SEAMIC Newsletter Vol. 10

MINERAL RESOURCES OF TANZANIA
BY GEOLOGICAL SURVEY OF TANZANIA
Tanzania is blessed to have a geological environment conducive for hosting diverse types of
mineral deposits. The country hosts a mining investment area close to one million square
kilometres with litho-types virtually representing all the known chrono-stratigraphical units of
the world ranging from Archean, Proterozoic, Phanerozoic to Quaternary ages. These
geological formations host a variety of minerals such as gold, basemetals, Platinum Group
Metals (PGM), diverse types of gemstones (including tanzanite, diamond, emerald, sapphire,
coloured quartz, ruby, beryl, tourmaline, garnet, etc.), various industrial minerals (coal, salt,
kaolin, phosphates, mica, corundum), building materials and hydrocarbons (mainly natural
gas).
GEOLOGICAL ENVIRONMENT
Much of the central and northern part of the country is underlain by the Tanzanian Archean
Craton. The central part of the country is composed of the high grade metamorphic terrain
whereas the northern part is covered by the Greenstone Belt. The Tanzania Archean Craton is
well known as a host for world-class gold deposits similar to other Archean Cratons around the
world. The Craton is also intruded by a number of diamondiferous kimberlitic pipes.
The Tanzania Archean Craton is engulfed to the southeast and southwest by Palaeoproterozoic
Usagaran and Ubendian mobile belts respectively, with high grade crystalline metamorphic
rocks with a number of post-orogenic gabbroic and granitic intrusives hosting base metals,
shear zone hosted gold, various types of gemstones and industrial minerals. The eastern part of
the Usagaran Belt is mobilized by the Neoproterozoic Pan African Orogeny forming the
Mozambique Belt with lithological, structural and metallurgical characteristics similar to that
of the Usagaran - Ubendian Belt.
The Palaeoproterozoic Ubendian mobile belt is bound to the west by the mildly
metamorphosed Mesoproterozoic Fold Belt. The supercrustal rocks of this Belt are intruded by
post orogenic granites which have alteration haloes containing veins with tin and tungsten
mineralization. The Belt is also characterized by post-orogenic basic intrusives hosting PGM.
The Uha-Malagarasi Neoproterozoic to Early Palaeozoic age is an intracratonic formation
consisting of sedimentary-volcanic depositional sequences of sandstones, quartzites, shales, red
beds, dolomitic limestones, cherts and amygdaloidal lavas with indications of strata-bound
copper deposits and various industrial minerals.
The Phanerozoic formations in Tanzania include the following:-
(i) The Karoo Supergroup of late Carboniferous to Jurassic age
(ii) Marine Formations that are dominated by shelf-facies clay bound sands, marls and some
isolated coral reefs
(iii) Neogene to Quaternary continental formations in
a. isolated basins and river channels composed of clays, limestone, evaporates and sands;
b. volcanic rocks ranging in composition from lavas, tuffs, ash and pumice;
c. volcanic fumarolic exhalative deposits.
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