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Troctolite
Troctolite (from Greek τρώκτης 'trout' and λίθος 'stone') is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene. It is an olivine-rich anorthosite, or a pyroxene-depleted relative of gabbro. However, unlike gabbro, no troctolite corresponds in composition to a partial melt of peridotite. Thus, troctolite is necessarily a cumulate of crystals that have fractionated from melt. Troctolite is found in some layered intrusions such as in the Archean Windimurra intrusion of Western Australia, the Voisey's Bay nickel-copper-cobalt magmatic sulfide deposit of northern Labrador, the Stillwater igneous complex of Montana, the Duluth Complex of the North American Midcontinent Rift, and the Tertiary Rhum layered intrusion of the island of Rùm, Scotland. Troctolite is also found, for example, in the Merensky Reef of the Bushveld Igneous Complex, South Africa and in the Lizar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anorthosite
Anorthosite () is a phaneritic, intrusive rock, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present. Anorthosites are of enormous geologic interest, because it is still not fully understood how they form. Most models involve fractional crystallization (geology), separating plagioclase crystals based on their density. Plagioclase crystals are usually less dense than magma; so, as plagioclase crystallizes in a magma chamber, the plagioclase crystals float to the top, concentrating there. Anorthosite on Earth can be divided into five types: # Archean anorthosites # Proterozoic anorthosite (also known as massif or massif-type anorthosite) – the most abundant type of anorthosite on Earth # Layers within Layered intrusion, Layered Intrusions (e.g., Bushveld Igneous Complex, Bushveld and Stillwater igneous com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apollo 17
Apollo 17 (December 7–19, 1972) was the eleventh and final mission of NASA's Apollo program, the sixth and most recent time humans have set foot on the Moon. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on the Moon, while Command Module Pilot Ronald Evans (astronaut), Ronald Evans orbited above. Schmitt was the only professional geologist to land on the Moon; he was selected in place of Joe Engle, as NASA had been under pressure to send a scientist to the Moon. The mission's heavy emphasis on science meant the inclusion of a number of new experiments, including a Fe, Fi, Fo, Fum, and Phooey, biological experiment containing five mice that was carried in the command module. Mission planners had two primary goals in deciding on the landing site: to sample Lunar highlands, lunar highland material older than that at Mare Imbrium and to investigate the possibility of relatively recent Volcano, volcanic activity. They therefore selected Taurus–Littrow, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stillwater Igneous Complex
The Stillwater igneous complex is a large layered mafic intrusion (LMI) located in southern Montana in Stillwater, Sweet Grass and Park Counties. The complex is exposed across 30 miles (48 km) of the north flank of the Beartooth Mountain Range. The complex has extensive reserves of chromium ore and has a history of being mined for chromium. More recent mining activity has produced palladium and other platinum group elements.The Stillwater Complex: A review of the geology by I. S. McCallum http://serc.carleton.edu/files/NAGTWorkshops/petrology03/McCallum.Stillwater.doc Geology The Stillwater complex is a large layered intrusion with many similarities to the Bushveld igneous complex of South Africa. The complex was intruded into existing gneisses during the Archean at about 2700 Ma. Host rocks on the northern side are Archean sedimentary rocks while the southern boundary includes Precambrian rocks of granite, granite gneiss and schist. The Precambrian rock on its sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windimurra Intrusion
The Windimurra Igneous Complex is a giant ultramafic-mafic intrusion emplaced within the Yilgarn craton of Western Australia. It is located approximately 100 kilometres south east of the town of Mount Magnet. Setting The Windimurra Igneous Complex is part of the c. 2813 Ma Meeline Suite of mafic-ultramafic layered intrusions of the central Murchison Domain, Yilgarn Craton of Western Australia. It is a conical body, approximately 7 km thick, primarily composed of layered gabbroic rocks, which intrude into c. 2820 Ma Norie Group rocks of the Murchison Supergroup. The intrusion is approximately 85 x 37 km (2500 km2) in extent. Lithology Windimurra contains in excess of 13,000m of intact igneous stratigraphy formed of cumulate layering by a process of fractional crystallization. Individual rock types can be grouped into a troctolite phase or series, a gabbro phase or series and a gabbronorite phase or series. Anorthosite cumulates are preserved in the roof section ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tertiary Period
The Tertiary ( ) is an obsolete Period (geology), geologic period spanning 66 million to 2.6 or 1.8 million years ago. The period began with the extinction of the non-bird, avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic, Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end of the Pliocene, Pliocene Epoch. The Tertiary has not been recognised by the International Commission on Stratigraphy (ICS) since the late 1980s, with the timespan of the Tertiary now being split in to the earlier Paleogene and the more recent Neogene periods, though the Tertiary continues to be used in some scientific publications. Historical use of the term The term Tertiary was first used by Giovanni Arduino (geologist), Giovanni Arduino during the mid-18th century. He classified geologic time into primitive (or primary), secondary, and tertiary periods based on observations of geology in Northern Italy. Later a fourth period, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labrador
Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its population. It is separated from the island of Newfoundland by the Strait of Belle Isle. It is the largest and northernmost geographical region in the four Atlantic provinces. Labrador occupies most of the eastern part of the Labrador Peninsula. It is bordered to the west and south by the province of Quebec. Labrador also shares a small land border with the territory of Nunavut on Killiniq Island. The indigenous peoples of Labrador include the Northern Inuit of Nunatsiavut, the Southern Métis of NunatuKavut, and the Innu of Nitassinan. Etymology Labrador is named after João Fernandes Lavrador, a Portuguese explorer who sailed along the coasts of the Labrador Peninsula in 1498–99. Kevin Major, '' As Near to Heaven by Sea: A Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montana
Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, and the Provinces and territories of Canada, Canadian provinces of Alberta, British Columbia, and Saskatchewan to the north. It is the List of U.S. states and territories by area, fourth-largest state by area, but the List of U.S. states and territories by population, eighth-least populous state and the List of U.S. states and territories by population density, third-least densely populated state. Its List of capitals in the United States, capital is Helena, Montana, Helena, while the List of municipalities in Montana, most populous city is Billings, Montana, Billings. The western half of the state contains numerous mountain ranges, while the eastern half is characterized by western prairie terrain and badlands, with smaller mountain ranges f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duluth Complex
The Duluth Complex, the related Beaver Bay Complex, and the associated North Shore Volcanic Group are rock formations which comprise much of the basement bedrock of the northeastern part of the U.S. state of Minnesota in central North America. The Duluth and Beaver Bay complexes are intrusive rocks formed about 1.1 billion years ago during the Midcontinent Rift; these adjoin and are interspersed with the extrusive rocks of the North Shore Volcanic Group produced during that same geologic event. These formations are part of the Superior Upland physiographic region of the United States, which is associated with the Laurentian Upland of the Canadian Shield, the core of the North American Craton. Location The Duluth Complex includes much of Minnesota's Arrowhead Region north of Lake Superior. From the west near Duluth, Minnesota, it arcs north and northeast to about 48° north latitude south of Knife Lake, proceeds east at that latitude some five to twenty kilometers distant from a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troctolite 76535
Troctolite 76535 is a lunar sample discovered and collected on the Apollo 17 mission in 1972 in the Taurus–Littrow valley. It has a mass of about and is about across at its widest point. It was collected by geologist astronaut Harrison Schmitt as part of a "rake sample" of lunar soil at Geology Station 6, near the base of the North Massif. Troctolite 76535 has been called the most interesting sample returned from the Moon. Description Troctolite 76535 is a coarse-grained plutonic rock that is believed to have had a slow cooling history. The rock originates from early in the Moon's history. Geologists have described it as a coarse-grained olivine-plagioclase cumulate with a granular polygonal texture. Olivine and plagioclase are of about equal quantities within 76535, while the remaining approximately 4% is made up of primarily orthopyroxene. According to early studies, the sample cooled at a depth of about , as well as its reequilibration and annealing. Later work indicate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rùm
Rùm (), a Scottish Gaelic language, Scottish Gaelic name often Anglicisation, anglicised to Rum ( ), is one of the Small Isles of the Inner Hebrides, off the west coast of Scotland, in the district of Lochaber. For much of the 20th century the name became Rhum, a spelling invented by the former owner, George Bullough, 1st Baronet Bullough, Sir George Bullough, because he did not relish the idea of having the title "Laird of Rum". It is the largest of the Small Isles, and the 15th largest Scottish island, and is inhabited by 40 people, all of whom live in the hamlet of Kinloch, Rùm, Kinloch on the east coast. The island has been inhabited since the 8th millennium BC and provides some of the earliest known evidence of human occupation in Scotland. The early Celts, Celtic and Norsemen, Norse settlers left only a few written accounts and artefacts. From the 12th to 13th centuries on, the island was held by various clans including the Clan MacLean, MacLeans of Coll. The population ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfide
Sulfide (also sulphide in British English) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to large families of inorganic and organic compounds, e.g. lead sulfide and dimethyl sulfide. Hydrogen sulfide (H2S) and bisulfide (HS−) are the conjugate acids of sulfide. Chemical properties The sulfide ion does not exist in aqueous alkaline solutions of Na2S. Instead sulfide converts to hydrosulfide: :S2− + H2O → SH− + OH− Upon treatment with an acid, sulfide salts convert to hydrogen sulfide: :S2− + H+ → SH− :SH− + H+ → H2S Oxidation of sulfide is a complicated process. Depending on the conditions, the oxidation can produce elemental sulfur, polysulfides, polythionates, sulfite, or sulfate. Metal sulfides react with halogens, forming sulfur and metal salts. :8 MgS + 8 I2 → S8 + 8 MgI2 Metal de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merensky Reef
The Merensky Reef is a layer of igneous rock in the Bushveld Igneous Complex (BIC) in the North West, Limpopo, Gauteng and Mpumalanga provinces of South Africa which together with an underlying layer, the Upper Group 2 Reef (UG2), contains most of the world's known reserves of platinum group metals (PGMs) or platinum group elements (PGEs)—platinum, palladium, rhodium, ruthenium, iridium and osmium. The Reef is 46 cm thick and bounded by thin chromite seams or stringers. The composition consists predominantly of cumulate rocks, including leuconorite, anorthosite, chromitite, and melanorite. Composition The UG2 Reef, the composition of which is relatively consistent throughout the BIC, is rich in chromite. However, the UG2 Reef lacks the Merensky's gold, copper and nickel by-products, though its reserves may be almost twice those of the Merensky Reef. Overall, the Merensky Reef is observed to be a lower layer composed of anorthosite or norite with a thin layer of chromiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
