Section
Physical Sciences
Abstract
The high grade metamorphic rocks of Eastern Tanzania belong to two distinct tectonothermal belts; the early Proterozoic Usagaran Belt and the late Proterozoic (Pan–African) Mozambique Belt. Rocks of the Usagaran Belt, which locally sow evidence of eclogite facies metamorphism, experienced peak metamorphic conditions at ⁓ 2000 Ma. Tectonic activity in the Usagaran added at ⁓ 1800 Ma with the emplacement of post-organic granites. In contrast, the Mozambique Belt, which is characterized by extensive granulite complexes, experienced peak metamorphic conditions at about 700 Ma. Due to the similarity of both structural trends and metamorphic grade, the boundary between the two belts cannot be easily established by field methods. However, geochronological data in the south-eastern highlands indicated a gradual and cryptic boundary with Usagaran rocks being progressively involved in Mozambiquean tectonism eastwards. The progressive reworking of Usagaran rocks into the Mozambique Belt is also consistent with Nd isotopic data which indicate that amphibolite facies granitic gneisses, which constitute a major component of the rocks in the Mozambique Belt, represent Usagaran crust which was tectonothemally reworked during Pan-African time. The only rock units in the Mozambique belt which are of non-Usagaran derivation are the thrust-bound granulite complexes which are made up of juvenile Pan-African crust mixed with variable proportions of older Usagaran components.
Recommended Citation
MABOKO, M.A.H.
(1995)
"The mozambique of eastern tanzania: evidence for pan-african reactivation of early proterozoic usagaran basement,"
Tanzania Journal of Science: Vol. 21:
Iss.
1, Article 2.
Available at:https://doi.org/10.65085/2507-7961.2420
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This work is licensed under a Creative Commons Attribution 4.0 License.
