Geology of Angola

Angola is a country located in Southern Africa, with a diverse geological history. The formation of Angola’s geology can be traced back to the Precambrian era, which lasted from around 570 to 635 million years ago.

Geology of Angola

During this time, the continent of Gondwana began to break apart, forming the modern-day African continent. Angola’s geology is characterized by a combination of igneous, metamorphic, and sedimentary rock formations.

Some key geological formations in Angola include:

1. Kibara Craton: The Kibara Craton is a large, ancient craton that forms the core of Angola. It is composed primarily of igneous and metamorphic rocks, with some sedimentary layers. The Kibara Craton is believed to have been formed during the breakup of Gondwana.
2. Benguela Belt: The Benguela Belt is a series of igneous rocks that runs along the western coast of Angola. This belt is part of the larger West African Craton and is characterized by its granitic and gneiss rocks. The Benguela Belt is thought to have formed during the breakup of Gondwana and the subsequent movement of tectonic plates.
3. Cuanza Basin: The Cuanza Basin is a sedimentary basin located in the central part of Angola. It is characterized by its deep-water sedimentary rocks, which were deposited during the Mesozoic and Cenozoic eras. The Cuanza Basin is an important source of oil and natural gas for the country.
4. Lualaba-Congo Craton: The Lualaba-Congo Craton is a smaller craton that is located in the northeastern part of Angola. It is composed primarily of igneous and metamorphic rocks, with some sedimentary layers. The Lualaba-Congo Craton is thought to have formed during the breakup of Gondwana.

Angola’s diverse geology is a result of its location at the intersection of several tectonic plates and the movement of these plates over millions of years. This has led to the formation of a variety of rock types and mineral deposits, which are important for the country’s economy and natural resources.

Rocks of possibly Neoarchean age outcrop in the northeast of Angola belonging to the Kasai Craton (Fig). The country is underlain by Paleoproterozoic, Mesoproterozoic and Neoproterozoic rocks of various composition in the west, which include Neoproterozoic Bembe System basal tillites. Oolitic limestones and stomatolites underlay these. The northern central part of the country is underlain by volcanic and sedimentary rocks of the Karoo Supergroup. Precambrian basement is directly overlain by a thick sequence of Mesozoic to Cenozoic marine sedimentary rocks in the coastal basin. The eastern part of Angola is largely covered by Kalahari Group sands and related deposits. The oldest formations known in Angola are located in the northeast of the country, related to those more studied in Kasai (Democratic Republic of Congo) and have been affected by metamorphic episodes corresponding to the Neoarchean Moyo and Musefu parts of Kasai. In the basement of western Angola, Isolated Archean rocks are also exposed in some places such as at Dondo, Malanje and south of the River Cuanza near Cariango. Here Archean assemblages show NE–SW and E–W trends, comprising kinzigites, enderbites, charnockites, and granulite gneisses. The volcano-sedimentary Jamba Group South of Nova Lisboa is also of Archean age. Complex greenstone belts of Paleoproterozoic age are present in the southern central part of the country.It has been concluded that an orogeny affected most of this region at about 2.15 Ga, during which the main metamorphism, granitization and deformation took place, followed by extensive late- and post tectonic, and anorogenic granitic intrusions and volcanic activity between 2.05 and 1.75 to 1.65 Ga. From Gabon southwards through the Republic of Congo, the Democratic Republic of the Congo, to northern Angola the West Congolian mobile belt extends for over 1300 km. From east to west it contains three structural zones, the external zone with sub-horizontal strata, the median folded zone and the internal zone consisting of intrusive and pre-west basement rocks.

Representing the infilling of a Kibaran-age continental rift, the Mayumbian and the Zadinian Supergroups are the older rocks in the internal zone, which was deformed and thrust eastwards during the Pan-African orogeny in the West Congolian. A sequence of low-grade metasediments of the external and median zones contain the West Congolian Supergroup. The occurrence of high-energy debris flow deposits (mixtites), red beds and basic volcanics in its lower part. Because of its elongate basin geometry sedimentation has been assumed to have started probably at around 1.1 Ga.in a fault-bounded continental rift. Mainly preserved in the northern central to north-western geological depression are sediments of Paleozoic to Mesozoic age of the Cassanje Graben. These magmatic and sedimentary rocks are correlated with the Karoo Supergroup. Magmatic activities during this period caused the emplacement of diverse volcanic to sub-volcanic bodies, including carbonatites, kimberlites, basalts, syenites, dolerites, trachytes and phonolites. The kimberlite and carbonatite bodies are located along a major trend line, which transects Angola southwest to northeast diagonally. Cretaceous to Pleistocene marine sediments cover the western margins of Angola. From north to south these basins started developing during Lower Cretaceous times. And are: The Congo, the Kwanza and the Namib marine coastal basins. Three types of Tertiary to Quaternary rocks can be distinguished, constituting the youngest geological units of Angola. These are Quaternary colluvial and alluvial deposits, Tertiary to Quaternary Kalahari Group continental sediments, and early Tertiary laterite residues. Nearly 50% of Angola is covered by these sedimentary rocks. The Kalahari Group consists mainly of quartzitic sandstones and sand. In the eastern and central part of Angola the lateritic residue forms the substratum of the Kalahari Group. Quaternary colluvial and alluvial deposits in the form of clay, sands, gravels and rubbles occur mainly in river valleys and/or depressions.

Mineral resources of Angola

Angola is a mineral-rich country with a diverse geology. The country is home to significant deposits of diamonds, cobalt, copper, gold, iron ore, and uranium.

Some of the key mineral resources in Angola include:

1. Diamonds: Angola is one of the world’s leading producers of diamonds, with the majority of its diamonds coming from the Lualaba-Congo Craton. The country’s diamond reserves are estimated to be among the largest in the world.
2. Cobalt: Angola is also a significant producer of cobalt, which is an essential material in the production of lithium-ion batteries used in electric vehicles and smartphones. The country’s cobalt reserves are located in the Lualaba-Congo Craton.
3. Copper: Angola has significant copper reserves, which are concentrated in the Cuanza Basin. The country is a major producer of copper and has been investing in the development of its copper mining sector.
4. Gold: Angola has gold deposits in the Lualaba-Congo Craton and the Benguela Belt. The country’s gold production is relatively small, but it has potential for growth.
5. Iron Ore: Angola has significant iron ore reserves, which are concentrated in the Cuanza Basin. The country is a major exporter of iron ore and has been investing in the development of its iron ore mining sector.
6. Uranium: Angola has uranium deposits in the Lualaba-Congo Craton and the Benguela Belt. The country has been investing in the development of its uranium mining sector, with a focus on the production of uranium for nuclear power and other applications.

Angola’s diverse geology and mineral resources have played a significant role in shaping its economy and natural resources. The country has been investing in the development of its mining sector, with a focus on the production of diamonds, cobalt, copper, gold, iron ore, and uranium.