论文部分内容阅读
Indus river valley basin in Northwest Indian Himalaya is tectonically unstable, exhibiting a complex topography, landscape relief and varied Quaternary sedimentation. A 422 km transact along the Indus river valley from Nyoma to Batalik in Ladakh(Trans Himalayas) reveals the damming of the river four places and existence of four major palaeolakes in the Late Quaternary Period. The commencement and breeching of the palaeolake sequences and the seismites preserved therein mark of the tectonic pluses in the area but the contribution of climate cannot be ruled out. The major geomorphic landforms are alluvial fans, debris cones, unsorted pedestals, fluvio-lacustrine deposits, scree, talus cone etc. Ubiquitous mass movements and catastrophic land sliding, due to tectonic activity and abnormally high precipitation has transported the material from steep slopes to valley bottoms, was responsible of forming lakes(preserved as thick piles of fine sediment), while the outburst floods redistributed the sediment down valley. Chronologies of two lakes are available which reveal the presence of one during post LGM times around 17000 a BP which breached out prior to Older Dryas indicating of warmer and congenial rainfall and melt water supply between these two globally marked cold episode. Other lake was formed after the Younger Dryas and existed till ~1000 a BP indicative of the Holocene warming responsible for its sustenance.
Indus river valley basin in Northwest Indian Himalaya is tectonically unstable, exhibiting a complex topography, landscape relief and varied Quaternary sedimentation. A 422 km transact along the Indus river valley from Nyoma to Batalik in Ladakh (Trans Himalayas) reveals the damming of the river four places and existence of four major palaeolakes in the Late Quaternary Period. The commencement and breeching of the palaeolake sequences and the seismites preserved notated marks of the tectonic pluses in the area but the contribution of climate can not be ruled out. The major geomorphic landforms are alluvial fans, debris cones, unsorted pedestals, fluvio-lacustrine deposits, scree, talus cone etc. ubiquitous mass movements and catastrophic land sliding, due to tectonic activity and abnormally high precipitation has transported the material from steep slopes to valley bottoms, was responsible of forming lakes (preserved as thick piles of fine sediment), while the outburst floods redistributed the sediment down valley. Chronologies of two lakes are available which reveal the presence of one during post LGM times around 17000 a BP which breached out prior to Older Dryas indicating warmer and congenial rainfall and melt water supply between these two global marked cold episode. Other lake was formed after the Younger Dryas and dated ~ 1000 a BP indicative of the Holocene warming responsible for its sustenance.