Kenyte is a type of igneous rock. More specifically, it is a variety of porphyritic phonolite or trachyte with rhomb-shaped phenocrysts of anorthoclase with variable amounts of olivine and augite in a glassy matrix; the glass may be devitrified. [1]
It was originally described and named by J. W. Gregory in 1900 for the occurrence on Mount Kenya. [2] [3] Kenyte has also been reported from Mount Kilimanjaro (Tanzania) and Mount Erebus (Antarctica). [4]
Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term gabbro may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic". By rough analogy, gabbro is to basalt as granite is to rhyolite.
Ross Island is an island formed by four volcanoes in the Ross Sea near the continent of Antarctica, off the coast of Victoria Land in McMurdo Sound. Ross Island lies within the boundaries of Ross Dependency, an area of Antarctica claimed by New Zealand.
Mount Erebus is the second-highest volcano in Antarctica, the highest active volcano in Antarctica, and the southernmost active volcano on Earth. It is the sixth-highest ultra mountain on the continent. With a summit elevation of 3,794 metres (12,448 ft), it is located in the Ross Dependency on Ross Island, which is also home to three inactive volcanoes: Mount Terror, Mount Bird, and Mount Terra Nova.
In geology, rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects.
Phonolite is an uncommon shallow intrusive or extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous rock trachyte that contains nepheline or leucite rather than quartz. It has an unusually high (12% or more) Na2O + K2O content, defining its position in the TAS classification of igneous rocks. Its coarse grained (phaneritic) intrusive equivalent is nepheline syenite. Phonolite is typically fine grained and compact. The name phonolite comes from the Ancient Greek meaning "sounding stone" due to the metallic sound it produces if an unfractured plate is hit; hence, the English name clinkstone is given as a synonym.
Petrology is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and phase diagrams. Sedimentary petrology is, on the other hand, commonly taught together with stratigraphy because it deals with the processes that form sedimentary rock.
Mount Kenya is an extinct stratovolcano in Kenya and the second-highest peak in Africa, after Kilimanjaro. The highest peaks of the mountain are Batian, Nelion and Point Lenana. Mount Kenya is located in the former Eastern and Central provinces of Kenya; its peak is now the intersection of Meru, Embu, Kirinyaga, Nyeri and Tharaka Nithi counties, about 16.5 kilometres south of the equator, around 150 km (90 mi) north-northeast of the capital Nairobi. Mount Kenya is the source of the name of the Republic of Kenya.
Mount Terror is a large shield volcano that forms the eastern part of Ross Island, Antarctica. It has numerous cinder cones and domes on the flanks of the shield and is mostly under snow and ice. It is the second largest of the four volcanoes that make up Ross Island and is somewhat overshadowed by its neighbour, Mount Erebus, 30 km (19 mi) to the west. Mount Terror was named in 1841 by Sir James Clark Ross for his second ship, HMS Terror. The captain of Terror was Francis Crozier, a close friend of Ross for whom the nearby Cape Crozier is named.
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lithology may refer to either a detailed description of these characteristics, or a summary of the gross physical character of a rock. Examples of lithologies in the second sense include sandstone, slate, basalt, or limestone.
The Royal Society Range is a mountain range in Victoria Land, Antarctica. With its summit at 4,025 metres (13,205 ft), the massive Mount Lister forms the highest point in this range. Mount Lister is located along the western shore of McMurdo Sound between the Koettlitz, Skelton and Ferrar glaciers. Other notable local terrain features include Allison Glacier, which descends from the west slopes of the Royal Society Range into Skelton Glacier.
Mount Melbourne is a 2,733-metre-high (8,967 ft) ice-covered stratovolcano in Victoria Land, Antarctica, between Wood Bay and Terra Nova Bay. It is an elongated mountain with a summit caldera filled with ice with numerous parasitic vents; a volcanic field surrounds the edifice. Mount Melbourne has a volume of about 180 cubic kilometres (43 cu mi) and consists of tephra deposits and lava flows; tephra deposits are also found encased within ice and have been used to date the last eruption of Mount Melbourne to 1892 ± 30 years. The volcano is fumarolically active.
Mount Morning is a shield volcano at the foot of the Transantarctic Mountains in Victoria Land, Antarctica. It lies 100 kilometres (62 mi) from Ross Island. Mount Morning rises to an elevation of 2,723 metres (8,934 ft) and is almost entirely mantled with snow and ice. A 4.1 by 4.9 kilometres wide summit caldera lies at the top of the volcano and several ice-free ridges such as Hurricane Ridge and Riviera Ridge emanate from the summit. A number of parasitic vents mainly in the form of cinder cones dot the mountain.
The geology of Antarctica covers the geological development of the continent through the Archean, Proterozoic and Phanerozoic eons.
John Walter Gregory,, was a British geologist and explorer, known principally for his work on glacial geology and on the geography and geology of Australia and East Africa.
The Karoo and Ferrar Large Igneous Provinces (LIPs) are two large igneous provinces in Southern Africa and Antarctica respectively, collectively known as the Karoo-Ferrar, Gondwana, or Southeast African LIP, associated with the initial break-up of the Gondwana supercontinent at c.183Ma. Its flood basalt mostly covers South Africa and Antarctica but portions extend further into southern Africa and into South America, India, Australia and New Zealand.
The Erebus hotspot is a volcanic hotspot responsible for the high volcanic activity on Ross Island in the western Ross Sea of Antarctica. Its current eruptive zone, Mount Erebus, has erupted continuously since its discovery in 1841. Magmas of the Erebus hotspot are similar to those erupted from hotspots at the active East African Rift in eastern Africa. Mount Bird at the northernmost end of Ross Island and Mount Terror at its eastern end are large basaltic shield volcanoes that have been potassium-argon dated 3.8–4.8 and 0.8–1.8 million years old.
The Drakensberg Group is a geological group named after the Drakensberg mountain range where in its uppermost sections the rocks are found. The Drakensberg Group lies over most of Lesotho and localities in the Eastern Cape, KwaZulu-Natal, and Free State provinces of South Africa. It forms part of the greater Karoo Igneous Province, which occurs over an extensive area of southern Africa.
Mount Rittmann is a volcano in Antarctica. Discovered in 1988–1989 by an Italian expedition, it was named after the volcanologist Alfred Rittmann (1893–1980). It features a 2 kilometres (1.2 mi) or 8 by 5 kilometres wide caldera which crops out from underneath the Aviator Glacier. The volcano was active during the Pliocene and into the Holocene, including large explosive eruptions; a major eruption occurred in 1254 CE and deposited tephra over much of Antarctica. Currently, the volcano is classified as dormant.
The McMurdo Volcanic Group is a large group of Cenozoic volcanic rocks in the western Ross Sea and central Transantarctic Mountains areas of Antarctica. It is one of the largest provinces of alkaline volcanism in the world, having formed as a result of continental rifting along the West Antarctic Rift System. The McMurdo Volcanic Group is part of the Western Ross Supergroup, a stratigraphic unit that also includes the Meander Intrusive Group.
 | This igneous rock-related article is a stub. You can help Wikipedia by expanding it. |