Evidence of Forebulge Uplift in Late Quaternary Stratigraphy of the Southern Ganga Plains: Insights from the Chambal Basin, India

Forebulge uplift plays a significant role in foreland-basin evolution; however, uplift history and stratigraphic expression are often difficult to resolve within continental interiors, where deformation is subtle and typically modelled over million-year timescales. A key question that remains unresolved is how slow forebulge uplift manifests itself in sedimentary facies architecture and geomorphic response at shorter (kiloyear) timescales.

Chambal River Basin, the largest cratonic tributary of the Ganga River and forming the western extent of the Southern Ganga Plains (SGP) in the Himalayan Foreland is characterized by extensive badland development that has resulted in exceptional sedimentary sections that preserve signatures of coupled forebulge dynamics and climatic fluctuations.

Through integrated sedimentary facies analysis and optically stimulated luminescence (OSL) dating, we identify a basin-wide stratigraphic framework comprising a laterally extensive paleosol/interfluve unit (~113 ka), overlain by channel deposits (60–40 ka), and capped by Holocene floodplain sediments (~7 ka). The spatial extent and age equivalence of the basal paleosols correlated with regional records from Kalpi (~119 ka), Dahelkhand (~120 ka), and Ganga–Yamuna interfluve boreholes indicate a region-wide phase of landscape stability during MIS-5. While younger incision–aggradation cycles are linked to late Quaternary climatic fluctuations, the lateral continuity, maturity, and thickness of the MIS-5 paleosols point to prolonged landscape stability and fluvial incision, which we interpret as the geomorphic response to Central Indian Forebulge (CIF) uplift.

Our results demonstrate that even low-magnitude forebulge movements can manifest in sediment routing, modulate base levels, and generate regionally consistent pedogenic surfaces over shorter timescales. These findings highlight the sensitivity of craton-draining rivers to subtle flexural forcing.