Central African Shear Zone > 자유게시판

The Central African Shear Zone (CASZ) (or Shear System) is a wrench fault system extending in an ENE route from the Gulf of Guinea by way of Cameroon into Sudan. The structure is not nicely understood. The shear zone dates to no less than 640 Ma (million years ago). Motion occurred along the zone in the course of the break-up of Gondwanaland within the Jurassic and Cretaceous periods. Some of the faults in the zone have been rejuvenated more than as soon as earlier than and during the opening of the South Atlantic within 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 submit-Cretaeous formation. The Benue Trough lies to the north, and the Foumban Shear Zone to the south. Volcanic activity has occurred alongside most of the size of the Cameroon line from 130 Ma to the present, and may be associated to re-activation of the CASZ.

The lithosphere beneath the CASZ on this space is thinned in a comparatively slender belt, with the asthenosphere upwelling from a depth of about 190 km to about one hundred twenty km. The Mesozoic and Tertiary movements have produced elongated rift basins in central Cameroon, durable garden trimmer northern Central African Republic and southern Chad. The CASZ was previously thought to extend eastward only to the Darfur area of western Sudan. It's now interpreted to extend into central and japanese Sudan, with a total length 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 world. Objections to this idea are that the Bahr el Arab and Blue Nile rifts prolong northwest past one proposed line for the shear zone. However, the alignment of the northwestern ends of the rifts in this areas supports the idea. 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 research throughout the Central African Shear Zone in the Adamawa area of Cameroon, West Africa". Foulger, Gillian R.; Jurdy, Donna M. (2007). Plates, durable garden trimmer plumes, and planetary processes. Geological Society of America. Ibrahim, A. E.; Ebinger, C. J.; Fairhead, durable garden trimmer J. D. (20 April 1996). "Lithospheric extension northwest of the Central African Shear Zone in Sudan from potential field research". Pankhurst, Robert J. (2008). West Gondwana: pre-Cenozoic correlations across 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. One hundred 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, financial geology, geohazards, geosites and geoscientific education of each nation. シュプリンガー・ジャパン株式会社.

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