Luminescence chronology of incision and channel pattern changes in the River Ganga, India |
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Authors: | Pradeep Srivastava Maneesh Sharma Ashok K Singhvi |
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Institution: | a Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India;b Department of Geology, Lucknow University, Lucknow 261 007, India |
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Abstract: | The River Ganga in the central Gangetic plain shows the incision of 20 m of Late Quaternary sediments that form a vast upland terrace (T2). The incised Ganga River Valley shows two terraces, namely the river valley (terrace-T1) and the present-day flood plain (terrace-T0). Terrace-T1 shows the presence of meander scars, oxbow lakes, scroll plains, which suggests that a meandering river system prevailed in the past. The present-day river channel flows on terrace-T0 and is braided, sensu stricto. It is thus inferred that the River Ganga experienced at least two phases of tectonic adjustments: (1) incision and (2) channel metamorphosis from meandering to braided.Optical dating of samples from three different terraces has bracketed the phase of incision to be <6 and 4 ka. Different ages of the top of terrace-T2 show that this surface experienced differential erosion due to tectonic upwarping in the region, which also caused the river incision. River metamorphosis occurred some time during 4 and 0.5 ka. |
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Keywords: | Gangetic plain River Ganga River incision Channel pattern changes Luminescence dating |
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