Md Morshadul Haque’s scientific contributions

The Bhuban Formation along the Hari River section in Sylhet consists predominantly of shale, silty shale and sandy shale with subordinate siltstone, sandstone and conglomerate. Five lithofacies viz. Gm, Sp, Sm, S and F have been identified in the Formation. Numerous well-defined complete and incomplete Bouma sequences were recorded in turbidite sandstone facies (ST). The complete sequence is rare. The incomplete Bouma sequences are present as Ta-b, Tb, Tb-c, Ta-c-d-e and Ta-b-d-e whereas complete one is Ta-b-c-d-e. Higher dip values of paleocurrent data are suggestive of a primarily higher slope of the depositional area.the vertical and lateral distribution of facies, thickness of sandstone and/or conglomerate beds and their geometries, sand/shale ratio, paleocurrent data and channel axes suggest submarine fan environment for the deposition of the Bhuban Formation. A proximal fan environment is identified in the lower part of the succession with Gm, Sp, Sm and classical turbidite sandstone (ST) along with bluish black shale (F) facies. Classical S, in association with base missing distal turbidites and hemipelagic as well as pelagic-mud facies in the middle part suggests distal fan deposits. Middle fan deposits are represented by classical ST with complete and incomplete Bouma sequences and bluish black hemipelagites in the upper part of the formation. Basin plain facies association is marked by monotonous hemipelagic and pelagic mud. Sandstone/shale ration, sandstone and/or conglomerate bed thickness, grain size and erosive feature decrease from proximal to distal fan (southward), whereas beds become more regular, parallel sided, better graded, micro-cross-laminated and parallel laminated towards the distal part. Four stages of progradation and retrogression each have been recognized in whole sequence.

The Bhuban Formation of Lower Miocene Surma Group, exposed along the Hari river section, Jaintiapur, Sylhet. Bangladesh is composed mainly of shale with subordinate silty shale, sandy shale, siltstone and sandstone with occasional conglomerate. A total of ten samples, five from sandstones and five from shale, were analyzed for petrographic study. Light mineral fraction of the sandstone includes both mono- and polycrystalline quartz (average 47.20%), feldspar including orthoclase, microcline and plagioclase (average 5.10%), mica (both muscovite and biotite- average 5.37%) and unidentified minerals (average 1%). Heavy mineral fraction (total 6.37%) consists of zircon, garnet, chlorite, pyroxenes and amphiboles. Rock fragments of igneous, sedimentary and metamorphic origin constitute 15.25% of the sandstones Matrix is about 19.86%. These sandstones are classified ad lithic greywacke. Clay minerals within the shales, include illite, chlorite, and kaolinite with or without montmorillonite. Other minerals of shales are quartz, feldspar, calcite and dolomite. All these minerals, both of sandstone and shale, might have derived from the Precambrian igneous, and metamorphic rocks and pre-existing sedimentary rocks of Mesozoic and Tertiary age, even older than Miocene of the adjoining area.