“Central African Shear Zone”的意思、由来-开放百科全书

词条

Central African Shear Zone

释义

Description
Sudan
References
Sources books

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.{{sfn|Ibrahim|Ebinger|Fairhead|1996|pp=79–97}}

The structure is not well understood.

{{As of|2008}}, there was still no general agreement about how the individual shears along the lineament link up.{{sfn|Pankhurst|2008|pp=404}}

Description

The shear zone dates to at least 640 Ma (million years ago).{{sfn|Dorbath|Dorbath|Fairhead|Stuart|1986|pp=751-766}}

Motion occurred along the zone during the break-up of Gondwanaland in the Jurassic and Cretaceous ages.{{sfn|Ibrahim|Ebinger|Fairhead|1996|pp=79–97}}

Some of the faults in the zone were rejuvenated more than once before and during the opening of the South Atlantic in the Cretaceous era.{{sfn|Dorbath|Dorbath|Fairhead|Stuart|1986|pp=751-766}}

The Pernambuco fault in Brazil is a continuation of the shear zone to the west.{{sfn|Dorbath|Dorbath|Fairhead|Stuart|1986|pp=751-766}}

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.{{sfn|Schlüter|Trauth|2008|pp=60}}

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.{{sfn|Foulger|Jurdy|2007|pp=16}}

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.{{sfn|Plomerova|Babuska|Dorbath|Dorbath|1993|pp=381–390}}

The Mesozoic and Tertiary movements have produced elongated rift basins in central Cameroon, northern Central African Republic and southern Chad.{{sfn|Dorbath|Dorbath|Fairhead|Stuart|1986|pp=751-766}}

Sudan

The CASZ was formerly thought to extend eastward only to the Darfur region of western Sudan.{{sfn|Dorbath|Dorbath|Fairhead|Stuart|1986|pp=751-766}}

It is now known to extend into central and eastern Sudan, with a total length of 4,000 km.{{sfn|Ibrahim|Ebinger|Fairhead|1996|pp=79–97}}

In the Sudan, the shear zone may have acted as a structural barrier to development of deep Cretaceous-Terriary 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.{{sfn|Selley|1997|pp=113}}

However, the alignment of the northwestern ends of the rifts in this areas supports the theory.{{sfn|Bowen|Jux|1987|pp=143}}

References

Sources books

{{cite book |ref=harv

|url=https://books.google.com/books?id=FPFdQN7laoMC&pg=PA143
|title=Afro-Arabian geology: a kinematic view
|first1=Robert |last1=Bowen |first2=Ulrich |last2=Jux
|publisher=Springer
|year=1987
|ISBN=0-412-29700-0}}

{{cite journal |ref=harv

|journal=Geophysics
|year=1986 |volume=86
|title=A teleseismic delay time study across the Central African Shear Zone in the Adamawa region of Cameroon, West Africa
|first1=C. |last1=Dorbath |first2=L. |last2=Dorbath |first3=J. D. |last3=Fairhead |first4=G. W. |last4=Stuart |doi=10.1111/j.1365-246x.1986.tb00658.x}}

{{cite book |ref=harv

|url=https://books.google.com/books?id=l9a7tIJBYbkC&pg=PA16
|title=Plates, plumes, and planetary processes
|first1=Gillian R. |last1=Foulger |first2=Donna M. |last2=Jurdy
|publisher=Geological Society of America
|year=2007
|ISBN=978-0-8137-2430-0}}

{{cite journal |ref=harv

|title=Lithospheric extension northwest of the Central African Shear Zone in Sudan from potential field studies
|first1=A. E. |last1=Ibrahim |first2=C. J. |last2=Ebinger |first3=J. D. |last3=Fairhead
|journal=Tectonophysics
|volume=255| issue = s 1-2
|date=20 April 1996 |doi=10.1016/0040-1951(95)00080-1 |pages=79–97}}

{{cite book |ref=harv

|title=West Gondwana: pre-Cenozoic correlations across the South Atlantic Region
|first=Robert J. |last=Pankhurst
|publisher=Geological Society
|year=2008
|ISBN=1-86239-247-1}}

{{cite journal |ref=harv

|url=http://cat.inist.fr/?aModele=afficheN&cpsidt=3755964
|journal=Geophysical Journal International
|ISSN=0956-540X
|year=1993
|volume=115| issue = 2
|title=Deep lithospheric structure across the Central African Shear Zone in Cameroon
|last1=Plomerova |first1=J |last2=Babuska|first2=V |last3=Dorbath|first3=C.|last4=Dorbath|first4=L.|last5=Lillie|first5=R. J.
|accessdate=2011-01-27
|doi=10.1111/j.1365-246x.1993.tb01193.x |pages=381–390}}

{{cite book |ref=harv

|url=https://books.google.com/books?id=KaxnNYz2g6EC&pg=PA113
|title=African basins
|first=Richard C. |last=Selley
|publisher=Elsevier
|year=1997
|ISBN=0-444-82571-1}}

{{cite book |ref=harv

|url=https://books.google.com/books?id=IfvKWpsISTQC&pg=PA60
|title=Geological atlas of Africa: with notes on stratigraphy, tectonics, economic geology, geohazards, geosites and geoscientific education of each country
|first1=Thomas |last=Schlüter|first2=Martin H. |last2=Trauth
|publisher=シュプリンガー・ジャパン株式会社
|year=2008
|ISBN=3-540-76324-4}}{{refend}}{{Major African geological formations}}

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