Restraining bends in high temperature shear zones: The "Central Cameroon Shear zone'', Central Africa

Research areas:
Year:
2008
Authors:
  • Emmanuel Njonfang
  • Vincent Ngako
  • Christian Moreau
  • Pascal Affaton
  • Hervé Diot
Journal:
JOURNAL OF AFRICAN EARTH SCIENCES
Volume:
52
Number:
1-2
Pages:
9-20
Month:
September
ISSN:
1464-343X
BibTex:
Abstract:
A detailed structural study of the Central Cameroon Shear Zone (CCSZ)
segment, in the Bamoun plateau (BP) and the Tikar plain (TP) (West
Cameroon), reveals a complex strain geometry of this shear zone. It
shows thick mylonite bands wrapping around lenses of various country
rock types, at small, medium and large scales. The mylonite foliation
trends N40 degrees E in the Tikar plain, and progressively curves into a
N60 degrees E to N70 degrees E direction, to the NE and SW, defining a
large scale S-type bend at the transition zone between two en-echelon
segments, known as the Foumban and Central Cameroon Shear Zones (CCSZ).
The structural, kinematic and metamorphic features of the Tikar
mylonites characterize a restraining bend formed at a deep crustal level
during a major dextral shear deformation. Its geometry suggests that the
western extension of the CCSZ including its Brasiliano southernmost
pre-drift counterpart form a left lateral stepping (en-echelon) shear
zone system. (C) 2008 Elsevier Ltd. All rights reserved.