|
Barberton Greenstone Belt
The Barberton Greenstone Belt is situated on the eastern edge of Kaapvaal Craton in South Africa. It is known for its gold mineralisation and for its komatiites, an unusual type of ultramafic volcanic rock named after the Komati River that flows through the belt. Some of the oldest exposed rocks on Earth (greater than 3.6 Ga) are located in the Barberton Greenstone Belt of the Eswatini–Barberton areas and these contain some of the oldest traces of life on Earth, second only to the Isua Greenstone Belt of Western Greenland. The Makhonjwa Mountains make up 40% of the Baberton belt. History and description In April 2014, scientists reported finding evidence of the largest terrestrial meteor impact event to date near the Barberton Greenstone Belt. They estimated the impact occurred about 3.26 billion years ago (during the Paleoarchean era of the Archean eon of the Precambrian supereon) and that the impactor was approximately wide, roughly five times larger than the impactor re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South African Greenstone Belt
South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþaz'' ("south"), possibly related to the same Proto-Indo-European root that the word ''sun'' derived from. Some languages describe south in the same way, from the fact that it is the direction of the sun at noon (in the Northern Hemisphere), like Latin meridies 'noon, south' (from medius 'middle' + dies 'day', cf English meridional), while others describe south as the right-hand side of the rising sun, like Biblical Hebrew תֵּימָן teiman 'south' from יָמִין yamin 'right', Aramaic תַּימנַא taymna from יָמִין yamin 'right' and Syriac ܬܰܝܡܢܳܐ taymna from ܝܰܡܝܺܢܳܐ yamina (hence the name of Yemen, the land to the south/right of the Levant). Navigation By convention, the ''bottom or down-facing side'' of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chicxulub Crater
The Chicxulub crater () is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore near the community of Chicxulub, after which it is named. It was formed slightly over 66 million years ago when a large asteroid, about in diameter, struck Earth. The crater is estimated to be in diameter and in depth. It is the second largest confirmed impact structure on Earth, and the only one whose peak ring is intact and directly accessible for scientific research. The crater was discovered by Antonio Camargo and Glen Penfield, geophysicists who had been looking for petroleum in the Yucatán Peninsula during the late 1970s. Penfield was initially unable to obtain evidence that the geological feature was a crater and gave up his search. Later, through contact with Alan R. Hildebrand in 1990, Penfield obtained samples that suggested it was an impact feature. Evidence for the crater's impact origin includes shocked quartz, a gravity anomaly, and tektites ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barberton Mountains
The Makhonjwa Mountains are a range of small mountains and hills that covers an area of , about 80% in Mpumalanga, a province of South Africa, and the remainder in neighbouring Eswatini. It constitutes 40% of the Barberton Greenstone Belt. Geography The area ranges in altitude from above mean sea level. It has a number of rocky hills, with moist grassy uplands and forested valleys. The region lies within the Barberton centre of endemism. The mean annual precipitation is , with wet summers and dry winters. Geology The mountains lie on the eastern edge of the Kaapvaal Craton. The range is best known for having some of the oldest exposed rocks on Earth, estimated to be between 3.2 and 3.6 billion years (Ga) old, dating from the Paleoarchean. The mountain range's extreme age and exceptional preservation have yielded some of the oldest undisputed signs of life on Earth and provide insight into the hostile nature of the Precambrian#Life forms, Precambrian environment under which this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accretion (geology)
Accretion, in geology, is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses. The added material may be sediment, volcanic arcs, seamounts, oceanic crust or other igneous features. Description Accretion involves the addition of material to a tectonic plate via subduction, the process by which one plate is forced under the other when two plates collide. The plate which is being forced down, the subducted plate, is pushed against the upper, over-riding plate. Sediment on the ocean floor of the subducting plate is often scraped off as the plate descends. This accumulated material is called an accretionary wedge (or accretionary prism), which is pushed against and attaches to the upper plate. In addition to accumulated ocean sediments, volcanic island arcs or seamounts present on the subducting plate may be amalgamated onto existing continental crust on the upper plate, increasing the continental ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barberton, South Africa
Barberton is a town in the Mpumalanga province of South Africa, which has its origin in the 1880s gold rush in the region. It is situated in the De Kaap Valley and is fringed by the Makhonjwa Mountains. It is south of Mbombela and east of Johannesburg. Barberton was the seat of the Umjindi Local Municipality until the day of the 2016 Municipal Elections, when the Umjindi Local Municipality was merged into the Mbombela Local Municipality. History Prehistoric The mountains around Barberton are amongst the oldest in the world, dating back 3.5 billion years, and these mountains include some of the oldest exposed rocks on the planet. These volcanic rocks, which scientists call the Barberton Greenstone Belt, have given direct evidence of the conditions of life on the surface of the very early Earth. In the satellite image, the bare rocks of mountain peaks appear as a pale gray-green, accentuated by the sharp relief of sunlit slopes and their shadows. Deeper shades of green ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pluton
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and compositions, illustrated by examples like the Palisades Sill of New York and New Jersey; the Henry Mountains of Utah; the Bushveld Igneous Complex of South Africa; Shiprock in New Mexico; the Ardnamurchan intrusion in Scotland; and the Sierra Nevada Batholith of California. Because the solid country rock into which magma intrudes is an excellent insulator, cooling of the magma is extremely slow, and intrusive igneous rock is coarse-grained (phaneritic). Intrusive igneous rocks are classified separately from extrusive igneous rocks, generally on the basis of their mineral content. The relative amounts of quartz, alkali feldspar, plagioclase, and feldspathoid is particularly important in classifying intrusive igneous rocks. Intrusions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own distinctive geologic history, which is different from that of the surrounding areas—hence the term "exotic" terrane. The suture zone between a terrane and the crust it attaches to is usually identifiable as a fault. A sedimentary deposit that buries the contact of the terrane with adjacent rock is called an overlap formation. An igneous intrusion that has intruded and obscured the contact of a terrane with adjacent rock is called a stitching pluton. Older usage of ''terrane'' simply described a series of related rock formations or an area having a preponderance of a particular rock or rock groups. Overview A tectonostratigraphic terrane is not necessarily an independent microplate in origin, since it may not contain the full thickness ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syenite
Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proportions of components and smaller amounts of felsic material than most granites; those are classed as being of . The equivalent of syenite is |
Monzogranite
Monzogranites are biotite granite rocks that are considered to be the final fractionation product of magma. Monzogranites are characteristically felsic (SiO2 > 73%, and FeO + MgO + TiO2 < 2.4), weakly (Al2O3/ (CaO + Na2O + K2O) = 0.98–1.11), and contain , , and as accessory |
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] |
Barberton Etm 2001121 Lrg
Barberton may refer to: * Barberton, Mpumalanga, South Africa * Barberton, Ohio, United States * Barberton, Washington, United States * Barberton, Western Australia * Barberton Greenstone Belt The Barberton Greenstone Belt is situated on the eastern edge of Kaapvaal Craton in South Africa. It is known for its gold mineralisation and for its komatiites, an unusual type of ultramafic volcanic rock named after the Komati River that flows ... {{disambiguation, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megatsunami
A megatsunami is a very large wave created by a large, sudden displacement of material into a body of water. Megatsunamis have quite different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activity (movement of the earth's plates) and therefore occur along plate boundaries and as a result of earthquakes and the subsequent rise or fall in the sea floor that displaces a volume of water. Ordinary tsunamis exhibit shallow waves in the deep waters of the open ocean that increase dramatically in height upon approaching land to a maximum run-up height of around in the cases of the most powerful earthquakes. By contrast, megatsunamis occur when a large amount of material suddenly falls into water or anywhere near water (such as via a meteor impact or volcanic activity). They can have extremely large initial wave heights ranging from hundreds and possibly up to thousands of metres, far beyond the height of any ordinary tsunami. These giant wave hei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.png "Click for more on -> Megatsunami")