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Mount Titiraupenga
Titiraupenga (also known as Mount Titiraupenga) is an extinct high basaltic andesite stratovolcano on whose southern slopes is located the geographical centre of the North Island of New Zealand. It is in the Pureora Forest Park between Lake Taupō and Te Kuiti on the North Island Volcanic Plateau in New Zealand. The area of the mountain is in a scenic reserve that is "recognised as one of the finest rain forests in the world". Geography The mountain is covered in native forest and is in the southern Waikato region. Geology Mount Titiraupenga has a prominence above the surrounding countryside of about and a diameter of about . It is to the north east of a larger stratovolcano, Mount Pureora, and both are located to the south of the extinct Mangakino caldera on a basement of Waipapa composite terrane. The basaltic andesite lavas are made up of plagioclase, clinopyroxene and orthopyroxene, with rare olivine and hornblende phenocrysts with an age of 1.89 ± 0.02 Ma. Acce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waikato
Waikato () is a Regions of New Zealand, local government region of the upper North Island of New Zealand. It covers the Waikato District, Waipa District, Matamata-Piako District, South Waikato District and Hamilton, New Zealand, Hamilton City, as well as Hauraki Plains, Hauraki, Coromandel Peninsula, the northern King Country, much of the Taupō District, and parts of Rotorua, Rotorua District. It is governed by the Waikato Regional Council. The region stretches from Coromandel Peninsula in the north, to the north-eastern slopes of Mount Ruapehu in the south, and spans the North Island from the west coast, through the Waikato and Hauraki to Coromandel Peninsula on the east coast. Broadly, the extent of the region is the Waikato River catchment. Other major catchments are those of the Waihou River, Waihou, Piako River, Piako, Awakino River (Waikato), Awakino and Mokau River, Mokau rivers. The region is bounded by Auckland Region, Auckland on the north, Bay of Plenty on the east ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinopyroxene
The pyroxenes (commonly abbreviated to ''Px'') are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents calcium (Ca), sodium (Na), iron (Fe II) or magnesium (Mg) and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium (Cr), aluminium (Al), magnesium (Mg), cobalt (Co), manganese (Mn), scandium (Sc), titanium (Ti), vanadium (V) or even iron (Fe II) or (Fe III). Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a common structure consisting of single chains of silica tetrahedra. Pyroxenes that crystallize in the monoclinic system are known as clinopyroxenes and those that crystallize in the orthorhombic system are known as orthopyroxenes. The name ''pyroxene'' is derived from the Ancient Greek words for 'fire' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanoes Of Waikato
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, volcanoes are most often found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, deep in the Earth. This results in hotspot volcanism, of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide pa ... [...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] |
Dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz. Dacite is relatively common, occurring in many tectonic settings. It is associated with andesite and rhyolite as part of the subalkaline volcanic rock, subalkaline tholeiite, tholeiitic and calc-alkaline magma series. Composition Dacite consists mostly of plagioclase feldspar and quartz with biotite, hornblende, and pyroxene (augite or enstatite). The quartz appears as rounded, corroded phenocrysts, or as an element of the ground-mass. The plagioclase in dacite ranges from oligoclase to andesine and labradorite. Sanidine occurs, although in small proportions, in some dacites, and when abundant gives rise to rocks that form rhyodacite, transitions to the rhyolites. The rel ... [...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] |
Ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrounding atmosphere. New Zealand geologist Patrick Marshall (1869-1950) coined the term ''ignimbrite'' from the Latin ''igni-'' [fire] and ''imbri-'' [rain]. Ignimbrites are made of a very poorly sorted mixture of volcanic ash (or tuff when Lithification, lithified) and pumice lapilli, commonly with scattered lithic fragments. The ash is composed of glass shards and crystal fragments. Ignimbrites may be loose and unconsolidated, or lithified (solidified) rock called lapilli-tuff. Near the volcanic source, ignimbrites often contain thick accumulations of lithic blocks, and distally, many show meter-thick accumulations of rounded cobbles of pumice. Ignimbrites may be white, grey, pink, beige, brown, or black depending on their composition and d ... [...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] |
List Of Volcanoes In New Zealand
This is a partial list of active, dormant, and extinct volcanoes in New Zealand. Kermadec Arc and Havre Trough North Island Taupō Volcanic Zone Elsewhere Mangakino Culdera South Island Other Ross Dependency New Zealand also has ''de facto'' administration over Ross Dependency in Antarctica, which contains the following volcanoes: References External links {{GeoGroupTemplateNew Zealand's Volcanoesat GNS Science New Zealand 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, volcanoes are most often found where tectonic plates a ... Geography of the Kermadec Islands ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State Highway 32 (New Zealand)
State Highway 32 (SH 32) is a New Zealand state highway in the Central North Island. It forms part of a western traverse of Lake Taupō and a less busy alternative to , avoiding Taupō. Route description The route begins at SH 1 in Tokoroa and travels west along Maraetai Road, leaving Tokoroa where the road angles in a more southerly direction through the Kinleith Forest. It eventually meets at a three way junction. From here both SH 32 and SH 30 share a short concurrency (road), concurrency of , crossing the Waikato River over the Whakamaru Dam. Shortly after reaching the locality of Whakamaru, SH 32 leaves the concurrency and continues south. The highway continues for the remaining until it reaches Kuratau Junction and terminates with . From there, motorists can continue eastbound to reach SH 1 and complete the alternative north–south route. Major intersections History SH 32, when first established, consisted of only the section be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State Highway 30 (New Zealand)
State Highway 30 (SH 30) is a New Zealand state highway, linking the Waikato and Bay of Plenty towns of Te Kuiti, Mangakino, Rotorua, and Whakatane. At 219 kilometres, SH 30 is New Zealand's fifth longest provincial (two-digit) state highway, after SH 25, SH 35, SH 73, and SH 94. With the exception of , it has junctions with every national (one-digit) state highway in the North Island. SH 30 has the most concurrencies of all the state highways. It shares sections with, from west to east, , , , (albeit briefly), and . Route SH 30 starts in the southern end of the Waikato town of Te Kuiti at an intersection with . At first, SH 30 follows the North Island Main Trunk railway south-east as far as Benneydale. The highway then leaves the railway and turns east, crossing into Manawatū-Whanganui briefly as it passes through the Pureora Forest Park. The road now turns north-east and heads for the Waikato River. Near Mangakino, SH 30 turns sharply south-east, and bypas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenocryst
300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter 2.3 cm) for scale. A phenocryst is an early forming, relatively large and usually conspicuous crystal distinctly larger than the grains of the rock groundmass of an igneous rock. Such rocks that have a distinct difference in the size of the crystals are called porphyries, and the adjective porphyritic is used to describe them. Phenocrysts often have euhedral forms, either due to early growth within a magma, or by post-emplacement recrystallization. Normally the term ''phenocryst'' is not used unless the crystals are directly observable, which is sometimes stated as greater than .5 millimeter in diameter. Phenocrysts below this level, but still larger than the groundmass crystals, are termed ''microphenocrysts''. Very large phenocrysts a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
