Original paper

Tectonic and climatic controls on the Quaternary landscape evolution of the Piedmont Zone of the Ganga Plain, India

Goswami, Pradeep K.; Mishra, Jay K.

Abstract

Fieldwork substantiated satellite remote sensing and Digital Terrain Model (DTM) based investigations have been carried out to identify and map various geomorphic and tectonic features of a hitherto uninvestigated part of the densely forested and largely inaccessible Piedmont Zone (PZ) of the western Ganga Plain. The 27–49 km wide, gently south to southwestward sloping PZ is composed of alluvia emplaced by sediment gravity and fluvial processes. A large alluvial fan and incised river valley surfaces with numerous cut-off channels/palaeochannels are the main landforms of the area. The proximal basin margin, against the Himalaya mountain range, is defined by the active Himalayan Frontal Thrust (HFT), which is offset along the transverse Jhirna Fault (JF) and Kalagarh Fault (KF). The middle part of the PZ is longitudinally traversed by the blind, oblique-slip Najibabad Fault (NF). Mountain-front sinuosity (Smf) and valley floor to height ratio (Vf) indicate variable levels of tectonic activities and thus variable subsidence rates along the basin margin (i.e. the HFT), which ultimately controlled the accommodation space for fan sedimentation and thus its location, size and shape. The incised river valley surfaces have developed in response to climate driven reduction in sediment and water budget. However, tectonic activities have influenced their disposition by controlling the channel swinging and migration. Active movements along the faults have further sculpted the landforms of the area.

Keywords

active tectonicsganga plaingeomorphologylandscapepiedmont zone