TITLE:
Tarkwaian Deposits of the Birimian Belt of Houndé: Petrological, Structural and Geochemical Study (Burkina-Faso, West Africa)
AUTHORS:
Yao Honoré Koffi, Urbain Wenmenga, Sagbrou Chérubin Djro
KEYWORDS:
Tarkwaian, Birimian, Sandstone, Polygenic Conglomerat, Molassic, Fluvio-Deltaic
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.5,
May
23,
2016
ABSTRACT: The Tarkwaian deposits of
the Birimian belt of Houndé are located in the Baoule-Mossi Paleoproterozoic
area of the West African Craton. The sedimentary units consist of sandstone
heterometric pelitic feldspthic sandstone with locally interbedded breccias,
puddings and polygenic conglomerates. Lithic pebbles and macroscopic fragments
that are similar to vein type originated quart castings and andesitic-dacitic
projections, felsic sub-volcanic rocks evolving from microdioritic to
microgranite composition are detected in terrigenous sediments. The volcanic
packages form a linear strip composed of basic to intermediate rocks and
andesitic to daciticvolcaniclastites.
The contacts between these units are not clearly exposed but the different
facies between the polygenic conglomerates and sandstones show discordant
tectonic contacts with the Tarkwaian and the Birimian. The geochemical nature
of these Tarkwaian formations is strongly influenced by the relative decline of
the dominant quartz of feldspars and phyllites. The improperly classified and
immature feldspathic sandstones show context affinities of island arc probably
dictated by Birimian lithic products. Sedimentologically, the cross-bedded stratification
and the predominance of sandstone terrigenous lands indicate a deposition in a
fluvio-deltaic hydrodynamic setting along intermontane Birimian rift. The
similarities between these Tarkwaian formations and the typical Tarkwaian of
the Tarkwa basin in Ghana are probably limited to petrographic and not
stratigraphic aspects, which lead to likening them to flyscho?d or molassic
tardi Birimian deposits.