Dasgupta, Ananda S.1, Rajiv Sinha1, S.K. Tandon2,
(1) Indian Institute of Technology Kanpur, Kanpur, India
(2) University of Delhi, Delhi 110007, India
(3) Dalhousie University, Halifax, NS
ABSTRACT: Quaternary Stratigraphy and Sedimentology of the Ganga-Yamuna Interfluve, Himalayan Foreland Basin, India
The Gangetic Plains of northern India constitute one of the world’s most extensive alluvial tracts in the Himalayan foreland basin. Our ongoing research in the western and southern Gangetic plains based on photomosaics, detailed stratigraphic measurements and graphic facies logging of exposed cliff sections has resulted in recognition of prominent stratigraphic discontinuities marked by erosional relief, small channels, early calcite cementation and reworking of pedogenic carbonate. The discontinuities define allostratigraphic units characterized by alternate aggradation and incision events. Further, we have recognized in-sequence deep gully erosion and filling in the upper part of the exposed sections which foreshadows the period of incision that created the present narrow valley. This work was followed up by drilling and coring along the Kanpur-Kalpi transect with the objective to correlate the stratigraphic sections to understand the competition between the Himalayan and cratonic river systems and to pick out the cycles of floodplain aggradation and degradation vis-a-vis the forcing factors such as climate and tectonics. Our preliminary investigation of the drill cores (50-60 meters) indicate that the cycles of floodplain aggradation and degradation as observed in the exposed sections have operated for much longer time scales. An important finding is the recognition of southern-sourced sand at the bottom of the cores much north of the present-day Yamuna. This suggests a southward shift of the Yamuna and displacement of cratonic drainage in the geologic past. We suggest that such major avulsions and floodplain aggradation/ degradation cycles in the Gangetic plains have been climatically driven.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.