中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 33 No. 6 June 2023 |
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-physics, Central South University, Changsha 410083, China;
2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;
3. School of Geosciences, China University of Petroleum (East China), Qingdao 266580, China;
4. Faculty of Oil, Gas and New Energies, University of Kinshasa, B. P. 127 Kinshasa XI, D. R. Congo;
5. Official University of Bukavu, Bukavu, South Kivu, D. R. Congo;
6. National Geological Service, Ministry of Mines, Kinshasa, D. R. Congo;
7. Geophysical Research Center, Ministry of Research and Technological Innovation, Kinshasa, D. R. Congo）
Abstract:This paper reports the results from an investigation on petrogenesis and geochemistry of the Lemera granite pegmatites in Kivu region of Karagwe-Ankole Belt, D. R. Congo and the related tin ore deposits. Seven granite pegmatite samples were collected from outcrops and analyzed for bulk-rock geochemistry analysis using ICP-MS and XRF spectrometry. The analyzed samples show a relative abundance of Al2O3 over Fe2O3(T) and MgO (12.95, 0.96, and 0.16, all in wt.%, on average and respectively). The alumina saturation index ranges from 1.33 to 2.05. The abundances of some important rare metals, as well as some related key parameters, are as follows: Sn ((1-138)×10-6), Ta ((0.20-0.60)×10-6), Nb ((1-8)×10-6), Cs ((1.20-3.20)×10-6), Rb ((3-223)×10-6), Zr ((7-201)×10-6), w(K)/w(Rb) (150-272); w(K)/w(Cs) (9.06-23.3); w(Nb)/w(Ta) (3.33-14). The results indicate that the Lemera granite pegmatites crystallized from a fertile, peraluminous, and S-type granitic magma through a fractional crystallization process in a late to post-collisional setting. Mineralization of Sn and Zr of Lemera granite pegmatites is noticed.
Key words: Kibaran Belt; Lemera granite pegmatites; tin ore deposits; S-type granites; fractional crystallization
