Origin of the Bouarfa Manganese ore deposit (Eastern High Atlas, Morocco): insights from petrography and geochemistry of the mineralization

Abstract. The Bouarfa ore deposit represents one of the
main Manganese ore deposits of Morocco. The
mineralization corresponds to a stratabound deposit in a
liassic dolostone unit. Previous studies have suggested
that this deposit has been formed during sedimentation at
the sedimentary water interface. However, the location of
the Bouarfa district along the North Atlasic Front in a fold
cut by a thrust fault questions the influence of this
structure on the mineralization, its origin and evolution.
The petrographic characterization of the dolostone
emphasizes a late diagenetic dolomitization process prior
to Mn mineralization. Moreover, petrographical, mineralogical
and trace element geochemistry demonstrate that
the fluids involved in the mineralization precipitated Mn
tunnel-like structure oxides in a high oxidised
environment. The fluids probably derived from hydrothermal
systems. These elements argue for a postsedimentary
model for the mineralization.