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| Titel |
Relative importance of fluvial and glacial erosion in shaping the Chandra Valley, western Himalaya, India |
| VerfasserIn |
Patricia Eugster, Rasmus C. Thiede, Dirk Scherler, Alexandru T. Codilean, Manfred Strecker |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082609
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| Zusammenfassung |
| Although glaciers are often believed to be the principal erosional agents and the cause for
increasing the relief of mountain belts, quantifying their contribution to long-term erosion
and exhumation is challenging. This is particularly true for the Himalaya, where present-day
ice coverage is relatively high, but evidence for extensive glaciations in the past more limited,
presumably due to high erosion rates that quickly remove the depositional and geomorphic
evidence of glacial impacts. Previous work indicates that the Chandra Valley, in the
headwaters of the Chenab River, was strongly glaciated during the Quaternary. In
addition, existing thermochronological data suggest a large change in exhumation rates
along the valley. This change spatially corresponds to a major fluvial knickpoint,
the joining of several large glaciers, a lithological break, and a steep precipitation
gradient.
In this study we determine spatial and temporal variations in valley incision through
fluvial and glacial erosion on different timescales by using cosmogenic radionuclide
(CRN) dating of glacially-carved and striated surfaces, various low-temperature
thermochronometers, and morphometric analysis. Knickzones are found at elevations of
~3900 m asl along several tributaries of the Chandra/Chenab valleys and other valleys
throughout Lahul, potentially indicating a causal relationship with glacial processes. Our field
observations and preliminary CRN data suggest major glacial occupation of the Chandra
Valley, particularly by the Bara Shigri Glacier, prior to 14 ka. Our data also confirm former
CRN measurements in that area.
We hypothesize that these observations coincide with the glacially carved surface of the
valley, which indicates a minimum altitude of ~4100 m asl for glaciation in the lower
Chandra Valley. Here, glacial carving has been the first-order erosional agent during the
Quaternary. Furthermore, published AFT cooling ages are young below an elevation of 4100
m asl and increase strongly in the upper part of the valley above this elevation and the
observed knickpoints, suggesting slower erosional exhumation in the more arid upper
Chandra Valley.
The ultimate goal of this study is to better understand the regional erosion pattern within
the Chandra Valley, and to possibly determine whether glaciers influenced by local conditions
(tectonics, climate), impede or accelerate erosion. |
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