Uranium exploration in Bangladesh

The sedimentary succession of Bangladesh has continental sandstones with lignite and organic matter which are favourable host rocks for sedimentary uranium. The shield areas around Bangladesh are considered good source areas for uranium. Encouraged by this idea, the Bangladesh Atomic Energy Commission (BAEC) started an exploration programme in 1976 with the assistance of the IAEA and the United Nations Development Programme. Preliminary reconnaissance radiometric surveys carried out in 1976-1977 in the Chittagong, Chittagong hill tract and Sylhet districts identified some anomalies with 3 to 5 times the background (XBG). This was followed by regional reconnaissance radiometric surveys which were carried out between 1977 and 1985 in some of the anticlines of the Chittagong and Sylhet districts, including an airborne (helicopter) survey over the Jaldi area. These surveys resulted in the discovery of more than 300 radiometric anomalies of 3 to 60 XBG. They occur in the medium to fine grained ferruginous sandstones of the Dupitila and Tipam Formations of Mio-Pliocene age. These anomalous beds show variation in slime and heavy mineral contents. Some samples collected from the anomalous beds contain uranium and thorium ranging from 20 to 100 ppm and 100 to 1000 ppm, respectively. Exploratory drilling to a depth of about 400 ft was carried out on a very limited scale in the northeastern part of the Sylhet district. Gamma logging of these holes indicated many subsurface anomalies (3 to 21 XBG) in the Dupitila Formation. These anomalies are linked to thin layers with restricted lateral extensions. Geochemical orientation studies and radon surveys were done in some selected areas of Sylhet to test their suitability for further surveys. 9 refs, 13 figs, 4 tabs