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Mwembeshi Dislocation
The Mwembeshi Shear Zone is a ductile shear zone about 550 million years old that extends ENE-WSW across Zambia. In Zambia, it separates the Lufilian Belt to the northwest from the Zambezi Belt to the southeast. It is associated with a sinistral strike slip movement. The Mwembeshi Shear Zone lies between the Congo craton to the NW and the Kalahari craton to the SE, to the west (in today's orientation) of the Mozambique Belt, which is on the north and east side of the Kalahari Craton. It was formed during the Pan-African orogeny when "North" and "South" Gondwana were amalgamated along the Kuunga orogeny zone between 580 Ma and 480 Ma. The date of around 550 Ma for the Mwembeshi shear zone is based on U-Pb zircon ages of syntectonic granites from the Hook massif and of associated hypabyssal rhyolite. During the amalgamation there was sinistral transpression In geology, transpression is a type of strike-slip deformation that deviates from simple shear beca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Zone
In geology, a shear zone is a thin zone within the Earth's crust or upper mantle that has been strongly deformed, due to the walls of rock on either side of the zone slipping past each other. In the upper crust, where rock is brittle, the shear zone takes the form of a fracture called a Fault (geology), fault. In the lower crust and mantle, the extreme conditions of pressure and temperature make the rock ductile. That is, the rock is capable of slowly deforming without fracture, like hot metal being worked by a blacksmith. Here the shear zone is a wider zone, in which the ductile rock has slowly flowed to accommodate the relative motion of the rock walls on either side. Because shear zones are found across a wide depth-range, a great variety of different rock types with their characteristic structures are associated with shear zones. General introduction A shear zone is a zone of strong deformation (with a high strain rate) surrounded by rocks with a lower state of Deforma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kuunga Orogeny
The Kuunga orogeny (from Swahili, "to unite") was an orogeny that occurred in South-east Africa during the Ediacaran and Cambrian. Composed of three separate orogenic belts (Damara, Zambesi, and Lurio) that are slightly younger than the East African orogeny, the Kuunga orogeny documents the collision between north and south Gondwana, or what is today Dronning Maud Land in Antarctica and northern Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ... in Africa. The name was proposed in 1995 by J. G. Meert, R. van der Voo and S. Ayub. References Sources * * {{Tectonics-stub Orogenies of Africa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of Africa
The geology of Africa is varied and complex, and gives rise to the wide variety of landscapes found across the continent. The African continent rests over two main plates. The African plate, accounting for the whole of north Africa, and the Somali plate, which accounts for the eastern side of mid and southern Africa. The Somali plate is moving away from the African plate in a split from Djibouti in the north, to Eswatini in the south. The parting of these two plates formed the southern part of what used to be known as The Great Rift Valley. In geological terms, the African and Somali plate separation has formed the East African Rift System (EARS), comprising two separate rifts systems - the Eastern Rift Valley, and a western branch known as the Albertine Rift. Two massive domes were formed, the Kenyan dome and the Ethiopian dome (known as the Ethiopian Highlands). The Albertine Rift follows the western edge of the Kenyan dome. This runs from Lake Malawi in the south, up into Lake ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damara Orogeny
The Damara orogeny was part of the Pan-African orogeny. The Damara orogeny occurred late in the creation of Gondwana, at the intersection of the Congo and the Kalahari cratons.; ; ; ; The Damara orogeny involved the suturing A surgical suture, also known as a stitch or stitches, is a medical device used to hold body tissues together and approximate wound edges after an injury or surgery. Application generally involves using a needle with an attached length of threa ... of the Congo– São Francisco and Río de la Plata cratons at 580–550 Ma (together with India forming northern Gondwana) before the amalgamation of the Kalahari and Mawson cratons in the Kuunga–Damara orogeny at 530 Ma (southern Gondwana). The Adamastor Ocean closed southwards from the Araçuaı́ Belt (São Francisco Craton, now in South America) to the Kaoko Belt (Congo Craton, now in Africa) 580–550 Ma and 545–530 Ma Gariep Belt (Kalahari Craton, now in southern Africa) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tanzania Craton
The Tanzania Craton is an old and stable part of the continental lithosphere in central Tanzania. Some of the rocks are over 3 billion years old. Setting The Tanzania Craton forms the highest part of the East African Plateau. The craton is surrounded by Proterozoic mobile belts of various ages and grades of metamorphism. These include the Ubendian, Usagaran, Karagwe-Ankolean and Bukoban systems. The Mozambique Belt lies to the east. The craton divides the east and west branches of the East African Rift. The southern end of the Gregory Rift Valley terminates against the craton. The volcanic area of this rift covers the surface interface between the Mozambique orogenic fold belt and the Tanzania Craton. A superplume exists beneath the craton. An indirect effect of rift and plume associated volcanism in the Tanzania Craton is the high levels of soil nutrients in Serengeti provided by volcanic ash from Ol Doinyo Lengai. Composition The craton is a composite of several different te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transpression
In geology, transpression is a type of strike-slip deformation that deviates from simple shear because of a simultaneous component of shortening perpendicular to the fault plane. This movement ends up resulting in oblique shear. It is generally very unlikely that a deforming body will experience "pure" shortening or "pure" strike-slip. The relative amounts of shortening and strike-slip can be expressed in the convergence angle alpha which ranges from zero (ideal strike-slip) to 90 degrees (ideal convergence). During shortening, unless material is lost, transpression produces vertical thickening in the crust. Transpression that occurs on a regional scale along plate boundaries is characterized by oblique convergence. More locally, transpression occurs within restraining bends in strike-slip fault zones. Transpressional structures Transpressional shear zones are characterized by an association of structures that suggest zone-normal shortening and zone-parallel shearing. Commonly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subvolcanic Rock
A subvolcanic rock, also known as a hypabyssal rock, is an intrusive igneous rock that is emplaced at depths less than within the crust, and has intermediate grain size and often porphyritic texture between that of volcanic rocks and plutonic rocks. Subvolcanic rocks include diabase (also known as dolerite) and porphyry. Common examples of subvolcanic rocks are diabase, quartz dolerite, microgranite, and diorite. See also * Cone sheet * Dike (geology) * Igneous intrusion * Sill (geology) In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock. A ''sill'' is a ''concordant intrusive sheet'', ... References Igneous petrology Volcanology {{Volcanology-stub he:סלע געשי#סלעים תת-געשיים ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hook Massif
The Hook granite massif is a large formation in central Zambia formed around 550 million years ago during the Pan-African orogeny. It lies in the inner part of the Lufilian arc. Today, the south-western extension of the massif lies under the Kafue National Park. Formation Field studies and U-Pb (uranium-lead) dating show that the massif is a large composite batholith that has intruded into the upper Katangan (Kundelungu) strata of sediments in the Lufilian arc during or after tectonic activity. Sample U-Pb dates for syntectonic granite in the massif are 559±18 and 566±5 Ma, and for post-tectonic granite 533±3 Ma. These show that the Kundelungu sediments date to before 570 Ma; the deformation of the inner Lufilian arc and voluminous syntectonic granite plutonism took place around 560–570 Ma; and the major tectonic activity had ended by around 530–540 Ma. The Hook massif is bounded to the south by the Mwembeshi dislocation, a Pan-African transcurrent shear zone. Syntectoni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene. Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name (see ), it is also commonly called Gondwanaland. Gondwana was formed by the accretion of several cratons. Eventually, Gondwana became the largest piece of continental crust of the Palaeozoic Era, covering an area of about , about one-fifth of the Earth's surface. During the Carboniferous Period, it merged with Laurasia to form a larger supercontinent called Pangaea. Gondwana (and Pan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zambia
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] |
