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Authors
Affiliations
1 Department of Geology and Mining, University of Rajshahi, Rajshahi-6205, BD
2 Department of Geological Sciences, Jadavpur University, Kolkata, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 71, No 5 (2008), Pagination: 724-730
Abstract
The rock sequences of the Sylhet Limestone Formation, Dauki River section, Gwainghat, Sylhet were studied to identify their various petrological units, non-clastic minerals and fossil content. Limestones are of two varieties crystalline in lower horizon and fossiliferous in upper horizon. The various petrological units identified in the non-clastic portion of the Sylhet Limestone Formation include micrites, dismicrites, intramicrites, pelrmicrites, spantes, intrasparites, pelsparites, and oosparites. Calcite, dolomite and fossils with minor amount of clay, mica, chert, quartz, zircon, tourmaline, rutile, and opaque minerals constitute the limestones. Fossiliferous limestone consists of smaller and larger foraminiferal genera, such as Nummulites, Discocyclina Alveolina, Operculina, Assilina etc. with some Bryozoans and Brachiopod shells. The various petrological units mght have deposited in shallow marine environment with nonreducing as well as reducing condition by tidal, winnowing and non-agitating currents. Algal growth aided the various units in formation.
Keywords
Sylhet Limestone Formation, Dauki River, Gwainghat,Northeastern Sylhet, Bangladesh.
