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60-725: The East Anatolian Fault runs in a northeasterly direction, starting from the Maraş triple junction at the northern end of the Dead Sea Transform , and ending at the Karlıova triple junction where it meets the North Anatolian Fault . Another 350 km (220 mi) strand of the fault exists north of the main strand known as the Sürgü–Misis Fault System . In 1963, geologists published descriptions about

120-507: A M s   7.2 earthquake ruptured a segment of the fault that meets the Karlıova triple junction . Since 1998, there has been a series of earthquakes on or near the East Anatolian Fault. These started with the 1998 Adana–Ceyhan earthquake and include the 2003 Bingöl earthquake , the 2010 Elâzığ earthquake , the 2020 Elâzığ earthquake and the 2023 Turkey–Syria earthquakes . The 2003 earthquake did not rupture along

180-491: A Nb depletion. These chemical signatures support the ophiolites having formed in a back-arc basin of a subduction zone. Ophiolite generation and subduction may also be explained, as suggested from evidence from the Coast Range ophiolite of California and Baja California, by a change in subduction location and polarity. Oceanic crust attached to a continental margin subducts beneath an island arc. Pre-ophiolitic ocean crust

240-782: A continuation of the Dead Sea Fault, or a transition fault between the East Anatolian and Dead Sea Transform faults. Its southernmost trace ends at the Amik Basin where it meets the Hacıpaşa Fault (part of the Dead Sea Transform) and Cyprus Arc Fault at a triple junction. The M w   7.2 earthquake of 1872 likely ruptured the southern portion of the Amanos segment. The Amanos segment also ruptured during

300-483: A fault structure near Karlıova where the North Anatolian Fault terminates. In their findings, based on geomorphology , they described a fault extending over 70 km (43 mi) southwest from Karlıova to Bingöl . The fault to its southwest was not described. Geologist Clarence Allen explained in his 1969 journal, regarding the abrupt termination of the North Anatolian Fault east of Karlıova, that

360-460: A left-lateral slip sense. Significant attention to this structure arose following an earthquake in Bingöl on 22 May 1971. Ground cracks associated with the earthquake exhibited a dominant left-lateral component that aligned with the trend of valleys associated with the fault. This discovery supported the theory of a mainly left-lateral mechanism for the East Anatolian Fault. This mechanism and trend

420-415: A low occurrence of silica-rich minerals; those present have a high sodium and low potassium content. The temperature gradients of the metamorphosis of ophiolitic pillow lavas and dykes are similar to those found beneath ocean ridges today. Evidence from the metal-ore deposits present in and near ophiolites and from oxygen and hydrogen isotopes suggests that the passage of seawater through hot basalt in

480-946: A passive continental margin. They include the Coast Range ophiolite of California, the Josephine ophiolite of the Klamath Mountains (California, Oregon), and ophiolites in the southern Andes of South America. Despite their differences in mode of emplacement, both types of ophiolite are exclusively supra-subduction zone (SSZ) in origin. Based on mode of occurrences, the Neoproterozoic ophiolites appear to show characteristics of both mid-oceanic ridge basalt (MORB)-type and SSZ-type ophiolites and are classified from oldest to youngest into: (1) MORB intact ophiolites (MIO); (2) dismembered ophiolites (DO); and (3) arc-associated ophiolites (AAO) (El Bahariya, 2018). Collectively,

540-458: A range of trace elements as well (that is, chemical elements occurring in amounts of 1000  ppm or less). In particular, trace elements associated with subduction zone (island arc) volcanics tend to be high in ophiolites, whereas trace elements that are high in ocean ridge basalts but low in subduction zone volcanics are also low in ophiolites. Additionally, the crystallization order of feldspar and pyroxene (clino- and orthopyroxene) in

600-399: A recent large earthquake. No surface rupturing occurred when the segment produced a M s   5.8 earthquake in 1986 . The Çardak segment between Nurhak and Göksun is 85 km (53 mi) in length and separated into two sections by a right stepover . Prior to 2023, the only known historical earthquake on this fault occurred in 1544, estimated at M uk   6.8. Nine hours after

660-494: A restraining bend at Göksun. It can be traced southwest to Sumbas . At Çiğşar , the fault is divided into two via a right stepover. The 20 km (12 mi) northern half is characterized by scarps ranging in height of 0.5–5 m (1 ft 8 in – 16 ft 5 in). Gullies were observed to be displaced by 5 m (16 ft). The southern half measures 41 km (25 mi) long and exhibits Holocene fault scarps along some portions. A left stepover separates

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720-532: A seismic study on an ophiolite complex ( Bay of Islands, Newfoundland ) in order to establish a comparison. The study concluded that oceanic and ophiolitic velocity structures were identical, pointing to the origin of ophiolite complexes as oceanic crust. The observations that follow support this conclusion. Rocks originating on the seafloor show chemical composition comparable to unaltered ophiolite layers, from primary composition elements such as silicon and titanium to trace elements. Seafloor and ophiolitic rocks share

780-750: A series of normal faults trending northwest and east of the Toprakkale segment. This segment represents the western border of the Amanos Mountains . The total vertical offset at Erzin is 80–90 m (260–300 ft). The Yakapınar segment runs from the mountainous area in the north to south in the Ceyhan plain. This northeast-striking left-lateral fault was the source of the 1998 Adana–Ceyhan earthquake (M w   6.2). Two other earthquakes in 1945 (M w   6.0) and 1266 (M w   6.3) occurred on this fault. This segment runs parallel to

840-420: A southwest-striking fault also terminated within the same area . He identified fault-related features such as linear valleys, sag ponds and scarps from Palu to Lake Hazar ; fault scarps of Quaternary age were discovered along Lake Hazar's shores. He calculated that this fault structure would intersect the left-lateral Dead Sea Transform if it continued along its southwest trend, and suspected it also had

900-686: A subduction zone, and contact with air. A hypothesis based on research conducted on the Bay of Islands complex in Newfoundland as well as the East Vardar complex in the Apuseni Mountains of Romania suggest that an irregular continental margin colliding with an island arc complex causes ophiolite generation in a back-arc basin and obduction due to compression. The continental margin, promontories and reentrants along its length,

960-659: A type of geosyncline called eugeosynclines were characterized by producing an "initial magmatism" that in some cases corresponded to ophiolitic magmatism. As plate tectonic theory prevailed in geology and geosyncline theory became outdated ophiolites were interpreted in the new framework. They were recognized as fragments of oceanic lithosphere , and dykes were viewed as the result of extensional tectonics at mid-ocean ridges . The plutonic rocks found in ophiolites were understood as remnants of former magma chambers. In 1973, Akiho Miyashiro revolutionized common conceptions of ophiolites and proposed an island arc origin for

1020-449: Is also consistent with north–south convergence acting as the predominant tectonic regime. In 1976, Dan McKenzie described the fault in the journal Earth and Planetary Science Letters ; a 550 km (340 mi) strike-slip fault extending from the Gulf of Alexandretta to the North Anatolian Fault. The description of its southern end contradicts that of Allen. McKenzie also stated that

1080-409: Is attached to the subducting oceanic crust, which dips away from it underneath the island arc complex. As subduction takes place, the buoyant continent and island arc complex converge, initially colliding with the promontories. However, oceanic crust is still at the surface between the promontories, not having been subducted beneath the island arc yet. The subducting oceanic crust is thought to split from

1140-506: Is found in the name of ophiolites, because of the superficial texture of some of them. Serpentinite especially evokes a snakeskin. (The suffix -lite is from the Greek lithos , meaning "stone".) Some ophiolites have a green color. The origin of these rocks, present in many mountainous massifs , remained uncertain until the advent of plate tectonic theory. Their great significance relates to their occurrence within mountain belts such as

1200-408: Is generated by a back-arc basin. The collision of the continent and island arc initiates a new subduction zone at the back-arc basin, dipping in the opposite direction as the first. The created ophiolite becomes the tip of the new subduction's forearc and is uplifted (over the accretionary wedge ) by detachment and compression. Verification of the two above hypotheses requires further research, as do

1260-455: Is that the thick gabbro layer of ophiolites calls for large magma chambers beneath mid-ocean ridges. However, seismic sounding of mid-ocean ridges has revealed only a few magma chambers beneath ridges, and these are quite thin. A few deep drill holes into oceanic crust have intercepted gabbro, but it is not layered like ophiolite gabbro. The circulation of hydrothermal fluids through young oceanic crust causes serpentinization , alteration of

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1320-649: Is unknown. Earthquakes in 1875 and 1905 may have occurred on the Pütürge segment. This segment was associated with a ~45 km (28 mi) rupture during the January 2020 M w   6.7 earthquake . This segment runs from Yarpuzlu to Gölbaşı . The cumulative offset along the Erkenek segment is 26–22.5 km (16.2–14.0 mi). Stream channels crossing the fault were observed to have been offset by several meters to 0.5 km (0.31 mi). Recent seismic activity

1380-507: The 1866 Bingöl earthquake (M w   7.1) surface rupture . This segment has not experienced a major earthquake since 1866. The segment terminates at the Göynük restraining bend connecting the Ilıca segment. This segment runs through mountainous terrain from the Göynük restraining bend to Ilıca along a single branch. It traverses through Palaeozoic strata and volcanic-sedimentary strata from

1440-506: The Alps and the Himalayas , where they document the existence of former ocean basins that have now been consumed by subduction . This insight was one of the founding pillars of plate tectonics , and ophiolites have always played a central role in plate tectonic theory and the interpretation of ancient mountain belts. The stratigraphic -like sequence observed in ophiolites corresponds to

1500-671: The Arabian plate . The Maraş triple junction is found where the side-by-side African and Arabian plates, both drifting north and demarcated by the north–south trending Dead Sea Transform (itself an extension of the African Rift Valleys), come up against the Anatolian plate lying across their path at the East Anatolian Fault . The junction site is near the Gulf of Alexandretta , and is ~700 km distant from

1560-620: The Delihalil volcano . The fault segment in the south around Toprakkale is characterized by small volcanic cones. The fault displays 2–5 m (6 ft 7 in – 16 ft 5 in) of normal scarps cutting through the Quaternary basalt. It runs 12 km (7.5 mi) along a river valley carved by the Ceyhan River ; some Holocene streams have been offset by 20–30 m (66–98 ft). The Düziçi–İskenderun segment are

1620-494: The Integrated Ocean Drilling Program and other research cruises have shown that in situ ocean crust can be quite variable in thickness and composition, and that in places sheeted dikes sit directly on peridotite tectonite , with no intervening gabbros . Ophiolites have been identified in most of the world's orogenic belts . However, two components of ophiolite formation are under debate:

1680-528: The Karlıova triple junction . After a long quiescence, the Maraş triple junction was ruptured by the violent 2023 Turkey–Syria earthquake . This plate tectonics article is a stub . You can help Misplaced Pages by expanding it . Ophiolite An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks. The Greek word ὄφις, ophis ( snake )

1740-697: The closure of the Tethys Ocean . Ophiolites in Archean and Paleoproterozoic domains are rare. Most ophiolites can be divided into one of two groups: Tethyan and Cordilleran. Tethyan ophiolites are characteristic of those that occur in the eastern Mediterranean sea area, e.g. Troodos in Cyprus, and in the Middle East, such as Semail in Oman, which consist of relatively complete rock series corresponding to

1800-607: The geosyncline concept. He held that Alpine ophiolites were "submarine effusions issuing along thrust faults into the active flank of an asymmetrically shortening geosyncline". The apparent lack of ophiolites in the Peruvian Andes , Steinmann theorized, was either due to the Andes being preceded by a shallow geosyncline or representing just the margin of a geosyncline. Thus, Cordilleran-type and Alpine-type mountains were to be different in this regard. In Hans Stille 's models

1860-428: The lithosphere -forming processes at mid-oceanic ridges . From top to bottom, the layers in the sequence are: A Geological Society of America Penrose Conference on ophiolites in 1972 defined the term "ophiolite" to include all of the layers listed above, including the sediment layer formed independently of the rest of the ophiolite. This definition has been challenged recently because new studies of oceanic crust by

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1920-539: The "Steinmann Trinity": the mixture of serpentine , diabase - spilite and chert . The recognition of the Steinmann Trinity served years later to build up the theory around seafloor spreading and plate tectonics . A key observation by Steinmann was that ophiolites were associated to sedimentary rocks reflecting former deep sea environments. Steinmann himself interpreted ophiolites (the Trinity) using

1980-527: The East Anatolian Fault; it ruptured a perpendicular strike-slip fault. The 1971 Bingöl earthquake produced surface ruptures along the fault. The 2023 earthquake produced up to 400 km (250 mi) of surface rupture along the fault. Mara%C5%9F triple junction The Maraş triple junction is a geologic triple junction of three tectonic plates : the Anatolian plate , the African plate and

2040-531: The Kyrenia–Misis Fault Zone under the Gulf of Alexandretta. This segment comprises a 17 km (11 mi)-long by 1 km (0.62 mi)-wide shutter ridge at its eastern portion before continuing west for 20 km (12 mi). The westernmost length consists two parallel fault strands which eventually integrate at Nurhak . A Holocene surface rupture through Holocene alluvial fan is evidence of

2100-471: The M w   7.8 earthquake in 2023. It was followed two weeks later by a M w   6.4 aftershock at its southernmost tip. The East Anatolian Fault branches away from the main strand to form a northern strand near Çelikhan . This strand, also known as the Sürgü–Misis Fault System, also consists multiple left-lateral fault segments with a total length of 380 km (240 mi). It joins

2160-467: The M w   7.8 earthquake on 6 February 2023, a M w   7.6 earthquake ruptured the Sürgü and Çardak segments. It produced 98 km (61 mi) of surface rupture and displayed a maximum surface offset of 10.0–12.6 m (32.8–41.3 ft); one of the largest surface offset ever observed from an earthquake. The northeast–southwest striking Savrun segment connects the western Çardak segment via

2220-533: The Mio-Pliocene and Quaternary. Previous studies of the East Anatolian Fault consider it part of the Karlıova segment rather than an independent segment. The 1971 Bingöl earthquake (M s   6.8) produced 35 km (22 mi) of surface faulting on this segment, but did not extend beyond northeast of Göynük. This segment extends between Lake Hazar and Palu for 77 km (48 mi). The northern part of

2280-457: The Palu segment was associated with a M w   6.1 earthquake on 8 March 2010. Young scarps and offsets measuring 2.5–4 m (8 ft 2 in – 13 ft 1 in) were observed. The last major earthquake occurred on 3 May 1874, estimated at M w   7.1. East of Lake Hazar, a 2.6 m (8 ft 6 in) offset was reported; the average offset associated with the event along

2340-525: The above observations, there are inconsistencies in the theory of ophiolites as oceanic crust, which suggests that newly generated ocean crust follows the full Wilson cycle before emplacement as an ophiolite. This requires ophiolites to be much older than the orogenies on which they lie, and therefore old and cold. However, radiometric and stratigraphic dating has found ophiolites to have undergone emplacement when young and hot: most are less than 50 million years old. Ophiolites therefore cannot have followed

2400-488: The cental part was 3.5 + 0.5 m (11.5 + 1.6 ft). The area where the Pütürge segment runs through is mountainous and characterized by Paleozoic-Mesozoic metamorphic and Mesozoic ophiolite mélange and clastic rocks. Measurements of basement rocks and offsets along the Euphrates revealed geologic offsets of 9–22 km (5.6–13.7 mi). Although there are Holocene scarps, the precise date when they formed

2460-477: The classic ophiolite assemblage and which have been emplaced onto a passive continental margin more or less intact (Tethys is the name given to the ancient sea that once separated Europe and Africa). Cordilleran ophiolites are characteristic of those that occur in the mountain belts of western North America (the " Cordillera " or backbone of the continent). These ophiolites sit on subduction zone accretionary complexes (subduction complexes) and have no association with

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2520-557: The classic ophiolite occurrences thought of as being related to seafloor spreading (Troodos in Cyprus , Semail in Oman ) were found to be "SSZ" ophiolites, formed by rapid extension of fore-arc crust during subduction initiation. A fore-arc setting for most ophiolites also solves the otherwise-perplexing problem of how oceanic lithosphere can be emplaced on top of continental crust. It appears that continental accretion sediments, if carried by

2580-401: The continental margin to aid subduction. In the event that the rate of trench retreat is greater than that of the island arc complex's progression, trench rollback will take place, and by consequence, extension of the overriding plate will occur to allow the island arc complex to match the trench retreat's speed. The extension, a back-arc basin, generates oceanic crust: ophiolites. Finally, when

2640-503: The downgoing plate into a subduction zone, will jam it up and cause subduction to cease, resulting in the rebound of the accretionary prism with fore-arc lithosphere (ophiolite) on top of it. Ophiolites with compositions comparable with hotspot -type eruptive settings or normal mid-oceanic ridge basalt are rare, and those examples are generally strongly dismembered in subduction zone accretionary complexes. Ophiolites are common in orogenic belts of Mesozoic age, like those formed by

2700-640: The fault represented a boundary between the Anatolian and Arabian plates. The northeast–southwest trending main strand runs for 580 km (360 mi) from Karlıova in the north to Antakya in the south. The Karlıova segment represents the northeasternmost trace of the East Anatolian Fault and extends 25 km (16 mi) from the triple junction to Göynük. Its morphology is charactierized by young scarps; streams offset from several to hundreds of meters; pressure ridges ; linear valleys and hot springs . A 3.5 m (11 ft) offset located 1 km (0.62 mi) southeast of Boncukgöze could be associated with

2760-497: The first, he used ophiolite for serpentinite rocks found in large-scale breccias called mélanges . In the second publication, he expanded the definition to encompass a variety of igneous rocks as well such as gabbro , diabase , ultramafic and volcanic rocks. Ophiolites thus became a name for a well-known association of rocks occurring in the Alps and Apennines of Italy. Following work in these two mountains systems, Gustav Steinmann defined what later became known as

2820-410: The full Wilson cycle and are considered atypical ocean crust. There is yet no consensus on the mechanics of emplacement, the process by which oceanic crust is uplifted onto continental margins despite the relatively low density of the latter. All emplacement procedures share the same steps nonetheless: subduction initiation, thrusting of the ophiolite over a continental margin or an overriding plate at

2880-481: The gabbros is reversed, and ophiolites also appear to have a multi-phase magmatic complexity on par with subduction zones. Indeed, there is increasing evidence that most ophiolites are generated when subduction begins and thus represent fragments of fore-arc lithosphere. This led to introduction of the term "supra-subduction zone" (SSZ) ophiolite in the 1980s to acknowledge that some ophiolites are more closely related to island arcs than ocean ridges. Consequently, some of

2940-591: The investigated ophiolites of the Central Eastern Desert (CED) fall into both MORB/back-arc basin basalt (BABB) ophiolites and SSZ ophiolites. They are spatially and temporally unrelated, and thus, it seems likely that the two types are not petrogenetically related. Ophiolites occur in different geological settings, and they represent change of the tectonic setting of the ophiolites from MORB to SSZ with time. The term ophiolite originated from publications of Alexandre Brongniart in 1813 and 1821. In

3000-611: The northern shores of the Gulf of Alexandretta. This segment consists of two eastern and western sections measuring 16.5 km (10.3 mi) and 24.5 km (15.2 mi), respectively. The Karataş segment runs for 64 km (40 mi) and is subparallel to the Yumurtalık segment but located north of that segment. The fault produced large earthquakes in 1789 (M 7.2), 1795 (M 7.0), 1872 (M 7.2) , 1874 (M 7.1), 1875 (M 6.7), 1893 (M 7.1) and 1905 (M w   6.8). The M s   7.1 earthquake in 1893 killed over 800 people. In 1866,

3060-500: The oceanic lithosphere is entirely subducted, the island arc complex's extensional regime becomes compressional. The hot, positively buoyant ocean crust from the extension will not subduct, instead obducting onto the island arc as an ophiolite. As compression persists, the ophiolite is emplaced onto the continental margin. Based on Sr and Nd isotope analyses, ophiolites have a similar composition to mid-ocean-ridge basalts, but typically have slightly elevated large ion lithophile elements and

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3120-412: The origin of the sequence and the mechanism for ophiolite emplacement. Emplacement is the process of the sequence's uplift over lower density continental crust. Several studies support the conclusion that ophiolites formed as oceanic lithosphere . Seismic velocity structure studies have provided most of the current knowledge of the oceanic crust's composition. For this reason, researchers carried out

3180-628: The other hypotheses available in current literature on the subject. Scientists have drilled only about 1.5 km into the 6- to 7-kilometer-thick oceanic crust, so scientific understanding of oceanic crust comes largely from comparing ophiolite structure to seismic soundings of in situ oceanic crust. Oceanic crust generally has a layered velocity structure that implies a layered rock series similar to that listed above. But in detail there are problems, with many ophiolites exhibiting thinner accumulations of igneous rock than are inferred for oceanic crust. Another problem relating to oceanic crust and ophiolites

3240-465: The peridotites and alteration of minerals in the gabbros and basalts to lower temperature assemblages. For example, plagioclase , pyroxenes , and olivine in the sheeted dikes and lavas will alter to albite , chlorite , and serpentine , respectively. Often, ore bodies such as iron -rich sulfide deposits are found above highly altered epidosites ( epidote - quartz rocks) that are evidence of relict black smokers , which continue to operate within

3300-572: The seafloor spreading centers of ocean ridges today. Thus, there is reason to believe that ophiolites are indeed oceanic mantle and crust; however, certain problems arise when looking closer. Beyond issues of layer thicknesses mentioned above, a problem arises concerning compositional differences of silica (SiO 2 ) and titania (TiO 2 ). Ophiolite basalt contents place them in the domain of subduction zones (~55% silica, <1% TiO 2 ), whereas mid-ocean ridge basalts typically have ~50% silica and 1.5–2.5% TiO 2 . These chemical differences extend to

3360-462: The southern half is also concave. This segment extends from Gölbaşı to Türkoğlu . Its cumulative geologic offset has been estimated at 19–25 km (12–16 mi); based on paleoseismological studies, the slip rate in the Holocene was estimated at 9 mm (0.35 in) per year. About 4 km (2.5 mi) southeast of Elmalar, 5 ± 0.2 m (16.40 ± 0.66 ft) of offset

3420-483: The vicinity of ridges dissolved and carried elements that precipitated as sulfides when the heated seawater came into contact with cold seawater. The same phenomenon occurs near oceanic ridges in a formation known as hydrothermal vents . The final line of evidence supporting the origin of ophiolites as seafloor is the region of formation of the sediments over the pillow lavas: they were deposited in water over 2 km deep, far removed from land-sourced sediments. Despite

3480-569: The Çokak segment from the Savrun segment. The main strand strikes approximately northeast–southwest; its northern end consisting of a normal fault while the remaining, a left-lateral fault. Another left-lateral fault runs subparallel to the west along its southern half. It accumulated a total offset of 2.5 km (1.6 mi) during the Late Pliocene to Quaternary. The 50 km (31 mi)-long Toprakkale segment extends from Boynuyoğunlu to

3540-454: Was inferred by the precense of young fault scarps. In 1893, a M s 7.2 earthquake produced a 4.5 m (15 ft) offset near Çelikhan . The northern part of the Erkenek segment produced 10 km (6.2 mi) of surface rupture during the M w   7.8 earthquake of 2023. The trace of the Pazarcık segment is reminiscent of a smooth sine curve; its northern half is concave while

3600-526: Was reported along a stream, possibly associated with an earthquake in 1513. The Pazarcık segment may have also produced surface ruptures during the 1114 earthquake . This was one of the segments that ruptured during the M w   7.8 earthquake of 2023. The Amanos segment, also known as the Karasu segment, measures 120 km (75 mi) in length and represents the southern part of the East Anatolian Fault. However, some geologists also consider this segment

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