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Geology Of The Central African Republic
The geology of Central African Republic (CAR) is part of the broader geology of Africa. CAR occupies a swath of ancient rocks, dating back billions of years that record significant aspects of Earth history and yield minerals vital to the country's small economy. Geologic history Southern CAR is part of the Congo craton, Congo Craton, a stable landmass dating to the Archean that was once fused with the Sao Francisco Craton until the opening of the South Atlantic Ocean. Some of the oldest rocks in CAR belong to the 3.4 billion year old Bomu Complex which includes migmatite gneiss and metasedimentary schist spanning from the Democratic Republic of Congo. The Congo Craton once functioned as a small continent, until it was joined with Siberia during the formation of the supercontinent Columbia (supercontinent), Columbia, between 2.1 and 1.8 billion years ago. A string of large igneous province (LIP) volcanic events took place in three pulses during the time that the craton was part of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bangui Magnetic Anomaly
The Bangui magnetic anomaly is a local variation in the Earth's magnetic field centered at Bangui, the capital of the Central African Republic. The magnetic anomaly is roughly elliptical, about , and covers most of the country, making it one of the "largest and most intense crustal magnetic anomalies on the African continent". The anomaly was discovered in the late 1950s, explored in the 1970s, and named in 1982. Its origin remains unclear. History In 1962, Raymond Godivier and Lucien Le Donche reported on a magnetic anomaly in the Central African Republic, which they identified by analyzing their surface magnetic activity data of 1956. These results were confirmed and built upon by the high-altitude aeromagnetic surveys carried out by the US Naval Oceanographic Office, as well as by the satellite measurements conducted in 1964 with Cosmos 49 and in the 1970s with the Orbiting Geophysical Observatory at altitudes. This data was combined in 1973 and yielded a spatial map of Ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenstone Belt
Greenstone belts are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that occur within Archaean and Proterozoic cratons between granite and gneiss bodies. The name comes from the green hue imparted by the colour of the metamorphic minerals within the mafic rocks: The typical green minerals are chlorite, actinolite, and other green amphiboles. Greenstone belts also often contain ore deposits of gold, silver, copper, zinc, and lead. A greenstone belt is typically several dozens to several thousand kilometres long. Typically, a greenstone belt within the greater volume of otherwise homogeneous granite-gneiss within a craton contains a significantly larger degree of heterogeneity and complications and forms a tectonic marker far more distinct than the much more voluminous and homogeneous granites. Additionally, a greenstone belt contains far more information on tectonic and metamorphic events, deformations, and paleogeologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dekoa Belt
Dekoa (Dékoua) is a sub-prefecture and town in the Kémo Prefecture of the south-eastern Central African Republic. History In the nineteenth century freebooter Rabih az-Zubayr brought Dekoa under his sway and made it a part of the Bornu Empire. In March 1899, the sultan captured and imprisoned the explorer Ferdinand de Béhagle at Dekoa. Béhagle was subsequently hanged after the French battled the sultan's troops at Kouno in October of that year. Civil war On 28 December 2012 Séléka rebels took control of Dekoa. On 8 April 2014 Anti-balaka attacked ex-Seleka positions in Dekoa resulting in 30 deaths. On 17 August 2018 FACA was deployed in Dekoa. Three UN peacekeepers from Burundi were killed in Dekoa and Bakouma on December 26, 2020, one day before the 2020 Central African general election. Three Anti-balaka leaders in Kaga-Bandoro Kaga-Bandoro (formerly Fort-Crampel and Crampel) is a market town and capital of the Nana-Grébizi prefecture of the Central African Repu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gneiss
Gneiss (pronounced ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures ranging from 2 to 15 kbar, sometimes even more, and temperatures over 300 °C (572 °F). Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct Cleavage (geology), cleavage. Gneisses are common in the ancient crust of Continental Shield, continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss. Description image:Orthogneiss Geopark.jpg, Orthogneiss from the Czech Republic In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding (gneissic banding) but poorly developed schistosity and indistinct Cleavage (geology), cleavage. In other words, it i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphibolite
Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure. The small flakes of black and white in the rock often give it a salt-and-pepper appearance. Amphibolite frequently forms by metamorphism of mafic igneous rocks, such as basalt. However, because metamorphism creates minerals entirely based upon the chemistry of the protolith, certain 'dirty marls' and volcanic sediments may also metamorphose to an amphibolite assemblage. Deposits containing dolomite and siderite also readily yield amphibolite ( tremolite-schist, grunerite-schist, and others) especially where there has been a certain amount of contact metamorphism by adjacent granitic masses. Metamorphosed basalt (metabasalt) creates ''ortho-amphibolite'' and other chemically appropriate lithologies create ''par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tillite
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is diagnostic of till. image:Glacial till exposed in roadcut-750px.jpg, Glacial till with tufts of grass Till or glacial till is unsorted glacier, glacial sediment. Till is derived from the erosion and entrainment of material by the moving ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial and ground moraines. Till is classified into primary deposits, laid down directly by glaciers, and secondary deposits, reworked by fluvial transport and other processes. Description Till is a form of '' glacial drift'', which is rock material transported by a glacier and deposited directly from the ice or from running water emerging from the ice. It is distinguished from other forms of drift in that it is dep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
