First geophysical and shallow ice core investigation of the Kazbek plateau glacier, Caucasus Mountainsстатья
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Дата последнего поиска статьи во внешних источниках: 3 марта 2021 г.
Аннотация:First-ever ice core drilling at Mt. Kazbek (Caucasus
Mountains) took place in the summer of 2014. A
shallow ice core (18 m) was extracted from a plateau at
*4500 m a.s.l. in the vicinity of the Mt. Kazbek summit
(5033 m a.s.l.). A detailed radar survey showed that the
maximum ice thickness at this location is *250 m.
Borehole temperature of -7 C was measured at 10 m
depth. The ice core was analyzed for oxygen and deuterium
isotopes and dust concentration. From the observed
seasonal cycle, it was determined that the ice core covers
the time interval of 2009–2014, with a mean annual snow
accumulation rate of 1800 mm w. eq. Multiple melt layers
have been detected. d18O values vary from -25 to -5%.
The dust content was determined using a particle sizing and
counting analyzer. The dust layers were investigated using
scanning electron microscopy and X-ray diffraction analysis.
Dust can be separated into two categories by its origin:
local and distant. Samples reflecting predominantly
local origin consisted mainly of magmatic rocks, while
clay minerals were a characteristic of dust carried over
large distances, from the deserts of the Middle East and
Sahara. The calculated average dust flux over three years at
Kazbek was of 1.3 mg/cm2 a-1. Neither d18O nor dust
records appear to have been affected by summer melting.
Overall, the conditions on Kazbek plateau and the available
data suggest that the area offers good prospects of future
deep drilling in order to obtain a unique environmental
record.