Geology
Regional Geological Setting
See to Description of the Business - A2 Dabalova Project – Geological Setting – Regional Geological Setting.
Property and Local Geology
The Andavakoera fault structure extends for about 170 km along a northeastern trend from the Sambriano
Valley in the southwest to the Loky River valley in the northeast. The region is underlain by a
Proterozoic/Archean metamorphic crystalline assemblage and is uncomformably overlain by Permian to
Jurassic sediments.
Gold mineralization is found in quartz-barite veins contained in a northeast striking fault
system that also partially controls the contact between basement and younger overlying rocks.
The mineralizing event has been dated at 350 Ma, which corresponds with base of the Carboniferous.
The controlling structure follows a topographic depression bounded by cliff-forming sandstones to
the northwest and the sloping margins of the basement plateau to the southeast.
Proterozoic Basement
The Precambrian basement is composed of strongly deformed, amphibolite facies rocks derived from
volcano-sedimentary assemblage. Dominant strata consist of gneissic members interstratified with
schists, quartzites, marbles and migmatitic intrusions. Gneissic strata includes both ortho and
paragneisses, muscovite, biotite and amphibolitic schists and amphibolites. Quartzites vary from
relatively pure and massive to fissile and mica rich and also as a magnetite rich phase.
Granites, microsyentites, gabbros, and labradorite all intrude the metamorphic basement.
Later pegmatitic intrusions are locally recognized. The age of the parent rocks and subsequent
tectonic events remains in dispute, but the present metamorphic lithologies probably formed during
the Pan African Orogeny (550 Ma). Pseudo bedding generally strikes to the northwest and dips variably.
Foliations suggest a strong and complex history of deformation.
Permian Strata
Permian sedimentary rocks uncomformably overlie the Precambrian basement with a variable thickness of
either a conglomerate or a coarse-grained arkose. The base unit is overlain by arkosic cross-bedded
sandstones containing lenses of black pyritic shales. Fossils suggest a depositional environment that
varied from a high-energy, deltaic to static, lagoon conditions. Permian strata pinch out and swell to 80m.
Triassic Strata
The lower Triassic is composed of a gray to yellow fossil bearing marine schist overlain by non-marine
massive sandstone that forms the cliffs and ridges of Andavakoera.
Structure
The overall attitude of younger sediments is fairly uniform with a regular 30˚ dip to the northwest
while the older basement shows a compositional layering that dips variably from 50˚ to 70˚ to the
northwest. A major system of post-Triassic high-angle faulting marks the contact zone between
exposed basement and post Precambrian cover to the northwest. The fault system is composed of at
least two sets of structures with the dominant member striking 50˚ along the general trend of the
system and a cross-cutting 20˚ structure. Basement rocks have been affected by an older deformation
causing broad silicified shear zones.
Cross-faults, striking 120˚, are the last significant event to affect the region. Current
geological activity is indicated by numerous hot-springs along the Andavakoera trend.
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