International Journal of Marine Science 2015, Vol.5, No.31, 1-6
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Figure 4 The stratigraphy sequence of Urmia lake sub bottom
sediments
The available facies markers in mentioned
sedimentary units illustrate the transformation of the
depositional environment of lake from late Cretaceous
up to now (Amini 2010). The active faults in the lake
bed lead to layers vertical displacement and are
important effective factors in bed subsidence and
changing its facies nature (Figure 4). Consequently,
the lake environment has been dominant from
Holocene up to now about 10,000 years, which its
level has been affected seriously by climatic factors
(rainfall and evaporation), also the existence of
gypsum and salt horizons in clay and silty sand layers,
is an obvious evidence of variable hydrochemical
situation of Urmia Lake at mentioned period under the
effect of climatic parameters (the markers of layers in
A and B units). But in C and D sedimentary units, the
deposits are mostly sedimentary facies of brackish to
fresh water lake type and belong to Pleistocene period
(Figure 4). There is a good structural similarity
between these sediments and the residual deposits in
sedimentary terraces (Djamali 2008).
Main results of seismic survey have distinguished that
Urmia lake bed rock was located under 178 meters
and the thickness of bed rock is approximately 734
meters with pyroclastic composition and volcanic
breccia and Islami Island was made during the last
volcanic eruption phase in Pleistocene(Tarh No
Andishan Company 2005).
Due to locating the volcanic masses on the Miocene
sedimentation layers, they are probably belong to
upper Miocene up to Pleistocene or lower Pleistocene,
and upper layers, which located with an identifiable
sedimentary discontinuities belong to the beginning of
Pleistocene. Consequently the sedimentary hole of
Urmia Lake, realistically formed in lower Pleistocene
and continuing the sedimentation process up to now
leads to deposition of a very thick lake sedimentary
material layer. The conducted studies on pollens in
sedimentary 100-m long cores of ShahidKalantari
highway (Djamali 2008) indicated that the lower
deposits of this part of lake belong to 200,000 years
ago. In this study the different pollen species of glacial
and interglacial periods have been detected in
sedimentary sequences. Generally the adaptable plants
with past coastal environment of Urmia Lake, lived in
various habitants such as: salty marshes and salty mud
zones with special order of algae: Chenopodiaceae,
mountainous regions dark forage steppe plants such as
Artemisia type and forestry plants in mountainous
high elevated areas, such as different species of oaks
in west part of Urmia Lake at the border of Iran and
Turkey. Five pollen bio zones have been detected in
100-m depth sedimentary layers under the lake bed by
the help of palynology studies. The pollens were
divided in to two parts: Arboreal pollens and
non-Arboreal pollens and their relative amounts were
studied in cores (Djamali 2008). The obtained results
showed that along with the beginning of interglacial
period and increasing the earth temperature and
therefore more evaporation rates, the amount of forage
plants pollens (Artemisia) have been increased in
Urmia Lake watershed. At the same time the chemical
and evaporative sediments were dominant, the
vegetation cover around the lake was lower dense and
the biochemical activities in Urmia Lake watershed
have flowed very weak. But due to increment of
moisture amount and rainfall events in glacial period,
the vegetation cover has been developed and
