TITLE:
Polycyclic Evolution of Paleoproterozoïc Rocks in the Southwestern Part of the Mako Group (Eastern Senegal, West Africa)
AUTHORS:
Papa Moussa Ndiaye, Edmond Dioh, Famara Diatta, Alassane Traore, Makhoudia Fall, Ousmane Balde
KEYWORDS:
Paleoproterozoïc, Eastern Senegal, Volcanic-Rocks, Polycyclic Deformation, Silicification
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.7,
June
23,
2014
ABSTRACT: After an extensional stage giving rise to
tholeiitic basalts and gabbros, the south western part of Kédougou Kéniéba
Inlier (KKI) was affected by three phases of compressionnal deformation. The
first phase (D1) was related to NE-SW stress that led to northeastward
thrusting. Early granitoids would be implemented during this tectonic event.
The second phase (D2) was due to East-West compressional stress that created
combined strike sleep faults: NNW-SSE and NNE-SSW respectively sinistral and
dextral. During this phase, some volcanic rocks and gabbros were mylonitized,
hydrothermalized and transformed into quartzites. These quartzites were
considered as sedimentary rocks in previous studies. Granitic plutons and
andesites took place during this tectonic phase. D3 deformation occurred
towards the end of the Eburnean orogeny. It would be held in two episodes. In the
first episode, WNW-ESE stresses created conjugate shears: sinistral NNW-SSE and
dextral NE-SW. In the second episode, stresses moved toward the NE-SW direction
and made the resulting brittle structures arranged in NS dextral corridors.