Central African Shear Zone

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The Central African Shear Zone (CASZ) (or Shear System) is a wrench fault system extending in an ENE direction from the Gulf of Guinea by way of Cameroon into Sudan. The construction shouldn't be nicely understood. The shear zone dates to at least 640 Ma (million years in the past). Motion occurred alongside the zone throughout the break-up of Gondwanaland in the Jurassic and Cretaceous periods. Among the faults within the zone were rejuvenated greater than as soon as before and in the course of the opening of the South Atlantic in the Cretaceous period. It has been proposed that the Pernambuco fault in Brazil is a continuation of the shear zone to the west. In Cameroon, the CASZ cuts across the Adamawa uplift, a publish-Cretaeous formation. The Benue Trough lies to the north, power shears and the Foumban Shear Zone to the south. Volcanic exercise has occurred alongside a lot of the size of the Cameroon line from 130 Ma to the present, and could also be related to re-activation of the CASZ.



The lithosphere beneath the CASZ on this area is thinned in a relatively narrow belt, with the asthenosphere upwelling from a depth of about 190 km to about a hundred and twenty km. The Mesozoic and Tertiary movements have produced elongated rift basins in central Cameroon, northern Central African Republic and southern Chad. The CASZ was formerly thought to extend eastward only to the Darfur region of western Sudan. It is now interpreted to extend into central and japanese Sudan, with a complete size of 4,000 km. In the Sudan, the shear zone might have acted as a structural barrier to improvement of deep Cretaceous-Tertiary sedimentary basins in the north of the realm. Objections to this principle are that the Bahr el Arab and Blue Nile rifts lengthen northwest beyond one proposed line for the shear zone. However, the alignment of the northwestern ends of the rifts in this areas supports the speculation. Ibrahim, Ebinger & Fairhead 1996, pp.



Dorbath et al. 1986, pp. Schlüter & Trauth 2008, pp. Foulger & Jurdy 2007, pp. Plomerova et al. 1993, pp. Bowen & Jux 1987, pp. Bowen, Robert; Jux, Ulrich (1987). Afro-Arabian geology: a kinematic view. Dorbath, C.; Dorbath, L.; Fairhead, J. D.; Stuart, G. W. (1986). "A teleseismic delay time examine throughout the Central African Shear Zone in the Adamawa region of Cameroon, West Africa". Foulger, Gillian R.; Jurdy, Donna M. (2007). Plates, power shears plumes, and planetary processes. Geological Society of America. Ibrahim, A. E.; Ebinger, C. J.; Fairhead, J. D. (20 April 1996). "Lithospheric extension northwest of the Central African Shear Zone in Sudan from potential subject studies". Pankhurst, Robert J. (2008). West Gondwana: pre-Cenozoic correlations throughout the South Atlantic Region. Plomerova, J; Babuska, V; Dorbath, C.; Dorbath, L.; Lillie, R. J. (1993). "Deep lithospheric structure across the Central African Shear Zone in Cameroon". Geophysical Journal International. A hundred and fifteen (2): 381-390. Bibcode:1993GeoJI.115..381P. Selley, Richard C. (1997). African basins. Schlüter, Thomas; Trauth, Martin H. (2008). Geological atlas of Africa: with notes on stratigraphy, tectonics, economic geology, geohazards, geosites and geoscientific training of every country. シュプリンガー・ジャパン株式会社.



Viscosity is a measure of a fluid's charge-dependent resistance to a change in form or to motion of its neighboring parts relative to one another. For liquids, it corresponds to the informal idea of thickness; for example, syrup has a higher viscosity than water. Viscosity is outlined scientifically as a pressure multiplied by a time divided by an area. Thus its SI items are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal frictional drive between adjacent layers of fluid that are in relative motion. As an example, when a viscous fluid is forced by a tube, it flows extra quickly near the tube's middle line than near its walls. Experiments present that some stress (equivalent to a strain distinction between the 2 ends of the tube) is required to maintain the stream. It is because a force is required to beat the friction between the layers of the fluid that are in relative motion. For a tube with a continuing price of circulate, the strength of the compensating force is proportional to the fluid's viscosity.



Usually, viscosity depends upon a fluid's state, such as its temperature, strain, and rate of deformation. However, the dependence on some of these properties is negligible in certain instances. For instance, the viscosity of a Newtonian fluid does not vary considerably with the rate of deformation. Zero viscosity (no resistance to shear stress) is noticed solely at very low temperatures in superfluids; in any other case, the second law of thermodynamics requires all fluids to have constructive viscosity. A fluid that has zero viscosity (non-viscous) is called ideally suited or inviscid. For non-Newtonian fluids' viscosity, there are pseudoplastic, plastic, and dilatant flows that are time-independent, and there are thixotropic and rheopectic flows that are time-dependent. The phrase "viscosity" is derived from the Latin viscum ("mistletoe"). Viscum additionally referred to a viscous glue derived from mistletoe berries. In materials science and engineering, there is usually interest in understanding the forces or stresses concerned within the deformation of a cloth.