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Bransfield Basin
The Bransfield Basin is a back-arc rift basin located off the northern tip of the Antarctic Peninsula. The basin lies within a Northeast and Southwest trending strait that separates the peninsula from the nearby South Shetland Islands to the Northwest. The basin extends for more than from Smith Island (South Shetland Islands) to a portion of the Hero Fracture Zone. The basin can be subdivided into three basins: Western, Central, and Eastern. The Western basin is long by wide with a depth of , the Central basin is long by wide with a depth of , and the Eastern basin is long by wide with a depth of over . The three basins are separated by the Deception Island and Bridgeman Island. The moho depth in the region has been seismically interpreted to be roughly deep. Tectonic development The Bransfield Basin is considered to be a back-arc basin that is located behind the South Shetland Islands. The Islands are believed to have formed from a period of subduction that occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Back-arc Basin
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics. Structural characteristics Back-arc basins are typically very long and relatively narrow, often thousands of kilometers long while only being a few hundred kilometers wide at most. For back-arc extension to form, a subduction zone is required, but not all subduction zones have a back-arc extension feature. Back-arc basins are found in area ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian reptiles, like the dinosaurs; an abundance of conifers and ferns; a hot Greenhouse and icehouse earth, greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since Cambrian explosion, complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic. The era began in the wake of the Permian–Triassic extinction event, the largest well-documented mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, Pterosaur, pterosaurs, Mosasaur, mosasaurs, and Plesiosaur, plesiosaurs. The Mesozoic was a time of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Period
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The Last Glacial Period ended about 15,000 years ago. The Holocene is the current interglacial. A time with no glaciers on Earth is considered a greenhouse climate state. Quaternary Period Within the Quaternary, which started about 2.6 million years before present, there have been a number of glacials and interglacials. At least eight glacial cycles have occurred in the last 740,000 years alone. Penultimate Glacial Period The Penultimate Glacial Period (PGP) is the glacial period that occurred before the Last Glacial Period. It began about 194,000 years ago and ended 135,000 years ago, with the beginning of the Eemian interglacial. Last Glacial Period The last glacial period was the most recent glacial period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bransfield Basin Cross Section(revised) (born 1943), American Catholic clergyman
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Bransfield is a surname. Notable people with the surname include: *Edward Bransfield ( 1785–1852), Irish sailor and naval officer *Kitty Bransfield (1875–1947), American baseball player * Marjorie Bransfield, American actress *Michael J. Bransfield Michael Joseph Bransfield (born September 8, 1943) is an American prelate of the Roman Catholic Church. Bransfield served as bishop of the Diocese of Wheeling-Charleston in West Virginia from 2005 to 2018. After Bransfield retired in 2018, a chu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orca Seamount
Orca Seamount is a seamount (underwater volcano) near King George Island in Antarctica, in the Bransfield Strait. While it is inactive, last volcanic activity at Orca Seamount is judged to have occurred in the recent past as there are temperature anomalies in the seawater around the seamount. Thermophilic and hyperthermophilic microorganisms have been found at the seamount. The crater rim is about 3 km wide and about 500 m above the ocean floor. The seamount was first named by Professor O. González-Ferrán of Chile in 1987, after the orca (killer whale) often sighted in these waters. It was mapped and studied by the ship RV ''Polarstern'' during an Antarctic cruise (number ANT-XI/3) in 2005. The variant name of Viehoff Seamount (approved in 6/95 ACUF 263) was named for Dr. Thomas Viehoff, a remote sensing specialist in marine sciences. Name proposed by Dr. G.B. Udintsev, Vernadsky Institute of Geochemistry (VIG). Geology The submarine volcano is a Pleistocene- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seamount
A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to in height. They are defined by oceanographers as independent features that rise to at least above the seafloor, characteristically of conical form.IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratovolcanoes
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as . Stratovolcanoes are sometimes called composite volcanoes because of their composite stratified structure, built up from sequential outpourings of erupted materials. They are among the most common types of volcanoes, in contrast to the less common shield volcanoes. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penguin Island (South Shetland Islands)
Penguin Island (also known as Georges Island, Île Pingouin, Isla Pingüino, and Penguin Isle) is one of the smaller of the South Shetland Islands of Antarctica. History Penguin Island was sighted in January 1820 by a British expedition under Edward Bransfield, and so named by him because penguins occupied the shores of the island. Description The island, which is ice-free and oval shaped, wide by long, lies close off the south coast of the much larger King George Island, and marks the eastern side of the entrance to King George Bay. It has a shoreline of low cliffs, with a beach on the north coast providing access. There is a small lake in the north-east. It is capped by Deacon Peak, a basaltic scoria cone. Deacon Peak was last thought to be active about 300 years ago. Petrel Crater, a maar crater, is located on the east side of the island, and is thought to have last erupted in or around 1905. Geology The island is the top of a Pleistocene-Recent stratovolcano with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ridge
A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The lines along the crest formed by the highest points, with the terrain dropping down on either side, are called the ridgelines. Ridges are usually termed hills or mountains as well, depending on size. Smaller ridges, especially those leaving a larger ridge, are often referred to as spurs. Types There are several main types of ridges: ;Dendritic ridge: In typical dissected plateau terrain, the stream drainage valleys will leave intervening ridges. These are by far the most common ridges. These ridges usually represent slightly more erosion resistant rock, but not always – they often remain because there were more joints where the valleys formed or other chance occurrences. This type of ridge is generally somewhat random in orientation, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotia Plate
The Scotia Plate () is a tectonic plate on the edge of the South Atlantic and Southern oceans. Thought to have formed during the early Eocene with the opening of the Drake Passage that separates South America from Antarctica, it is a minor plate whose movement is largely controlled by the two major plates that surround it: the South American Plate and the Antarctic Plate. The Scotia Plate takes its name from the steam yacht ''Scotia'' of the Scottish National Antarctic Expedition (1902–04), the expedition that made the first bathymetric study of the region. Roughly rhomboid, extending between and , the plate is wide and long. It is moving WSW at /year and the South Sandwich Plate is moving east at /year in an absolute reference frame. The Scotia Plate is made of oceanic crust and continental fragments now distributed around the Scotia Sea. Before the formation of the plate began (40Ma), these fragments formed a continuous landmass from Patagonia to the Antarctic Penin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinistral And Dextral
Sinistral and dextral, in some scientific fields, are the two types of chirality (" handedness") or relative direction. The terms are derived from the Latin words for "left" (''sinister'') and "right" (''dexter''). Other disciplines use different terms (such as dextro- and laevo-rotary in chemistry, or clockwise and anticlockwise in physics) or simply use left and right (as in anatomy). Relative direction and chirality are distinct concepts. Relative direction is from the point of view of the observer; a completely symmetric object has a left side and a right side, from the observer's point of view, if the top and bottom and direction of observation are defined. Chirality, however, is observer-independent: no matter how one looks at a right-hand screw thread, it remains different from a left-hand screw thread. Therefore, a symmetric object has sinistral and dextral directions arbitrarily defined by the position of the observer, while an asymmetric object that shows chirality ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slab Rollback
Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic trenches are a feature of the Earth's distinctive plate tectonics. They mark the locations of Convergent boundary, convergent plate boundaries, along which Lithosphere, lithospheric Plate tectonics, plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year. Oceanic lithosphere moves into trenches at a global rate of about 3 km2/yr. A trench marks the position at which the flexed, subduction, subducting Slab (geology), slab begins to descend beneath anothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
