Permafrost

The Ak-shirak Range is one of the centers of modern mountain glaciation of Tien Shan. It
separates the upper courses of 2 large river systems of Middle Asia – the Tarim and the Syr
Daria. The range is a slightly separated elevation with an average altitude in central parts about
4600 km. The region is characterized by continuous permafrost of 90-370 m thick. Taliks are
found only under large valley glaciers. Annual ice mounds formation that are fed by thawed
waters from outwash plains at the valleys of Lysy, Davidov’s, Sarytor, Boordu glaciers is an
indirect confirmation of it.
The thickest glaciers are in the west of the Ak-shirak; they are mainly characterized by
vast snowfields and rather small morainic deposits. Average thickness of ice at the firn line is
120-140 m.
The content of fresh snow that was taken at the Ak-shirak mountain range (actual elevation
of 3600 m) is of low mineralization and of subacid reaction.
The content of the majority of microelements in fresh snow is very low. Cobalt,
molybdenum and aurum were found in those samples that were taken at the end of continuous
snowfall. Those metals are typical for metallogenic specification of the region and they are an
evidence of considerable role of the earth surface chemical composition in formation of
precipitations geochemistry.
Ice mineralization of the glaciers varies from 7.5 to 73.9 mg/l and is 22 mg/l in average.
Chemically ices are sulphate- or chloride- hydrocarbonate with a compound set of cations, but
with natrium prevalence and in general are close to chemical composition of snow. The
+ 2+ 2+ −
following ratio of cations (Na > Ca > Mg ) and anions (НСО 3 > SO − 2
150
4 > Cl - ) is typical for
the glaciers. The content of almost all the ions in ice increases comparing to that of snow.
Natural waters of those streams that run out right under the glaciers are of various chemical
composition. The closest to snow chemical composition is chemical composition of a stream in
the southern part of Petrov’s glacier - at the contact of the glacier and lateral moraine so the
chemical composition formation of this waterflow is virtually due to glacier melting. Boordu
stream chemical composition differs from the one of Boordu glacier because of considerable
role of the subglacial flows that are present at the contact of the glacier and basal moraine in
formation of chemical composition of the stream. Chemical composition of the majority of the
streams that start under the glaciers (Sarytor, Davidov’s, Lysy, № 121) differs greatly from
those of glaciers. This is caused by various reasons. For example, formation of chemical
composition of the stream from the glacier № 121 is due to anthropogenic processes –
interaction of precipitations and thawed glaciers waters with dumps from mine working rich in
sulphide minerals that oxidize quickly. However anthropogenic factor is very slight in
formation of chemical composition of flows from the other glaciers. Similarity in chemical
composition of the streams from Syrator, Davidov’s and Lysy glaciers with the one of
underground waters of the region that are revealed by mining works and reveal themselves as
springs at the Kumtor river valley is conspicuous.
The above-mentioned glaciers are warm ones; there are taliks at their beds through which
underground waters are discharged. Considerable difference in chemical composition of a
glacier and a waterflow evidences the presence of infrapermafrost discharge and its rather
considerable role in formation of surface discharge. Similarity of chemical composition of