Palyno-petrographical Study of the Siwalik Rocks of Some Areas of Arunachal Pradesh, North-Eastern India to Understand Palaeo-climatic Evolution of this Region

Abstract

The palynological assemblages within the Siwalik shale rock samples from some areas of Arunachal Pradesh is studied to determine the palaeoclimatic condition. The petrographic study of the Shales also taken as the supportive to the determined palaeoclimate by the study of Palynological assemblages of 32 species and 30 genera taken separately from three distinct Siwalik strata, upper, middle and lower, collected from open exposures of Itanagar Banderdewa Roadside, Julu Village, and Pinjoli area of Arunachal Pradesh. The Palyno-petrographic study overall suggests that, during the lower siwalik, the region was highly coastal influenced with a dominating Tropical, humid climate. During the middle Siwalik, coastal influence was lowered, which shows coastline getting wiped out, and the temperature condition of Tropical- Sub-tropical climate. Upper Siwalik shows a further decreased coastal influence, with mainly a sub-tropical climate with an indication of temperate condition, which is indicative and supportive for the Pleistocene Glaciation in the global geological history.