Explorations

Reserves are the cornerstone of Optima Global’s business and, whether by exploration or acquisition, reserve replacement is a critical component of sustainable success. Optima Global believes in consistent investment in exploration and acquisitions of properties with early stage potential, which will allow the Company to replace reserves on a timely basis. Much of Optima’s exploration potential lies near existing infrastructure, where the likelihood of reserve replacement is enhanced and the cost of proving up ounces is reduced. A significant portion of Optima’s budget will be spent on studies and exploration in order to continue improving its reserve position.

Regional Geology

Ghana is part of the extensive West African Precambrian Shield. Much of south-western Ghana, as well as part of Ivory Coast, Mali and Burkina Faso are underlain by units belonging to the Proterozoic Eburnean tectonic province (1.8 2.0 billion years). These greenstone belts represent Island arc volcanism that has been mildly metamorphosed to lower greenschist facies (A metamorphic schist containing chlorite and epidote (which are green) and formed by low-temperature, low-pressure metamorphism). In Central and Northern Ghana, the Eburnean rocks are covered by flat lying Infracambrian to early Paleozoic sediments (marked by the presence of marine invertebrates, fish, amphibians, insects, and land plants) referred to as Voltaian sequences.

The Eburnian province in Ghana is dominated by three main sequences: the Lower and the Upper Birimian series (2.7 – 2.18 billion years), and the marginally Tarkwaian Series (2.1 – 2.13 billion years). The Lower Birimain Series largely of phyllites, schist’s, (A general term for minerals with a layered crystal structure), Meta greywackes and in places, Meta volcaniclastics. This is dominantly Meta sedimentary series (indicates a mineral species that is a dehydration product of another mineral species or is a polymorph) in conformably overlain and, in part, inter bedded with dominantly Meta volcanic units grouped as the Upper Birimain Series. These Meta volcanic include lavas and pyroclastics, but also contain fine to medium Meta sediments unlike the Lower Birimain units. The greenstone belt differ in some minor from the more familiar `type’ Archaean (A type of rock. Acheozoic rock) examples most notably in the absence of banded iron formations, chert, (Granular cryptocrystalline silica, similar to flint but usually light in colour) pillow lavas and komatites (Magnesium-rich ultramafic volcanic rock of high temperature origin), and by the presence of manganese rich formations. This difference probably reflects a more oxygen rich environment, given equal or similar concentration of availability iron and manganese. Volcanism in the belt is regarded as being both sub-aerial and of mainly a tholeiitic (low alkali) composition.

The Birimain is overlain by a thick Tarkwaian sedimentary sequence. These units are largely derived from the Birimian rocks and from a variety of granitoid (Pertaining to or composed of granite) instructions that are widespread among the Birimian units. The greenstone belt and the intervening sedimentary basins were both intruded by massive granites, which can be loosely divided into `belt’ and `basin’ types. The belt-type granites seen to be co-magmatic with the belt volcanic, as suggested by limited radiometric age dating of both types at 2.1 billion years old. There is also radiometric dating evidence indication that most of the hornblende bearing- belt-type granitoids are also older (60-90 million years) than the biotite foliated basin granites (“Black mica," ranging in colour from dark brown to green. Rock-forming ferromagnesian silicate mineral with tetrahedral in sheets) in the Sunyani and the Kumasi Basin. Belt-type granitoids, which are usually smaller bodies but more widespread are believed to be mantle sourced. In contrast, basin-type granitoid generally show narrower compositional ranges that suggest a partial melt from the base of the sedimentary pile (``S-type’’).

The sequence was folded and metamorphosed under greenschist fades conditions during the Eburnian tectonothermal event (21 Ga). Structural investigations reveal that Tarkwaian and Birimain rocks were deformed jointly during a single progressive event which involved regionally penetrative low – strain phase producing SI foliation, followed by the formation of high-strain zone, commonly close to the basin/belt contacts, which locally display S2 foliation. Major trust and shears resulting from the deformational event acted as channels for mineralizing hydrothermal fluids.

In general, contacts between the Lower and Upper Birimian, as well as the overall distribution of the Tarkwaian sediments, are closely aligned along major regional structures that trends northeast and extend for hundred kilometres. These structures are vital to gold exploration, since virtually all the major known gold occurrences are closely associated with them.

The geology in the Kibi-Akyem Oda region is dominated by a variety of Birimian meta sediments, volcaniclastics, and volcanics, (A general collective term for extrusive igneous and pyroclastic (rock fragment formed in volcanic eruption) material and rocks) which have been intruded by numerous belt type granitoids. Much of the belt dominated by the step sided Atewa Mountain Range, which is largely underlain by volcanic flow units described as greenstones (altered basalts, andesites) (A fine-grained igneous rock dominated by dark-coloured minerals, consisting of plagioclase feldspars (over 50 percent) and ferromagnesian silicates. Basalts and andesites represent about 98 percent of all extrusive rocks), phyllites meta-tuffs, epidiorites, (A metamorphosed gabbro or diabase in which generally fibrous amphibole (uralite) has replaced the original clinopyroxene (commonly augite)), Meta greywackes and cherts. It would appear that the flow components of these units is relatively minor and that pyroclastic (rock fragment formed in volcanic eruption) and volcaniclastic units may predominate.