ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

posmon, height, orientation and asymmetry of the sedimentary
structures (mainly sand ripples with a height ranging
from 0.20 to 1.50 m) that develop in the sediment of
the area. Such registrations were repeated several times in
the period 1995-1996, with at least 1 month of interval.
Part of the side scan sonar registrations were realized in a
digital way, by means of the program Delph2. This implies
that the recorded images are immediately stored on files
and the processing (correlation of different images, mapmaking,...)
is carried out on the Pc.
In the same area, grab samples were taken in a regular pattern,
with 300-400 m distance between them. They were
subject to a detailed granulometrical analysis and a computer
program was used to calculate the statistical parameters.
The content of CaC03 and organic matter was determined
as well.
When all results of the study are compared, interesting relations
seem to exist between the geomorphological structures,
sedimentology and hydrodynamics.
The residual sediment transport paths are determined in
two different ways. They are defined from the orientation
and asymmetry of the bedforms. It is assumed that sand
ripples move forward in the direction of their steep slopes,
thus representing the sediment transport in that direction.
On the other hand, McLarcn & Bowles (1985) elaborated
a statistical approach to determine the sediment transport
directions along a line by examining the sedimentological
parameters of all possible pairs of samples on a sample line.
Each sample is compared with its eight neighbouring
samples with respect to their mean size, sorting and skewness.
According to the McLaren model, the sediment becomes
either finer, better sorted and more negatively
skewed, either coarser, better sorted and more positively
skewed in the direction of transport. This method was
used as well to define the sediment transport directions in
the maritime part of the ScheIdt estuary.
There exist quite some differences between the sediment
transport paths determined according to the two respective
methods, which allows an interesting comparison.
In the determination of the residual sediment transport
paths, it is very important to take into account the influence
of the dredging activities that are carried out in the framework
of the present deepening program of the Scheldt
estuary.
YUillI K. VASILICHUK 1 & ALLA C. VASILICHUK 2
Late Pleistocene syngenetic ice-wedges formation in
intermountain depressions of the Magadan Region
1 Department of Cryolithology and Glaciology, Faculty of Geography,
Moscow State University named M.V. Lomonosov, Vorobuyovy Gory,
119899 and Theoretical Problems Department, The Russian Academy
of Sciences, Denezhnyi pereulok, 12, 121002 Moscou, Russia
2 Institute of Cell Biophysics. The Russian Academy of Sciences. 142292,
Pushchino, Moscou Region, Russia
390
The problem of formation of the thick syngenetic sediments
with large ice - wedges (named «edoma» in Siberia)
is very complicated and its decision is the key for periglaciallandscapes
evolution during Late Quaternary. It is believed
that alluvium, loess and lacustrine sediments conditions
are the medium of the thick syngenetic ice-wedges
formation.
It is very important to demonstrate that the slope sediments
conditions are also favorable for thick syngenetic
ice-wedges formation. The edoma sediments with rock debris
and rock gruss are very interest for identification of
the geomorphological conditions of sedimentation. Such
edoma thicknesses in 'permafrost zone have not been study
earlier.
We have studied large Late Pleistocene syngenetic ice
wedges widespread in the intermountain depressions in
valley Upper Kolyma River (west of Magadan Region): at
quarry near Sinegor'e town, «Phoenix» sequence (height
about 15 m, location is more than 400 m a.s.l) and at
quarry near Utinoe settlement (height about 8 m, location
is more than 330 m a.s.l). The main features of the edoma
were the interbedding of the loam layers with rock debris
layers and peat. Dimensions of the some rock debris were
more than 10 cm. Their content was more than 300/0. It is
clear pointed out on the slope genesis of the thicknesses.
The oxygen isotope study of different kind of ice has been
used for determination of time and climate condition of
edoma formation. 5 180 determinations were received from
upper fragment of ice wedge complex outcrop «Phoenix»
from Late Pleistocene syngenetic repeated ice wedges:
+406 m: -30,6%0; +407 m: -30,4%0; +410 m: -32,4%0;
+411 m: -32,2%0; +412 m: -32,1%0; +413 m: -32,6%0;
+414 m: -32,2%0. Values %0 18
0 of textureforming ice from
the same interval are: +409 m: -25,2%0; +412 m: -26,2%0,
and from overlapping sandy loam is +415 m: -23,5%0. The
lowermost fragments of ice wedges, located in base of ice
wedge complex, near bedrock, have more positive oxygen
isotopic composition: in quarry «Phoenix» are - +402 m:
-25,7%0; +403 m: -26,7%0; +404 m: -27,4%0; +405 m:
-27,7%0; in quarry «Utinoe» - +331,5 m: -29,3%0; +332 m:
-25,3%0; +332,8 m: -26,9%0; +333 m: -27,4%0; +333,5 m:
-24,9%0. The feature of oxygen isotope vertical distribution
may be connected with origin features of ice wedge
complex. There is possibility of river water participation in
forming of bottom fragment. Values of %0 180
of recent repeated
ice wedges (shoots) is: in Upper Kolyma near
Verkhniy Seimchan settlement: -27,1%0, in Upper Kolyma
floodplain near Taskan River mouth: -27,0%0; -25,6%0;
-27,0%0. Values of %0 18
0 of Upper Kolyma River water is
(in August): -22,0%0, of Utinaya River is: -19,2%0, of Yasnaya
River near quarry «Phoenix» is: -22,8%0. Textureforming
ice has values %0 180
as follow: in Holocene peat
«Chukachi» near Verkhniy Seimchan settlement are 0,5 m:
-21,3%0; 0,8 m: -20,1%0; 1,5 m: -18,6%0 and 1,6 m:
-18,9%0, and in Holocene thicknesses in Upper Kolyma
floodplain (Ivanovskiy Island): -19,0%0.
The comparison of the isotope data is confirmed of the Late
Pleistocene (about 35-15 ka BP) age of the Phoenix end
Utinoe edoma thicknesses in the intermountain depres-