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Baikal Rift Zone
The Baikal Rift Zone is a series of continental rifts centered beneath Lake Baikal in southeastern Russia. Current strain in the rifts tends to be extending with some shear movement. A series of basins form along the zone for more than , creating a rift valley. The rifts form between the Eurasian Plate to the west and the Amur Plate to the east. Structures To the northwest of the rifts is the Siberian Craton, on the Eurasian Plate. The Sayan-Baikal and Mongolia-Okhotsk mobile belts are formations to the southeast of the rifts; beyond the Sayan-Baikal fold belt is the Amur Plate. Basins form along the rift. There are three basins in the area, the South Basin, Central Basin, and North Basin. In the North, half-grabens form smaller basins, such as the North Baikal Basin, and the Chara-Tokka Basin. The Central Basin is the deepest in the rift system. The largest fault it contains is the Morskiy Fault; however, another fault, the Primorsky is becoming the primary fault in the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Sill (geology)
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock. A sill is a ''concordant intrusive sheet'', meaning that it does not cut across preexisting rock beds. Stacking of sills builds a sill complex. and a large magma chamber at high magma flux. In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. Formation Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source. The rocks must be brittle and fracture to create the planes along which the magma intrudes the parent rock bodies, whether this occurs along preexisting planes between sedimentary or volcanic beds or weakened planes related to foliation in metamorphic rock. These planes or weakened areas allow the intrusion of a thin sheet-like body of magma paralleling the existi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Fold And Thrust Belt
A fold and thrust belt is a series of mountainous foothills adjacent to an orogenic belt, which forms due to contractional tectonics. Fold and thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates outwards. Fold and thrust belts usually comprise both folds and thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...s, commonly interrelated. They are commonly also known as thrust-and-fold belts, or simply thrust-fold belts. Geometry Fold and thrust belts are formed of a series of sub-parallel thrust sheets, separated by major thrust faults. As the total shortening increases in a fold and thrust belt, the belt propagates into its foreland. New thrusts develop at the front of the belt, folding the older thrusts that have become inactiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Paleozoic
The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six period (geology), geologic periods (from oldest to youngest), Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Some geological timescales divide the Paleozoic informally into early and late sub-eras: the Early Paleozoic consisting of the Cambrian, Ordovician and Silurian; the Late Paleozoic consisting of the Devonian, Carboniferous and Permian. The name ''Paleozoic'' was first used by Adam Sedgwick (1785–1873) in 1838 to describe the Cambrian and Ordovician periods. It was redefined by John Phillips (geologist), John Phillips (1800–1874) in 1840 to cover the Cambrian to Permian periods. It is derived from the Ancient Greek, Greek ''palaiós'' (π� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Precambrian
The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is named after Cambria, the Latinized name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons ( Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago ( Ga) to the beginning of the Cambrian Period, about million years ago ( Ma), when hard-shelled creatures first appeared in abundance. Overview Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history, and what is known has largely been discovered from the 1960s onwards. The Precambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Olkhon Island, Coast, Lake Baikal, Russia
Olkhon (, also transliterated as Olchon; , ''Oikhon'') is the third-largest lake island in the world. It is by far the largest island in Lake Baikal in eastern Siberia, with an area of . Structurally, it constitutes the southwestern margin of the Academician Ridge. The island measures in length and in width. There are two versions regarding the origin of the name of the island and both are derived from the language of the Buryats, the indigenous people of Olkhon. The first is that the island's name comes from the word ''oyhon'' – “woody”, and the second is that it comes from ''olhan'' – “dry”. It is still debated which of the two is the actual origin of the name Olkhon as both words describe the island perfectly. Much of the island is still covered by forests and the amount of precipitation is extremely low – about per year. Geography Olkhon has a dramatic combination of terrain and is rich in archaeological landmarks. Steep mountains line its eastern shore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Azas Plateau
Azas Plateau is a volcanic field in Russia. It is also known as East Tuva Plateau, Khamsara-Biykhem Plateau and Northeast Tuva Plateau. It covers a surface area of west of Lake Baikal. Volcanic activity in the area also occurred at the Oka Plateau and the Jom-Bolok volcanic field. The field is formed by a late Pliocene lava plateau. Several volcanoes formed under the influence of ice and are constructed by lava flows and hyaloclastite, these are so-called tuyas which form by eruptions of volcanoes into ice. Ice meltwater floods may have accompanied this activity. The youngest dated volcanic centre was active 48,000 ± 20,000 years ago, but some lava flows may be even younger. Geography The field is located in southern Siberia, between the East Sayan Mountains and the Todzha basin. There it covers a surface area of west of Lake Baikal, at an altitude of . Volcanic landforms include cones, lava fields, tuyas, and other volcanic structures including scoria cones, volcanic dy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Oka Plateau
Oka or OKA may refer to: * "Officially known as", used to introduce an official name Vehicles * Oka (automobile), a small car designed by AvtoVAZ and produced by ZMA and SeAZ * OKA (truck), a large 4-wheel-drive vehicle made in Western Australia by the OKA Motor Company Military * 2B1 Oka, Soviet 420 mm self-propelled mortar * OTR-23 Oka, a theatre ballistic missile deployed by the Soviet Union Places * Oka (Bithynia), a town of ancient Bithynia, now in Turkey * Oka, Quebec, Canada, a village * Oka National Park, near Oka, Quebec * Oka, Akoko, the capital city of Akoko South-West Local Government of Ondo State, Nigeria * Oka (river), in the European part of Russia * Oka (Angara), a river in Siberia, Russia * Oka, West Virginia, United States, an unincorporated community * Oca (river), in northern Spain, spelled "Oka" in the Basque language * Igbo spelling of Awka, a city in Nigeria, capital of Anambra State Codes * Naha Airport, near Naha, Okinawa, IATA airport code OKA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Udokan Plateau
The Udokan Plateau is a volcanic field in Transbaikalia, Russia. It covers a surface area of northeast of Lake Baikal in North Asia. Volcanism in the Udokan Plateau included both basaltic lava flows and later individual volcanic cones. Volcanism commenced in the Miocene and continued on into the Holocene. Volcanism in the field ranges from lava flows forming thick lava flow sequences formed out of basalt to explosive eruptions forming cinder cones accompanied by lava flows and ignimbrite eruptions during the late stages of volcanic activity. Volcanic activity commenced 14 million years ago and the youngest three radiocarbon dates indicate persistence of volcanic activity into the Holocene. Recent seismic activity has been reported. General geology The Udokan Plateau lies east-northeast of the eastern end of Lake Baikal in the Emnakh River watershed. It covers a surface area of within the Udokan range at altitudes of . The basement rock is of Precambrian age. The Udokan Plate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Oligocene
The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from Ancient Greek (''olígos'') 'few' and (''kainós'') 'new', and refers to the sparsity of Neontology, extant forms of Mollusca, molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" because it has 18% fewer modern marine invertebrates than the Pliocene has. The Miocene followed the Oligocene and preceded the Pliocene. As Earth went from the Oligocene through the Miocene and into the Pliocene, the climate slowly cooled towards a series of ice ages. The Miocene boundaries are not marked by distinct global events but by regionally defined transitions from the warmer Oligocene to the cooler Pliocene Epoch. During the Early Miocene, Afro-Arabia collided with Eurasia, severing the connection between the Mediterranean and Indian Oceans, and allowing the interchange of fauna between Eurasia and Africa, including the dispersal of proboscideans and Ape, hominoids into Eurasia. During the late Miocene, the conn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cenozoic
The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three geological eras of the Phanerozoic Eon, preceded by the Mesozoic and Paleozoic. The Cenozoic started with the Cretaceous–Paleogene extinction event, when many species, including the non-avian dinosaurs, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the Chicxulub impactor. The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were mammalsthe eutherians ( placentals) in the Northern Hemisphere and the metatherians (marsupials, now mainly restricted to Australia and to some extent South America) in the Southern Hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
