SOURCE ROCK CHARACTERISTICS OF THE LATE PROTEROZOIC NAGTHAT FORMATION, NW KUMAUN LESSER HIMALAYA, INDIA

The Nagthat siliciclastics consist of sublithic-arenite and subarkose with subordinate proportion of quartz wacke, lithic graywacke, quartz arenite, lithic arenite and arkosic wacke. Triangular plot of lithic fragments, variable diagrams of quartz types and heavy mineral assemblage collectively suggest their derivation mainly from low to high grade metamorphic terrain with minor contribution from sedimentary and plutonic igneous rocks. This is further supported by the dominance of brown luminescing quartz and blue to non-luminescent feldspars. The palaeoflow analysis reveal three prominent modes NE, NW, ESE and suggests that the source areas for the Nagthat sediments was towards the SW, SE and WNW directions. Taking all these points into consideration, it can be inferred that the major part of the detrital framework materials for the Nagthat siliciclastics were possibly supplied due to uplift and subsequent erosion of Aravalli-Delhi mountain chain and Bundelkhand granite-gneiss massif sometime during Aravalli and Delhi orogenic events,