Arabian Journal of Geosciences

, 11:567 | Cite as

FEG-EPMA mapping and Fe-Ti oxide mineral chemistry of Brahmaputra River sediments in Bangladesh: provenance and petrogenetic implications

  • A. S. M. Mehedi Hasan
  • Ismail HossainEmail author
  • Md. Aminur Rahman
  • Md. Sazzadur Rahman
  • Mohammad Nazim Zaman
  • Pradip Kumar Biswas
Original Paper


The present research deals with the FEG-EPMA mapping and Fe-Ti oxide mineral chemistry of Brahmaputra River sediments in Bangladesh. Major heavy minerals in the sediments consist of garnet (8.5–21.3%), kyanite (5.35–11.9%), monazite (2.3–5.3%), sillimanite (1.8–4.7%), zircon (3.6–9.1%), and a considerable amount of opaques mainly Fe-Ti oxide minerals (23.1–35.4%). The detrital Fe-Ti oxide minerals carry significant clues to the parent rocks or sources. In these contexts, detrital opaques (Fe-Ti oxides) have been analyzed with an electron probe microanalyzer (EPMA). These opaques (Fe-Ti oxide) display six types of textural patterns, dominantly seriate with granular, emulsion, and acicular sandwich structures and trellis type of textural patterns. These textural patterns belong to five intergrowths of Fe-Ti oxide minerals such as (1) ilmenite-hematite, (2) magnetite-ilmenite, (3) hematite-rutile, (4) ilmenite-hematite-rutile, and (5) ilmenite-rutile, where ilmenite-hematite intergrowth is common. Alteration is seen in both exsolved and unexsolved ilmenites. Textural patterns and mineral chemistry of the studied ilmenite minerals provide lines of evidence of low-temperature magmatic inheritance, later modified by diffusional processes. The estimated temperature and oxygen fugacity from the magnetite-ilmenite exsolution range from 547.6 to 558.2 °C and from 10−21.4 to 10−21.7, respectively. The data are also consistent with hematite-ilmenite temperature (between 537 and 540 °C) and oxygen fugacity (10−21.7 to 10−21.9) measurements in Cox’s Bazar beach placers. These temperatures and oxygen fugacities specify Fe-Ti oxide assemblages equilibrated in a T-fO2 field very near to the FMQ buffer curve suggesting a crustal source (magmatic and/or metamorphic), which is modified significantly by metamorphic processes.


Opaque minerals Ilmenite Exsolution Geothermometry Oxygen fugacity 



The authors cordially thank Mark I. Pownceby (co-worker at CSIRO, Australia) for his great contribution to carry out the XRD and EPMA data from the laboratory housed in CSIRO, Australia. The authors are extremely grateful to other scientists, technicians, and other laboratory attendants of the Institute of Mining, Mineralogy and Metallurgy (IMMM) for their help during sample collection, preparation, and analytical services. The authors are also grateful to the anonymous reviewers for their constructive reviews and comments.

Funding information

The authors acknowledge the financial support in the form of research fellowship (Professor Mofizuddin Ahmed Sriti Fellowship, Bangladesh Council of Scientific and Industrial Research) provided by the Ministry of Science and Technology, Bangladesh, and also the Chairman of BCSIR for supporting the laboratory’s equipment.


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Copyright information

© Saudi Society for Geosciences 2018

Authors and Affiliations

  • A. S. M. Mehedi Hasan
    • 1
  • Ismail Hossain
    • 2
    Email author
  • Md. Aminur Rahman
    • 1
  • Md. Sazzadur Rahman
    • 2
  • Mohammad Nazim Zaman
    • 1
  • Pradip Kumar Biswas
    • 1
  1. 1.Institute of Mining, Mineralogy and Metallurgy (IMMM)Bangladesh Council of Scientific and Industrial Research (BCSIR)JoypurhatBangladesh
  2. 2.Department of Geology and MiningUniversity of RajshahiRajshahiBangladesh

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