A reconnaissance study of the mineralogy of sand fractions from East Pakistan sediments and soils

Two major sandbars, including almost all sediments in East Pakistan, can be identified by their sand mineralogy. The state is composed of folded Tertiary sedimentary layers adjacent to East, East and East Pakistan and old clay "Madhupur Clay" occupying a region like the central and western wide terraces. These deposits are characterized by low levels of feldspar and mica, and heavy sand including high proportions of hypnotic, zircon, tourmaline, kayanite, cross rock and sillimanite. In addition to this youngest sedimentary layer of the Pliocene-Pleistocene, this major state sediment may be mainly from the crystalline rocks of the old Indian peninsula.

The second major sandbar contains some of the smaller and lower floodplain sediments of the Brahmaputra River, Ganges River, Magna, Tista, and nearby and second floodplains. Parts of sand from units are characterized by relatively high contents of feldspar, mica and amphiboles. They may be mainly from Himalayan crystalline rocks. Depending on the relative importance of the various heavy minerals, this state can be subdivided into smaller states. Each of these subregions usually corresponds to one or more geographical units recognized during the soil survey conducted in East Pakistan (in preparation, Brammer).

Soil formation and weathering have little effect on the composition of the sand composition of soil in East Pakistan. Even the oldest soil samples, these soils are the young red soil soil formed in the Madhupur clay deposit, and relatively weathered minerals such as feldspar are similar in appearance to non-weathered base metals. Biotite is the only mineral showing remarkable signs of weathering in most soils. Due to the rapid weathering, this mineral is completely destroyed and seems to occur in seasonal floods and muddy layers of flood plains and rice paddies in rice fields. A similar weathering process can occur in some of the bleaching subsoil developed in the Madhupur clay deposit with insufficient drainage.

Gravel, sand, and silt are larger soil particles whose mineralogy is often inherited from the base material of the soil, but weathering products (such as calcium carbonate and iron oxide) or residues of the life of plants and animals It may contain. . Quartz is the most common mineral in sand and silt because it is resistant to chemical weathering except for hot weather and other common minerals are feldspar, mica, and pyroxene , Amphiboles, peridot and other ferromagnetic minerals. They are converted to lysis or clay under the combined effects of physicochemical and biological processes

Two major sandbars, including almost all sediments in East Pakistan, can be identified by their sand mineralogy. The state is composed of folded Tertiary sedimentary layers adjacent to East, East and East Pakistan and old clay "Madhupur Clay" occupying a region like the central and western wide terraces. These deposits are characterized by low levels of feldspar and mica, and heavy sand including high proportions of hypnotic, zircon, tourmaline, kayanite, cross rock and sillimanite. In addition to this youngest sedimentary layer of the Pliocene-Pleistocene, this major state sediment may be mainly from the crystalline rocks of the old Indian peninsula.