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Lufilian Arc
The Lufilian Arc (or Lufilian Belt) is part of a system of orogenic belts in southern Africa formed during the Pan-African orogeny, a stage in the formation of the Gondwana supercontinent. It extends across eastern Angola, the Katanga Province of the southern Democratic Republic of the Congo and the northwest of Zambia. The arc is about long. It has global economic importance owing to its rich deposits of copper and cobalt. Evolution The Katanga Supergroup of Neoproterozoic sediments rests on a basement formed in the Paleoproterozoic or Mesoproterozoic eras. The lower basement is made of granites, gneisses and schists formed during the Eburnean age, about 2100–2000 Ma. The upper basement extends under part of the arc in Zambia and is mostly made of schists, quartzites and quartz-muscovite schists. The Kibaran orogeny deformed and metamorphosed the upper basement between 1350 Ma and 1100 Ma. The Katanga supergroup sediments are from to thick. Rifting between the Congo and Ka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zambia 3
Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most central point. Its neighbours are the Democratic Republic of the Congo to the north, Tanzania to the northeast, Malawi to the east, Mozambique to the southeast, Zimbabwe and Botswana to the south, Namibia to the southwest, and Angola to the west. The capital city of Zambia is Lusaka, located in the south-central part of Zambia. The nation's population of around 19.5 million is concentrated mainly around Lusaka in the south and the Copperbelt Province to the north, the core economic hubs of the country. Originally inhabited by Khoisan peoples, the region was affected by the Bantu expansion of the thirteenth century. Following the arrival of European exploration of Africa, European explorers in the eighteenth century, the British colonised the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schist
Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes or plates. This texture (geology), texture reflects a high content of platy minerals, such as micas, talc, chlorite group, chlorite, or graphite. These are often interleaved with more granular minerals, such as feldspar or quartz. Schist typically forms during regional metamorphism accompanying the process of mountain building (orogeny) and usually reflects a medium Metamorphism#Metamorphic grades, grade of metamorphism. Schist can form from many different kinds of rocks, including sedimentary rocks such as mudstones and igneous rocks such as tuffs. Schist metamorphosed from mudstone is particularly common and is often very rich in mica (a ''mica schist''). Where the type of the original rock (the protolith) is discernible, the schist is us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fold And Thrust Belt
A fold and thrust belt (FTB) is a series of mountainous foothills adjacent to an orogenic belt, which forms due to contractional tectonics. Fold and thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates outwards. Fold and thrust belts usually comprise both folds and thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...s, commonly interrelated. They are commonly also known as thrust-and-fold belts, or simply thrust-fold belts. Geometry Fold and thrust belts are formed of a series of sub-parallel thrust sheets, separated by major thrust faults. As the total shortening increases in a fold and thrust belt, the belt propagates into its foreland. New thrusts develop at the front of the belt, folding the older thrusts that have become i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticline (PSF)-vector
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the location where the curvature is greatest, and the limbs are the sides of the fold that dip away from the hinge. Anticlines can be recognized and differentiated from antiforms by a sequence of rock layers that become progressively older toward the center of the fold. Therefore, if age relationships between various rock strata are unknown, the term antiform should be used. The progressing age of the rock strata towards the core and uplifted center, are the trademark indications for evidence of anticlines on a geologic map. These formations occur because anticlinal ridges typically develop above thrust faults during crustal deformations. The uplifted core of the fold causes compression of strata that preferentially erodes to a deeper strati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithify
Diagenesis () is the process that describes physical change, physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition (geology), deposition. Increased pressure and temperature only start to play a role as sediments become buried much deeper in the Earth's crust. In the early stages, the transformation of poorly consolidated sediments into sedimentary rock (lithification) is simply accompanied by a reduction in porosity and water expulsion (clay sediments), while their main mineralogy, mineralogical assemblages remain unaltered. As the rock is carried deeper by further deposition above, its organic content is progressively transformed into kerogens and bitumens. The process of diagenesis excludes surface alteration (weathering) and deep metamorphism. There is no sharp boundary between diagenesis and metamorphism, but the latter occurs at higher temperatures and pressures. Hydrothermal solutions, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olistostrome
An olistostrome is a sedimentary deposit composed of a chaotic mass of heterogeneous material, such as blocks and mud, known as olistoliths, that accumulates as a semifluid body by submarine gravity sliding or slumping of the unconsolidated sediments. It is a mappable stratigraphic unit which lacks true bedding, but is intercalated amongst normal bedding sequences, as in the Cenozoic basin of central Sicily. The term olistostrome is derived from the Greek ''olistomai'' (to slide) and ''stroma'' (accumulation).Ernesto Abbate, et al., "Olistostromes and olistoliths", ''Sedimentary Geology'', 4 (1970), 521-557. See also *Submarine landslide Submarine landslides are marine landslides that transport sediment across the continental shelf and into the deep ocean. A submarine landslide is initiated when the downwards driving stress (gravity and other factors) exceeds the resisting str ... References Sedimentary rocks {{Geology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nappe
In geology, a nappe or thrust sheet is a large sheetlike body of rock (geology), rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones. Nappes form when a mass of rock is forced (or thrust fault, "thrust") over another rock mass, typically on a low angle fault plane. The resulting structure may include large-scale recumbent Fold (geology), folds, shearing along the fault plane,Twiss, Robert J. and Eldridge M. Moores, ''Structural Geology,'' W. H. Freeman, 1992, p. 236 Thrust fault#Thrust duplex, imbricate thrust stacks, Window (geology), fensters and klippes. The term stems from the French word for ''tablecloth'' in allusion to a rumpled tablecloth being pushed across a table. History Nappes or nappe belts are a major feature of the European Geology of the Alps, Alps, Dinaric Alps, Dinarides, Carpathians and S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Craton
A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates; the exceptions occur where geologically recent rifting events have separated cratons and created passive margins along their edges. Cratons are characteristically composed of ancient crystalline basement rock, which may be covered by younger sedimentary rock. They have a thick crust and deep lithospheric roots that extend as much as several hundred kilometres into Earth's mantle. Terminology The term ''craton'' is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable. Cratons are composed of two layers: A continental ''shield'', in which the basement rock crops out at the surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congo Craton
The Congo Craton, covered by the Palaeozoic-to-recent Congo Basin, is an ancient Precambrian craton that with four others (the Kaapvaal, Zimbabwe, Tanzania, and West African cratons) makes up the modern continent of Africa. These cratons were formed between about 3.6 and 2.0 billion years ago and have been tectonically stable since that time. All of these cratons are bounded by younger fold belts formed between 2.0 billion and 300 million years ago. The Congo Craton occupies a large part of central southern Africa, extending from the Kasai region of the DRC into Sudan and Angola. It forms parts of the countries of Gabon, Cameroon, and the Central African Republic. A small portion extends into Zambia as well, where it is called the Bangweulu Block. Congo–São Francisco The Congo Craton and the São Francisco Craton are stable Archaean blocks that formed a coherent landmass until the opening of the South Atlantic Ocean during the break-up of Gondwana ( 2000–130 Ma). They ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kalahari Craton
The Kalahari Craton is a craton, an old and stable part of the continental lithosphere, that occupies large portions of South Africa, Botswana, Namibia and Zimbabwe. It consists of two cratons separated by the Limpopo Belt: the larger Kaapvaal Craton to the south and the smaller Zimbabwe Craton to the north. The Namaqua Belt is the southern margin of the Kaapvaal Craton. Parts of the Kalahari Craton are now in East Antarctica (the Grunehogna Craton) and West Antarctica (Haag Nunataks) and the Falkland Islands. The name was first introduced by . Formation Following a terminology introduced in 2008, the Archaean-Palaeoproterozoic core of the craton is called the Proto-Kalahari Craton. This core plus accreted Mesoproterozoic crust and dispersed non-African fragments compose the Kalahari Craton. Before the Pan-African Orogeny, the Kalahari Craton was much larger than it is today, but its sutures and therefore its extent are difficult to locate due to later overprinting. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kibaran Orogeny
The Kibaran orogeny is a term that has been used for a series of orogenic events, in what is now Africa, that began in the Mesoproterozoic, around 1400 Ma and continued until around 1000 Ma when the supercontinent Rodinia was assembled. The term "Kibaran" has often been used for any orogenic rocks formed during this very extended period. Recently, it has been proposed that the term should be used in a much narrower sense for an event around 1375 Ma and a region in the southeast of the Democratic Republic of the Congo (DRC). These orogenic events are also known as the Grenville orogeny in North America and the Dalslandian orogeny in Western Europe. Broad sense Regions that contain relics of Kibaran age include the Kibara Mountains of the eastern DRC and Namaqua-Natal belt in southern Africa. Rocks of this age have been found in the Hoggar Mountains, in northwest and southwest Nigeria and in Cameroon to the north of the Congo Craton. The orogeny in northwest Nigeria was a major t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscovite
Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage yielding remarkably thin laminae (sheets) which are often highly elastic. Sheets of muscovite 5 meters × 3 meters (16.5 feet × 10 feet) have been found in Nellore, India. Muscovite has a Mohs hardness of 2–2.25 parallel to the 01face, 4 perpendicular to the 01and a specific gravity of 2.76–3. It can be colorless or tinted through grays, browns, greens, yellows, or (rarely) violet or red, and can be transparent or translucent. It is anisotropic and has high birefringence. Its crystal system is monoclinic. The green, chromium-rich variety is called fuchsite; mariposite is also a chromium-rich type of muscovite. Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
