Kazakhstania ( Kazakh : Qazaqstaniya ), the Kazakh terranes , or the Kazakhstan Block , is a geological region in Central Asia which consists of the area roughly centered on Lake Balkhash , north and east of the Aral Sea , south of the Siberian craton and west of the Altai Mountains . The Junggar basin in Xinjiang , China , is also part of Kazakhstania, though sometimes referred to as the Junggar Block . Because the Kazakh terranes merged during the Late Ordovician as part of the Central Asian Orogenic Belt they are also referred to as the Kazakh Orogen . These terranes are located in what is today Kazakhstan , north-eastern Uzbekistan , northern Kyrgyzstan and south-western China . Today Kazakhstania is surrounded by three large, former continents: to the north-east the Gornostaev Shear Zone separates it from Siberia with which it collided during the Carboniferous ; to the north-west is Baltica which lay adjacent to the Kazakh Tourgai terrane but far away from Kazakhstania; to the south and east was Gondwana stretching from the South Pole to the Equator. Not far away from the dispersed Kazakh terranes were South China , North China , and Tarim , but how these continental blocks were positioned relative to Gondwana is not known.
43-683: In the Early Palaeozoic the Kazakh terranes were widely distributed north or northeast of the Mangyshlak , Karakum , Karakorum and Tarim terranes. The location, origin, and faunal affinities of these terranes has, however, been the subject of two competing hypotheses: one described these terranes as an enormous island arc called the Kipchak arc, the other as a series of more or less parallel belts. Faunal analyses indicate that some of
86-500: A fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth 's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults . Energy release associated with rapid movement on active faults
129-422: A terrane ( / t ə ˈ r eɪ n , ˈ t ɛr eɪ n / ; in full, a tectonostratigraphic terrane ) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured " to crust lying on another plate. The crustal block or fragment preserves its distinctive geologic history, which is different from the surrounding areas—hence the term "exotic" terrane. The suture zone between
172-405: A fault as oblique requires both dip and strike components to be measurable and significant. Some oblique faults occur within transtensional and transpressional regimes, and others occur where the direction of extension or shortening changes during the deformation but the earlier formed faults remain active. The hade angle is defined as the complement of the dip angle; it is the angle between
215-582: A fault hosting valuable porphyry copper deposits is northern Chile's Domeyko Fault with deposits at Chuquicamata , Collahuasi , El Abra , El Salvador , La Escondida and Potrerillos . Further south in Chile Los Bronces and El Teniente porphyry copper deposit lie each at the intersection of two fault systems. Faults may not always act as conduits to surface. It has been proposed that deep-seated "misoriented" faults may instead be zones where magmas forming porphyry copper stagnate achieving
258-489: A fault plane, where it becomes locked, are called asperities . Stress builds up when a fault is locked, and when it reaches a level that exceeds the strength threshold, the fault ruptures and the accumulated strain energy is released in part as seismic waves , forming an earthquake . Strain occurs accumulatively or instantaneously, depending on the liquid state of the rock; the ductile lower crust and mantle accumulate deformation gradually via shearing , whereas
301-408: A fault's age by studying soil features seen in shallow excavations and geomorphology seen in aerial photographs. Subsurface clues include shears and their relationships to carbonate nodules , eroded clay, and iron oxide mineralization, in the case of older soil, and lack of such signs in the case of younger soil. Radiocarbon dating of organic material buried next to or over a fault shear
344-427: A hanging wall or foot wall where a thrust fault formed along a relatively weak bedding plane is known as a flat and a section where the thrust fault cut upward through the stratigraphic sequence is known as a ramp . Typically, thrust faults move within formations by forming flats and climbing up sections with ramps. This results in the hanging wall flat (or a portion thereof) lying atop the foot wall ramp as shown in
387-484: A major fault. Synthetic faults dip in the same direction as the major fault while the antithetic faults dip in the opposite direction. These faults may be accompanied by rollover anticlines (e.g. the Niger Delta Structural Style). All faults have a measurable thickness, made up of deformed rock characteristic of the level in the crust where the faulting happened, of the rock types affected by
430-400: A manner that creates multiple listric faults. The fault panes of listric faults can further flatten and evolve into a horizontal or near-horizontal plane, where slip progresses horizontally along a decollement . Extensional decollements can grow to great dimensions and form detachment faults , which are low-angle normal faults with regional tectonic significance. Due to the curvature of
473-421: A non-vertical fault are known as the hanging wall and footwall . The hanging wall occurs above the fault plane and the footwall occurs below it. This terminology comes from mining: when working a tabular ore body, the miner stood with the footwall under his feet and with the hanging wall above him. These terms are important for distinguishing different dip-slip fault types: reverse faults and normal faults. In
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#1732780910733516-481: A part subducted under another plate, the terrane failed to subduct, detached from its transporting plate, and accreted onto the overriding plate. Therefore, the terrane transferred from one plate to the other. Typically, accreting terranes are portions of continental crust which have rifted off another continental mass and been transported surrounded by oceanic crust, or they are old island arcs formed at some distant subduction zones. A tectonostratigraphic terrane
559-399: A preponderance of a particular rock or rock group. A tectonostratigraphic terrane did not necessarily originate as an independent microplate , since it may not contain the full thickness of the lithosphere . It is a piece of crust that has been transported laterally, usually as part of a larger plate, and is relatively buoyant due to thickness or low density. When the plate of which it was
602-464: A reverse fault, the hanging wall displaces upward, while in a normal fault the hanging wall displaces downward. Distinguishing between these two fault types is important for determining the stress regime of the fault movement. Faults are mainly classified in terms of the angle that the fault plane makes with the Earth's surface, known as the dip , and the direction of slip along the fault plane. Based on
645-444: A terrane and the crust it attaches to is usually identifiable as a fault . A sedimentary deposit that buries the contact of the terrane with adjacent rock is called an overlap formation . An igneous intrusion that has intruded and obscured the contact of a terrane with adjacent rock is called a stitching pluton . There is also an older usage of the term terrane , which described a series of related rock formations or an area with
688-422: Is a horst . A sequence of grabens and horsts on the surface of the Earth produces a characteristic basin and range topography . Normal faults can evolve into listric faults, with their plane dip being steeper near the surface, then shallower with increased depth, with the fault plane curving into the Earth. They can also form where the hanging wall is absent (such as on a cliff), where the footwall may slump in
731-436: Is a fault-bounded package of rocks of at least regional extent characterized by a geologic history that differs from that of neighboring terranes. The essential characteristic of these terranes is that the present spatial relations are incompatible with the inferred geologic histories. Where terranes that lie next to each other possess strata of the same age, they are considered separate terranes only if it can be demonstrated that
774-423: Is a zone of folding close to a fault that likely arises from frictional resistance to movement on the fault. The direction and magnitude of heave and throw can be measured only by finding common intersection points on either side of the fault (called a piercing point ). In practice, it is usually only possible to find the slip direction of faults, and an approximation of the heave and throw vector. The two sides of
817-492: Is arid and practically no water flows from the region to the oceans, there is extensive grazing of cattle , sheep and camels on the grasslands which cover most of the region today. Kazakhstania was too dry for extensive glaciation during the Quaternary . Kazakhstania contains as much as a quarter of the world's proven uranium reserves and is also one of the world's major source of lead , zinc , and antimony ores. On
860-544: Is defined by the direction of movement of the ground as would be seen by an observer on the opposite side of the fault. A special class of strike-slip fault is the transform fault when it forms a plate boundary. This class is related to an offset in a spreading center , such as a mid-ocean ridge , or, less common, within continental lithosphere , such as the Dead Sea Transform in the Middle East or
903-543: Is often critical in distinguishing active from inactive faults. From such relationships, paleoseismologists can estimate the sizes of past earthquakes over the past several hundred years, and develop rough projections of future fault activity. Many ore deposits lie on or are associated with faults. This is because the fractured rock associated with fault zones allow for magma ascent or the circulation of mineral-bearing fluids. Intersections of near-vertical faults are often locations of significant ore deposits. An example of
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#1732780910733946-492: Is particularly clear in the case of detachment faults and major thrust faults . The main types of fault rock include: In geotechnical engineering , a fault often forms a discontinuity that may have a large influence on the mechanical behavior (strength, deformation, etc.) of soil and rock masses in, for example, tunnel , foundation , or slope construction. The level of a fault's activity can be critical for (1) locating buildings, tanks, and pipelines and (2) assessing
989-425: Is the cause of most earthquakes . Faults may also displace slowly, by aseismic creep . A fault plane is the plane that represents the fracture surface of a fault. A fault trace or fault line is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A fault zone is a cluster of parallel faults. However,
1032-762: The Alpine Fault in New Zealand. Transform faults are also referred to as "conservative" plate boundaries since the lithosphere is neither created nor destroyed. Dip-slip faults can be either normal (" extensional ") or reverse . The terminology of "normal" and "reverse" comes from coal mining in England, where normal faults are the most common. With the passage of time, a regional reversal between tensional and compressional stresses (or vice-versa) might occur, and faults may be reactivated with their relative block movement inverted in opposite directions to
1075-925: The orogenic belt where they had eventually ended up. It followed that the present orogenic belt was itself an accretionary collage, composed of numerous terranes derived from around the circum- Pacific region and now sutured together along major faults. These concepts were soon applied to other, older orogenic belts, e.g. the Appalachian belt of North America.... Support for the new hypothesis came not only from structural and lithological studies, but also from studies of faunal biodiversity and palaeomagnetism . When terranes are composed of repeated accretionary events, and hence are composed of subunits with distinct history and structure, they may be called superterranes . Africa Asia Taiwan Tibet Australasia Europe Fennoscandia North America South America Fault (geology) In geology ,
1118-657: The seismic shaking and tsunami hazard to infrastructure and people in the vicinity. In California, for example, new building construction has been prohibited directly on or near faults that have moved within the Holocene Epoch (the last 11,700 years) of the Earth's geological history. Also, faults that have shown movement during the Holocene plus Pleistocene Epochs (the last 2.6 million years) may receive consideration, especially for critical structures such as power plants, dams, hospitals, and schools. Geologists assess
1161-581: The Equator. Key units in this assemblage were the Boshchekul (in north Kazakhstan), Chingiz-Tarbagatai (east Kazakhstan), and Chu-Ilu (south Kazakhstan) terranes. The Atashu-Zhamshi microcontinent was located in the southwestern margin of the archipelago. A few terranes probably merged as early as the Middle Ordovician but Kazakhstania is very unlikely to have formed a single continent before
1204-413: The ability of crustal fragments to "drift" thousands of miles from their origin and attach themselves, crumpled, to an exotic shore. Such terranes were dubbed " accreted terranes " by geologists . Geologist J. N. Carney writes: It was soon determined that these exotic crustal slices had in fact originated as "suspect terranes" in regions at some considerable remove, frequently thousands of kilometers, from
1247-403: The brittle upper crust reacts by fracture – instantaneous stress release – resulting in motion along the fault. A fault in ductile rocks can also release instantaneously when the strain rate is too great. Slip is defined as the relative movement of geological features present on either side of a fault plane. A fault's sense of slip is defined as the relative motion of the rock on each side of
1290-436: The direction of slip, faults can be categorized as: In a strike-slip fault (also known as a wrench fault , tear fault or transcurrent fault ), the fault surface (plane) is usually near vertical, and the footwall moves laterally either left or right with very little vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults and those with right-lateral motion as dextral faults. Each
1333-668: The end of the period. During the Carboniferous and Permian , Siberia collided with Kazakhstania to form the Altai Mountains , later Baltica collided in the Ural orogeny , creating the basis for most of present-day Eurasia . Kazakhstania is mainly flat: only in the east near Karaganda are there mountains, and these only rise to 1,565 metres (5,130 feet) in the Tarbagatay Range . Although most of Kazakhstania
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1376-456: The fault and of the presence and nature of any mineralising fluids . Fault rocks are classified by their textures and the implied mechanism of deformation. A fault that passes through different levels of the lithosphere will have many different types of fault rock developed along its surface. Continued dip-slip displacement tends to juxtapose fault rocks characteristic of different crustal levels, with varying degrees of overprinting. This effect
1419-402: The fault concerning the other side. In measuring the horizontal or vertical separation, the throw of the fault is the vertical component of the separation and the heave of the fault is the horizontal component, as in "Throw up and heave out". The vector of slip can be qualitatively assessed by studying any drag folding of strata, which may be visible on either side of the fault. Drag folding
1462-576: The fault plane and a vertical plane that strikes parallel to the fault. Ring faults , also known as caldera faults , are faults that occur within collapsed volcanic calderas and the sites of bolide strikes, such as the Chesapeake Bay impact crater . Ring faults are the result of a series of overlapping normal faults, forming a circular outline. Fractures created by ring faults may be filled by ring dikes . Synthetic and antithetic are terms used to describe minor faults associated with
1505-401: The fault plane, the horizontal extensional displacement on a listric fault implies a geometric "gap" between the hanging and footwalls of the fault forms when the slip motion occurs. To accommodate into the geometric gap, and depending on its rheology , the hanging wall might fold and slide downwards into the gap and produce rollover folding , or break into further faults and blocks which fil in
1548-427: The fault-bend fold diagram. Thrust faults form nappes and klippen in the large thrust belts. Subduction zones are a special class of thrusts that form the largest faults on Earth and give rise to the largest earthquakes. A fault which has a component of dip-slip and a component of strike-slip is termed an oblique-slip fault . Nearly all faults have some component of both dip-slip and strike-slip; hence, defining
1591-475: The gap. If faults form, imbrication fans or domino faulting may form. A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate compressive shortening of the crust. A thrust fault has the same sense of motion as a reverse fault, but with the dip of the fault plane at less than 45°. Thrust faults typically form ramps, flats and fault-bend (hanging wall and footwall) folds. A section of
1634-428: The geologic evolutions are different and incompatible. There must be an absence of intermediate lithofacies that could link the strata. The concept of tectonostratigraphic terrane developed from studies in the 1970s of the complicated Pacific Cordilleran orogenic margin of North America , a complex and diverse geological potpourri that was difficult to explain until the new science of plate tectonics illuminated
1677-500: The original movement (fault inversion). In such a way, a normal fault may therefore become a reverse fault and vice versa. In a normal fault, the hanging wall moves downward, relative to the footwall. The dip of most normal faults is at least 60 degrees but some normal faults dip at less than 45 degrees. A downthrown block between two normal faults dipping towards each other is a graben . A block stranded between two grabens, and therefore two normal faults dipping away from each other,
1720-412: The right time for—and type of— igneous differentiation . At a given time differentiated magmas would burst violently out of the fault-traps and head to shallower places in the crust where porphyry copper deposits would be formed. As faults are zones of weakness, they facilitate the interaction of water with the surrounding rock and enhance chemical weathering . The enhanced chemical weathering increases
1763-543: The southern boundary in the Turan Depression are large deposits of natural gas . [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania Terrane In geology ,
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1806-468: The term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the distinction, as the rock between the faults is converted to fault-bound lenses of rock and then progressively crushed. Due to friction and the rigidity of the constituent rocks, the two sides of a fault cannot always glide or flow past each other easily, and so occasionally all movement stops. The regions of higher friction along
1849-693: The terranes probably originated in Gondwana rather than Baltica or Siberia. A 2006 analysis of brachiopods indicated that the Chu-Ili Mountains must have formed an independent, Peri-Gondwanan terrane in the Late Ordovician located not far from the North and South China cratons . More recent studies suggest that in the Late Ordovician the Kazakh terranes formed an archipelago composed of clusters of island arcs and microcontinents centered on
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