Radiometric chronology of Changme-Khangpu glacier, Sikkim

Nijampur, V. N. ; Bhandari, N. ; Borole, D. V. ; Bhattacharya, U. (1985) Radiometric chronology of Changme-Khangpu glacier, Sikkim Journal of Glaciology, 31 (107). pp. 28-33. ISSN 0022-1430

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The 32Si concentration in a sample of surface ice from the snout of Changme-Khangpu glacier is 0.36 disintegrations per minute/tonne compared to the fall-out value of 0.7 d.p.m./tonne. If this decrease is assumed to be solely due to decay of 32Si, an age of c. 100 years is estimated for the surface ice of the snout, leading to an average flow velocity of c. 40 m/year for the past century. A vertical profile of 210Pb in a core taken at an altitude of 5040 m shows two horizons where this isotope is enriched, one between 3 and 4 m and another between I I and 12 m, indicating that the primary concentration of 2l0Pb can change by physicochemical processes like adsorption on dust. None the less, a longitudinal profile along the glacier shows a systematic decrease of 2l0Pb activity with decreasing altitude, the surface ice of the snout giving a value of 0.2 d.p.m./I, corresponding to an age of 100 years which is concordant with the 32Si age. This surface flow-rate of the glacier is much larger than the average contemporary flow-rate (c. 13 m/year). The difference can be understood of the past history of advance and recession of the glacier as revealed by the geomorphic evidence.

Item Type:Article
Source:Copyright of this article belongs to International Glaciological Society.
ID Code:18494
Deposited On:17 Nov 2010 09:07
Last Modified:17 May 2016 03:12

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