¹Department of Geology,Lumding College Lumding, Assam India

²Department of Geological Sciences, Guuhati University, Guuhati, Assam India

Heavy minerals from Barail sandstones occurring in and around Mandardisa of N.C. Hills, Assam have been studied to determine the provenance (source) depositional history and maturity of the sandstones. An attempt has also been made to correlate the area with some neighbouring areas of Meghalaya and Assam where Barail sandstones are well exposed. The heavy mineral assemblage contains a good amount of stable and unstable minerals consisting of non-opaque minerals viz. zircon, tourmaline, rutile, epidote, staurolite, kyanite etc. and opaque iron minerals. This assemblage suggests that the sediments of Barail sandstones were derived mostly from metamorphic and igneous rocks with minor derivation from sedimentary rock. The source rocks are mostly from neighbouring areas of Meghalaya Plateau and Arunachal Himalaya. The statistical analyses namely length frequency breadth frequency and elongation quotient frequency diagrams of zircon indicate two or more diverged provenance (sources). The scatter diagram of zircon is also indicative of nearer provenance and hence shorter transportation of the sediments from the sources. The study of primary and secondary growths of zircon grains also indicate dual nature of origin of the sandstones. A very few grains of rounded heavy minerals suggest reworked nature of some sediments.