Geochemistry plays a crucial role in the study of sedimentology, offering insights into the petrogenetic history encompassing provenance, paleoclimate, paleoweathering, and paleotectonic settings of minerals within sedimentary rocks. It aids in understanding the behaviour of elemental redistributions during both syn- and post-depositional stages of sedimentation. The present study focuses on the petrographic and geochemical analyses of sandstones from the Barail Group (Surma Basin) exposed in and around Ngopa, Mizoram, India. The sandstones are characterised by a fine to very fine-grained texture, with well-sorted, angular to sub-rounded clasts, cemented by siliceous to ferruginous materials. Quartz (monocrystalline and polycrystalline) is the most abundant framework mineral (mean 67.43%) followed by rock fragments (mean 16.68%) and feldspar (mean 5.43%). The undulatory extinction of quartz grains suggests orogenic deformation, supported by kink-band-like structures observed in micas. The high degree of sediment compaction resulted in sutured contacts between the quartz grains. These sandstones exhibit classifications ranging from arkose, litharenite, and lithic sandstone, whilst their mineral content categorises them as sublitharenite. The micropetrographic composition indicates that the sediments were deposited in a near-shore terrestrial freshwater environment, likely in a fluvio-deltaic setting. In addition, the silica content (64.79-74.56 wt%), TiO2/Zr ratio(11.92-46.71), La/Sc (3.11-9.78), La/Co (2.68-13.47), Th/Sc (1.10-2.96), Th/Co (0.99-4.64), LREE/HREE, and europium anomaly (0.60-0.69), amongst others, trace back the origin of the Barail sandstones to felsic rocks such as granite, along with their equivalents like rhyolite and granodiorite. Besides, the abundance and associations of certain major and trace elements (C value = 0.25-0.66) imply prevailing semi-arid to sub-humid climatic conditions leading to moderate chemical weathering of the felsic provenance. Likewise, geochemical weathering indices, like chemical index of alteration (63.45-76.08) and plagioclase index of alteration (67.96-84.02), suggest the origin of the clastic sediments from mildly to moderately weathered provenance. The sediments depict a low degree of mechanical breakdown and moderate chemical alterations. The index of compositional variation (ICV = 1.15-1.91) further reflects that the sediments comprising the Barail sandstones are compositionally immature. Moreover, the presence of specific trace elements and their ratios (Sr/Ba = 0.14-0.29) suggest sediment deposition in a freshwater environment (near-shore terrestrial/fluvio-deltaic), with predominantly oxic to suboxic conditions. This study, thus, represents a fascinating effort to reconstruct Oligocene climatic conditions through the integration of micropetrography and comprehensive geochemistry of sedimentary archives from Ngopa, Mizoram, in northeast India. The findings indicate that cool, semi-arid to sub-humid climatic conditions likely prevailed during the Oligocene, leading to mild to moderate weathering of felsic parent rocks. As a result, immature sediments were deposited in a fluvio-deltaic environment, eventually forming sandstones over geological time.