[B-CG04] Decoding the history of Earth: From Hadean to the present

[BCG04-06] Paleoproterozoic magmatic flare-up of the Ubendian Belt, SW Tanzania: A crustal growth history events before the amalgamation of the Central African Shield

*Ariuntsetseg Ganbat¹, Tatsuki Tsujimori^1,2, Nelson Boniface⁴, Daniel Pastor-Galan^1,2,3, Shogo Aoki^5,6, Kazumasa Aoki⁶ (1.Graduate School of Science, Tohoku University, 2.Center for Northeast Asian Studies, Tohoku University, 3.Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 4.Department of Geology, University of Dar es Salaam, 5.Graduate School of International Resource Sciences, Akita University, 6.Center for Fundamental Education, Okayama University of Science)

Keywords:Ubendian Belt, Slab-failure magmatism, Paleoproterozoic, U–Pb zircon geochronology

The Ubendian Belt (UDB) is a Paleoproterozoic orogeny between the Archean Tanzania Craton (TZC) and the Bangweulu Block (BWB), which are part of the Congo Craton assembled at ~1.8 Ga, forming the Central African Shield, during the amalgamation of the Columbia Supercontinent and the Gondwana assembly (Ganbat et al., 2021). This study presents the new LA-ICPMS zircon and apatite U–Pb ages, Hf-in-zircon isotope compositions, and whole-rock geochemistry for the metagranitoids from the Ufipa Terrane of the Western Ubendian Corridor of UBD and the BWB. LA-ICPMS zircon U–Pb ages confirmed magmatic events from 1.89 to 1.85 Ga. The metagranitoids of the Western Corridor of UBD and that of the BWB are compositionally similar and are contemporaneous. The geochemistry of 1.89–1.85 Ga metagranitoids and granoporphyries are suggested that they are originated from slab-failure magma. The melt derived from the mafic upper portion of the detached slab induced the partial melting of crust which can form felsic magmatism in the BWB and the UBD. The development of thick sediments (the Mporokoso Group) overlying the BWB implies a crustal extension after the Orosirian magmatic flare-up due to the slab failure. Zircons from two metagranitoids from the Northern Ufipa Terrane evidence the tectonothermal event at ~570 Ma. However, we found non-annealed Orosirian apatites in metagranitoids from the Southern Ufipa Terrane and the BWB, implying that the Neoproterozoic overprint in the Ufipa Terrane was heterogeneous. Zircon εHf(t) value and the model ages are indicate interaction with older crust underlying the BWB.