Spatial position and features of destruction of ore bodies (1983)

Scientists discuss the structural features of deposits.

The basis of modern prospecting work is the analysis of the geological position of deposits on a structural-information basis, as well as taking into account the geomorphological and landscape-climatic conditions of the location of ore within certain geological-structural zones.

Map of geological-structural zones.

A geologist collects rock samples.

Prospecting work includes studying the composition of primary ores and the products of their formation in the hypergenesis zone.

Samples taken during prospecting are transferred for further laboratory research.

Map of the USSR. The map shows shields and uplifted folded areas.

Alternating frames of the landscape of these areas.

These areas are characterized by manifestations of both folded and faults.

An example is shown in the soil arrangement diagram.

A cartoon showing shields and uplifted folded areas and their characteristics.

They are characterized by ore-controlling structures of subvertical orientation.

Subsequent active ascending movements in the area of shields and folded areas contribute to the development of erosion processes and the destructive work of rivers.

Shots of mountain range erosion, waterfalls and rivers.

Here a characteristic, highly dissected erosional-tectonic relief is formed.

Examples.

A cartoon showing the processes of physical, mechanical and chemical destruction of ores under the influence of weathering.

Due to this, a wide dispersion of ore matter is formed.

It forms a variety of hypergene halos.

Types of halos.

The predictive assessment of such areas is based on the natural erosional opening of ore-bearing geological formations.

Geologists on the route.

Collecting soil samples.

Prospecting work in the areas of shields and folded regions includes the study and testing of geological outcrops, placer survey, lithochemical, atmogeochemical, hydrochemical testing.

Aerial research methods.

A helicopter with special equipment installed.

Map of the USSR with open areas of platforms.

This type of regional-geological structures is characterized by a two-tier structure.

The lower structural tier of the platforms is a crystalline basement.

It is characterized by deposits of chromium, iron, precious and other metals.

Scheme of the structure of the lower tier.

The upper structural tier is composed of weakly dislocated sedimentary strata.

They usually contain sheet, lenticular deposits of ferrous and non-ferrous metals and bodies of non-metallic minerals.

Scheme.

The formation of endogenous deposits of precious, non-ferrous, rare metals, as well as diamonds, is associated with periods of tectonomagmatic activation in open areas of the platforms.

Intensive dissection of the relief occurs in areas of active ascending movements of the geological and structural zone under consideration.

Scheme.

In this case, ore deposits of hydrothermal and sedimentary origin in the upper sedimentary cover of the platforms are exposed and destroyed.

As a result of these processes, various hypergene dispersion halos are formed here.

Cartoon explaining this process.

Halos are detected using geochemical and mineralogical studies, which are carried out within the areas exposed by erosion.

Geologists conduct such studies.

These searches are combined with traditional ground geological and geophysical observations.

Support structural exploration drilling is carried out.

Aeromagnetic observations.

In areas where tectonic activity is insignificant, erosive dissection of the relief is weak.

Here, outcrops of bedrock are observed only in developed river valleys.

Steep river bank.

In them, mineral bodies are exposed by erosion only in the upper structural tier.

Panorama of the river from a helicopter.

In such conditions, mainly geochemical dispersion halos are formed.

Prospecting work in areas of open platforms is based on geochemical observations and complex studies of the hydraulic network.

The selected hydrochemical, bottom, and placer samples are subjected to laboratory testing.

Map of the USSR showing closed areas of shields and folded regions with a regional cover of cover deposits, as well as marginal parts of platforms.

Closed areas of shields and folded regions are characterized by the absence of recent ascending movements.

Accumulation processes predominate here.

The most common relief is flat, undissected.

In closed areas of shields and folded regions, mineral bodies are located at significant depths, so the migration of ore matter is difficult.

As a result, buried and weakened surface dispersion halos are formed.

Washing ore deposits, groundwater is enriched with soluble ore components.

To identify these anomalies in natural waters, a hydrochemical search method is used.

Cartoon showing the process of accumulation of ore substances in plants and, after death, their accumulation in the soil.

Anomalies arise that are revealed by geobotanical and geochemical searches.

A geologist cuts flowers for analysis.

In these areas, hydrochemical ground studies are accompanied by exploratory core drilling.

Borehole geophysical observations and geochemical testing are also used.

Cartoon explaining how the core drilling method helps to identify ore anomalies.

Reindeer teams travel across the tundra.

Alternation of frames with different natural landscapes.

Prospecting practice has shown that not only the geological-structural position, but also landscape and climatic factors determine the direction of the processes of destruction of primary ores.

Analysis of these factors allows us to find the necessary set of prospecting works in predictive assessments of territories.

A geologist draws routes on a map of the region.

Camels walk across the steppe.

The arid zone is characterized by strong insolation, sharp changes in daily temperatures, and little precipitation.

A turtle crawls on the sand.

Here, the processes of mechanical destruction of ore bodies prevail, so the migration of ore matter is difficult.

With an increase in humidity in the arid zone, the processes of chemical weathering are activated.

Low-contrast salt halos appear.

As a result of the capillary rise of underground mineralized waters and their evaporation, salt efflorescence of the ore matter is formed.

A cartoon explaining this process.

Salt anomalies are revealed by mineralogy and geochemical prospecting.

Geologists taking soil samples in the desert.

Rapids on a river in the forest.

Humid zones are characterized by excessive moisture, acidic or neutral environment, deep chemical decomposition of primary ores, intensive migration of secondary products.

Geochemical anomalies are typical of flat and slightly rugged relief of humid regions.

Panorama of flat regions of the USSR. Alternating frames with geologists taking various geochemical samples.

Mid-mountain regions of humid zones are characterized by more diverse anomalies.

Cartoon showing the formation of ore substance anomalies in such regions.

Geologist washing concentrate.

Nival zone.

Panorama of the mountains.

In mountainous regions lying above the snow line, the physical destruction of ore bodies outpaces the process of their chemical decomposition.

Therefore, unoxidized primary ores come to the surface.

Geologist takes soil samples in the mountains.

Frost weathering contributes to the formation of coarse-grained mechanical dispersion halos.

The leading methods of prospecting in the nival zone are the clastic-fluvial and boulder-glacial methods.

For successful prospecting, it is also important to take into account the material composition of the ores and the nature of their changes in the hypergenesis zone.

Geologists examine the collected samples.

Laboratory analysis of the samples.

A type of stable minerals subject to the influence of physical and mechanical processes without chemical transformation.

Stable minerals include, for example, gold, platinum, diamond, which migrate in mineral form without being destroyed.

Washing of the concentrate.

Concentrate testing and comprehensive laboratory study of concentrates are the leading methods of prospecting for primary and placer deposits of stable ores.

A map with concentrate anomalies identified during prospecting, which allow one to identify promising areas.

Samples of ores composed of unstable minerals subject to deep chemical transformations in the hypergenesis zone.

A cartoon showing the formation scheme of an "iron hat".

Searches for unstable ores of non-ferrous and rare metals are based on mineralogical and chemical studies.

Alternation of shots with geologists studying deposits.