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64-593: The mountain is covered by an ice cap , and Polylepis tarapacana trees occur up to 5,000 metres (16,000 ft) elevation. Nevado Sajama is located in the Sajama Province of the Oruro Department in Bolivia, about 18.6 kilometres (11.6 mi) from the border with Chile . Cholcani volcano lies southeast of Sajama, and another neighbouring volcano, Pomerape , resembles Sajama in its appearance. A road runs along

128-405: 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 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

192-598: A massif . Ice flows away from this high point (the ice divide ) towards the ice cap's periphery. Ice caps significantly affect the geomorphology of the area they occupy. Plastic moulding, gouging and other glacial erosional features become present upon the glacier's retreat. Many lakes, such as the Great Lakes in North America, as well as numerous valleys have been formed by glacial action over hundreds of thousands of years. The Antarctic and Greenland contain 99% of

256-829: 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 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

320-449: A potassium -rich calc-alkaline suite and formed through various processes, including assimilation of country rock , fractional crystallization and magma mixing (particularly in the Sayara lavas). At Cosapa on the foot of Sajama, annual mean temperatures are about 7.3 °C (45.1 °F) while the town of Sajama sees annual temperatures of 4.3 °C (39.7 °F); precipitation there

384-504: A 95 ± 29  mm rise in global sea levels until they reach equilibrium. However, environmental conditions have worsened and are predicted to continue to worsen in the future. Given that the rate of melting will accelerate, and by using mathematical models to predict future climate patterns, the actual contribution of ice caps to rising sea levels is expected to be more than double from initial estimates. High-latitude regions covered in ice, though strictly not an ice cap (since they exceed

448-574: 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

512-500: 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 the brittle upper crust reacts by fracture – instantaneous stress release – resulting in motion along

576-410: 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 the seismic shaking and tsunami hazard to infrastructure and people in

640-408: 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

704-409: 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, 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

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768-541: A football match on top of Mount Sajama in an effort to show that altitude itself is not a limitation to physical strain. In 2015, a challenge to hold a political debate on the summit of Sajama was made by a candidate to an election. The 50- boliviano Bolivian banknote launched in October 2018 shows Sajama on its reverse. Ice cap In glaciology , an ice cap is a mass of ice that covers less than 50,000 km (19,000 sq mi) of land area (usually covering

832-415: A highland area). Larger ice masses covering more than 50,000 km (19,000 sq mi) are termed ice sheets . Ice caps are not constrained by topographical features (i.e., they will lie over the top of mountains). By contrast, ice masses of similar size that are constrained by topographical features are known as ice fields . The dome of an ice cap is usually centred on the highest point of

896-552: Is Biscayarfonna in Svalbard . Hypothetical runaway greenhouse state Tropical temperatures may reach poles Global climate during an ice age Earth's surface entirely or nearly frozen over Fault (geology) In geology , 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

960-603: Is a compound volcano . Two later volcanic units are known as the Colquen Wilqui lavas and the Jacha Khala tuff . The Sajama volcano rises within a caldera that has been buried by later volcanic activity so that it is only recognizable on its eastern-northeastern side. A circular structure around Sajama may be the origin of the 2.7 million years old Lauca-Perez Ignimbrite . Argon-argon dating has yielded ages of 679,000 years ago from Sajama and of 80,900 to 25,000 years ago for

1024-402: Is a stratovolcano located atop several lava domes . The stratovolcano consists of lava flows and pyroclastic material that radiate away from the centre of the volcano. Some parasitic vents occur southeast of Sajama and have produced lava domes and lava flows. The parasitic vents away from the volcano are older and their location appears to be controlled by radial dikes ; the whole complex

1088-516: Is about 327 millimetres per year (12.9 in/year). The daily temperature range approaches 40 °C (72 °F) there. Sajama is located between two climate regimes, a westerly one characterized by a dry climate and the Southeast Pacific High and an easterly one with a moister atmosphere. During the southern hemisphere summer, easterly winds carry moist air towards Sajama where solar insolation then triggers showers and thunderstorms ;

1152-464: Is available. The current woods are remnants; whether the decrease is caused by human impact or climate change is not clear. Protecting these woodlands was the impetus for the 1939 creation of the Sajama National Park . Above 5,600 metres (18,400 ft), Sajama is extensively glaciated . It is among the southernmost mountains in the region with significant glaciers; farther south the atmosphere

1216-669: Is determined by the landscape it lies on, as melting patterns can vary with terrain. For example, the lower portions of an ice cap are forced to flow outwards under the weight of the entire ice cap and will follow the downward slopes of the land. Ice caps have been used as indicators of global warming, as increasing temperatures cause ice caps to melt and lose mass faster than they accumulate mass. Ice cap size can be monitored through different remote-sensing methods such as aircraft and satellite data. Ice caps accumulate snow on their upper surfaces, and ablate snow on their lower surfaces. An ice cap in equilibrium accumulates and ablates snow at

1280-441: Is little correlation. While the vegetation of the surroundings of Sajama is considered to be a dry grassland known as puna , on the mountain itself there is some vertical gradation. Below 4,000 metres (13,000 ft) shrubs such as asteraceae , cactaceae , fabaceae and solanaceae dominate the vegetation. Between 4,000–4,800 metres (13,100–15,700 ft) the last three families become less important. Here especially during

1344-543: 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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1408-452: Is too dry to permit the development of glaciers. Two ice cores were taken from the summit area in 1997, preceded by a religious ceremony, as the local Aymara people feared that the mountain deities would be angered by the drilling otherwise. Rock glaciers also occur above the zero degree isotherm above 4,800 metres (15,700 ft), such as on lateral peaks. Meltwater from the glaciers partially seeps underground and only reappears away from

1472-682: The Altiplano . Nevado Sajama lies in the Western Andes of Bolivia and in the western side of the Altiplano; more specifically the mountain is located before the Western Cordillera . Nevado Sajama rises about 2.2 kilometres (1.4 mi) from the surrounding terrain to a height of 6,542 metres (21,463 ft) (earlier estimates of its height are 6,572 metres (21,562 ft)), making it the highest mountain of Bolivia. Below 4,200 metres (13,800 ft)

1536-456: 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 a major fault. Synthetic faults dip in the same direction as the major fault while the antithetic faults dip in

1600-643: The Andes, where volcanism is triggered by the subduction of the Nazca Plate beneath the South America Plate . Changes in the subduction regime took place during the Oligocene and directed an increase of volcanic activity in the region. Volcanoes in the region have ages ranging from Pleistocene to Miocene and grew on top of earlier ignimbrites ; the whole volcanic activity was controlled by faults . The mountain

1664-693: The Huaythana River, which flows directly south and then makes a sharp turn to the east. The Sajama River originates on the western side of the volcano, flowing due south and increasingly turning southeast before joining the Lauca River . The other rivers draining Sajama and its ice cap also eventually join the Lauca River and end in the Salar de Coipasa . Nevado Sajama is part of the Central Volcanic Zone of

1728-679: The Kkota Kkotani lavas, which are unrelated to the main Sajama volcano. The date of the last eruption is not known, it may have occurred in the Pleistocene or Holocene . Hot springs occur on the Junthuma River and reflect the presence of geothermal heat with temperatures of about 250–230 °C (482–446 °F) on the western foot of Sajama, and volcanic rocks of Sajama bear traces of fumarolic activity. Three major geologic lineaments occur in

1792-403: 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 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

1856-414: 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 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

1920-433: 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 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

1984-409: 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 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,

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2048-532: 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 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

2112-461: 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 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

2176-406: 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 the fault concerning the other side. In measuring the horizontal or vertical separation, the throw of

2240-450: The flat summit plateau of Sajama but other records do not indicate the presence of a crater. The Patokho, Huaqui Jihuata and Phajokhoni valleys are located on the eastern flank; at lower elevations the whole volcano features glacially deepened valleys. The terrain is characterized by a continuous ice cover in the central sector of the mountain, exposures of bedrock , deposits and rock glaciers in some sites, alluvial fans and scree in

2304-428: 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 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

2368-531: 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, 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

2432-429: 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 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

2496-601: The glaciers lead to lava flows and matorral and tolar vegetation, and finally to grassland at lower altitudes. A number of wetlands called bofedales occur on the mountain. Starting in the lake Laguna Huana Kkota on the northwestern foot of Sajama, the Tomarapi River flows first northeastward, then east, south and southeast around the northern and eastern flanks of the volcano; the Sicuyani River, which originates on Sajama, joins it there. The southern flanks give rise to

2560-440: The ice volume on earth, about 33 million cubic kilometres (7.9 million cubic miles) of total ice mass. Ice caps are formed when snow is deposited during the cold season and fails to completely melt during the hot season. Over time, the snow builds up and becomes dense, well-bonded snow known as perennial firn . Finally, the air passages between snow particles close off and transforms into ice. The shape of an ice cap

2624-491: 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 is particularly clear in the case of detachment faults and major thrust faults . The main types of fault rock include: In geotechnical engineering ,

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2688-464: 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 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

2752-433: The latter occur up to 5,221 metres (17,129 ft) elevatn. Nevado Sajama features the highest treeline on Earth at 5,200 metres (17,100 ft) elevation, as Polylepis tarapacana forms woodlands that have both a sharp upper and a sharp lower limit on the mountain. The trees are usually no higher than 5 metres (16 ft) and are separated by large distances from each other and appear to localize to spots where water

2816-458: The long term, the AAR of glaciers has been about 0.57. In contrast, data from the most recent years of 1997–2006 yields an AAR of only 0.44. In other words, glaciers and ice caps are accumulating less snow and are out of equilibrium, causing melting and contributing to sea level rises. Assuming the climate continues to be in the same state as it was in 2006, it is estimated that ice caps will contribute

2880-456: The maximum area specified in the definition above), are called polar ice caps ; the usage of this designation is widespread in the mass media and arguably recognized by experts. Vatnajökull is an example of an ice cap in Iceland . Plateau glaciers are glaciers that overlie a generally flat highland area. Usually, the ice overflows as hanging glaciers in the lower parts of the edges. An example

2944-408: 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 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

3008-485: The moisture ultimately originates in the Atlantic Ocean . During winter, dry westerly winds prevail although cold air outbreaks from the westerlies belt sometimes trigger intense snowfall which is often underestimated by precipitation data. Overall, on the Altiplano precipitation diminishes from the northeast to the southwest. Summer precipitation is typically reduced during El Nino years, but on Nevado Sajama there

3072-435: 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 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

3136-433: The mountain is characterized by parasitic vents and a cover of lava fragments and volcanic ash . Two secondary summits 5,031 metres (16,506 ft) and 5,161 metres (16,932 ft) occur west and east-northeast from Sajama respectively; the former is named Cerro Huisalla and the second is Huayna Potosi. The mountain has a conical shape and is capped by a summit crater that, owing to its ice fill, appears to be linked to

3200-482: 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 the fault and of the presence and nature of any mineralising fluids . Fault rocks are classified by their textures and

3264-463: The periphery of Sajama and moraines forming a girdle around the upper sector of Sajama. The ground moraines are the most prominent moraines on Sajama, and have varying colours depending on the source of their component rocks. Vegetation and small lakes occur in their proximity, while other parts are unvegetated. They mostly occur within glacial valleys, but some appear to have formed underneath small plateau ice caps on flatter terrain. At lower elevations

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3328-680: The region, the north-northwesterly trending Sajama lineament, a west-southwesterly one aligned with high topographical features and a west-northwesterly one. The west-southwesterly one played an important role in the development of Sajama volcano. The volcano has erupted rocks ranging from andesite to rhyodacite , with the main stratovolcano formed by andesites that contain hornblende and pyroxene and phenocrysts of augite , biotite , iron oxide , olivine , orthopyroxene , pargasite , plagioclase , quartz and titanium oxide . Deposits of copper , gold , lead , silver and sulfur were reported as well. The volcanic rocks erupted by Sajama define

3392-667: The regional communities, and a number of oral traditions record beliefs involving Sajama. In one myth, Sajama is the head of the Mururata mountain after the latter was decapitated by Illimani mountain, both in the Eastern Cordillera . Other mythologies assert that the Nevados de Payachata ( Pomerape and Parinacota ) are the children of Sajama and Anallaxchi. In another local belief, Tacora and Sajama were two mountains in competition for two women (the Nevados de Payachata ). Depending on

3456-412: 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

3520-411: 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 a fault plane, where it becomes locked, are called asperities . Stress builds up when

3584-423: The same rate. The AAR is the ratio between the accumulation area and the total area of the ice cap, which is used to indicate the health of the glacier. Depending on their shape and mass, healthy glaciers in equilibrium typically have an AAR of approximately 0.4 to 0.8. The AAR is impacted by environmental conditions such as temperature and precipitation. Data from 86 mountain glaciers and ice caps shows that over

3648-451: The southeastern flank of the volcano, with additional roads completing a circle around Sajama. The village of Sajama lies on its western foot, with the village of Caripe to the northeast of the mountain and Lagunas to the southwest, and there are a number of farms. In Bolivia, the Andes mountain chain splits into two branches separated by a 3,500–4,000 metres (11,500–13,100 ft) high plateau,

3712-453: The specific myth either the two women drove Tacora off and removed the top of the mountain, or Sajama did and injured Tacora; Tacora subsequently fled, shedding blood and a piece of its heart. There are a number of archaeological sites on the mountain, including chullpa burials and pukara fortifications, distributed over various altitudes and connected through paths. About 40 such sites have been found, most of them at low elevations on

3776-416: 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 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

3840-400: 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 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

3904-570: 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

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3968-479: The volcano. Sajama and neighbouring mountains featured much larger glaciers in the past. The history of glaciation on Sajama in general is poorly known, but it appears that the outermost glacial features originated during the late last glacial maximum and the intermediary features during the Middle Holocene which is usually considered to be a warm and dry period in the region. Sajama is a sacred mountain for

4032-423: The western and northern foot of Sajama. Some of these sites have yielded ceramics . The archaeological sites demonstrate a direct link between the mountain and their builders and with the resolution of local conflicts. During the second undisputed ascent on the mountain in 1946, one mountaineer disappeared and his body was never found. In August 2001, two teams of Sajama villagers and Bolivian mountain guides played

4096-478: The wet season poaceae grasses become more important; finally above 4,800 metres (15,700 ft) frost-tolerant herbs such as Azorella and asteraceae , caryophyllaceae , malvaceae and poaceae make up most of the vegetation. In depressions or places where water occurs, peat bogs called bofedales develop. Taxa that occur here include apiaceae , cyperaceae , Azolla , Distichia and Plantago . Animals include birds, vicuñas , vizcachas and mice;

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