FEDERAL AGENCY FOR EDUCATION GOU VPO Saratov State University named after N.G. Chernyshevsky "
Department of General Geology and Mineral Resources.
COURSE WORK
Karst and karst sediments
Completed: student
1 course, geol. fact,
Group No. 151, day department.
Sokolov Egor Semyonovich
The possibility of future expansion of ownership requires the development of a governance framework to ensure effective coordination between different groups. Long-term protection and management commitments for the South China Karst include the need to ensure coordination in the main property as a whole through the establishment of a Protection and Management Coordination Committee in the interests of world heritage South China Karst; improving the participation of local communities and maintaining the traditional practices of the indigenous peoples concerned; strengthening management of the entire catchment area to ensure water quality protection and pollution prevention; and strict prevention of negative impacts of tourism, agriculture and urban development activities on property values.
Scientific adviser:
assistant Yampolskaya O.B.
annotation
The work is devoted to issues related to karst and karst sediments. It reveals the concept of karst. The main forms of karst relief, the factors of formation, the reasons for the accumulation of mineral substances and their sources are described. The classification and methods of karst research are stated. Mineral resources of the karst facies are considered.
Torrents are streams that have layers too steep to form the smallest deposit, the latter all being passed downstream, where the stream ends in less dwindling area. There are three parts to the torrenting process: top to bottom.
Receiving funnel, zone of collection and rupture of meteoric water; - flow channel, zone for material transfer and deepening of the layer by mechanical erosion; - the cone of depressions, a sedimentation zone especially feeding during floods, when the torrent hesitates due to its floods, since at the end of each one it seeks to clog up its bed with materials it does not contain, is more capable of evacuating below.
Introduction
Chapter 1. General information
1.1 The concept of karst
1.2 Karst forms
1.3 Classification of karst and the question of its zoning
1.4 Technique of karst research
Chapter 2. Factors of karst formation
2.2 Rock structure
2.3 Fracturing of rocks
2.4 Tectonic structures and thickness of karst rocks
Lots of torrent images can be found here. Among the most representative examples are the following examples. This term refers to a flat alluvial zone where pebbles are distributed in a polygonal pattern, encompassing zones of clay loam with a diameter of 0.5 to 3 meters. Along a polygonal line, flattened pebbles are located mainly at the edge.
This is due to the alternation of freezing and thawing on swampy soils by melting snow. At each thaw, the space open by melting ice is filled with the best particles, which somehow merge to the areas where there was the most water and, therefore, the least amount of stones: ultimately, the latter are pushed back to the periphery of these zones by dilatation of water at every freeze. As soon as there is a slight slope, the polygons go in the direction of the latter, and get "striped floors".
2.5 Covering formations and topography
2.6 The steepness of the slope of the topographic surface
2.7 Gravity
2.8 Underground rivers
Chapter 3. Reasons for the accumulation of minerals in karst facies
Chapter 4. Sources of karst sediment matter
Chapter 5 Mineral Resources of the Karst Facial Area
5.1 Types of minerals
The page "Periglacial landforms". Landforms due to glacial erosion in mountain valleys. This is because the ice uses the flanks more as one descends along the walls, as the pressure builds downward. A latch is a projection that bends around the longitudinal profile of a valley at a certain width and that the river has a more or less deep notch and is a place where glacial erosion has not been deeply dehydrated, downstream and upstream, and is referred to as the navel for the depression area upstream downstream and superficially, to indicate the fact that the ice may have been digging deeper there than the bolt, however located downstream.
5.2 Ore minerals
5.3 Non-metallic minerals
Conclusion
Bibliography
Introduction
The topic of this course work is karst. I believe that every geologist should know about karst, since different scientific directions are developing in the doctrine of karst (karst science). The most widely represented are geographic and geomorphological. At the same time, karst is the result of certain transformations of rocks. In the course of them, the destruction of rock-forming minerals, the transportation of substances and the accumulation of new formations are carried out. Consequently, in the theory of karst there is a range of problems that are solved by geological sciences. Discussion of these problems on the basis of extensive factual material is of scientific and practical interest. Karst also significantly affects the landscape features of the territory, its relief, runoff, groundwater, rivers and lakes, soil and vegetation cover, and economic activities of the population. In the karst areas, there are fabulous underground palaces-caves richly decorated with nature.
If the latch is not completely cut by the river throat, the navel will occupy the lake, which will be transformed by alluvial filling into a flat area where the river wanders. The side slopes of the glacial valley are particularly steep and are connected upward to more moderate slopes that have not been excavated by the glacier of the valley, by a rather rough bend called the "shoulder." waters often cut this shoulder through the "connecting groove". In other cases, these are furrows dug by ice before the glacier is removed in the valley into a trough.
Relief forms due to peri-glacial sedimentation. At the tip of the glacial tongue, the moraines left during the parking episodes surround the frontal umbilical cord and represent a kind of natural amphitheater, the terraces of which are moraines and associated terraces called the moraine valum.
Expand the concept of karst
Give a description of the main underground and surface karst landforms
To characterize the factors influencing the development of the karst process and the formation of karst landforms
Find the reasons for the accumulation of minerals in karst forms.
Explore the sources of material in karst sediments
In the lateral valleys, where the presence of a glacial tongue at their mouths accumulates glacial deposits, often lacustrine, forming stepped terraces called "kame terraces". They bind the pouring alluvial deposits of moraine wash products that are diluted in lake water or marginal streams.
This term refers to the splitting of a glacial tongue around an obstacle: the diffuser tongue deviates from the main tongue and enters a lateral valley. Of the many types of formations recognized throughout the world and at different levels of the stratigraphic scale, two are of particular importance in the Alps.
Describe the minerals of the karst facies area
Chapter 1 General Information
1.1 The concept of karst
The karst process is a long-term process of dissolution and leaching of fractured soluble rocks by groundwater and surface waters. As a result of the activity of karst processes, both negative forms of relief appear on the earth's surface, and various cavities, channels of grottoes or caves at a depth. The term "karst" comes from the distorted Austrian name for the Karst plateau in Slovenia, where these phenomena are pronounced and well studied by European researchers. Karst phenomena are extremely widespread. According to geological conditions, approximately one third of the land area of the globe has potential for their development.
They are cemented clayey limestone sandstones containing glauconium grains, which give them a green hue that turns yellow with change. The dissolution of the limestone cementing the grain makes the surface of the rock loose after prolonged exposure to the open air. These are ancient sea sands that were deposited in the deltas. It weaves conglomerates formed from pebbles cemented with sandstone.
They are most often associated with the Triassic strata because they are a kind of byproduct of gypsum behavior that occurs almost exclusively at this stratigraphic level in the Alps. They are most often found along tectonic dislocations, faults and most often overlap, along which they, apparently, were introduced.
There are several conditions necessary for the development of karst phenomena.
Firstly, it is the presence of rock soluble in natural waters, permeable due to fracturing or porosity.
Secondly, the presence of a solvent, i.e. water aggressive to the rock.
Third, the presence of conditions that ensure water exchange - the outflow of water saturated with a dissolved substance and a constant inflow of fresh solvent. If the first condition is determined by the geological structure of the area, then the second and partly the third are closely related to the physical and geographical situation, the second with the soil and vegetation cover and climate, and the third with geomorphological and hydrological conditions in addition to the geological structure and hydrogeological features.
Kargneuly are breccias, most often formed at the expense of dolomite shores, because this rock is especially fragile. They appear to be formed by injecting water under pressure into the pores and fractures of the rock, causing it to rupture. The compressed interstitial water would turn the original rock into a gravel purée that could inject and even act as a lubricant along the fracture surfaces and sliding of the moving rock mass. At the same time, these waters, filled with dissolved gypsum, had the ability to convert dolomite into calcite.
Typically karsting rocks are mono- and bimineral rocks - rock salt, gypsum, anhydrite, chalk, limestone, dolomite, islamic - dolomite rocks, varieties of marble, magnolite, carbonatite. The leading role in this list is played by carbonate rocks, both due to their wide distribution (about 15% of the land area) and due to the contrast in compositions between them and loose sediments, which causes side interactions leading to further karstification.
When this water could avoid decompression, it caused the crystallization of solutes and, in particular, the calcite it contained. After a meteoric change or near the soil surface, fragments of the fracture rock dissolve or disintegrate, giving vacuoles, while the cement is more or less membranous, essentially calcite.
Their origin is completely different, associated with the deposition of limestone from spring water before their appearance. There have been many discussions and even disputes about the exact origin of carbogul, both in relation to the formation of breccia and its vacuolization: we will find echoes in the bibliographic list.
The concept of dissolution (solubility) refers to chemical compounds, including minerals. There are two types of dissolution of a substance - congruent, when all its components are transferred into a solution, and the reaction is reversible, and incongruent, when not all components of the substance pass into the solution. In this case, a solid phase remains and the reaction is irreversible. Both types of dissolution are manifested in the hypergenesis zone, but congruent dissolution is characteristic of karstification, and incongruent dissolution is characteristic of crust formation and leaching metasomatism.
Moreover, the name covers the fuzzy clusters, recognizable by their brick red color from the ferruginous clays. This suggests that they are the result of continental soil formation of the end Triassic or Lias age. Some common sedimentary rock names.
Marble, relatively clean and homogeneous limestone, whose grains are cemented by recrystallization of calcium carbonate under the influence of metamorphism. Also "cypolines". Quartzites Homogeneous sandstones whose grains are cemented by recrystallization of silica. Most of the time this is the effect of metamorphism. Beautiful white to greenish quartzites, well characterized, characterize the Triassic basal of the Brianzanese zone.
Distinguish between open, or bare karst, when soluble rocks come out to the day surface, and closed, when they lie deep underground and are covered from the surface by strata of insoluble rocks.
Surface karst forms include kars, ponors, karst niches, sinkholes, hollows and fields, as well as wells and abysses.
It forms an almost constant but variable thickness at the bottom of the Bryanson Triassic quartzites. Dolomites Carbonate rocks in which magnesium carbonate is added in greater or lesser proportions to calcium carbonate. "Primary" dolomites come directly from the nature of the sediment, while "secondary" dolomites are a consequence of the subsequent replacement of calcium with magnesium.
Marnes. Kalyar-argillaceous deposits with more than 35% clayey limestones Marly have from 5 to 35% clay, and limestone marl - alternating marls and marble limestones. Argillites The deposits are purely argillaceous, not carbonate. Pelita. Very fine, fine-grained deposits of various natures, usually clayey sandstones.
Underground karst forms represented by caves by canals.
Karst processes create not only certain forms of relief, but also take part in the formation of peculiar deposits. On the surface and at the bottom of karst landforms, residual formations from dissolution are located - this is a carbonate-free, mainly aluminosilicate material remaining after dissolution. It is called terra-rossa (red earth). On the surface and in the caves there are landslide accumulations - products of the collapse of the arches of karst cavities or from blocks sliding down the slopes of karst valleys and funnels. The caves contain peculiar alluvial sediments formed by underground rivers. There are also travertines - sintered forms of calcareous tuff, as well as original sinter forms - stalactites, growing from the roof of the cave downward. Their delicate weaves are often referred to as stalactite curtains. Stalagmites grow up from the bottom of the caves.
Squid, detrital rocks with a sandy texture, but with calcareous elements more or less predominant on the paste that binds them. Sometimes called "sandy limestone", it is wrong because they are not loose stones. They can be terrigenous, but often "bioclastic", i.e. formed from shell fragments. When these debris are crystallized enough to be thrown off the scintillation edges, the limestone is called spastic limestone.
This term is used to refer to any rock with a parallel sheet flow that is a few millimeters thick or less. In fact, the term "shale" does not refer to the nature of the rock, but refers to the type of rock mass flow. In fact, almost any rock can become slate, but few rocks are formed from leaves from their origin. Most often, lamination is a flattening effect after the initial sediment has settled, either under a simple mass of supra-absorbing rocks, or under the influence of tectonic compression.
1.2 Karst forms
Landforms formed as a result of the karst process are divided into surface and underground.
1 surface forms of karst
Surface karst forms include carry, gutters and ditches, craters, saucers and depressions, hollows, polya, outliers.
According to their genetic origin, carrs should be distinguished into forms that have arisen on the bare surface of a soluble rock, and forms that have formed under the soil-vegetation cover with its subsequent removal. Cars of the second type are found in many countries of the world.
Morphologically, carriages are subdivided into grooved, wall, hole, tubular (in the form of tubular cylindrical depressions in gypsum) kamenitsa, carry in the form of traces, grooved, meander, and fissured. Another type has been identified - structural karrs; on a steep limestone slope, karr depressions have been developed in chemically relatively pure limestone, separated by narrow ridges that correspond to highly siliceous interlayers.
By genesis, grooved and fissure carriages are especially distinguished. Flute carrs are formed under the influence of atmospheric precipitation only, as a result of the first three phases of limestone dissolution, without the participation of the fourth phase, while the other types of carr are formed under the action of all dissolution phases: waters enriched with biogenic carbon dioxide due to the contact of atmospheric precipitation and melt water with soil and vegetation cover.
(Figure 1) flute carr
Fissure karrs differ from the rest in ways of removing solute. While in most other types of karrs it is carried out by surface runoff, then during the formation of fissure karrs, the removal of dissolved matter by underground means, through cracks, is also involved.
Karst trenches and ditches (deeper and always with steep sides) develop along open tectonic cracks (often as a result of unloading on steep slopes) or along slope subsidence cracks, or “side-push” cracks. They stretch for tens and hundreds of meters, and sometimes for several kilometers, reaching various widths and depths. At the ends they are closed, at the bottom they can have numerous depressions. Straight ditches in limestones, developed along vertical tectonic cracks, 2 ~ 4 m wide and up to 5 m deep in Yugoslavia are called bogazi.
Among the sinkholes, three main genetic types are distinguished:
Surface leaching funnels, or purely corrosive. They are formed due to the removal of rock leached on the surface through underground channels in a dissolved state.
Failure funnels, or gravity. Formed by the collapse of the vault of an underground cavity, which arose due to the leaching of karst rocks at depth and the removal of matter in a dissolved state
Suction funnels, or corrosive suffusion. They are formed by washing and subsidence of loose cover sediments into wells and cavities of a karst basement, carrying out particles into underground channels and removing them through them in a turbid and suspended state.
(Figure 2) karst sinkhole.
Saucers, depressions are indistinctly defined small funnels.
Basins. Funnels of all genetic types, merging with their edges, form double, triple and more complex baths and basins. There are two main types of basins - complex ones, which are formed at the confluence of several large funnels and have depressions at the bottom, and flat-bottomed basins. The following genetic types of hollows are distinguished: surface leaching, sinkhole, suction, and also created in combination with other processes, for example, erosion. Large basins of surface leaching are often formed due to the corrosive action of melt water, snow and firn patches. Many of these basins are a legacy of the periglacial conditions of the last ice age.
The Polje is a vast closed depression with steep sides, with a flat bottom, which has reached a temporary or permanent maximum level of karst, with karst-type hydrography.
Polye arises as a result of the development and connection of karst basins formed from merged sinkholes.
Polya by its origin, until recently, was divided into: 1) tectonic, 2) arising by underground mechanical removal of insoluble rock, lying among karst limestones or in contact with them, 3) formed by the merger of a group of adjacent craters and hollows (ridge) during their growth in the horizontal direction, 4) failure.
Large depressions of purely tectonic origin (grabens, synclinal troughs) cannot be considered polis. With the formation of glazes, leaching and removal of the dissolved substance through underground channels are required. Therefore, the first group should include tectonic-corrosion and tectonic-corrosion-erosion. This group includes the Polish Yugoslavia. Glades of the third type are usually small, of irregular lobed shape in plan. They are characteristic not only for carbonate, but also for gypsum karst, and are found even in platform conditions.
Remnant karst is a mature stage of dissection of an uplifted flat-topped limestone massif. The steepness of the slopes of the outliers is due to the vertical fracturing of limestones and the weakening of the slope runoff due to their permeability. Of great importance is the crumbling of limestone along the cracks due to the erosion of the outliers from below by waters that flood the plains at their base, or by groundwater lying at the base surface. Because of this, at the base of the remnants, corrosion niches developing in the horizontal direction arise. The erosion of outliers from below by lateral corrosion of surface waters is facilitated by the accumulation of waterproof sedimentary clays on the base surface. The distribution of relict remnant karst is consistent with the displacement of the equator during the geological history of the Earth. Since in low latitudes humid-tropical climatic conditions have already existed for more than one geological period, the outlier karst widespread there can be considered not only modern, but also ancient.
The transition from surface forms to grotto-type caves is represented by awnings and niches. Often they are interesting from an archaeological point of view. Often these are surface formations that have arisen due to more intensive leaching of individual layers or layers of layers by waters flowing down the cliff, with a high value of biochemical weathering (under the action of lower plants settling on periodically moistened surfaces). In river valleys and on the shores of the seas, river and sea waters play the main role in surface leaching. On the seashore, the dissolving effect of sea water is combined with abrasion.
In the process of the formation of deeper niches, corrosion due to water seeping through cracks in the rock, and, in addition, the collapse of rock blocks due to the expansion of cracks due to leaching of their planes, acquire significant importance.
In limestone niches of subtropical and tropical regions, drip-drip formations are found. Stalactites merge to form curtains and draperies.
Natural bridges and arches most often occur when the ceiling of cave tunnels and sometimes niches collapse.
1.2.2 underground karst forms
Among the underground karst forms, one can distinguish karst wells and mines, abysses and caves.
Karst wells and shafts are vertical or steeply inclined abysses, differing in depth; mines include abysses deeper than 20 meters, reaching several tens, or even hundreds of meters. The cavities of wells and mines can be failure (gravitational), gravitational-corrosive, formed by leaching karst rock with water along cracks and partial collapses; nival-corrosive, resulting from the corrosive action (along cracks) of melted snow water; corrosion-erosion, which are formed by water streams rushing down the cracks, producing erosion, prepared by dissolution along the adhesions of rock grains; formed by a similar action of artesian waters ascending along the cracks.
Karst chasms are combinations of natural mines with horizontal and inclined cave passages. These include, in particular, the deepest karst abysses in the world, reaching depths of 1000 meters or more.
The largest underground forms of karst relief are karst caves. They represent a system of horizontal or several inclined channels, tunnels, complexly branching and forming huge halls or grotto, having a height of several tens of meters. The caves can be connected with each other by tunnels, gaps or narrow crevices. Underground rivers often flow through the canals, and underground lakes are located at the bottom of the caves. The undergrounds of the river not only leach the rocks in contact with them, but also produce a great erosive effect.
Majority karst caves is formed with the leading role of leaching, often with the combined action of dissolution and erosion of rocks (erosion prepared by dissolution along grain adhesions). The role of rock collapse is also significant, especially at the mature stages of the development of cave cavities. Some of the caves were created under the influence of thermal and mineral waters. Cave cavities of the so-called "ore karst" developed under the influence of sulfuric acid solutions on limestone, formed during the oxidation of pyrite and other sulfides. There are caves, which are basically very open tectonic cracks, but modeled by the processes of leaching (underground karr, etc.) and the deposition of drip formations along the walls of cracks.
(Fig. 3) Flow formations in the Katerloch cave, Austria.
Cave cavities can develop in the aeration zone, i.e. in the zone of vertical circulation of infiltrating waters. However, large karst caves originated mainly when the cave channels were completely filled with groundwater, in the zone of complete saturation, and the water in them circulated under hydrostatic pressure. There are a number of stages of their development, relating to the epochs of full and partial filling with water - the pressurized epoch and the non-pressurized one. Based on the processing of G.A. Maksimovich L.I. Maruashvili identified seven stages: three - in the pressure era of evolution (fissure, crevice, canal) and four in the free-flow (vockluz, water-gallery, dry-gallery, grotto-chamber).
With the ascending development of the earth's crust in conditions of high thickness of limestone strata and folded structure, multi-storey systems of cave galleries arise
Significant multi-storey cave systems are known. Paleozoological and archaeological data indicate an older age of the upper floors in comparison with the lower ones, indicating some analogy in the development of caves and terraced levels of river valleys.
In the morphology of cave cavities, fracturing of karst rocks and drip formations play an important role. When developing cave tunnels along vertical and steeply inclined cracks, they are distinguished by their straightness and sharp "elbow" bends. Branches branch off from them at different slopes. Tunnels often intersect, forming complex lattice labyrinths. The evolution of drip-and-drip formations depends on a decrease in the inflow of water into the cave during the transition from the vocluse to the water-gallery and dry-gallery stages. At first, the influxes on the floor of the cave, gurus develop, then stalagmites with a wide base, which are replaced further by stick-like ones. And only when the inflow of water decreases to 0.1 - 0.01 cubic meters. cm per second, stalactites appear. With a general decrease in the water content of the cave in the course of its evolution, at the same stage, unequal inflows of water are observed in different parts of the cave cavity, which is why different forms of drip formations appear.
Glacier caves are characterized by icy drip and crystalline formations. Seven types of karst glacier cavities have been identified, differing in the conditions for the occurrence of cave cold, accumulation of snow and ice. Three types belong to the permafrost area, where the cave ice represents its special form.
(Figure 4) Ice cave at the edge of the Fall Glacier, Svalbard.
1.3 Classification of karst and the question of its zoning
At the international speleological conference in Brno (1964), a classification of the USSR karst was proposed, based on the combination of six morphological-genetic and five lithological types. Now this classification has been supplemented and here it will also be said about the types of karst that are not found on the territory of the former USSR, but are known in other countries, mainly in tropical latitudes.
The identified morphological and genetic types differ significantly from each other by morphologically and genetically different surface and sometimes underground karst forms and their combinations. Lithological differences are taken into account already when distinguishing types, because different solubility of rocks, the rate of dissolution and the rate of saturation of the solvent, differences in the processes of dissolution of carbonate and non-carbonate rocks, their different changes from temperature, and therefore climatic conditions - all this affects the development of karst , its morphology and engineering-geological assessment.
The types of karst obtained by combining the morphological-genetic and lithological classifications are grouped into two classes of plain and mountain karst (with subclasses of low-mountain, mid-mountain and high-mountain).
MM. Sweeting identifies four main types of karst:
real karst (holokarst);
fluviokarst;
glacial-nival karst, including permafrost karst;
arid and semi-arid karst (the latter type is considered in the chapter on tropical karst and is characterized only by the features of its tropical and subtropical variants).
Outlines of such a general geographic classification were given earlier, however, it seems that the general geographic types of karst identified by Sweeting are too wide, each of them includes several types of a more detailed classification of Gvozdetsky, taking into account not only the general physical and geographical setting of karst development, but also the nature and thickness of the cover over karst rocks (the identification of one type of fluviokarst does not give this) and very important lithological features.
Gvozdetsky identified the following morphological and genetic types of karst: 1) buried or fossil karst; 2) armored karst; 3) covered karst; 4) soddy karst; 5) semi-turf and partially turf karst; 6) naked karst; 7) remnant tropical karst (on the territory of the former USSR only relic karst); 8) karst developing in permafrost conditions; 9) marine karst.
The main lithological types, with which morphological and genetic ones are combined, are as follows: 1) limestone karst; 2) dolomite karst; 3) karst in marbles; 4) chalk karst, including in chalk-like marls; 5) gypsum-anhydrite karst; 6) salt karst.
The types of karst obtained by combining both classifications are named as follows: bare limestone karst, covered with gypsum-anhydrite karst, buried chalk karst, and such types can be attributed to the plain or mountain class.
All morphological and genetic types of karst identified on the territory of the USSR are also found in other countries. For example, karst, combined with permafrost, is developed in Svalbard, Canada.
Ostantsovy tropical karst is modern, although quite ancient at the beginning of its formation, developed in tropical latitudes. It is represented by several subtypes: tower, conical and domed karst. Tower (with flat-topped steep outliers) and conical karst are often called international terms borrowed from the German language - "turmkarst" and "kegelkarst". Sometimes outliers rise among the marginal plains, in other cases they are not associated with them and then are combined with numerous depressions.
In tropical latitudes, morphological and genetic types are also widespread, analogs of which are also found in the karst of temperate latitudes. A special morphological and genetic type of tropical karst should include the karst of coral reefs raised above the level of the ocean surf.
A peculiar variant of bare karst is found in the subboreal belt in the area of glacial drift, which is associated here with the bare limestone surface.
Since karst significantly affects individual components of the geographical landscape and the physical-geographical complex as a whole, this allows us to consider karst territories as special geographical landscapes. Their classification rank is determined by the degree of influence of karst on various components of the landscape and the landscape as a whole. And this degree of influence depends primarily on the type of karst.
The difference between zoning karst from most other types of natural zoning lies in the discontinuity of its distribution. The identification of regional units, especially of a higher taxonomic rank, is based on the identification of discontinuous areas.
Since the very existence of karst is determined by lithological conditions, then geological (lithological and tectonic) factors should be the basis for zoning. But, in addition, it is necessary to take into account the physical and geographical conditions, which largely determine the features of karst, often its morphological and genetic type and the classification rank of the geographic landscape of the karst territory.
The following taxonomic system of zoning karst can be proposed: karst country - region - province - district - district. Within the area, during a detailed study, it is recommended to distinguish typological units (areas of different types of karst), however, if necessary, subdistricts and microdistricts can also be distinguished as individual units.
1.4 Technique of karst research
The karst process is not continuous. Secular, seasonal, even daily changes in the temperature regime, precipitation and air humidity affect its intensity. The ups and downs cause changes in the periods of activation and decay of karsting. When waters move from the feeding area to the karst basis, the deposition of the transferred salts occurs. This is evidenced by the secondary mineralization of cavities in rocks, colmatage and filling of macro- and microcracks, high-thickness drip formations in underground cavities. In addition to the unevenness of the karst process in time, its unevenness within the geological space is very clearly manifested, due to the inhomogeneity of the material composition, structures and textures of rocks, as well as tectonic fracturing.
The main tasks of karst-speleological research are accounting, forecasting and development of measures to prevent the harmful effects of karst on human economic activity. The study of lithology and fracture permeability of karst rocks, as the main conditions for the development of karst, should contribute to the solution of these problems.
The identification of types and varieties of rocks, to varying degrees of karsting, is carried out primarily according to their material composition. Of particular importance are the quantitative ratios and structural relationships of soluble rock-forming minerals. They are determined by all modern methods, from microscopic to chemical-analytical, X-ray structural, thermal, staining, luminescence and infrared spectroscopy. A special role is played by the elucidation of the nature of secondary processes that change the permeability of rocks: dolomitization, recrystallization, sulfatization.
An important point is the analysis of insoluble impurities. In this case, it is necessary not only to find out the mineralogy of the insoluble residue, depending on which the cultivation capacity of the rock decreases or increases, but also to establish its granulometric composition, which determines the ratio of corrosion and erosion in the karst process. The structural and textural characteristics of the rock, depending on its material composition, depositional conditions and sediment transformation, are investigated in lithological-facies analysis, carried out both in the field and in office. Large thin sections are studied under a microscope, where one can observe the transition of some sections of microstructures to others, and find out the nature of secondary processes. In such thin sections, it is necessary to determine the pore and micro-fracture permeability. For the identified varieties of rocks, it is necessary to determine the input-physical and engineering-geological characteristics. After statistical processing of the characteristics of rocks obtained in field and laboratory conditions, a number of factors can be identified that affect the rate of karst formation, the morphology of karst manifestations, and the intensity of the karst process.
The results of analytical work allow you to build a number of maps and diagrams. These maps can serve as a basis for karstological zoning and forecasting the course of modern geodynamic processes.
The study of rock fracturing is carried out in stages. Each subsequent stage can be effective only if the previous stage is completed and the corresponding secondary materials are obtained.
At the first stage, during field research, factual material is collected. Traditional methods of studying cracks make it possible to identify and document the elements of their orientation in space, the nature of the surfaces, the dimensions of the elements of cracks (length, gap), composition and degree of filling, data on water yield. The characteristics of the fracture density can be obtained by direct measurement, however, in most cases, this requires recalculations for the shear angle by the outcrop front. It is obligatory to fix the confinement of cracks to the elements of tectonic structure and lithological complexes of rocks, as well as the location of cracks within the outcrop and the size of the studied areas.
At present, photomethods are gaining more and more importance: phototheodolite surveying and aerial photography, which allow not only to reduce the time for conducting field studies, but also to increase the measurement accuracy of large cracks interpreted in the images, as well as to delineate and tie with high accuracy to maps areas with different types of fracturing. These methods make it possible to study large and rare cracks, detected by changes in the reflectivity of soils, small relief forms, and the nature of the distribution of vegetation. Often, karst landforms are confined to such cracks (or to their intersections), and cavities and caves are oriented along them. The primary material in this case is the photograph and the elements of its binding to the terrain and equipment. To proceed to the statistical processing of fracture data, a cameral stage of image decryption and a diagram of the information recorded on it with the use of stereocomparators are required.
Recently, methods of morphostructural analysis of territories using large-scale topographic maps have become widespread. They can be considered as related to photomethods, however, since they use secondary materials (maps constructed using stereophotogrammetry), reflecting mainly relief elements, hydrographic and erosional networks, in this case even larger lineaments can be distinguished. To study the permeability of rocks, it is advisable to use petrographic methods for studying fracturing in thin sections and grinding, when the object of study is small and microcracks.
The second stage in the study of fracturing consists in the statistical processing of the primary material, which makes it possible to proceed to the characterization of fracturing as a set of fracture systems closely related to each other genetically and confined to certain geological bodies. The applied methods determine the detail and reliability of the conclusions during the subsequent fracture analysis. Taking into account the accuracy of the original data becomes important. Modeling of crack surfaces leads to a decrease in the accuracy of their orientation, which makes it necessary to rank measurements by classes of increased width when compiling crack distributions.
Statistical processing of the primary material makes it possible to group the material in accordance with the geological task, obtain descriptive characteristics of fracturing, perform graphical constructions, calculate distribution statistics and identify the main fracture systems, calculate the values of the density of fractures of various directions and total density, evaluate the anisotropy of the section properties caused by fracturing. Unfortunately, the study of fracturing is often descriptive, less often of a comparative nature and ends with the compilation of azimuthal rose diagrams. The possibilities of identifying the links of fracturing with the tectonic structure of the region, with the material composition and engineering-geological characteristics of rocks, with the watering of the section remain unused. At the third stage, fracturing is analyzed. In this case, the results of statistical processing are used, considered against the background of the tectonic structure, lithological, engineering-geological or hydrogeological characteristics of the section of the studied area. At this stage, a working hypothesis is selected, statistics of connections are calculated, and the correlation of statistics of fracture distributions with the characteristics of the studied phenomena is checked, the agreement of the distribution with the working hypothesis is assessed, influences not taken into account by the working hypothesis are analyzed, regular, usually stochastic, less often functional relationships between fracturing and the phenomena under study are established. ... As a result, it is possible to obtain a mathematical model of the phenomenon or one-dimensional (profile), two-dimensional (section, plan) or three-dimensional (map) graphic material characterizing this model.
At the final stage, a forecast of the phenomenon under study is made. The forecast can be used to construct maps for areas that are not sufficiently characterized by the primary material, but which makes it possible to assess the likelihood of the applicability of the resulting model. It is more difficult to predict the dynamics of the process, since the resulting model does not always allow for the possibility of direct extrapolation in time.
Studying the parameters and characteristics of fracturing, fracture permeability, fracture anisotropy of the section, as well as identifying connections and the influence of fracturing on the hydrogeological and engineering-geological characteristics of karst strata, is a necessary, but not sufficient condition for predicting the course of the karst process and developing a scheme of measures to reduce either prevention of its harmful effects on the national economy and the environment. In this regard, a special lithological study of the rate of karsting of various genetic and structural varieties of karst rocks, the influence of insoluble impurities on the karst process, as well as the identification of signs of activation or attenuation of karst in the study of secondary mineralization of rocks and fillers of fissure-cavity systems, is of great importance. In this case, it is also advisable to use the apparatus for statistical processing of the obtained primary materials.
The introduction of computer technology into geological practice can sharply reduce the complexity of computing operations and increase the efficiency of karst-speleological research.
Chapter 2. Factors of karst formation
Among the factors determining the process of karst formation, N.A. Gvozdetsky distinguishes the following: the chemical composition of rocks, their structure, fracturing, cover formations and relief, gravity, groundwater, tectonic structures, the thickness of karst rocks.
2.1 Chemical composition of rocks
It can be argued that, other things being equal, the degree of karst content is greater where it contains more insoluble impurities. The influence of other factors, such as fracturing of the rock, the amount, speed of movement and aggressiveness of the circulating waters, can greatly obscure the influence of the chemical composition of the rock and sometimes dramatically change the picture.
However, there are exceptions to the above rule. The study of the effect of groundwater on marls and other non-dissolving rocks showed that it is necessary to distinguish between the concepts of dissolution and destruction of rocks. Destruction is understood as the total result of leaching of soluble substances from the rock and mechanical removal of the insoluble residue by the current of water. It happens that the destruction of the rock is many times more intense than dissolution. Where the movement of water slows down, the insoluble residue settles, suspended particles of turbidity settle, - karst or cave clay is deposited
The destruction of the rock in comparison with dissolution is especially important in the formation of karst forms, as well as in the case when the rock consists of unequally soluble minerals.
If the rock consists of minerals with unequal solubility and dissolution rate, the process of its destruction becomes more complicated. In calcareous dolomites, for example, dolomite and quartzite dissolve at different rates, depending on their quantitative ratio in the rock and the speed of water movement. With a dolomite content of about 2 percent. the dissolution rate of calcite is less than that of dolomite; with an increase in the amount of dolomite, the ratio of dissolution rates becomes reversed, and calcite is leached out first. Therefore, when dissolving highly dolomitized limestones and calcareous dolomites. Loose dolomite accumulates in the form of a residual product of leaching.
It is noted that in such lithological conditions the karst process manifests itself in the development of small numerous caverns, in the high porosity of the rock, its negligible strength, and in the final stage of the process - the destruction of the rock with its transformation into a loose powdery mass.
2.2 Rock structure
The influence of the chemical composition of the rock, expressed in the presence or absence of a significant amount of insoluble impurities, is superimposed on the influence of the rock structure, which obscures the influence of the chemical composition at small variations.
Of great importance is porosity, which makes it possible for water to penetrate into the rock blocks enclosed between fractures, and even seep through non-fractured strata. Porosity greatly increases the water-to-rock contact surface, which facilitates rock breakdown by dissolution.
In laboratory studies of the solubility of dolomites, it was found that the most soluble are medium-grained and especially uneven-grained rocks. Micro-grained and coarse-crystalline carbonate rocks are much more difficult to dissolve. But the solubility of small crystals is higher than that of large ones, and the poor solubility of fine-crystalline rocks is associated with their low porosity.
2.3 Fracturing of rocks
Fracturing of rocks is the main condition for the development of karst. Limestones are dense, impermeable rocks; water circulation in them can occur only through cracks. The same dense waterproof rocks in most cases are gypsum and other karst rocks. That is why rock fracturing plays an exceptional role in the karsting process.
The influence of fracturing on the development of karst has been emphasized by many researchers of karst forms, especially by researchers of caves.
Geological natural monuments as outcrops of rare rocks and minerals. Geomorphological areas of river valleys with widespread rocky outcrops. Caves and karst landforms. The Ural karst country is one of the largest in Russia.
The concept of karst and description of the main underground and surface karst landforms. Factors influencing the development of the karst process and the formation of karst landforms. Characteristics of the main karst areas within the Krasnoyarsk Territory.
Denudation is the destruction of rocks, and accumulation is the accumulation, the rise of the earth's surface. Characterization of the processes of deflation, waving and corrosion. Danger of ravines and landslides. Denudation activity of groundwater, sea and glacial processes.
The essence and main factors provoking the development of karst processes in nature, their results. Characteristics of karst caves, stages of their development, classification and varieties. Karst wells, mines and abysses. Conditions, possibilities of karst formation.
Engineering geology in the design and construction of industrial and civil structures and their operation. Indicators of the physical properties of soils, their units of measurement. Ground water... Darcy's law, filtration coefficient. Fissured groundwater.
Study of the essence and origin of karst (karst phenomena) - a number of phenomena caused by the dissolution (leaching) of certain rocks. Distinctive features karst phenomena in the Novo-Athos cave in the Caucasus. Features of cave fauna, speleofauna.
general characteristics Earth as a planet: structure, basic elements of the land surface and the bottom of the oceans. The main rock-forming minerals, their classification. Geology of groundwater activity; karst and suffusion deposits; intrusive magmatism.
Engineering development and transformation of the geological environment. Physico-geographical sketch of the Altai-Sayan region. Stratigraphy and Tectonics. History of geological development. Pre-Cenozoic and Cenozoic stages of development. Hydrogeological conditions.
CHAPTER. Origin and changes of carbonate rocks SEDIMENTOGENESIS. As is known, carbonate rocks are often composed of strata of considerable thickness. It is believed that the initial material for the formation of carbonate rocks was calcium and magnesium salts dissolved in water. With excess ...
Description geographic location and climatic conditions Gafuri district. Conducting seasonal measurements of the height and girth of the Askinskaya cave glacier. Identification of possible causes of changes in ice stalagmites in unorganized recreational load.
Classification of reservoirs of terrigenous and carbonate composition. Granulometric composition of rocks. Cracks of diagenetic origin. Regularities in the location and orientation of cracks in the rock. Methods for determining residual water in reservoirs.
Mobility and inconstancy of physical states crust, gaseous and water shells, processes affecting the relief. Features of the relief of the Earth, morphology of plains and mountainous countries... Geomorphological processes occurring on the earth's surface.
The difference in the use of the term "eluviation" in geology and soil science. Landforms associated with karst processes. The main factors that determine modern sedimentation. Table of factors causing proper gravitational processes.
The history of the development and formation of relief in the south of the Ivanovo region. Geomorphology of the territory: glacial landforms and morphology of river valleys. Typical manifestations of exogenous geological processes and factors affecting them. Karst processes.
DICTIONARY OF SPECIAL TERMS General geological terms The basis of denudation is the bottom of a slope, from which weathering products are carried down by denudation processes.
Exogenous and endogenous origin of groundwater. Physical and geographical phenomena associated with the activity of groundwater: landslide, suffusion, karst. Features of the water balance, modes of the aeration zone. Temperature and hydrochemical regimes of groundwater.
The relief is divided into surface, transitional and underground.
If the karst rocks directly overlook earth surface, that is open or naked karst. If they are covered from above by non-karst sediments, then this is covered karst .
Naked Karst occurs in mountainous areas, and covered - on the plains. Stands out yet indoor karst, which is noted in areas where karst rocks are thick and contain a large number of various impurities.
After the soluble part of these rocks is completely leached, a weathering crust is formed, not completely red in color and is called terra rossa(red earth). In the future, the development of karst under this crust proceeds in the usual way. This karst is called closed.
In the area of open karst, under the influence of rain or melt water, a microrelief is formed on the surface of limestones carrow... This is a system of ridges and furrows separating them, up to 2 m deep. Such a surface is called tar fields.
Transitional forms connect surface and underground zones. In places of increased fracturing of limestones, with vertical circulation of water, ponors, that is, channels absorbing surface waters... When they expand, sinkholes having a slit or saucer shape. With a large expansion, cracks turn into wells and shafts that can reach great depths. Example: the depth of the Snezhnaya mine in the Caucasus is 1370 m.
Failure, or surface funnels, when merged, form blind ravines, ridges and the largest karst forms - polya... The fields are vast, usually flat-bottomed, with steep walls, karst depressions several kilometers, and sometimes several tens of kilometers across. So, the Popova polya area in Yugoslavia is 180 km 2.
Polya may have tectonic origin, that is, karst develops in large tectonic cracks. Sometimes they are formed due to a sinkhole over an underground river, or by erosion and removal of products of erosion of insoluble rocks that occur among limestones.
TO underground forms karst include caves and chasms.
Caves called underground cavities formed in karst areas and having one or more outcrops to the surface. They are formed when water expands underground cracks. In many caves, on the bottoms, walls or vaults, drip forms... On the ceiling in the form of icicles - stalactites, at the bottom of the cave - stalagmites. When they merge, drip columns are formed. There are often underground rivers in the caves. They originate either in the area of the karst massif, or begin outside of it. Sometimes underground rivers come to the surface.
Karst landforms (according to D.G. Panov)
1 - punishments; 2, 3 - surface leaching funnels; 4 - sinkhole funnel; 5 - karst valley; 6 - polie; 7 - cave.
Literature.
- Smolyaninov V.M.General geography: lithosphere, biosphere, geographic envelope... Study guide / V.M. Smolyaninov, A. Ya. Nemykin. - Voronezh: Origins, 2010 - 193 p.
