A Study on Geochemical Composition and Source  Area Weathering of the Tipam Sandstones from a  Few Oil Fields of Upper Assam Basin, India

Ananya Chutia; J. N. Sarma

Volume : III, Issue : VIII, August - 2013

A Study on Geochemical Composition and Source Area Weathering of the Tipam Sandstones from a Few Oil Fields of Upper Assam Basin, India

Ananya Chutia, J. N. Sarma

Abstract :

An attempt has been made in this paper to report on the geochemistry of the sandstones of the Tipam Sandstone Formation of Miocene age of Upper Assam Basin, India. Moreover, based on the study of the chemical composition of these sandstones, source area weathering of the same has been appraised. The study has shown that these Tipam sandstones have different elemental oxide content as SiO2 from 45.91 to 64.13%, Al2O3 from 11.96 to 14.57%, Na2O from 2.21 to 4.43%, Fe2O3(T) from 2.44 to 6.08%, K2O from 1.14 to 2.68%, MgO from 0.18 to 3.12%, TiO2 from 0.41 to 1.16%, P2O5 from 0.03 to 0.27%, MnO from 0.06 to 0.47% and CaO from 0.35 to 8.47%. The values of chemical index of alteration (CIA) indicate moderate weathering in the source area. The study has shown that the source area was dominated by rocks of tonalitic and granodioritic composition and K–metasomatism played an insignificant role.