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Beebe Hydrothermal Vent Field
The Beebe Hydrothermal Vent Field (also known as the Piccard Vent Field) is located just south of Grand Cayman in the Caribbean, on the north side of the Mid-Cayman Spreading Centre in the Cayman Trough. Approximately south of Beebe is the Von Damm Vent Field. At nearly below sea level, Beebe is the world's deepest known hydrothermal vent site, and one of the few known in the abyssopelagic. The hydrothermal plume nicknamed "Piccard" was detected in 2010, and the Beebe site was confirmed later that year. The combined depth and vent fluid temperature make it a popular site for studying aqueous thermodynamics, high-pressure biology, and geochemistry. Expedition history The Beebe vent field was initially detected in October 2009 by CTD, Eh, and optical backscatter anomalies in the water column above the Mid-Cayman Rise aboard the R/V ''Cape Hatteras''. The team deployed HROV ''Nereus'' to conduct surveys which identified a double hydrothermal plume at and deep and subsequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mid-Cayman Rise
The Mid-Cayman Rise or Mid-Cayman Spreading Center is a relatively short (110 km long) divergent plate boundary in the middle of the Cayman Trough. It forms part of a dominantly transform boundary that is part of the southern margin to the North American Plate. It is an ultra-slow spreading center with an opening rate of 15–17 mm per year. Formation The Mid-Cayman Rise developed during the Eocene when the northern part of the Caribbean Plate collided with the Bahamas Platform, forcing the southern boundary to propagate southwards. This boundary initially formed as two strike-slip faults with a large left-stepping offset between them, generating a pull-apart basin. Continuing movement on the boundary and extension within the pull-apart led to the formation of an area of oceanic crust containing a north-south trending spreading center that remains active to the present day. When the spreading center formed, all the displacement on the Swan Islands Transform Fault w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrrhotite
Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is weakly magnetic. The magnetism decreases as the iron content increases, and troilite is non-magnetic.Vaughan, D. J.; Craig, J. R. "Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. . Structure Pyrrhotite exists as a number of polytypes of hexagonal or monoclinic crystal symmetry; several polytypes often occur within the same specimen. Their structure is based on the NiAs unit cell. As such, Fe occupies an octahedral site and the sulfide centers occupy trigonal prismatic sites. Materials with the NiAs structure often are non-stoichiometric because they lack up to 1/8th fraction of the metal ions, creating vacancies. One of such structures is pyrrhotite-4C (Fe7S8). Here "4" indicates that iron vacancies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrite
The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of ''fool's gold''. The color has also led to the nicknames ''brass'', ''brazzle'', and ''Brazil'', primarily used to refer to pyrite found in coal. The name ''pyrite'' is derived from the Greek language, Greek (), 'stone or mineral which strikes fire', in turn from (), 'fire'. In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel; Pliny the Elder described one of them as being brassy, almost certainly a reference to what we now call pyrite. By Georgius Agricola's time, , the term had become a generic term for all of the pyrite group, sulfide minerals. Pyrite is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scree
Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically have a concave upwards form, where the maximum inclination corresponds to the angle of repose of the mean debris particle size. The exact definition of scree in the primary literature is somewhat relaxed, and it often overlaps with both ''talus'' and ''colluvium''. The term ''scree'' comes from the Old Norse term for landslide, ''skriða'', while the term ''talus'' is a French word meaning a slope or embankment. In high-altitude arctic and subarctic regions, scree slopes and talus deposits are typically adjacent to hills and river valleys. These steep slopes usually originate from late-Pleistocene periglacial processes. Notable scree sites in Eastern North America include the Ice Caves at White Rocks National Recreation Area in southern Ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seafloor Massive Sulfide Deposits
Seafloor massive sulfide deposits or SMS deposits, are modern equivalents of ancient volcanogenic massive sulfide ore deposits or VMS deposits. The term has been coined by mineral explorers to differentiate the modern deposit from the ancient. SMS deposits were first recognized during the exploration of the deep oceans and the mid ocean ridge spreading centers in the early 1960s. Deep ocean research submersibles, bathyspheres and remote operated vehicles have visited and taken samples of black smoker chimneys, and it has been long recognised that such chimneys contain appreciable grades of Cu, Pb, Zn, Ag, Au and other trace metals. SMS deposits form in the deep ocean around submarine volcanic arcs, where hydrothermal vents exhale sulfide-rich mineralising fluids into the ocean. SMS deposits are laterally extensive and consist of a central vent mound around the area where the hydrothermal circulation exits, with a wide apron of unconsolidated sulfide silt or ooze which preci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Overseas Territories
The British Overseas Territories (BOTs), also known as the United Kingdom Overseas Territories (UKOTs), are fourteen dependent territory, territories with a constitutional and historical link with the United Kingdom. They are the last remnants of the former British Empire and do not form part of the United Kingdom itself. The permanently inhabited territories are internally Self-governance, self-governing, with the United Kingdom retaining responsibility for Defence (military), defence and foreign relations. Three of the territories are inhabited only by a transitory population of military or scientific personnel. All but one of the rest are listed by the Special Committee on Decolonization, UN Special Committee on Decolonization as United Nations list of non-self-governing territories, non-self-governing territories. All fourteen have the Monarchy of the United Kingdom, British monarch as head of state. three territories (the Falkland Islands, Gibraltar and the Akrotiri an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cayman Islands
The Cayman Islands () is a self-governing British Overseas Territory—the largest by population in the western Caribbean Sea. The territory comprises the three islands of Grand Cayman, Cayman Brac and Little Cayman, which are located to the south of Cuba and northeast of Honduras, between Jamaica and Mexico's Yucatán Peninsula. The capital city is George Town on Grand Cayman, which is the most populous of the three islands. The Cayman Islands is considered to be part of the geographic Western Caribbean Zone as well as the Greater Antilles. The territory is a major world offshore financial centre for international businesses and wealthy individuals, largely as a result of the state not charging taxes on any income earned or stored. With a GDP per capita of $91,392, the Cayman Islands has the highest standard of living in the Caribbean. Immigrants from over 130 countries and territories reside in the Cayman Islands. History No archaeological evidence for an indigenous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Territorial Waters
The term territorial waters is sometimes used informally to refer to any area of water over which a sovereign state has jurisdiction, including internal waters, the territorial sea, the contiguous zone, the exclusive economic zone, and potentially the extended continental shelf. In a narrower sense, the term is used as a synonym for the territorial sea. Baseline Normally, the baseline from which the territorial sea is measured is the low-water line along the coast as marked on large-scale charts officially recognized by the coastal state. This is either the low-water mark closest to the shore, or alternatively it may be an unlimited distance from permanently exposed land, provided that some portion of elevations exposed at low tide but covered at high tide (like mud flats) is within of permanently exposed land. Straight baselines can alternatively be defined connecting fringing islands along a coast, across the mouths of rivers, or with certain restrictions across the mou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endmember
An endmember (also end-member or end member) in mineralogy is a mineral that is at the extreme end of a mineral series in terms of purity of its chemical composition. Minerals often can be described as solid solutions with varying compositions of some chemical elements, rather than as substances with an exact chemical formula. There may be two or more endmembers in a group or series of minerals. For example, forsterite () and fayalite () are the two end-members of the olivine solid-solution series, varying in and in their chemical composition. So, the chemical formula of olivine can be better expressed as or . As another example, the tectosilicate feldspar can be described as a solid solution of the endmembers K-feldspar AlSi3O8 albite aAlSi3O8and anorthite aAl2Si2O8 Industrial Minerals Association. Retrieved on February 9, 2008. A specific feldspar can have varying quantities of potassium (K), sodium (Na) and calcium (Ca). See also * Larvikite Larv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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