Kaimoo.......................................................................................................................................................................................................................................................Kaimoo

Kaimu / Kaimu / Kaimoo (Eis und Sedimente) / Kaimoo（冰和沉积物） / Лёд и донные отложения / Kaimoo (ghiaccio e nei sedimenti) /

Platform or terrace made up of alternating layers of ice and sediment, which forms on the Arctic and Antarctic beaches, during the autumn and winter, when the beach is not reached by the waves.

See: « Shelf »
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« Glacio-Eustasy »
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« Astronomic Theory of Paleoclimates »

In terms of geomorphological signatures there are important differences exist between water-bodies covered with ice and not covered with ice. Fieldwork has shown classic formations created by water-bodies not covered by ice, such as sandbars, bars, berms, tombolos and abrasion platforms are absent when the water-bodies are covered by ice. The mentioned morphological forms are the result of the direct coupling of the wind and the free surface of the water. An ice sheet acts as a protective agent. The banks of ice-covered water-bodies are low-energy environments due to restricted or non-existent wave action. However, sectors of water not covered by ice may exist for 1/2 months per year, but the proximity of permanent ice greatly limits fetch distance and, consequently, the magnitude of wave action. Another barrier to any wave effect is the presence of a narrow strip of ice near the shore that is not affected by tidal movements. This narrow fringe of ice tied to the shore is what the geoscientists called ice foot. It is made up of sea ice, frozen snow and frozen salt (foam cloud formed by droplets of sea water and bubbles enclosing saline micro-crystals, resulting from the foam of the surf). In tidal regimes, a layer of ice with inter-stratified sediments is called a kaimoo. Kaimoo is an Eskimo word that designates, in the beaches of the cold climates, a small cliff composed of an alternation of sediments of beach and the ice. A kaimoo often develops on top of a beach by the action of waves before the formation of the ice-sea or the ice-foot*. During the uprush current (sea-water flowing towards the coast after the breaking of the waves, i.e., after the transformation of the osculation waves in translation waves), a thin layer of ice forms on the upper beach, which can be followed by the deposition of a layer of sand or gravel. The repetition of this succession forms an interval with intercalations of ice and sediments, whose thickness can reach several meters. The horizontal extent of a kaimoo is controlled by the length of the wave of the uprush current and the height is determined by the time period available for accretion before the ice base develops. On the low shores of Alaska, kaimoo forms a small coastal terrace, at the top of the coast, which is composed of ice interspersed with sediment. The kaimoo forms in the autumn, before the ice cover, under the action of the breaking waves that projects the water and the sediments on the upper margin of the coast. In regions where there is only open sea for 1/2 months a year, the proximity of permanent ice drastically limits fetch (the extent of the surface of the ocean over which the wind blows for some time to generate a wave or a wave system) and, consequently, the magnitude of the wave action. The ice foothills and kaimoo are important to protect the beaches from any action of the waves, which are undeveloped and narrow. In these areas, the most characteristic relief produced by the ice cover of the lakes are the ice push ridges. As illustrated in the larger photograph, these forms constitute discrete walls of boulders and sediments pushed one above the other along the shores of the lakes and seas. The coastlines are, generally, constructed with these walls that define the inner edge of the coast and which, generally, have a heterogeneous and thin mantle of stones, pebbles, sand and gravel, covering a core of ice which, later, melts leaving behind the sedimentary material in the form of irregular and discontinuous grooves. The ice core can persist for years if it is sufficiently isolated by the sedimentary layer.

(*) In glaciology, the ice foot correspond to the lower part of the front of a glacier or a snow bank hardened or partially converted to ice, located at the base of a steep hill (Jean-Claude Dionne, La Notion de pied de glace (Icefoot), in particular in the study of Saint-Laurent, Cahiers de Géographie du Québec, Vol. 17, No. 41, 1973, pp. 221-250).

Kame......................................................................................................................................................................................................................................................................Kame

Kame / Kame / Kame / 冰砾阜 / Кам / Kame /

Lower hill or irregular ridge, isolated or not, formed by sand or stratified gravel and deposited by a subglacial stream as a filling of a glacial cavity or the formation of a delta on the margin of a melting glacier.

Ver: « Outwash Plain »
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« Delta »
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« Moraine »

When a glacier (recrystallisation of snow, which flows downhill) begins to melt, the currents carry sedimentary particles and blocks of rocks to the lakes or to the cavities that form on glaciers and can form "kames" at the top of them. When the glacier completely melts, as is the case illustrated in the photograph of this figure, the deposits collapse to the surface of the terrain creating an inverted topography typical of mounds and depressions (as when the sand filling of a channel is inverted by differential compaction). Unlike the "drumlins" (upstream of the lake in the diagram on the right), which are more or less profiled hills, largely composed of till (un-worked and non-stratified sediments not reactivated by the waters and which deposit directly in front or under a glacier) and oriented in the direction in which the glacier has moved, the "kames" have a more or less irregular shape. The "drumlins" that are usually found on the bottom of the glacial valleys, are small hill shaped whale-back. Some geoscientists consider the drumlins are small or medium sized moraines deposited during a short period of stagnation of the glacier, at the time of its thinning or the filling of a large notch in the direction of the length of the glacier, formed by a current of water flowing to the surface of the glacier. The drumlins are made up of glacial deposits of the same type and organization as the moraines. The kames are composed of stratified and not by till deposits. They are almost always associated with stagnant ice, in which the melting produces large cavities, which are filled by sands and runoff gravel. When the ice walls of the cavities merge, an irregular mound shape replaces the channelling filling of the initial cavity. A kame terrace is formed of stratified sand and gravel deposited between the waste of the glacier and the walls of the glacier valley. When the glacier disappears, the deposit remains as a terrace along one side of the valley. These terraces can be deformed when ice walls collapse or when the glacier thickens (advances). A glacier does not retreat, since it is a thick mass of ice that moves, slowly, downhill, due to the action of gravity. In other words, by definition, a glacier can not retreat. When a glacier becomes thinner, that is, when ablation is greater than accumulation, the glacier retrogrades, that is to say, it advances less. Geoscientists call kame terrace to the fluvial terraces formed along the glacial valley by deposits of a river flowing between the wall rocky wall and glacier. These terraces are suspended above the valley when the ice of the glacier has melted. Eskers** sometimes occur between the kames (as illustrated in the photograph), as fills of water-meting channels, along the banks of glaciers where there is a large volume of debris and melting water. Eskers are formed as water flow deposits that flow near the base of the glacier (sub-glacial flows) along tunnels within the ice. They are, general, 20-30 meters high and are never found beyond the ice limit. As the currents flow through the tunnels within the ice, there is no possibility to form a plain. The channel bed is constructed with the deposited material, leaving it above the level of the surrounding terrain. Eskers are generally easy to spot in the landscape because they support vegetation, usually herbs and trees, which is quite different from the surrounding terrain, which is often used as agricultural land.

(*) The median or medial moraine is a mound of morainic material that moves to the centre of a glacial valley floor. It forms when two glaciers meet. The debris at the edges of the adjacent sides of the valley unite and are transported on top of the glacier thus enlarged. As the glacier melts or retrogrades, the debris are deposited and a mound forms at the bottom of the valley.

(**) Long and narrow ridge of sand and gravel, more or less, stratified. It is deposited by a subglacial stream that moves between the walls or tunnels of a stagnant or thinning glacier and which is abandoned when the ice melts. Its direction is usually perpendicular to the front of the glacier and the length varies between 100 and 500 km (discontinuities included), while the width varies between 3 and 200 m.

Karst...........................................................................................................................................................................................................Érosion du calcaire (Karst)

Karst (carso)/ Carst, Karst / Karst / 喀斯特地形 / Карст / Carsismo /

A morphological process affecting limestone rocks characterized by the dissolution of calcium carbonate and its transport in the form of bicarbonate, which creates a more or less chaotic surface topography.

See: « Karsification »
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« Karst (limestone erosion) »
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« Deposition (carbonates) »

Karst, which is also known as karst relief or karst system, is a type of orographic accident (in geography the orography is the study descriptive of the mountains of the terrestrial surface) characterized by the chemical dissolution (corrosion) of the rocks, which leads to the appearance of a number of physical features such as grottos or caves (natural cavities underground large enough for a man to explore and where normally sunlight does not penetrate), sinkholes (natural depressions or holes in the topographic surface caused by the removal of the soil or the underlying rock or both by water), dry valleys (valleys dug in a karst by a surface water course, which no longer has any subaerial circulation), blind or dead valleys (valleys in a karst region with inversion of the slope of its downstream bed, ending in a slope or escarpment), karst cones (hills of steep slopes and rocky walls, which resisted dissolution, subterranean rivers (which flow beneath the surface of the soil in a completely natural way), fluvio-karstic canyons*. Karstic relief occurs, predominantly, on limestone rocks, but can also occur on other types of carbonate rocks, such as marble and dolomitic rocks. The process of karsification or chemical dissolution begins by combining rainwater or surface rivers with carbon dioxide (CO₂) from the atmosphere or soil (vegetation roots and decaying organic matter). The result is a solution of carbonic acid (H₂CO₃) or acid water: H₂O + CO₂ → H₂CO₃. The karst landscape occurs, mainly, in regions with high rainfall, which guarantees a sufficient flow of water to dissolve large portions of rock. Also important is the presence of vegetation to ensure that water penetrates the soil and is not lost to the atmosphere. Karstic regions have very little surface water, since rain-water is, quickly, absorbed by the soil and accumulates in the water table. The water table is the free aquifer, which extends in depth until it reaches an impermeable level. It is in direct vertical contact with the atmosphere through the aeration zone and subject only to atmospheric pressure and has no upper confining layer. The depth of the compact substrate of the water table varies with the geological environment, from a few centimeters to several tens of meters, depending on the region. The water, when passing through the cracks, corrodes calcium carbonate (CaCO₃) or other constituent salts of the rock, such as calcium sulfate or magnesium carbonate. In the case of calcite, composed basically of calcium carbonate, the result of this reaction is a solution of calcium bicarbonate: CaCO₃ + H₂CO₃ → Ca(HCO₃). The salts removed from the rock are carried by the water towards the lower geological layers. Upon reaching the water table, water may flow into underground rivers, opening up cavities in the rock, mainly due to chemical erosion, but mechanical erosion may occur in vadose zones (above groundwater). Salts may sediment into lower geological layers or be drawn out through sources (where water emerges naturally, from a rock or soil, to the surface of the soil or to a body of surface water) or resurgence (where a current of groundwater reappears on the surface of the ground after disappearing upstream). Since groundwater contamination is closely related to the state of surface water, air, rain and soil, their protection must be treated at the same time to preserve the environment as a whole. When a geoscientist refers to the source of a river, he is referring to the point of the drainage basin furthest from the mouth and where the groundwater flows, which means that along a river there may be several sources and, only the most upstream source is that it corresponds, in fact, to the source of the river. It is this definition of the A. Johnston geographer of the Smithsonian Institute that was used by the National Geographic Society of the USA to locate the source of most rivers.

(*) Deep, narrow canyons, but in a karst zone), exposed rocky surface geology, on calcareous and dolomitic rocks, created by the flow of rainwater, which dissolves the rock, or by the cycles of ice and melting inside the rocks.

Karst (Limestone erosion)..................................................................................................................................................Érosion du calcaire (Karst)

Carso / Carst / Karst / 喀斯特地形 / Карст / Carsismo /

A landscape characterized by caves, underground rivers and crumbling (dolines) that form due to the action of groundwater in regions composed of easily soluble rocks (limestone and dolomites). The term "karst" is the German name for the region of Slovenia's limestone plateaus, whose Slavic name is "kras".

See: « Karsification »
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« Erosion »
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« Keep-up Carbonate »

The filling of the sinkholes (depressions, generally circular, with diameters that can reach more than 100 meters and that drain the underlying karst areas) by rain-water is a natural part of the hydrological systems in the karst regions. The filling occurs during periods of intense rain-fall: (i) When the amount of rain-water exceeds the drainage capacity of the sinkholes ; (ii) When the capacity of the cave systems to evacuate rain-water is exceeded and the water has to be temporarily stored ; (iii) When there is a return effect of the water flow, i.e., when the bottom of the sinkholes is lower than the water level during a flood. Karsification (the set of processes of genesis and evolution of surface and ground forms in a so-called karst relief region) can be the result of a wide variety of elements from different scales. It can be made to the surface of the ground or underground. In the exposed surfaces, the small scale (metric), the main forms of karst are: (a) Dissolving flutes or slits ; (b) Ditches ; (c) Lapiaz (section of a limestone, more or less, rounded away from adjacent sections by dissolution cracks) and (d) Dissolution Grikes (dissolution along fractures and diaclases). At a scale of tens of thousands of meters, the surface elements are: (1) Sinkholes or dolines* ; (2) Vertical wells ; (3) Inverted sinkholes or "foibas*" (locally designated as a karst structure, natural and deep type that forms due to the collapse of the part of the rock ceiling above a void) ; (4) Water-courses that disappear and currents that reappear, etc. On a large scale, there is predominance of : (a) Limestone pavements ; (b) Ships or karst vaults and (iii) Blind Valleys (valleys that end abruptly, and the water courses run underground, since there is a karst barrier higher than the bottom of the valleys). The mature karst landscapes, in which a large part of the rocks have been dissolved, are the Karst Towers and the residual mounds that predominate. In the sub-soil, it is the complex drainage systems, the large caves and caves that develop. The dissolved CO₃Ca precipitates, usually, where the water discharges, a little, the dissolved CO₂. Underground streams can emerge and form travertine terraces (a compact and hard limestone reservoir, essentially formed by the exterior runoff of the water coming from a karst region). In the caves a large variety of speleothems (constructive karsification) is formed from CO₃Ca and other dissolved minerals, such as: (a) Stalactites, which originate in the roof of a cave or cave, growing down, towards the by the deposition of calcium carbonate entrained by the water that drips on the ceiling and which often have a tubular or conical shape ; (b) Spirocones and Corkscrews (spiral-shaped stalactites or corkscrews) ; (c) Helictites (formed from the ceiling or walls and which change their axis relative to the vertical in one or more phases during their growth) and Heligmites (formed from the ground); (d) Curtains or draperies (speleothem formed on inclined roofs, where water, instead of dripping, always flows along the same path, creating thin wavy walls, which when they reach the ground become very thick and resistant) ; (e) Stalagmites (formed from the ground by limestone concretions made up of limestone still dissolved in drops of water falling on the ground (when a stalagmite encounters a stalactite, a column forms) ; (f) Flowings (when the water flows through the walls or around old speleothems and forms a whole series of figures) ; (g) Flowers (crystallizations of aragonite, calcite or gypsum (which is basically made up of hydrated calcium sulphate) which radiate from a central point or an axis in all directions) and needles (fine tubes consisting of transparent aragonite, with very small thickness, occurring to sets with tens or hundreds of needles close to each other, which may be born on the walls on the floor, rarely on the ceiling, as a result of exudation, etc. As illustrated on the tentative interpretation of a Canvas auto-trace of a detail of a Gulf of Thailand seismic line, in particular cases, when the karst forms morphology is superior to the seismic resolution, it is possible to recognize the karsification on the seismic lines.

(*) The name "doline" comes from dolina, the Slovenian word for this very common feature. The term "foiba" may also refer to a deep wide chasm of a river at the place where it goes underground.

Karstification.......................................................................................................................................................................................................Karstification

Carstificação / Carsificación / Karstification, Verkarstung / 岩溶 / Образование карстового рельефа / Carsismo /

Partial dissolution of limestone by acid waters and transport of calcium carbonate in the form of bicarbonate, which gives rise to a surface topography with a, more or less, chaotic appearance and forms of dissolution as well as deep runoff. The dissolution is faster along the fractures and diaclases that open up forming grikes, among which are formed, more or less, rounded blocks called lapiaz or clints.

See: « Deposition (carbonates) »
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« Karst »
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« Catch-up Carbonate »

Karsification is the set of processes of genesis and evolution of surface and subterranean forms in a region said with a karstic relief. As shown in this figure, a karst relief is typical of calcareous regions with forms resulting from the mechanical and chemical action of surface and underground waters. Karstic processes refer to calcareous and evaporite rocks. Similar processes called "pseudo-karstic" processes can develop in other types of rocks (non-carbonate sandstones, sedimentary quartzites, conglomerates, lavas, diorites, gabbros and even some granites and metamorphic rocks). Likewise, similar morphologies resulting from karstic or pseudo-karstic processes occur, frequently, in glacial areas: inlandsis, glaciers, ice seas, etc. Certain geoscientists call glacio-karstics, cryo-karstics or thermo-karstics, the glacial structures or the corresponding morphologies. The dissolution of carbonates is the main mechanism of karsification. The chemical reactions responsible for such dissolution are: (i) The dissolution of carbon dioxide ...... CO₂ + H₂O ➝ H₂ CO₃ ; (ii) The dissolution in water of carbonic acid ........ H₂ CO₃ + H₂O ➝ H₃O + HCO_3- ; (iii) The attack of the carbonates ........ H₃O + CaCO₃ ➝ Ca₂₊ + HCO_3- + H₂O and (iv) The equilibrium equation ......... CO₂ + H₂O + CaCO₃ ➝ Ca₂₊ + HCO_3-. As regards the bicarbonate content, one carbon atom comes from the limestone and the other from the carbonic gas. Carbon dioxide or carbon dioxide (CO₂) is mainly of biogenic origin. Its concentration in the soil is much more important than in the atmosphere. The two possible sources for carbon dioxide can easily be differentiated by the content of the carbon isotopes. Carbon isotopes are carbon atoms of the same atomic number, but with different mass numbers, that is, they have the same number of protons and electrons, but they do not differ from neutrons. Carbon has 15 isotopes, from carbon 8 to carbon 22, of which carbon 12 and carbon 13 are stable. The longest-lived radioisotope is ¹⁴C, with a half-life of 5,700 years. This is also the only radioisotope of carbon found in nature - the trace amounts are formed by the reaction ¹⁴N + 1n → ¹⁴C + 1H. The most stable artificial radioisotope is ¹¹C, which has a half-life of 20,334 minutes. All other radioisotopes have half-lives below 20 seconds, most less than 200 milliseconds. The least stable isotope is 8C, with a half-life of 2.0 x 10^-21 s. The average for natural abundances, the relative atomic mass for carbon is 12.0107. The segregation of ¹³C by living beings in the atmosphere, the molecules ¹³CO₂ coexist with the molecules of ¹²CO₂, to the height of approximately 1.1% of the total CO₂ ; plants use both types of carbon during photosynthesis, but the slightly heavier ¹³C is less absorbed than ¹²C. The dissolution of the carbonates and consequently the karsification is facilitated by: a) Abundance of water ; b) CO₂ content in water, which increases with pressure ; c) A small water temperature, meaning that the colder the water is, the higher the carbon dioxide content (this is why when the temperature of the oceans increases there is release of CO₂ into the atmosphere) ; d) Presence of living beings, since they reject carbon dioxide (CO₂) to the soil by respiration, which greatly increases the CO₂ content in the soil ; e) Rock composition (high content of calcium carbonate) ; f) Rock fracture* ; g) Time of contact of the water with the rock. A cold, humid and limestone region is more likely to develop karsification, which is not to say that karst is not found only in hot, humid regions. In karst regions various forms of karst may develop, for example: (i) Sinkholes (circular depressions of several to several hundred meters in diameter with the bottom, often occupied by de-calcifying clay) ; (ii) Terra Rossa (red soil, very fertile and, more or less, impermeable) ; (iii) Uvalas (coalescence of two or more dolines) ; (iv) Poljes (depressions resulting from the coalescence of several dolines, whose water is evacuated through a hole - ponor - to the water table) ; (v) Dissolution Slits (dissolution along fractures and diaclases) ; (vi) Lapiaz (section of a limestone, more or less, rounded off the adjacent sections by dissolving cracks) ; (vii) Incised and Calibrated Valleys (such as the Reka valley in Slovenia or the Songiahe valley upstream of the Dadong tunnel cave in southern China) ; (viii) Dry valleys (excavated in a karst by a surface water course, which normally no longer has any subaerial circulation) ; (ix) Sinks (places where a surface current disappears underground, or, for some geoscientists, the lateral or basal crevice or orifice that feeds a polje during the rainy season and serves to drain the water in the dry season) ; (x) Resurgences (places where a current of groundwater reappears on the surface of the ground after disappearing upstream), etc.

(*) Clints are limestones blocks (some of the blocks are loose and move underfoot) and the spaces between them are named grikes. Indeed, over time, water has eroded the limestone into these forms and, often, there are ferns and other plants growing in the spaces.

Katabatic (Wind)...........................................................................................................................................................................................Catabatique (Vent)

Catabático / Catabático (viento) / Katabatischen / Katabatic （风） / Нисходящий (о ветре) / Catabatico (vento) /

Wind that carries, by gravity, high density air from a raised area to a lower area. This is why this type of wind is sometimes called downwind. However, not all descending winds are katabatic.

See: « Atmosphere »
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« Transportation (sediments) »
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« Loess »

A katabatic wind is formed by the cooling by radiation of the air above a plateau, mountain, glacier or even on top of a hill. As the density of the air is inversely proportional to the temperature, i.e., the higher the air temperature the lower its density, the air flows downward by heating, adiabatically, as it descends. In an adiabatic heating no heat is transferred to or from the work of the fluid or, in other words, no heat is transferred from the surrounding environment. The temperature of the wind depends on the temperature of the region of origin and the temperature upstream of the descent. In some cases, the wind may warm up (but not always) by the time it reaches sea level. In Antarctica, the temperature of the wind is still, intensely, cold when it reaches sea level. Katabatic winds are very frequent in the large, high glaciers of Antarctica and Greenland. As illustrated in this scheme, the formation of very dense cold air above the ice caps and high ice accumulations creates a huge gravitational energy, which drives the winds sometimes at a faster speed than the strongest hurricanes. In Greenland these winds are called "Piteraq" and are more intense when an area of low pressure approaches the coast. The same happens from Tierra del Fuego (South America) and Alaska, where the katabatic winds can reach 180 to 360 km/h, making navigation very dangerous. A very particular case of katabatic wind is the mountain breeze or descending breeze hillside. In a mountain valley, morning warm-up occurs first on the highest parts of the slopes (mountainside), which creates a rising upward or ascending breeze that sucks in the lower air and amplifies in the valley breeze. The nocturnal cooling that begins in the higher parts increases the air density that flows downward forming a descending breeze of the hillside that is amplified into mountain breeze. Not all descending winds are katabatic. Thus, for example, the Foehn ** (in the Alps) and the Chinook (in the Rocky Mountains) are the remains of rainy winds. On the windward side of the mountains the rising wind is very humid (a lot of rain), while on the leeward side it is much drier and hotter. As an example of katabatic winds, we can mention Bora in the Adriatic Sea, Santa Ana in California, Oroshi in Japan, and Barber in New Zealand.

(*) In thermodynamics, an adiabatic transformation is a thermodynamic transformation, usuall,y irreversible and not nearly static (occurs in an extremely slow manner, such that the system goes from an initial equilibrium state A to a final equilibrium state B through a sequence of infinite equilibrium states separated by infinitesimal transformations and infinitesimal variations of system properties) in which a physical system does not, practically, exchange heat with the environment, even if it yields and cycles it back into pairs of elementary transformations.

(**) By mechanical forcing (the mountains force the air to rise) the humid air rises on the windward slopes of the Alps and cools with temperature. If the air is saturated with moisture, the water vapour condenses and generally causes abundant precipitation on the southern slope. If the mass of air is stable, a downward airflow occurs on the other side of the mountains which prevents formation of clouds and sometimes forms a foehn front or wall on the mountain tops. A hot, dry, high air descent blows over the valleys and piedmont (region at the foot of the Alps, bordered by the Italian regions of Valle d'Aosta, Lombardy, Liguria and Emilia-Romagna, and the Swiss cantons of the Valais and the Ticino, as well as the French regions of Auvergne-Rhône-Alpes and Provence-Alpes-French Riviera) from leeward. This downward wind inhibits, for tens of kilometers, the formation of clouds downstream of the ridge line which induces a sunny or at least cloudless climate at low and medium altitude.

Keep-up Carbonate................................................................................................................................Carbonate de compensation

Carbonato de compensaçãoi / Carbonato de compensación / Keep-up-Carbonat, Carbonate Entschädigung / 保持了碳酸盐, 碳酸盐补偿 / Компенсируемый карбонат / Keep-up carbonato, Carbonato di compensazione /

Carbonated deposit with a geometry, more or less, parallel, found mainly in highstand systems tracts (HST), i.e., in the transgressive interval (TI) and highstand prograding wedge (HPW) of a sequence-cycle. These deposits form when the relative sea level rise is compensated by carbonate accumulation. The result of such a balance is that all available space for the sediments (accommodation) is filled as it is created.

See: « Deposition (carbonates) »
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" Relative Sea Level Rise "
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" Accommodation "

The offshore East of the United States corresponds to the stacking of three types of basins of the classification of the sedimentary basins of Bally and Snelson (1980): (i) Basement or Paleozoic Folded Belt ; (ii) Triassic Rift-type basins and (iii) Mesozoic/Cenozoic Atlantic-type Divergent Margin. In this Canvas auto-trace of a Florida offshore seismic line, the Atlantic-type divergent margin is, mainly, represented by a post Middle Miocene carbonate platform, formed by catch-up carbonates*. Under the keep-up carbonates, the aggradational geometry of the pre-Middle Miocene sediments suggests the deposition of catch-up carbonates deposited in association with accelerating and discontinuous relative sea level rises (i.e., sediments are deposited during the stability period of relative sea-level that occurs after each marine ingression increment**). In this way, the available space for sediments (shelfal accommodation) created by the combined action of eustasy (changes of the absolute or eustatic sea level*) and tectonics (subsidence or uplift of the sea floor, respectively, when the predominant tectonic regime is in extension or in compression), is completely filled by the newly formed carbonated material. These conditions allow an aggradation and progradation of the platform. In this region, as suggested by the seismic data, during the Middle Miocene, the accommodation rate was compensated by the depositional rate. This type of carbonate contrasts with post-Middle Miocene catch-up carbonates, which are associated with relative sea level rises in acceleration followed by a slow rise. After the initial (rapid) relative sea level rise, the carbonate accumulation decreases due to the increase in water-depth, without the formation of carbonated material ceasing. As the rate of relative sea level rise then decreases, the carbonate platform is constructed, effectively, (vertically). If the rate of accumulation is greater than the rate of relative sea level rise, the carbonate formation will become, more and more, efficient. With the continuation of this process, the accumulation in the carbonated platform will recover the initial sharp depth-water increase until the maximum carbonate production is restored. Under conditions of high production and accumulation rates, the accommodation may become insufficient and lateral progradation (downstream) of the platform becomes imperative. Within a sequence-cycle, in general, catch-up carbonates, which have, basically, an aggradational geometry, deposit during transgressive interval (TI) in association with a relative sea level rise in acceleration, i.e.: (i) The creation rate of the available space for sediments increases and (ii) There is always space available so that the carbonate material can be deposited, practically, in situ. Keep-up carbonates, whose geometry is. progradational, are, generally, deposited in the highstand prograding wedge (HPW), in association with a rise in relative sea level deceleration. With the space created (accommodation) is insufficient to accommodate the carbonate produced, which is forced to prograde and be deposited on the slope. There are five main types of carbonate platforms: (i) Rimmed Platforms with limestone reefs or calcareous sands at the edge of the platform and clay sands in the lagoon or open platform ; (ii) Type-Ramp Platforms, in which the carbonated sands of the coast line pass, at the base of the ramp, to clay sands and deep water muds ; (iii) Epeiric Platforms, with tidal plains and protected lagoons ; (iv) Isolated Platforms, controlled by the orientation of the dominant winds and (v) Dead or Drowned Platforms, that are under the photic zone. In this Canvas auto-trace, due to the abrupt change in water-depth, the seismic horizons westward of the platform edge, in a depth converted seismic line, are much less deeper than the other horizons and some, probably, are sub-horizontal.

(*) Catch-up carbonates with oblique (progradational) geometry that are deposited when the rate of carbonate production exceeds accommodation (available space for sediments created by relative sea level rise). Keep-up carbonates (aggradational geometry) are deposited when the rate of carbonate production compensates for the rate of rise of relative sea level.

(**) A relative sea level rise, i.e., a marine ingression, is not done in continuity but in stages, i.e., by a series of eustatic paracycles separated between by stability periods of relative sea level. Any relative sea level fall exists between such an eustatic paracycles. The marine ingression increments, collectively, form the composite marine ingression, which can be in acceleration (increments increasingly important) or in deceleration (increments increasingly smaller).

Kenorland (Supercontinent)...........................................................................................................................................Kenorland (supercontinent)

Kenorland (supercontinent) / Kenorland (supercontinente) / Kenorland / Kenorland（超）/ Кенорленд / Kenorlandia /

Supercontinent that formed about 2.7 Ga and fractured there are about 2.5 Ga in different small supercontinents: (i) Laurentia ; (ii) Baltica ; (iii) Australia ; (iv) Kalahari, etc.

See: « Craton »

Kepler's Laws......................................................................................................................................................................................................Lois de Kepler

Leis de Kepler / Leyes de Kepler / Keplerschen Gesetze / 开普勒定律 / Закон Кеплера / Leggi di Keplero /

The planets move it in elliptical orbits around the Sun*, with the Sun at the focus of the ellipse. A straight line between a planet and the Sun sweeps across equal areas during the same time. The square of a planet's period is inversely proportional to the cube of the radius of its orbit.

See: « Astronomic Theory of Paleoclimates »
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« Equinoxial Precessions »
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« Orbit »

First law: The planets move in elliptical orbits, with the Sun in one of the focus. Second law: The straight line joining the Sun to planet sweeps equal areas in equal periods of time. Third law: The squares of the orbital periods of the planets are proportional to the cubes of their mean distances to the Sun. Modern measurements in the orbits of the planets show that they do not follow, precisely, these laws. Its development is considered an important milestone in the history of science. The first two laws were published in 1609 and the third in 1619. His publications put an end to the cycles and epicycles of Ptolemy. In Ptolemy's model, the planets moved in a small circle (epicycle), which in turn moved along a larger circle called the deferent. Both circles turned eastward and parallel to the plane of the Sun's orbit. Kepler's burning faith in the Copernian system "The Sun is not only at the centre of the Universe, but it is the spirit of the movement" brought him the misfortune of religious leaders and the title of "mad astronomer." In addition to discovering these three laws, he elaborated: (i) The tables of positions of the stars ; (ii) He developed the astronomical telescope ; (iii) He worked in infinitesimal calculus and logarithms ; (iv) He founded the science of geometrical optics ; (v) He studied the anatomy of the human eye ; (vi) He explained the tides of the oceans and (vii) He wrote, in Latin, the first history of science fiction the "Somnium**", in which he dreamed of building a ship to navigate the oceans of space in the universe. Kepler's laws refined the Copernican model. If the eccentricity of a planetary orbit is zero, Kepler's laws say: (i) The planetary orbit is a circle ; (ii) The Sun is in the centre ; (iii) The velocity of the planet in orbit is constant and (i) The square of the sidereal period is proportional to the cube of distance to the Sun. It is now known that: (a) The planetary orbit is not a circle but an ellipse ; (b) The Sun is not in the centre, but in a focal point ; (c) The velocity is not linear, nor is the angular velocity constant, only the velocity of the area is constant ; (d) The square of the sidereal period is proportional to the cube of the mean between the maximum and minimum distances to the Sun.

(*) A celestial body orbits Earth with the lowest possible orbit (circular). Its orbital velocity, that is to say, vc= (g x r)^1/2 should be 7.90 km / s, since g = 9,81 m/s² and radius of the Earth (r) is 6,371 km. If the speed increases, the orbit becomes more and more elliptical. At the minimum escape velocity (ve=(2)^1/2 vc = 11.18 km/s), the orbit becomes a parabola and leaves the Earth's gravity field. if the velocity is greater than the velocity of escape, the orbit will be a hyperbola and it will leave Earth's gravitational field. Although all planets and satellites have elliptical orbits, comets may have elliptical or parabolic or hyperbolic orbits. Hyperbolic parabolic orbits are open orbits, meaning that celestial bodies have no return.

 (**) Somnium (the Dream) presents a detailed imaginative description of how the Earth might look when viewed from the Moon, and is considered the first serious scientific treatise on lunar astronomy.

Kinetic Theory.....................................................................................................................................................................................Théorie cinétique

Teoria cinética / Théorie cinétique / Teoría cinética / Kinetische Theorie / 动力学理论 / Кинетическая теория / Teoria cinetica /

The properties of a gas depend on the movement of the atoms or molecules that compose it.

See: « Gas »
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« Entropy »
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« Atmosphere »

In the mid-nineteenth century, the British physicist James Joule devoted himself to the study of heat as a form of energy. By measuring the temperature rise of a mass of water into which a propeller blade wheel was driven, he calculated the mechanical equivalent of heat (about 4.2 joules per calorie ; it has the value 1 in the International System, because all forms are measured in joules). J. James surveyed, also, the gas pressure and postulated that it was due to millions of collisions between atoms or gas molecules in strong movement against the walls of the vessel. Joule conceived the gas as a collection of free-moving molecules. That is why a gas always fills the container that behaves. But if a gas, such as water vapour is, sufficiently, cooled, it condenses to form a liquid. In a liquid, although they are still in motion, the molecules remain under the surface, and the liquid takes the form of the container containing it. If the water is further cooled, it freezes, i.e., condenses to form a solid (ice). In the solid state, the molecules are, more or less, fixed in position in a crystalline structure, although they vibrate slightly. In 1738, Daniel Bernoulli published "Hydrodynamics," which laid the foundation for kinetic theory of gases. In this work, Bernoulli advanced the argument, still used today, that gases are formed by a large number of moving molecules in all directions, and that the impact of molecules against a surface causes the pressure of the gas we feel and what we experience as heat is simply the kinetic energy of its motion. The theory was not, immediately, accepted, partly, because energy conservation had not yet been established and was not obvious to physicists, how collisions between molecules could be perfectly elastic. Other pioneers of kinetic theory (which were forgotten by his contemporaries) were Lomonosov (1747), Le Sage (1780 and 1818), J. Herapath (1816) and J.J. Waterston (1843), who connected their research work with development of mechanical explanations of gravity. In 1856, August Karl Kronig (probably after knowledge of Waterston's article:  Thoughts on the Mental Functions, 1843) created a simple kinetic gas model, which considered just the translational motion of the particles.

Kirchhoff-Bunsen Theory..................................................................................................Théorie de Kirchhoff-Bunsen

Teoria de Kirchhoff-Bunsen / Teoría de Kirchhoff-Bunsen / Bunsen-Kirchhoff - Theorie / 本生，基尔霍夫理论 / Теория Кирхгофа-Бунзена / Teoria di Bunsen-Kirchhoff /

If a particular substance emits light of a given frequency, it also absorbs light of that frequency.

See: «Spectroscopy »
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« Albedo »
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« Cosmic Ray »

Kirchhoff proposed the three laws that describe the emission of light by incandescent objects: (i) A heated solid object produces light with a continuous spectrum* ; (ii) A thin gas produces light with wave-length spectral lines (distance between repeated values in a wave pattern, i.e., the distance between two crests or two consecutive troughs) depending on the chemical composition of the gas ; (iii) A solid object at high temperature surrounded by a fine gas at lower temperatures produces light in a continuous spectrum with voids at discrete wave-lengths whose positions depend on the chemical composition of the gas. These laws were, later, explained by Niels Bohr, which contributed, heavily, to the birth of quantum mechanics**. Kirchhoff is also the author of the fundamental laws of classical electric circuit theory. Within the solid state (heated or not) there are six types of solid: (i) Fragile Solid (Fragility) ; (ii) Hard Solid (Hardness) ; (iii) Resistant solid (Resistance) ; (iv) Elastic solid (Elasticity) ; (v) Flexible solid (Flexibility) ; (vi) Ductile Solid (Ductility). A fragile solid breaks, easily, without first deforming. The graphite is a example of fragile or brittle solid). A hard solid shows resistance when scratching its surface (precious stones are materials of great hardness). A resistant solid is able to withstand the action of intense forces without breaking (iron is a solid resistant to external forces). An elastic solid deforms and recovers the original shape when the force that produced the deformation is removed (rubber is a resilient material). A flexible solid folds without breaking (wool is a flexible solid). A ductile solid extends easily, forming wires (gold is a ductile solid, with 1 gram of gold it is possible to make a 2 km wire).

(*) A spectrum relates the transmitted, absorbed or reflected radiation intensity as a function of the wave-length or frequency the radiation.

(*) Physical theory that succeeds in the study of physical systems whose dimensions are near or below the atomic scale, such as molecules, atoms, electrons , protons and other subatomic particles, although in several cases it may also describe macroscopic phenomena.

Known Petroleum System (!).........................................................................................Système pétrolier connu (!)

Sistema petrolífero conhecido / Sistema petrolífero conocido (!) / Bekannte Erdöl-System (!) / 已知含油气系统 (!) / Известная нефтегазоносная система (!) / Petrolio sistema conosciuto (!) /

When the correlation between the source-rock and the hydrocarbons is known, in particular, by biomarkers (in the case of petroleum).

See : « Oil Pool (hydrocarbon) »
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« Source-Rock »
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« Reservoir-Rock »

The term "petroleum" means a compound that includes high concentrations of any of the following substances: (i) Biological and thermal gaseous hydrocarbons found in conventional reservoirs, as well as in the form of gas hydrates, low permeability reservoirs, fractured shales, and coal ; (ii) Condensates, crude oils and natural bitumen in reservoir rocks, usually siliciclastic rocks and carbonate rocks. An oil system describes the interdependent elements and processes that form the functional unit that generates accumulations of hydrocarbons, that is to say, the genetic relation between a parent rock and an accumulation of hydrocarbons. An oil system has three important temporal aspects: (A) Age ; (B) Critical moment and (C) Time of preservation. In 1987, Magoon considered three types of petroleum systems as a function of the degree of certainty, which indicates the confidence for which a particular pod of mature source-rock has generated the hydrocarbons in an accumulation: (1) Known Petroleum System ; (2) Hypothetical Petroleum System and (3) Speculative Petroleum System. At the end of the system's name, the level of certainty is indicated by (!) for known, (.) for hypothetical, and (?) for speculative. In a known petroleum system (!), the correlation between the source-rock and the hydrocarbons is perfectly known and corroborated by the biomarkers, especially in the case of oil. The Bucomazi Shales/Vermelho Sandstones (!) is an example of known petroleum system, in the Cabinda (Angola onshore), where the Bucomazi shales are the source-rocks and the Vermelho sandstones the reservoir-rocks. In an hypothetical petroleum system (.), there is a correlation between the source-rock and the hydrocarbons, but it is not or not yet corroborated by the geochemical analysis (biomarkers). A speculative petroleum system (?) is, just, based on geological or geophysical data and the presence of hydrocarbons (oil or gas) is not yet proven by wells. On this tentative interpretation of a Canvas auto-trace of a Canadian onshore seismic line (Rocky Mountains), the petroleum system Cardium/Belly River (!) has been known for many years and has been corroborated several times by geochemical study. The source-rock (rock rich in organic matter that has been sufficiently buried for its organic matter to reach maturity, i.e. the oil window) is found in the Cardium formation. The reservoir-rocks, i.e., rocks with a porosity and permeability allowing an accumulation and production of oil in economical amounts, saturated with hydrocarbons are found in the Belly River formation.

Kvenvoldenite ..................................................................................................................................................................................................Kvenvoldenite

Kvenvoldenite / Kvenvoldenite / Kvenvoldenite (Methanhydrat) / 水合物（kvenvoldenite） / Гидрат метана / Kvenvoldenite (Idrato di metano) /

The name given to the hydrate of methane by certain geoscientists, who consider that it has the characteristics of a mineral (natural substance with a defined crystalline structure) containing four molecules of methane and twenty-three of water (Kvenvolden, 1993). Synonym of Gas Hydrate.

Ver: « Methane »
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« Gas Hydrate »
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« Unconventional Gas »

At a time when probably half of proven oil reserves have already been produced, certain journalists and even certain men of science advance methane hydrates as the fuel of the future, since estimates of gas resources in methane hydrates are of the order of 100,000 Tcf. Some optimists even claim: "I think eventually the methane hydrate companies will replace the oil companies" (Sassen, 1998). Such a dream is far from being realized, as several geoscientists say: (i) "To produce hydrates it is necessary first to find a concentrated deposit and then to use thermal energy and energy of de-pressurization or solvents to release the gas" (Laherrere 2000 ) ; (ii) "Many in the industry think methane estimates for methane hydrates, recently, advanced on divergent margins, are extremely exaggerated, and furthermore, as methane hydrate is mostly dispersed and not concentrated, it will be very difficult to recover and very expensive "(Haq, 1998) ; (iii) "It is likely that much of the hydrate occurs at low concentrations without commercial potential" (Mielke, 1999) ; (iv) "Hydrates occur in low concentration and have no commercial value" (testimony of Chevron to the US Senate Commission in 1999) ; (v) "The lack of a geological, geophysical and petrophysical model makes it very difficult to determine the vertical and lateral distribution of hydrate gas deposits as well as the potential volume trapped" (Shell Gas Hydrate Team, 1999) ; (vi) "It is wrong to compare reserves and resources (volume on site), especially, when resources are not the volume of accumulations but rather a dispersion in the sediments" (Laherrere, 2000) ; (vii) "The values determined by Kvenvolden are exaggerated, since hydrates are discontinuous both horizontally and vertically" (Ginsburg, 1998). In other words, it is certainly not in the near future that oil companies will be replaced by methane hydrate companies.

Kerogen.............................................................................................................................................................................................................................................Kérogène

Cerogénio / Kerógeno / Kerogen / 油母質 / Кероген / Cherogene /

Fraction of sedimentary organic matter, which is insoluble in common organic solvents due to the large molecular weight of its constituents (the soluble fraction corresponds to bitumens). Kerogen is not an organic substance with a well-defined chemical composition, since it includes organic matter derived from continental areas and marine environments. Certain types of kerogens, when heated to certain temperatures, in the Earth's crust, produce oil and other gas.

See: « Oil Wondow »
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« Petroleum »
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« Source-Rock »

Taking into account the rates of hydrogen-carbon and oxygen/carbon, three main types of kerogen may be considered. (A) Type I ; (B) Type II and (C) Type III. Type I is characterized as follows: (i) Contains alginite (marine microfossils), amorphous organic matter, cyanobacteria, freshwater algae and resin from terrestrial plants ; (ii) The H:C ratio is greater than 1.25 ; (iii) The O:C ratio is less than 0.15 ; (iv) Has a strong tendency to produce liquid hydrocarbons ; (v) It mainly derives from lake algae and is formed only in anoxic lakes and rare marine environments ; (vi) It has several cycles or aromatic structures ; (vii) Formed mainly by protein and lipids. Type II, is characterized by the following elements: (a) The H:C ratio is less than 1.25 ; (b) The O:C ratio is between 0.03 and 0.18; (c) Tendency to produce a mixture of oil and gas ; (d) Can be formed by exinite (formed of crusts of pollen and spores), cutinite (formed from cuticle of terrestrial plants), resinite (formed from resins of terrestrial plants), liptinite ; (e) All these varieties have a strong tendency to produce oil and are all formed by lipids deposited under reducing conditions. Type III, is characterized by : (1) The H:C ratio is less than 1 ; (2) The O: C ratio is between 0.003 and 0.3 ; (3) Thick material similar to wood or charcoal ; (4) It tends to produce coal or gas ; (5) It has little hydrogen due to the importance of ring aromatic systems. Type III kerogen is formed from terrestrial vegetable matter, which is deficient in lipids or waxy matter. It is formed from cellulose, carbohydrate polymers (which form the rigid structure of terrestrial plants), lignin, a non-carbohydrate polymer formed of phenylpropane (which involves the cellulose fibres), terpenes* and phenolic components ** of many plants.

(*) Terpenes and isoprenoids are a vast and diverse class of organic compounds derived from isoprene (CH₂=C(CH₃)-CH=CH₂), a hydrocarbon of 5 carbon atoms.

(**) Organic compounds in which molecular structures contain at least one phenol group, an aromatic ring attached to at least one hydroxyl group.

Kettle...........................................................................................................................................................................................................................Marmite glaciaire

Marmita Glaciária / Marmita litoral / Gletscherhöhlen, Kessel / 冰川水壶 / Ледниковый котёл / Caldaia Glacial /

Depression created by the melting of an ice block (dead ice) buried in a superficial moraine.

See: « Erosion »
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« Littoral Pothole »
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« Pebble »

Kettles are typical topographic forms (landforms) of the out-wash plain, which form when ice blocks from the front of a glacier separate as the glacier thins. Once the ice blocks are isolated from the main ice mass, they become "dead ice" and are, partially or totally, buried by the glacial runoff. Glacier flow forms when the currents resulting from the glacier melt flow and deposit the sediments in the fluvio-glacial (out-wash) accumulation plain. When the dead ice blocks melt, the slower the more they are fossilized under the moraine, they leave a, more or less, circular cavity that is, often, occupied by a lake, which opens on the accumulation surface, as illustrated in this figure. kettles may also form in till sedimentary ridges (un-worked and non-stratified sediments deposited directly by or under a glacier and not reactivated by glacier melt-water) when the dead ice melts. The formation of a large number of glaciers in the out-wash plain accumulation creates a very typical topography characterized by the alternation of mounds and depressions. The melting of the dead ice overlies the ground moraine, rich in fine material, the superficial moraine (called ablation moraine) that is poor in fine material. Topographies created by a glacial and fluvio-glacial system are, rapidly, obliterated during the inter-glacial and post-glacial periods. Saalians forms (from the Saale glaciation in northern Europe) are very worn out, particularly, in northern Germany (contemporary of the Wolstonian phase and the Riss glaciation in the Alps*). In fact, they were subjected to the degradations imposed by the peri-glacial system (environments and processes that develop in cold non-glacial climates, regardless of age and proximity to glaciers). Fluvial erosion works to destroy them, in particular, by filling the depressions and digging deep valleys (linking gorges between two sections of the same valley, between a suspended valley and the main valley, etc.). If the Wurmian forms are still very visible, it is because they are more recent (maximum of the Wurm glacier extension occurred at about 18 ka).

(*) From study of the Quaternary moraines and fluvial terraces, several glacial periods have been highlighted particularly for the Alps (four main phases: Günz, Midel, Riss and Würm). The name of these phases were taken from the four tributaries of the right bank of the Danube River. Certain geoscientists consider two older phases (Donau and Biber) that were called from the river Donau and from a water-course that flows into Lake Constance (or Bondensee).

Key Bed (Marker bed)........................................................................................................................................................................................Couche repère

Camada de referência / Estrato de referencia / Marker-Bett, Marker - Schicht / 关键的床 / Опорный горизонт / Strato guida /

Bed or a group of geological beds that can be traced over large distances on the ground, electrical diagrams, and sometimes on seismic lines (when thickness is important and the seismic resolution good). A reference layer can have a significant chronostratigraphic value.

See: " Stratum "
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" Correlation "
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" Systems Tract ”

In the electrical logs of a North Sea (cratonic basin) oil exploration well, several levels (not layers, since the seismic resolution is about 20-30 meters) can, sometimes, be recognized. In this particular example, from top to bottom, one can identify: (i) A maximum flood surface (MFS) ; (ii) The first transgressive surface (1^st TS) of a transgressive interval (TI) ; (iii) An erosional surface that emphasizes the unconformity limiting two stratigraphic cycles called sequence-cycles (stratigraphic cycles deposited during 3^rd order eustatic cycles, whose time-duration varies between 0.5 and 3/5 My) ; (iv) The downlap surface (DS) of the highstand prograding wedge (HPW) of the lower sequence-cyle, which corresponds, roughly, to the maximum flooding surface (MFS) of the transgressive interval of the same sequence-cycle. The last two horizons, i.e., (i) The maximum flooding surface (MFS) separating the transgressive interval (TI) from the highstand prograding wedge (HPW) and the (ii) Lower sequence-cycle boundary (unconformity, which underlines a significant relative sea level fall, which has created the erosional surface, which, in this case, is characterized by the formation of an incised valley), are particularly interesting to establish correlations between different wells. The incised valley was, later, filled during the deposition of the upper part of the highstand prograding wedge (HPW). Between the maximum flooding surface (top of the transgressive interval of the lower sequence-cycle), which may also be a good key horizon, and the unconformity (erosional surface), which separates the two sequence-cycles, the morphology of the Gamma ray log (RG) suggest a coarsening and thickening upwards sedimentary interval, which corroborates the progradational geometry of the highstand prograding wedge (HPW) visible on the seismic lines of this area. The first flooding surface (base of the transgressive interval) may, in certain cases, be taken as a key marker. Within a sequence-cycle, in combination with the maximum flooding surface, which is a diachronic surface, is, often, deposited in the distal part of the shelf a condensed stratigraphic section (CS), which is almost always capped with a hardened surface. This condensed section, which is fossilized by the downlap surface of the highstand prograding wedge (HPW), is very rich in organic matter and underlines a peak of fauna*. Their fossils are used to date the geological events that occurred during the deposition of the sequence-cycle. However, as suggested by the electrical logs, in any case, the fauna associated with condensed stratigraphic section (top of the transgressive interval, colored green) allows to date the age of the unconformity, which in this case is stressed by a incised valley fill. The age of the unconformity, i.e., the age of the erosional surface or its correlative in deep water paraconformity, is the age of fall of relative sea level (local sea level, referenced to any point on the Earth's surface, which may be the sea floor or the base of the sediments, that is to say, the top of the continental crust), which is given by the smallest hiatus between the sequence-cycles that it delimits. In seismic data, most of these horizons can be considered chronostratigraphic, although in reality in the field (1:1 natural scale) they are not. However, taking into account the seismic resolution and the vastness of geological time, the error is, usually, not very large and has no major consequences. The spontaneous potential log (SP), which measures the potential difference between an electrode moving in a well and a fixed electrode on the surface, allows the identification of permeable intervals. The resistivity log (normal, lateral, lateralog) measure the resistivity of the sedimentary intervals, i.e., the resistance they oppose to the flow of electrons. When a sediment interval contains gas, oil and/or water mixed in the pores, the resistivity of that rock will increase considerably.

(*) This is, of course, used by amateur fossil hunters who empirically look for discontinuities between sloping clay sediments and subhorizontal underlying sediments, which in terms of sequential stratigraphy usually means at the level of a cycle-sequence, the interface defined between the highstand prograding wedge with the retrogradational maximum flooding surface.

(**) Practically, the relative age of an unconformity is given by the age of the pelagic shales deposited between the turbiditic layers of the submarine basin floor fans (SBFF) overlying the unconformity.

Kirchhoff (Migration)................................................................................................................................................................................Migration (Kirchhoff)

Migração (Kirchhoff) / Migración (Kirchhoff) / Kirchhoff Migration / 克希霍夫偏移 / Миграция Кирхгофа / Migrazione (Kirchhoff) /

Method used in petroleum exploration in depth image and velocity analysis. In the migration of an event, in a single trace, a band of the Kirchhoff migration spreads the energy of a source in all points of the subsoil. After covering all samples in all traces, a migration image is obtained by stacking all individual contributions.

See: « Seismic Line »
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« Migrated Line (seismic) »
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« Snell's Law »

Given a source and a geophone on the free surface, and a reflector inclined on a homogeneous acoustic medium, there will be only a primary reflection recorded in the seismic trace (left sketch). For convenience, multiples and direct waves will be ignored. The time of arrival of this event is equal to the transit time of energy to propagate from the source to the point "p" and point "p" to the geophone. The dashed line in the left schematic shows the radius associated with this trajectory. In this model, the reflectivity at point p is coiled with the source pulse, which produces a different wave of the observed pulse. Mathematically, the model is described by d = Lm, where "d" is the seismic data model, "L" is a linear operator model and m is the reflectivity model. The inverse process of direct seismic modelling is the seismic migration that projects the observed energy relative to its subsurface reflector. The migrated image is given by m = LTd. To implement the migration, you need to know the average speed. Applying the velocity analysis (technique to extract velocity information from the data), we can obtain a reasonable estimate of velocity distribution. Migration methods can not be performed without knowledge of the velocity distribution of the medium. The first step in the Kirchhoff (MK) migration is to calculate the traffic fields for the origin and for the geophone. Generally, the ray tracing method is used to generate a coarse traffic field to then obtain a much finer transit field by interpolation. It is also possible to calculate the traffic fields by solving the eikonal equation (non-linear partial differential equation found in wave propagation problems when the wave equation is approximated using the WKB theory), which is derivable from the Maxwell equations of electromagnetism, and provides a relationship between optical physics-wave and geometric-optical-rays.