Geology Of Ghana Pdf

Geology of Ghana

It stretches in a north-northeasterly direction from east of Prampram and enters the Republic of Togo. Texturally, the rocks vary from very fine-grained to coarse-grained. The age is quite controversial but the system is said to range from Upper Proterozoic to Paleozoic million years.

Yendaw economically viable operation is to be achieved. Krupp GmbH was entrusted with the execution of a feasibility study of the project. Huni sandstone transitional Tarkwa Phyllites beds and green Tarkwaian and greenish grey chloritic and sericitic phyllites and schists. It tends to be coarser grained at the base of the formation while it is thin bedded and somewhat shaly at the top. Yendaw by the Eastern boundary fault.

Gold frequently occurs in fractures in sheared and shattered quartz reefs, commonly as elongated flat bodies of irregular shape and thickness that lie along and within shear zones. The rocks weather into black or dark grey, calcareous clay and silt and usually contain white or grey and nodular carbonate concretions.

Today, the Pan-African mobile belt terrane spans eastern and southeastern Ghana, with several different units. The Dahomeyan System occupies the southeastern corner of Ghana and occurs as four alternate belts of acid and basic gneisses, trending south-southwest to north-northeast direction.

The samples collected sent to Krupp Labs in W. The series consists of great thicknesses of basaltic and andesitic lavas, beds of agglomerates, tuff and tuffaceous sediments. Sahrawi Arab Democratic Republic Somaliland. The Bongo granites are mainly reddish microcline granites found mainly in the Upper Region of Ghana in the Tongo and Bongo areas.

Navigation menu

There is no evidence of intrusives. The schistose rocks become more abundant as the margins of the Togo outliers are approached. The Opon-Mansi ore is an iron-rich laterite. Epidote and pyrite are rare except near dykes, faults and quartz veins.

PDF) Geology of Ghana

It continues further in a northeasterly direction and enters the Republic of Togo. The values are generally low. Most of the volcanic carapaces have since been eroded, and the distinctive circular and ring-shaped granite plutons that fed the volcanoes have been exposed as mountain and hill massifs. The Buem formation is completely folded whereas the Voltaian System is only gently folded.

Geology of Ghana

The sandstone displays perfect subaqueous cross- bedding. The pyroxenites are typically medium to coarse-grained, greenish black, massive and homogenous. The marine environment assists in the transformation of these deposits into hydrocarbons through a series of chemical and physical processes. Lower Arenaceous Lithic assemblage of meta-greywacke meta-sandstone, meta- siltstone, phyllite and tuffaceous varieties of these rock types.

This is in accordance with the placer origin hypothesis, since the gold would become concentrated in the bottom parts of the pebble and shingle beds over which the river flowed. No trace of hydrocarbon was found in this section. Further examination of the occurrence of bitumen in the Voltaian showed that they were not distributed in the natural bedding but always in fracture mostly transverse to bedding. The barren quartz often makes prominent outcrops.

Paleoproterozoic rock units belonging to Birimian Supergroup, common across West Africa, dominate northwest and southwest Ghana. The orogeny also uplifted and eroded the rocks, filling a large graben with a folded molasse series of new sedimentary rocks, known as the Tarkwaian Group. The most important ones are the breccias or greywacke with large sedimentary fragments and a tuffaceous greywacke. African and Eastern Trade Company also drilled with oil shoes.

There is evidence for a shallow water depositional environment for the Lower Birimian rocks. These where enriched with hematite, contain the most gold.

They are generally associated with Birimian metasediments. They are thus conformable with the compositional layering of the gneiss in altitude. The bauxite formed from the weathering of Paleoproterozoic phyllite.

No fossils are observed though. The pebbles are generally well rounded consisting of white quartz, lesser amounts of greenstone, green quartzite, phyllite and chert. Chromite is associated with these pyroxenites. Essential minerals are both ortho and clino-pyroxene, greenish brown hornblende, with occasional minor plagioclase and varying amounts of opaques and other accessory minerals.

Yaw Boasiako

They are connected by saddles and some of the hills are divided into two parts namely, north and south crests, being between m above the surroundings. The areas occupied by the mafic gneisses are especially flat and areas occupied by felsic gneisses tend to give rise to gently undulating topography. There were three long periods of sedimentation, although each period contained phases of erosion.

The dominant ferro-magnesian mineral may be hornblende, alone or with biotite, or muscovite alone. Nsuta in the Sekyere Central District of the Ashanti Region has a manganese oxide and carbonate mine. There are no source rocks in juxtaposition to allow possible inward normal hydrocarbon migration. However, grades of amphibolite facies are common and grades up to granulite facies do occur in several localities.

Geology of Ghana

In general, rocks of the acid Dahomeyan are composed of quartz, feldspar, epidote and mica. Geologists debate the age of the Tamale Supergroup which may have formed in the Late Neoproterozoic or possibly in the Cambrian of the Early Paleozoic era. Dips are generally high and are to the east.

Geology of ghana pdf

Almost one-third of the area of Ghana is covered by these horizontal sandstones, shale, mudstones and conglomerates considered to be late Precambrian to Paleozoic age. Quartz is the most objectionable impurity in aluminium production as it combines with alumina during reduction. Almost any combination of these types can be found in the same deposit. The gold is usually accompanied with arsenopyrite. The hills on which the iron ores occur have an average height of m and the Wuowuo hill, the largest and the highest is m above sea level.

The series is now represented by great thicknesses of isoclinally folded, steeply dipping, alternating slates, phyllites, greywacke and argillaceous beds with some tuffs and lavas. However, the sedimentary rocks are particularly characterized by extensive folding. Even though the Ghanaian end has experienced less subsidence throughout its geological history, the sands are probably closer to their source, are thicker, more massive and dirtier ie. Isoclinal folding with the axial planes of the folds inclined to the east-south-east at O.

Navigation menu

Wikimedia Commons has media related to Geology of Ghana. Refer to the geology of the Voltaian System. Geology The rocks of the diamond field may be classified as follows, in order of age, anesthesia big blue pdf the oldest being at the bottom of the table.