Testing Lithogenic Thorium‐232 for Fingerprinting of Slush Flows Debris Sources and Sinks in the Khibini Mountains, Kola Peninsula, North‐Western Russiaтезисы доклада
Дата последнего поиска статьи во внешних источниках: 9 марта 2017 г.
Место издания:Instituto Politecnico de Bragança Braganca, Portugal
Первая страница:130
Последняя страница:130
Аннотация:The Khibiny mountains is a developing ski resort at the Kola Peninsula, Northern
Russia. At the same time it is an arena of widespread hazardous processes, most
dangerous amongst which are slush flows and snow avalanches. Hackman valley
located in the southern Khibini is affected by frequent slush flows. This process is
similar to debris flows, but most of the oversaturated flow mass is represented by
snow and ice, while debris compose about 10%. To evaluate geomorphic effects of
these hazardous processes it is important to distinguish both main sediment sources
with their relative contribution and zones of debris deposition. Fingerprinting
approach has been proved to be useful for determination of sediment sources and
sinks in wide variety of geomorphic landscapes. Radionuclides can be used for
fingerprinting purposes in cases if their chemical properties determine dominant
redistribution in fixed conditions with sediment particles. We attempted to apply the
natural lithogenic radionuclide Thorium‐232 (232Th) for slush flows debris
fingerprinting. Hackman Valley geological structure is characterized by alternation of
plutonic complexes with different content of radioactive isotopes. In addition,
radioactive mineral exploration was active in the Hackman basin in 1930s. Later it was
closed, but its damps on the valley slope under the mine entrance still represent the
potential source of the radioactive material for the main stream and slush flows
sediment transport. The mine entrance is located on upper part of the right valley
slope in its middle reach. We have attempted to assess the radioactive 232Th transfer
from the sediment sources (slope screes, avalanche channel fans and eroded banks)
into the main stream channel bed sediment and debris deposition zone. The results
show that the fingerprinting approach make it possible to assess sediment sources,
debris transport distance and some specifics of slush flows dynamics in the case study
basin.