical methods. At the same time, when performing a VES, a network of observations of 4000 * 1000 or 2000 * 500 m, a profile magnetic survey of 2000 * 100 m, gravity survey - 4000 * 1000 or 2000 * 1000 m is required. In a complex area, a 1: 50,000 geological survey is accompanied by a symmetrical electrical profiling on the network 500 * 100-50 m and magnetic shooting on the network 500 * 50 m.

At the sites of the fifth group of deposits with distinct complex anomalies, the search is performed by a full range of methods that allows to identify complex complex anomalies and to concentrate mining and drilling operations on them. With reference to one or another type of mineral deposits, one has to develop one's own rational set of methods, focusing on the nature of possible anomalies created by the expected object. The density of the observation network will be determined by the minimum dimensions of the proposed industrial interest ore occurrences and usually does not exceed 2000 * 500 or 500 * 50 m.

In the general complex of search methods used to identify the deposits of the groups examined, the value of each chosen method is not the same. With respect to this or that type of deposits of different groups and within each group, it is necessary to develop its own rational set of methods, focusing on the nature of those anomalies that can be created by the expected object. Examples of systems of prospecting works used in the search for deposits of different groups are given in the training manual of VV Aristov [1975]. As a result, geological and prospecting maps of scales of 1: 25000 ... 1: 5000, sections are calculated and forecasted resources of mineral are classified in categories Р2, less often Р |.

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