|
Ankaramite
Ankaramite is volcanic rock type of mafic composition. It is a dark porphyritic variety of basanite containing abundant pyroxene and olivine phenocrysts.https://dialnet.unirioja.es/descarga/articulo/281059.pdf Luis Enrique Ortiz Hernández, ''An Arc Ankaramite Occurrence in Central Mexico,'' Revista Mexicana de Ciencias Geológicas, volumen 17, número 1 2000, p. 34-44 It contains minor amounts of plagioclase and accessory biotite, apatite, and iron oxides. Its type locality is Ankaramy in Madagascar. It was first described in 1916. It is also found in the Sierra de Guanajuato of Central Mexico, the South Pacific on islands such as Tahiti, Rarotonga, Samoa and in the Zealandia Zealandia (pronounced ), also known as (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L., ..., Alexandra Volcanic Group. References Porphyrit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian. History The term ''mafic'' is a portmanteau of "magnesium" and "ferric" and was coined by Charles Whitman Cross, Joseph P. Iddings, Louis Valentine Pirsson, and Henry Stephens Washington in 1912. Cross' group had previously divided the major rock-forming minerals found in igneous rocks into ''salic'' minerals, such as quartz, feldspars, or feldspathoids, and ''femic'' minerals, such as olivine and pyroxene. However, micas and aluminium-rich amphiboles were excluded, while some calcium minerals containing little iron or magnesium, such as wollastonite or apatite, were included ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Locality (geology)
Type locality, also called type area, is the locality where a particular rock type, stratigraphic unit or mineral species is first identified. If the stratigraphic unit in a locality is layered, it is called a stratotype, whereas the standard of reference for unlayered rocks is the type locality. The term is similar to the term type site in archaeology or the term type specimen in biology. Examples of geological type localities Rocks and minerals * Aragonite: Molina de Aragón, Guadalajara, Spain * Autunite: Autun, France * Benmoreite: Ben More (Mull), Scotland * Blairmorite: Blairmore, Alberta, Canada * Boninite: Bonin Islands, Japan * Comendite: Comende, San Pietro Island, Sardinia * Cummingtonite: Cummington, Massachusetts * Dunite: Dun Mountain, New Zealand. * Essexite: Essex County, Massachusetts, US * Fayalite: Horta, Fayal Island, Azores, Portugal * Harzburgite: Bad Harzburg, Germany * Icelandite: Thingmuli (Þingmúli), Iceland * Ijolite: Iivaara, Kuusamo, Finl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyritic Rocks
Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all types of igneous rocks can display some degree of porphyritic texture. Most Porphyritic rocks have bimodal size ranges, meaning the rock is composed of two distinct sizes of crystal. In extrusive rocks, the phenocrysts are surrounded by a fine-grained (aphanitic) matrix or groundmass of volcanic glass or non-visible crystals, commonly seen in porphyritic basalt. Porphyritic intrusive rocks have a matrix with individual crystals easily distinguished with the eye, but one group of crystals appearing clearly much bigger than the rest, as in a porphyritic granite. The term comes from the Ancient Greek (), meaning "purple". Purple was the color of royalty, and the "imperial porphyry" was a deep purple igneous rock with large crystals of pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexandra Volcanic Group
The Alexandra Volcanic Group (also known as Alexandra volcanic lineament or Alexandra Volcanics) is a chain of extinct calc-alkalic basaltic stratovolcanoes that were most active between 2.74 to 1.60 million years ago but is now known to have had more recent activity between 1.6 to 0.9 million years ago. They extend inland from Mount Karioi near Raglan with Mount Pirongia being the largest, with Pukehoua on the eastern slopes of Pirongia, Kakepuku, Te Kawa, and Tokanui completing the definitive lineament. The associated, but usually separated geologically basaltic monogenetic Okete volcanic field (also known as the Okete Volcanic Formation or Okete Volcanics), lies mainly between Karioi and Pirongia but extends to the east and is quite scattered. Geology The chain extends in the Alexandra volcanic lineament, an alignment striking north-west to south-east over in length and is an example of backarc, intraplate basaltic volcanism that is very rare on land. This is because the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zealandia
Zealandia (pronounced ), also known as (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L., 2004, Evolving force balance during incipient subduction: Geochemistry, Geophysics, Geosystems, v. 5, Q07001, https://doi.org/10.01029/02003GC000681 It has been described variously as a submerged continent, a continental fragment (or microcontinent), and a continent. The name and concept for Zealandia was proposed by Bruce Luyendyk in 1995, and satellite imagery shows it to be almost the size of Australia. A 2021 study suggests Zealandia is 1 billion years old, about twice as old as geologists previously thought. By approximately 23 million years ago the landmass may have been completely submerged. Today, most of the landmass (94%) remains submerged beneath the Pacific Ocean. New Zealand is the largest part of Zealandia that is above sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samoa
Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands (Savai'i and Upolu); two smaller, inhabited islands (Manono Island, Manono and Apolima); and several smaller, uninhabited islands, including the Aleipata Islands (Nu'utele, Nu'ulua, Fanuatapu and Namua). Samoa is located west of American Samoa, northeast of Tonga (closest foreign country), northeast of Fiji, east of Wallis and Futuna, southeast of Tuvalu, south of Tokelau, southwest of Hawaii, and northwest of Niue. The capital city is Apia. The Lapita culture, Lapita people discovered and settled the Samoan Islands around 3,500 years ago. They developed a Samoan language and Samoan culture, Samoan cultural identity. Samoa is a Unitary state, unitary Parliamentary system, parliamentary democracy with 11 Administrative divisions of Samoa, administrative divisions. It is a sovereign state and a member of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rarotonga
Rarotonga is the largest and most populous of the Cook Islands. The island is volcanic, with an area of , and is home to almost 75% of the country's population, with 13,007 of a total population of 17,434. The Cook Islands' Parliament buildings and Rarotonga International Airport, international airport are on Rarotonga. Rarotonga is a very popular tourist destination with many resorts, hotels and motels. The chief town, Avarua, on the north coast, is the capital of the Cook Islands. Captain John Dibbs, master of the colonial brig ''Endeavour'', is credited as the European discoverer on 25 July 1823, while transporting the missionary Reverend John Williams (missionary), John Williams. Geography Rarotonga is a kidney-shaped volcanic island, in circumference, and wide on its longest (east-west) axis. The island is the summit of an extinct Pliocene or Pleistocene volcano, which rises 5000 meters from the seafloor. The island was formed between 2.3 to 1.6 million years ago, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tahiti
Tahiti (; Tahitian ; ; previously also known as Otaheite) is the largest island of the Windward group of the Society Islands in French Polynesia. It is located in the central part of the Pacific Ocean and the nearest major landmass is Australia. Divided into two parts, ''Tahiti Nui'' (bigger, northwestern part) and ''Tahiti Iti'' (smaller, southeastern part), the island was formed from volcanic activity; it is high and mountainous with surrounding coral reefs. Its population was 189,517 in 2017, making it by far the most populous island in French Polynesia and accounting for 68.7% of its total population. Tahiti is the economic, cultural and political centre of French Polynesia, an overseas collectivity and an overseas country of the French Republic. The capital of French Polynesia, Papeete, is located on the northwest coast of Tahiti. The only international airport in the region, Faaā International Airport, is on Tahiti near Papeete. Tahiti was originally settled by Pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Mexico covers ,Mexico ''''. . making it the world's 13th-largest country by are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanajuato
Guanajuato (), officially the Free and Sovereign State of Guanajuato ( es, Estado Libre y Soberano de Guanajuato), is one of the 32 states that make up the Federal Entities of Mexico. It is divided into 46 municipalities and its capital city is Guanajuato. Guanajuato is in central Mexico. It is bordered by the states of Jalisco to the west, Zacatecas to the northwest, San Luis Potosí to the north, Querétaro to the east, and Michoacán to the south. It covers an area of . The state is home to several historically important cities, especially those along the "Bicentennial Route", which retraces the path of Miguel Hidalgo y Costilla's insurgent army at the beginning of the Mexican War of Independence. This route begins at Dolores Hidalgo, and passes through the Sanctuary of Atotonilco, San Miguel de Allende, Celaya, and the capital of Guanajuato. Other important cities in the state include León, the state's biggest city, Salamanca, and Irapuato. The first town established ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa across the Mozambique Channel. At Madagascar is the world's List of island countries, second-largest island country, after Indonesia. The nation is home to around 30 million inhabitants and consists of the island of Geography of Madagascar, Madagascar (the List of islands by area, fourth-largest island in the world), along with numerous smaller peripheral islands. Following the prehistoric breakup of the supercontinent Gondwana, Madagascar split from the Indian subcontinent around 90 million years ago, allowing native plants and animals to evolve in relative isolation. Consequently, Madagascar is a biodiversity hotspot; over 90% of wildlife of Madagascar, its wildlife is endemic. Human settlement of Madagascar occurred during or befo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ankaramy Be
Ankaramy Be (also Ankaramy or Ankaramibe) is a town and commune ( mg, kaominina) in Madagascar. It belongs to the district of Analalava, which is a part of Sofia Region. The population of the commune was estimated to be approximately 23,000 in 2001 commune census. Primary and junior level secondary education are available in town. The majority 90% of the population of the commune are farmers, while an additional 9% receives their livelihood from raising livestock. The most important crop is rice, while other important products are coffee and pepper. Services provide employment for 1% of the population. Ankaramy Be is the type locality of a type of volcanic rock called ankaramite Ankaramite is volcanic rock type of mafic composition. It is a dark porphyritic variety of basanite containing abundant pyroxene and olivine phenocrysts.https://dialnet.unirioja.es/descarga/articulo/281059.pdf Luis Enrique Ortiz Hernández, ''An .... References and notes Populated places ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Guanajuato"){kind=logo}