Degree of dismemberment of the relief - Geology. Deposits...

Degree of terrain division

Geomorphological conditions are the most important natural factor influencing the choice of effective methods of prospecting. The genetic classification of the relief is based on its division into erosion-tectonic and accumulative [17]. The first is formed with a general rise in the areas of the earth's crust and their denudation, the second - due to accumulation of precipitation against the background of a general lowering of the earth's surface as a result of its denudation and subsidence. The erosion-tectonic relief is represented by mountain and structural types. Among the mountainous terrain there are alpine, highlands, middle and low mountain subtypes.

The high-mountainous relief is characterized by considerable heights (up to 4000-7000 m) and sharp dismemberment (exceeding ridges above valleys to 2000-3000 m), which predetermines intensive physical weathering and good exposure of bedrock. Physical weathering outstrips the processes of chemical decomposition of ores, so the oxidation zone is practically absent, but the halos and the fluxes of mechanical scattering of ore matter are widely developed. The presence of deeply washed structures under conditions of a well-developed hydrosystem facilitates the formation of hydrogeochemical dispersion haloes. Effective methods of prospecting in high-altitude conditions is geological survey using aerospace photographs, clastic-river, clastic-glacial, schline, hydrochemical and sediment surveys. In connection with the difficulties of work (poor patency, lack of transport routes), the main method of prospecting in such areas is geological survey.

Highlands - Highly elevated and relatively poorly dissected mountain ranges located in the interior of mountain structures. Absolute marks from 700-1000 to 4000 m with a depth of dismemberment from 200-300 to 500-700 m. The relief is usually wavy, flattened or flat with rounded loaches and flat watersheds, covered with stone placers or marshy, and wide valleys made with alluvium. Large areas of uplands are covered with forests, marshes and stone placers, which makes it difficult to find. In such conditions, geochemical search methods are most effective in combination with aerogeological and aerogeophysical studies.

Middle-mountain relief is characterized by absolute elevations of up to 3000-3500 m with a depth of dismemberment from 500-1000 m and more. The degree of nakedness of the areas is different, but always worse than in high-mountain conditions. The northern slopes are covered with vegetation more than the southern ones. The processes of chemical decomposition of ores are intense, so the oxidation zone sometimes reaches a considerable depth. Mechanical, lithochemical and hydrochemical haloes and scattering flows are widely manifested. In these conditions, practically all search methods are applicable. At the same time, latitudinal climatic zoning must be taken into account. Geological survey (and searches) should be accompanied by the implementation of significant amounts of mine workings.

The low-mountainous relief (small hill) is characterized by absolute elevations from 100-200 to 1000 m with relative elevations of 100-300 m. Slopes, peaks and watersheds are shallow, covered with eluvial-deluvial sediments, soil layer and often vegetation. A significant role in the selection of search methods is played by climatic conditions. In low-mountain conditions, the search for geological survey methods is less effective than in high- and mid-mountain regions. Particularly unfavorable for the search are wide valleys and intermontane depressions. Due to poor nudity, large volumes of mining and drilling operations are required here. The effectiveness of prospecting in such areas is enhanced by the widespread use of clastic-river, schlich and, especially, geochemical (all types) and geophysical methods. Aerospace methods can be of great help.

Sculptural relief is expressed on the plateaus and plateaus, opened by river valleys. The subdivision is relatively weak, the depth of the relief subdivision does not exceed 200-350 m. The indigenous rocks usually have a subhorizontal bedding and are only opened on stepwise river valleys. The vast watershed areas are covered with ladders or powerful loose deposits. All this makes it difficult to conduct search operations. The main attention in such areas is given to river valleys and their slopes, where geological survey in combination with clastic-river and schlich methods of searches is most effective. Watershed spaces are studied mainly by deciphering aerial photographs, altitude and space images, as well as aerogeophysical methods.

The accumulative relief is characteristic for the lowered parts of the earth's surface (lowland plains, foothill plains and mezhgornyts hollows). The most typical extensive alluvial plains with absolute marks up to 200 m. The indigenous rocks in them are covered by a powerful cover of alluvium, lake and other deposits. There are glacial, eolian and marine accumulative relief. The areas of development of the accumulative relief forms are devoid of natural outcrops and extremely unfavorable for the search for endogenous deposits. Geological survey and searches in these conditions are carried out in combination with geophysical methods and are accompanied by large volumes of mining drilling operations. In the conditions of glacial relief, it is possible to use boulder-glacial and geochemical methods.

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