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Paper Number: 185
Three-Dimensional spatial
relations between intrusions and gold bearing ore deposit within the
Inata mine pit, Northern Burkina Faso (West Africa)
Ilboudo,
H.1, Sawadogo, S.2, Traore, A
S.3
2,3Department
of Earth Sciences, University of Ouagadougou, 03 BP 7021 Ouaga 03
(Burkina Faso
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The Inata gold mine is located in northerm Burkina Faso close Mali
border and at about 220 kilometers to the NNE of Ouagadougou. The
deposit belongs to the Djibo green stone belt and the gold is mined open
pit by Avocet Mining since April, 2010. Aeromagnetic signature trending
NS is conformable with gold anomaly. Following this signature, several
pits (namely north pit, central pit, south pit, southern area pit,
sayouba and Minfo) opened along strike have been continuously mined
since the beginning. The main pit actually slowly mined comprises a
predominantly steeply deeping volcano-sediment schist accommodating
numerous quartz veins and associated intrusions. The overall
superimposed by supergene alteration.
Different types of intrusions compositionally ranging from
mafic-intermediate to felsic appears systematically associated to the
ore. Spatially, intrusions are syn to post-tectonic and discriminable by
the texture, structure and colour.
According to the spatial organisation between intrusions and ore, the
following magmatic emplacement chronology is proposed at 50 m depth:
Figure 1: Relation between intrusion and ore
Emplacement of volcano-sediment sheared and mineralized. The
mineralization is deformed, with commonly hematite ± sericite, minor
chlorite near the contact to intrusion.
Emplacement of porphyritic diorite intrusion strongly to
moderately epidotized and chloritised. This intrusion cross cut the
ore.
Emplacement of gabbro composition strongly altered into yellow
colour associating syntectonic fine grain granite sill.
Emplacement of fine grain diorite dyke that cross cut the overall
unit.
