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Sturgeon Lake Caldera
Sturgeon Lake Caldera is a large extinct caldera complex in Kenora District of Northwestern Ontario, Canada. It is one of the world's best preserved mineralized Neoarchean caldera complexes, containing well-preserved mafic-intermediate pillow lavas, pillow breccias, hyaloclastite and peperites, submarine lava domes and dome-associated breccia deposits. The complex is some 2.7 billion years old Retrieved on 2007-07-20 with a minimum length of . Geology The Sturgeon Lake Caldera contains a well preserved north facing homoclinal chain of |
List Of Volcanoes In Canada
List of volcanoes in Canada is an incomplete list of volcanoes found in Mainland Canada, in the Canadian islands and in Canadian waters. All but one province, Prince Edward Island, have at least one volcano. Alberta British Columbia New Brunswick Newfoundland and Labrador Northwest Territories Nova Scotia Nunavut Ontario Quebec Saskatchewan Yukon See also * Outline of Canada * Bibliography of Canada * Index of Canada-related articles * Volcanism of Canada ** Volcanism of Northern Canada ** Volcanism of Western Canada ** Volcanism of Eastern Canada ** List of Northern Cordilleran volcanoes * List of mountains in Canada * List of Cascade volcanoes External links Catalogue of Canadian Volcanoes {{Canadian volcanism Canada Volcanoes Volcanoes Volcanoes A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenschist Facies
Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically and 2–10 kilobars (). Greenschists commonly have an abundance of green minerals such as chlorite, serpentine, and epidote, and platy minerals such as muscovite and platy serpentine. The platiness gives the rock schistosity (a tendency to split into layers.) Other common minerals include quartz, orthoclase, talc, carbonate minerals and amphibole (actinolite). Greenschist is a general field petrologic term for metamorphic or altered mafic volcanic rock. In Europe, the term ''prasinite'' is sometimes used. A ''greenstone'' is sometimes a greenschist but can also be rock types without any schistosity, especially metabasalt (spilite). However, basalts may remain quite black if primary pyroxene does not revert to chlorite or actinolite. To qualify for the name a rock must also exhibit schistosity or some foliation or layering. The rock is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calderas Of Ontario
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is gone. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur each century, the formation of a caldera is a rare event, occurring only a few times per century. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018. Etymology The term ''caldera'' comes from Spanish ', and Latin ', meaning "coo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanism Of Eastern Canada
The volcanology of Eastern Canada includes the hundreds of volcanic areas and extensive lava formations in Eastern Canada. The region's different volcano and lava types originate from different tectonic settings and types of volcanic eruptions, ranging from passive lava eruptions to violent explosive eruptions. Eastern Canada has very large volumes of magmatic rock called large igneous provinces. They are represented by deep-level plumbing systems consisting of giant dike swarms, sill provinces and layered intrusions. The most capable large igneous provinces in Eastern Canada are Archean (3,800-2,500 million years ago) age greenstone belts containing a rare volcanic rock called komatiite. Greenstone belts Abitibi greenstone belt The 2,677 million year old Abitibi greenstone belt in Ontario and Quebec is one of the largest Archean greenstone belts on Earth and one of the youngest parts of the Superior craton which sequentially forms part of the Canadian Shield. Komatii ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanism Of Canada
Volcanic activity is a major part of the geology of Canada and is characterized by many types of volcanic landform, including lava flows, volcanic plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes, and maars, along with less common volcanic forms such as tuyas and subglacial mounds. Though Canada's volcanic history dates back to the Precambrian eon, at least 3.11 billion years ago, when its part of the North American continent began to form, volcanism continues to occur in Western and Northern Canada in modern times, where it forms part of an encircling chain of volcanoes and frequent earthquakes around the Pacific Ocean called the Pacific Ring of Fire. Because volcanoes in Western and Northern Canada are in relatively remote and sparsely populated areas and their activity is less frequent than with other volcanoes around the Pacific Ocean, Canada is commonly thought to occupy a gap in the Ring of Fire between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanogenic Massive Sulfide Ore Deposit
Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and created by volcanic-associated hydrothermal events in submarine environments. These deposits are also sometimes called volcanic-hosted massive sulfide (VHMS) deposits. The density generally is 4500 kg/m3. They are predominantly stratiform accumulations of sulfide minerals that precipitate from hydrothermal fluids on or below the seafloor in a wide range of ancient and modern geological settings. In modern oceans they are synonymous with sulfurous plumes called black smokers. They occur within environments dominated by volcanic or volcanic derived (e.g., volcano-sedimentary) rocks, and the deposits are coeval and coincident with the formation of said volcanic rocks. As a class, they represent a significant source of the world's copper, zinc, lead, gold and silver ores, with cobalt, tin, barium, sulfur, selenium, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lapilli
Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range from in diameter. A pyroclastic particle greater than 64 mm in diameter is known as a volcanic bomb when molten, or a volcanic block when solid. Pyroclastic material with particles less than 2 mm in diameter is referred to as volcanic ash. Formation Lapilli are spheroid-, teardrop-, dumbbell- or button-shaped droplets of molten or semi-molten lava ejected from a volcanic eruption that fall to earth while still at least partially molten. These granules are not accretionary, but instead the direct result of liquid rock cooling as it travels through the air. Lapilli tuffs are a very common form of volcanic rock typical of rhyolite, andesite and dacite pyroclastic eruptions, where thick layers of lapilli can be deposited during a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous (for example, ''tuffaceous sandstone''). Tuff composed of sandy volcanic material can be referred to as volcanic sandstone. Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the ''moai'' statues on Easter Island. Tuff can be classified as either igneous or sedimentary rock. It is usually studied in the context of igneous petrology, although it is sometimes described using sedimentological terms. Tuff is often erroneously called tufa in guidebooks and in television programmes. Volcanic ash The material that is expelled in a volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite. Rhyolitic magma is extremely viscous, due to its high silica content. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been extensively used for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil amendment. Description Rhyolite i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyodacite
Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rapid cooling of lava relatively rich in silica and low in alkali metal oxides. Description Under IUGS guidelines, rhyodacites are not formally defined in either the QAPF classification, used to classify igneous rocks by their mineral content, or the TAS classification, used to classify volcanic rocks chemically. However, the IUGS allows the use of the term to describe rocks close to the boundary between the rhyolite and dacite fields in each classification scheme. Rhyodacite then describes a fine-grained igneous rock containing between 20% and 60% quartz and in which plagioclase makes up about two-thirds of the total feldspar content. Such a rock will contain between 69% and 72% silica by weight. The U.S. Geological Survey defines rhyodacite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Felsite
Felsite is a very fine-grained volcanic rock that may or may not contain larger crystals. Felsite is a field term for a light-colored rock that typically requires petrographic examination or chemical analysis for more precise definition. Color is generally white through light gray, or red to tan and may include any color except dark gray, green or black (the colors of trap rock). The mass of the rock consists of a fine-grained matrix of felsic materials, particularly quartz, sodium and potassium feldspar, and may be termed a quartz felsite or quartz porphyry if the quartz phenocrysts are present. This rock is typically of extrusive origin, formed by compaction of fine volcanic ash, and may be found in association with obsidian and rhyolite. In some cases, it is sufficiently fine-grained for use in making stone tools. Its fine texture and felsic components allow for good knapped pieces, much like working chert, producing conchoidal fracture. Dendritic manganese oxides such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur as dissolved minerals precipitate from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
