Английская Википедия:Central African Shear Zone

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Файл:Central African Shear Zone.svg

Central Africa showing the interpreted extent of the CASZ

Файл:Central African Rifts.svg

Rifts in Sudan and Kenya

The Central African Shear Zone (CASZ) (or Shear System) is a wrench fault system extending in an ENE direction from the Gulf of Guinea through Cameroon into Sudan.Шаблон:Sfn The structure is not well understood. Шаблон:As of, there was still no general agreement about how the individual shears along the lineament link up.Шаблон:Sfn

Description

The shear zone dates to at least 640 Ma (million years ago).Шаблон:Sfn Motion occurred along the zone during the break-up of Gondwanaland in the Jurassic and Cretaceous periods.Шаблон:Sfn Some of the faults in the zone were rejuvenated more than once before and during the opening of the South Atlantic in the Cretaceous period.Шаблон:Sfn

It has been proposed that the Pernambuco fault in Brazil is a continuation of the shear zone to the west.Шаблон:Sfn In Cameroon, the CASZ cuts across the Adamawa uplift, a post-Cretaeous formation. The Benue Trough lies to the north, and the Foumban Shear Zone to the south.Шаблон:Sfn Volcanic activity has occurred along most of the length of the Cameroon line from 130 Ma to the present, and may be related to re-activation of the CASZ.Шаблон:Sfn The lithosphere beneath the CASZ in this area is thinned in a relatively narrow belt, with the asthenosphere upwelling from a depth of about 190 km to about 120 km.Шаблон:Sfn The Mesozoic and Tertiary movements have produced elongated rift basins in central Cameroon, northern Central African Republic and southern Chad.Шаблон:Sfn

Sudan

The CASZ was formerly thought to extend eastward only to the Darfur region of western Sudan.Шаблон:Sfn It is now interpreted to extend into central and eastern Sudan, with a total length of 4,000 km.Шаблон:Sfn In the Sudan, the shear zone may have acted as a structural barrier to development of deep Cretaceous-Tertiary sedimentary basins in the north of the area. Objections to this theory are that the Bahr el Arab and Blue Nile rifts extend northwest beyond one proposed line for the shear zone.Шаблон:Sfn However, the alignment of the northwestern ends of the rifts in this areas supports the theory.Шаблон:Sfn

Sources books

• Шаблон:Cite book
• Шаблон:Cite journal
• Шаблон:Cite book
• Шаблон:Cite journal
• Шаблон:Cite book
• Шаблон:Cite journal
• Шаблон:Cite book
• Шаблон:Cite book