Active intra-basinal highs and palaeodrainage reversals in the late orogenic hominoid-bearing Siwalik basin

Abstract

The Himalayan mountain chain is a product of the continent-to-continent collision of India with Asia. Major mountain building activity in the Himalaya was followed by the shedding of sediments which were deposited in extensive non-marine basins on the Indian craton. The late orogenic hominoid-bearing Siwalik basin, comprising alluvial deposits, occurs along the northern margin of the Indian plate and has itself been uplifted. Major Siwalik palaeodrainages are believed to have originated in the Himalaya. We now report bed by bed measurement of palaeocurrent data of the Upper Siwalik rocks from the outermost Foothills Belt which suggest that active intra-basinal highs have locally caused palaeodrainage reversals. Discontinuity in apparently continuous stratigraphical sequences is recognized as the composite aggradation of alternating depositional events related to drainages controlled by basin margin and intra-basinal structural highs. The period of repeated uplift of these structures is estimated to be 1 to 5 × 10⁵ yr.