ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

island lands, answering the top part of the most actively
growing morphostructures (Alat and Mishovdag ridges,
Kharamin range and oth.), These island lands were later
experienced mainly the horizontal and vertical development,
not being covered by sea. The relief becomes complicated.
The mud volcanism and corresponding forms of
relief develop. The tectonic deformation becomes revived
and formed newly. Beginning from Late Khvalin the relief
of the territory gains the present outlines and peculiarities
and it is very interesting that even the sinclinal basins are
covered by sea alternately. It did not happen before. The
sea left the limits of mentioned territory only during the
deep regression which occured several times (between in
Tiirkanian time and before). The change of situation took
place repeatedly during 20 thousand years there which it is
impossible not to be affected on the development of relief
of the mentioned territory. A great help in reestablishment
the quantitative indecies of quaternary movements exerted
the sea terraces (about 14 levels). Palaeotectono-geomorphological
course of development of the territory
shows the succession and mobility the display of the latest
and present movements and development of relief.
VATCHE P. TCHAKERIAN\ PATRICK P. PEASE 1
& NEIL W. TINDALE 2
Geomorphology and sediments of the Wahiba sand sea,
Sultanate of Oman
1 Department of Geography, Texas A&M University,
College Station, TX 77843, USA
2 Departments of Meteorology and Oceanography,
Texas A&M University, College Station, TX 77843, USA
Geomorphological, geochemical and mineralogical analyses
of terrestrial sediment samples and aerosol dust were
undertaken in an effort to understand the geomorphology
and cycling of sediment through the Wahiba sand sea (erg)
in northeastern Oman. Sediment transport in the region is
associated with the geomorphic development of the erg
and the production, transport, and flux of desert dust material
from the Oman desert into the Arabian sea. The
Wahiba erg covers over 12,000 km 2 along the northeastern
coast of Oman. It is bordered by mountains on the north,
wadis on the west and east, and the Arabian Sea along the
southeast. Most of the erg is comprised of a linear, northsouth
trending draa system. The remaining areas are covered
by transverse dunes, barchanoid dunes, sand ridges,
and nabkha fields. Terrestrial sample collection included
surface sediment samples from the Wahiba erg, surrounding
wadis and sabkhas, and bedrock material. Aerosol
dust was collected on paper filters from a ship-borne
platform over the Arabian Sea for a semi-continuous one
year period. Sediment samples and aerosol filters were
analyzed for major and trace elements using elemental neu-
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tron activation analysis. Both short and long irradiation times
were used to quantify a wide range of elements. Mineralogy
was obtained with a combination of optical microscopy
and wavelength dispersive x-ray spectrometry.
The geochemistry and mineralogy of dune samples were
compared with those of wadi sediments and bedrock outcrops
in an attempt to define ultimate and proximate provenance
for the Wahiba sediments. This analysis suggested
that sediment sources for the erg came from multiply provenances
of varying lithologies contributed sediment to the
erg. Landsat Thematic Mapper (TM) imagery was used to
further extend the boundaries of the mineralogic sample
sites beyond the sample points. Regions where the composition
of sediments was determined from in situ chemical
data were linked to specific pixel regions on the imagery.
A combination of classification and band ratio techniques,
designed to enhance contrasts inherent in the spectral responses
of different mineral types, was employed to locate
axes of variability in the spectral signatures and identify
mineralogical boundaries as well as transport pathways.
Geochemical signatures from Wahiba samples were also
compared with those of aeolian dust samples. This comparison
was an attempt to determine the relative contribution
of Wahiba sediments to the regions atmospheric dust concentration.
These data are also important factors in the understanding
of global climate variability. This is because
aerosols with a significant atmospheric residence time may
impact radiation budgets. Also, the flux of mineral matter
is a potentially important factor in the biological productivity
of the Arabian Sea.
BELAY TEGENE
Soil-geomorphic units on piedmont slopes of
Wurgo valley, Welo Highlands, Ethiopia
Department of Geography, University of Addis Abeba,
p.o. box 1176, Addis Ababa, Ethiopia
An investigation of soil distribution in a piedmont valley of
a mountainous cathchment in the Welo highlands led to
the identification of clearly defined soil-geomorphic units.
Luvic Phaoezems are associated to divergent footslopes,
while Haplic Phaoezems occupied convergent footslopes,
and Eutric Vertisols mantled alluvial toeslopes.
The main characteristics of divergent footslopes-Luvic
Phaoezems consociation were concave slopes, saprolite parent
materials, truncated soils with stony surfaces and
Ap/Bt/Cr horizon arrangements.
The convergent footslopes-Haplic Phaoezems consociation
is marked by gentler slopes, colluvial parent materials,
deep young soils and A/Bw/Bb horizon sequences.
The alluvial toeslope-Vertisols consociation is characterized
by gentle to near level surfaces, alluvial parent materials,
deep uniform A horizons, cracking clays and
AIACICr or AIAC/Bb horizon arrangements.