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Quartz grains from the Kallamedu (late Maastrich-tian) and lower Niniyur (Danian) Formations, Cauvery Basin,Southeast India were examined under a scanning electron microscope,and twenty three distinct microtextures were observed. Thesemechanical (thirteen features), mechanical and/or chemical (fivefeatures) and chemical (five features) origins. Quartz grains fromthe Kallamedu and lower Niniyur Formations show conchoidalfractures, straight steps and arcuate steps which are the charac-teristic microtextures of quartz grains derived from crystallinesource rocks. Quartz grains from the upper Kallamedu and lowerNiniyur Formations show angular to subangular outline, whereasthose from the lower Kallamedu Formation show subangular torounded outline. The dominance of angular to subangular grainsand the presence of straight and arcuate steps suggest that theseclastic sediments were undergone short transportation and rapidKallamedu Formation suggests that significant amounts of quartzgrains are of recycled origin. Vs, straight scratches and curvedscratches, the characteristic features of marine environment, are com-mon on the quartz grains from the lower Niniyur Formation, whichis consistent with the previous interpretation. However, quartz grainsfrom the lower Kallamedu Formation exhibit very low frequency ofthese features, whereas they are moderately present in the upperKallamedu Formation, suggestive of a change in depositional con-ditions with time. The lower Kallamedu Formation exhibits planarenvironment. The unfossiliferous upper Kallamedu Formation containsappreciable amount of illite and mixed-layer (illite/smectite) clayminerals, which suggests that the saline conditions prevailed dur-ing its deposition. Microtextures on the quartz grains coupled withdominant clay mineral types suggest the deltaic depositional envi-ronments for the upper Kallamedu Formation.