Tectono-climatic imprints on the morphometric and sedimentologic developments in the Damodar River basin, Eastern India

The Damodar River and its tributaries flows towards southeast draining through the Chotanagpur Plateau, the Gondwana sedimentary rocks and the Bengal delta region has carved the landscape through time. Tectonic rejuvenation of the various pre-existing faults and lineaments resulted in multi-storey valleys, unpaired fluvial terraces, steep channel gradients, knickpoint, V-shaped valleys and gorges. The IAT index data indicates the upper reaches lie within relatively very high active tectonic zone and calculated Ksn values suggest higher uplifted rate in the north-west part of the basin. The increase in grain size, increase in scale of sedimentary structures and scoured bases of the lithounits indicates a turnover from dry to wet climatic conditions after ~17-18 ka. Evidences from mineral magnetic properties such as remanence coercivity (B(0)CR) signifying shift from mixed antiferromagnetic to detrital ferromagnetic mineralogy during post-LGM. The other environmental magnetic proxies (lf, ARM, SIRM/lf, S-ratio, and HIRM) and the geochemical signatures like CIA and Ruxton ratio further indicate moderate climatic amelioration after 18ka. Presence of medium-size mammals like Boselaphu stragocamelus and Bos namadicus and archaeological artifacts mostly microliths indicate an intricate habitat excursion due to climatic fluctuations. This piece of research though not exhaustive but based on the present archives within the age bracketed, post-18ka wetter phase of ISM dominated the region to reframe the landscape with various wetter phases at ~17 ka, ~15 ka, and ~11ka and during these time intervals, ISM was at a stronger phase than that of the present-day.