Trace and rare earth elements geochemistry of the basement complex in Madhyapara, Dinajpur, Bangladesh. | [Acta mineralogica pakistanica • 2001]

Author(s):

1. Mohammad Nazim Zaman: Department of Geology and Mining, University of Rajshahi, Rajshahi 6205, Bangladesh

2. Shamsuddin Ahmed Syed: Department of Geology and Mining, University of Rajshahi, Rajshahi 6205, Bangladesh

3. Badrul Islam Mohammad: Department of Geology and Mining, University of Rajshahi, Rajshahi 6205, Bangladesh

4. Sultan-Ul-Islam Mohammad: Department of Geology and Mining, University of Rajshahi, Rajshahi 6205, Bangladesh

5. Hiroaki Ishiga: Department of Geoscience, Faculty of Science and Engineering, Shimane University, Matsue, Japan

6. Maqbul-E-Elahi Mohammad: Managing Director, Madhyapara Hardrock Mining Project, Madhyapara, Phulbari 5260, Bangladesh

7. Chen Daogong: Department of Earth and Space Sciences, University of Science and Technology, China

8. Zhi Xiachen: Department of Earth and Space Sciences, University of Science and Technology, China

Abstract:

The geochemical characteristics of the sub-surface Basement Complex in Madhapara have been carried to synthesize its petrogenesis. The Basement Complex is composed of tonalite, granodiorite, granodiorite gneiss, granite, adamellite and quartz-monsonite. Granites, adamelllite and quartz-monzonite are intruded as vein into the tonalite-granodiorite (TG) suite with sharp contact. In silica variation diagrams the trace elements Sc, V and Cr of the TG suite show linear negative trends with increasing SiO2, while most of the trace elements concentrate as clusters. A large variation of the incompatible element content (e.g. Ba) as compared to compatible elements (e.g. Cr and Ni) suggests that partial melting played the dominant role for the evolution of the TG suite. Correlation between Sr and Rb/Sr versus Si)2, indicate insignificant role of plagioclase fractionation. The chondrite normalized rare earth element (REE) patterns shows that the TG suite is enriched in light-REE, moderately fractionated and characterized by no Eu anomalies. The Primitive Mantle normalized trace and REE pattern show negative Nb anomalies suggesting a subduction related magmatism. The Ocean Ridge Granite normalized trace and REE patterns marked a Nb-Ta negative anomaly i.e. forming a trough, indicating continental arc granitoid signature. Minor differences in LaN/SmN, GdN/YbN and LaN/YbN ratios and more or less parallel REE pattern indicate that the TG suite is possibly derived from a single source. Most of the REE patterns of this suite show a concave form at the HREE end. The geochemical characters of the TG suite suggest that both partial melting of the granitoid basement (amphibolite source rock) and fractionation of Fe-Mg phase, are responsible for the evolution of this suite in Madhyapara.

Page(s): 27-42

DOI: DOI not available

Published: Journal: Acta mineralogica pakistanica, Volume: 12, Issue: 1, Year: 2001

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