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Komatiites
Komatiite () is a type of ultramafic mantle-derived volcanic rock defined as having crystallised from a lava of at least 18 wt% MgO. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content. Komatiite was named for its type locality along the Komati River in South Africa, and frequently displays spinifex texture composed of large dendritic plates of olivine and pyroxene. Komatiites are rare rocks; almost all komatiites were formed during the Archaean Eon (4.0–2.5 billion years ago), with few younger (Proterozoic or Phanerozoic) examples known. This restriction in age is thought to be due to cooling of the mantle, which may have been hotter during the Archaean. The early Earth had much higher heat production, due to the residual heat from planetary accretion, as well as the greater abundance of radioactive isotopes, particularly shorter lived ones like uranium 235 which produce more decay heat. Lower temperature mantle melts such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Komatiite Lava In South Africa - CSIRO ScienceImage 11033
Komatiite () is a type of ultramafic mantle (geology), mantle-derived volcanic rock defined as having crystallised from a lava of at least 18 wt% MgO. Komatiites have low silicon, potassium and aluminium, and high to extremely high magnesium content. Komatiite was named for its Type locality (geology), type locality along the Komati River in South Africa, and frequently displays Triodia (grass), spinifex texture composed of large dendritic plates of olivine and pyroxene. Komatiites are rare rocks; almost all komatiites were formed during the Archean, Archaean Eon (4.0–2.5 billion years ago), with few younger (Proterozoic or Phanerozoic) examples known. This restriction in age is thought to be due to cooling of the mantle, which may have been hotter during the Archaean. The early Earth had much higher heat production, due to the residual heat from planetary accretion, as well as the greater abundance of radioactive isotopes, particularly shorter lived ones like uranium 235 which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultramafic
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks. Intrusive ultramafic rocks Intrusive ultramafic rocks are often found in large, layered ultramafic intrusions where differentiated rock types often occur in layers. Such cumulate rock types do not represent the chemistry of the magma from which they crystallized. The ultramafic intrusives include the dunites, peridotites and pyroxenites. Other rare varieties include troctolite which has a greater percenta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gorgona, Colombia
Gorgona is a Colombian island in the Pacific Ocean situated about off the Colombian Pacific coast. The island is long and wide, with a maximum height of and a total area of . Gorgona is separated from the continent by a deep underwater depression. Administratively the island is part of the Municipality of Guapí in the Department of Cauca. Gorgona functioned as a prison from 1959 until 1984 when it was turned into a National Natural Park. The island, noted for its many endemic species and unique ecosystems, was established as Gorgona Island National Park in 1985, in order to preserve its richly varied wildlife of the sub-tropical forest and the coral reefs offshore. History Early settlements Gorgona was first inhabited by people possibly associated with the Tumaco-Tolita culture. The indigenous Kuna or Cuna of Urabá (Colombia) and San Blas (Panama), have the tradition of being the first settlers of the island. They left archeological remains dating back to 1300 AD. They ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultramafic Rock
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content). The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks. Intrusive ultramafic rocks Intrusive ultramafic rocks are often found in large, layered ultramafic intrusions where differentiated rock types often occur in layers. Such cumulate rock types do not represent the chemistry of the magma from which they crystallized. The ultramafic intrusives include the dunites, peridotites and pyroxenites. Other rare varieties include troctolite which has a greater percentag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Winnipegosis Komatiite Belt
The Winnipegosis komatiite belt is a long and wide greenstone belt located in the Lake Winnipegosis area of central Manitoba, Canada. It has no surface exposure and was identified based on geophysical signatures and drilling during mineral exploration by Cominco during the 1990s.McGregor, C. R. 2011. Open File OF2011-1: GIS compilation of relogged sub-Phanerozoic Precambrian exploration drillcore from the Thompson Nickel Belt, eastern Flin Flon Belt and Winnipegosis Komatiite Belt (parts of NTS 63B, C, F, G, J, K). Manitoba Geological Survey. The belt has an age of 1870 ± 7 million years and is predominantly composed of basaltic and komatiitic volcanic rocks with minor intrusive and sedimentary rocks.Hulbert, L., Stern, R., Kyser, T. K., Pearson, J., Lesher, M., & Grinenko, L. 1994. The Winnipegosis Komatiite Belt, central Manitoba. Page 21 of: Manitoba Mining and Minerals Convention 1994, Program and Abstracts. Manitoba Energy and Mines.Waterton, P., Pearson, D. G., Kjarsgaard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from . The volcanic rock resulting from subsequent cooling is also often called ''lava''. A lava flow is an outpouring of lava during an effusive eruption. (An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water. Even so, lava can flow great distances before cooling causes it to solidify, because lava exposed to air quickly develops a solid crust that insulates the remaining liquid lava, helping to keep it hot and inviscid enough to continue flowing. The word ''lava'' comes from Italian and is probably derived from the Latin word ''labes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Picrite Basalt
Picrite basalt or picrobasalt is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine. It is dark with yellow-green olivine phenocrysts (20-50%) and black to dark brown pyroxene, mostly augite. The olivine-rich picrite basalts that occur with the more common tholeiitic basalts of Kīlauea and other volcanoes of the Hawaiian Islands are the result of accumulation of olivine crystals either in a portion of the magma chamber or in a caldera lava lake. The compositions of these rocks are well represented by mixes of olivine and more typical tholeiitic basalt. The name "picrite" can also be applied to an olivine-rich alkali basalt: such picrite consists largely of phenocrysts of olivine and titanium-rich augite pyroxene with minor plagioclase set in a groundmass of augite and more sodic plagioclase and perhaps analcite and biotite. Picrites and komatiites are somewhat similar chemically (defined as >18% MgO), but differ in having 1 to 2% total alkalis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manitoba
Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population of 1,342,153 as of 2021, of widely varied landscape, from arctic tundra and the Hudson Bay coastline in the Northern Region, Manitoba, north to dense Boreal forest of Canada, boreal forest, large freshwater List of lakes of Manitoba, lakes, and prairie grassland in the central and Southern Manitoba, southern regions. Indigenous peoples in Canada, Indigenous peoples have inhabited what is now Manitoba for thousands of years. In the early 17th century, British and French North American fur trade, fur traders began arriving in the area and establishing settlements. The Kingdom of England secured control of the region in 1673 and created a territory named Rupert's Land, which was placed under the administration of the Hudson's Bay Company. Rupe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
