Title: Pedochemical characterisation and landscape history of the Thangbi river terrace system, central Bhutan.
Author(s): Caspari T, Bäumler R, Dorji T, Norbu C, Tshering K, Baillie I
Source: ZEITSCHRIFT FÜR GEOMORPHOLOGIE 48 (2): 145-166 JUN 2004
Document Type: Article
The properties and development of soils formed on fluvial deposits in the valley of the river Chamkhar Chhu, 10 km north of Jakhar, central Bhutan, were examined. Fieldwork in 2000 and 2002 revealed a system of at least 28 river terraces rising to relative heights of nearly 300 meters. The largest and still well preserved terrace of the system is of late Pleistocene age. Polygenetic structures & buried topsoils indicate several interruptions of soil development under periglacial conditions. C-14 AMS dating suggests discontinuities at approximately 10.175, 8.710, 4.055 and 1.715 years BP. Pedochemical analyses showed that all examined soils are moderately weathered and leached and can mostly be classified as Cambisols. X-ray diffraction analyses of clay fractions revealed that especially on the upper terraces pedogenic chlorite formed at the expense of illite. Weighted profile averages of texture, specific surface area (BET), pedogenic iron compounds and weathering indices show significant trends within the terrace system and indicate that weathering and soil development continuously become more intense with increasing relative height above the current river level.
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Publisher: GEBRUDER BORNTRAEGER, JOHANNESSTR 3A, D-70176 STUTTGART, GERMANY
Subject Category: GEOGRAPHY, PHYSICAL; GEOSCIENCES, MULTIDISCIPLINARY IDS