TITLE:
New Approach of Structural Setting of Gold Deposits in Birimian Volcanic Belt in West African Craton: The Example of the Sabodala Gold Deposit, SE Senegal
AUTHORS:
Serigne Sylla, Mamadou Gueye, Papa Malick Ngom
KEYWORDS:
Gold, Mesothermal, Thrusting, Transcurrent, Sabodala, Birrimian, Senegal, West Africa
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.3,
March
31,
2016
ABSTRACT: The Sabodala gold deposit
in the Mako volcanic Belt (SE-Senegal, West African Craton) occurs in mafic and
ultramafic rocks overlain by clastic sedimentary rocks and felsic
volcanic-volcaniclastic sequences. It is a structurally controlled mesothermal
vein gold deposit developed in deformed rocks units near the Falombo pluton.
The Sabodala Goldfield comprises several faults systems striking N-S to NE-SW.
New structural evolution consisting of both thrusting and transcurrent events
has been defined for the Sabodala Goldfield. The majority of the gold at
Sabodala occurs on the western flank of a large, doubling plunging dome (the
Sabodala Antiform) and is also associated with sinistral wrenching that
overprints early structures within the Sabodala Mine. The gold bearing veins
are hosted by flat lying and NW-trending shear zones. The NW-trending faults
acted as transfers syn-gold mineralization, although only discrete segments of
these faults were active during the main stage of gold mineralization. Late
exhumation resulted in extension along fault zones was responsible for the
juxtaposition of medium and low grade metamorphic rocks. The granitic suite of
the Falombo pluton is linked to exhumation. Final dextral transpression
postdating exhumation produced shearing and folding. Gold lodes developed
during brittle deformation are associated with high fluid pressures in a
northwest-southeast shortening regime. These are termed mainly the Sabodala
deposit, and secondary the Niakafiri and Masato deposits.