|
Tephritic Phonolite
Tephriphonolite or tephri-phonolite is a mafic to intermediate extrusive igneous rock in composition between phonotephrite and phonolite. It contains 9–14% alkali content and 48–57% silica content (see TAS diagram). Tephriphonolite is roughly equivalent to tephritic phonolite of the QAPF classification. Tephriphonolite has been found, for example, at Colli Albani volcano in Italy and in the Asunción Rift of Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli .... References {{Igneous-rock-stub Volcanic rocks Mafic rocks Intermediate rocks ... [...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 V. 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 in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Geological Survey
The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The agency also makes maps of planets and moons, based on data from U.S. space probes. The sole scientific agency of the U.S. Department of the Interior, USGS is a fact-finding research organization with no regulatory responsibility. It is headquartered in Reston, Virginia, with major offices near Lakewood, Colorado; at the Denver Federal Center; and in NASA Research Park in California. In 2009, it employed about 8,670 people. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on its hundredth anniversary, was "Earth Science in the Pub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Rocks
Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "pyroclastics," and these are also technically sedimentary rocks. Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface. Ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraguay
Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Bolivia to the northwest. It has a population of around 6.1 million, nearly 2.3 million of whom live in the Capital city, capital and largest city of Asunción, and its surrounding metro area. Spanish conquistadores arrived in 1524, and in 1537 established the city of Asunción, the first capital of the Governorate of the Río de la Plata. During the 17th century, Paraguay was the center of Reductions, Jesuit missions, where the native Guaraní people were converted to Christianity and introduced to European culture. After the Suppression of the Society of Jesus, expulsion of the Jesuits from Spanish territories in 1767, Paraguay increasingly became a peripheral colony. Following Independence of Paraguay, independence from Spain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asunción Rift
The Asunción Rift is a composite graben and rift in eastern Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli .... The rift is at some localities filled with up to 2500 m of sediments. The rift has a width of 40 to 25 km and can be divided in three segments. The western segment has a NW-SE strike and runs a length of over 90 km between the localities of Benjamin Aceval and Paraguarí. The central section runs from Paraguarí to Villarrica in an E-W direction and has a length of 70 km. The eastern section has a NW-SE orientation and a length of 40 km and runs from Villarrica to the Ybytyruzú Mountains. References Rifts and grabens Geology of Paraguay Mesozoic rifts and grabens {{Paraguay-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elsevier
Elsevier ( ) is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell (journal), Cell'', the ScienceDirect collection of electronic journals, ''Trends (journals), Trends'', the ''Current Opinion (Elsevier), Current Opinion'' series, the online citation database Scopus, the SciVal tool for measuring research performance, the ClinicalKey search engine for clinicians, and the ClinicalPath evidence-based cancer care service. Elsevier's products and services include digital tools for Data management platform, data management, instruction, research analytics, and assessment. Elsevier is part of the RELX Group, known until 2015 as Reed Elsevier, a publicly traded company. According to RELX reports, in 2022 Elsevier published more than 600,000 articles annually in over 2,800 journals. As of 2018, its archives contained over 17 million documents and 40,000 Ebook, e-books, with over one b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Geology
''Chemical Geology'' is an international peer-reviewed academic journal. The journal is affiliated with the European Association of Geochemistry and it is published by Elsevier., publishing both subscription and open access articles. The journal is a hybrid open-access journal. ''Chemical Geology'' publishes original research papers on isotope, isotopic and elemental geochemistry, geochronology and cosmochemistry. The journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the Biophysical environment, environment and cosmochemistry. References External links * * Elsevier academic journals Geochemistry journals Academic journals established in 1966 English-language journals {{geochem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colli Albani
The Alban Hills () are the caldera remains of a quiescent volcanic complex in Italy, located southeast of Rome and about north of Anzio. The high Monte Cavo forms a highly visible peak in the centre of the caldera, but the highest point is Maschio delle Faete approximately to the east of Cavo and taller. There are subsidiary calderas along the rim of the Alban Hills that contain the lakes Albano and Nemi. The hills are composed of peperino (lapis albanus), a variety of tuff that is useful for construction and provides a mineral-rich substrate for nearby vineyards. History The hills, especially around the shores of the lakes, have been popular since prehistoric times. From the 9th to 7th century BC, there were numerous villages (such as the legendary Alba Longa and Tusculum). The area was inhabited by the Latini during the 5th to 3rd centuries BC. The ancient Romans called Monte Cavo Albanus Mons. On the summit was the sanctuary of Jupiter Latiaris, in which the cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QAPF Diagram
A QAPF diagram is a doubled-triangle plot diagram used to classify igneous rocks based on their mineralogy. The acronym QAPF stands for "quartz, alkali feldspar, plagioclase, feldspathoid (foid)", which are the four mineral groups used for classification in a QAPF diagram. The percentages (ratios) of the Q, A, P and F groups are normalized, i.e., recalculated so that their sum is 100%. Origin QAPF diagrams are created by the International Union of Geological Sciences (IUGS): ''Subcommission on the Systematics of Igneous Rocks'' as fostered by Albert Streckeisen (whence their alternative name: Streckeisen diagrams). Geologists worldwide use the diagrams in classifying igneous, especially plutonic rocks. Usage QAPF diagrams are mostly used to classify plutonic rocks ( phaneritic rocks), and can be used to classify volcanic rocks ( aphanitic rocks) if modal mineralogical compositions have been determined (for an example, see basalt). But QAPF diagrams are ''not used'' to cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TAS Classification
TAS stands for Total Alkali Silica. The TAS classification can be used to assign names to many common types of volcanic rocks based upon the relationships between the combined alkali and silica contents. These chemical parameters are useful because the relative proportions of alkalis and silica are important in determining both normative mineralogy and actual mineralogy. The classification can be simple to use for rocks that have been chemically analyzed. Except for the following quotation from Johannsen (1937), this discussion is based upon Le Maitre et al (2002). Use of the TAS classification Before using the TAS or any other classification, some particular guidance by Johannsen (1937) should be kept in mind. :''Many and peculiar are the classifications that have been proposed for igneous rocks. Their variability depends in part upon the purpose for which each was intended, and in part upon the difficulties arising from the characters of the rocks themselves. The trouble is not w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermediate Composition
In igneous petrology, an intermediate composition refers to the chemical composition of a rock that has 51.563 wt% SiO2 being an intermediate between felsic and mafic compositions. Typical intermediate rocks include andesite and trachyandesite among volcanic rocks and diorite and granodiorite Granodiorite ( ) is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from gra ... among plutonic rocks. Geochemistry Igneous rocks Intermediate rocks {{geochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored. Silicon dioxide is a common fundamental constituent of glass. Structure In the majority of silicon dioxides, the silicon atom shows Tetrahedral molecular geometry, tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
