Geology, Mineralogy, and Economic Potential of a Banded Iron Formation within the Precambrian Basement of the Masidpur Magnetic Body, Northwestern Bangladesh

Abstract

The Masidpur magnetic body, located at Alihat Union, Hakimpur Upazila, Dinajpur District, northwestern
Bangladesh, contains geologically significant iron mineralization within the Precambrian crystalline basement of the Rangpur
Saddle, a major basement high of the Bengal Basin. This study investigates the mineralogical composition, geochemical
characteristics, iron mineralization, and geological significance of the deposit using integrated petrographic, mineralogical, and
geochemical analyses. The investigation is based on four diamond drill holes completed by the Geological Survey of
Bangladesh (GSB). A total of 98 basement core samples were examined using transmitted- and reflected-light petrography, X
ray fluorescence (XRF), X-ray diffraction (XRD), field-emission scanning electron microscopy coupled with energy-dispersive
spectroscopy (FE-SEM/EDS), and inductively coupled plasma–optical emission spectrometry (ICP-OES). Petrographic
analysis indicates that magnetite (average 27.75 wt.%) and quartz (average 44.47%) are the dominant mineral phases,
accompanied by subordinate amphibole, pyroxene, mica, epidote, and feldspar. FE-SEM/EDS analyses corroborate the modal
mineralogy, yielding average abundances of 26.84% iron minerals and 41.47% quartz. XRF analyses reveal average
concentrations of 35.36 wt.% Fe₂O₃ and 39.50 wt.% SiO₂, whereas ICP-OES analyses of iron-rich intervals record Fe₂O₃
contents ranging from 46.20 to 77.67 wt.%. XRD patterns confirm magnetite–quartz as the principal crystalline assemblage
with subordinate amphibole, mica, and feldspar. Iron-rich horizons occur consistently between depths of approximately 426
and 548 m, with an average cumulative thickness of ~50 m. Alternating magnetite-rich and silica-rich bands, together with
their mineralogical, petrographic, and geochemical characteristics, indicate that the mineralization represents a metamorphosed
banded iron formation (BIF) comparable to Precambrian BIFs worldwide. The integrated dataset establishes the Masidpur
magnetic body as a geologically significant iron-mineralized system with promising exploration potential. However, its
economic significance remains to be evaluated through additional drilling, resource estimation, metallurgical testing, and
comprehensive feasibility studies.

Keywords: Magnetite, Precambrian basement, Banded Iron Formation (BIF), Iron ore mineralization.