Supervisors info:
Τριανταφύλλου Μαρία Αναπλ. Καθηγ. (επιβλέπουσα), Καρακίτσιος Βασίλειος Καθηγ., Γεραγά Μαρία Επικ. Καθηγ.
Summary:
The paleoenviromental conditions during the depositional interval of sapropel
S1 in the Northern Aegean (gravity core M-4, south Limnos basin) are studied
based on quantitative analysis of benthic foraminifera. The Aegean Sea is
located at the northern part of NE Mediterranean region, linked to the Black
Sea through the Dardanelles and the Bosporus Straits and to the eastern
Mediterranean through the Cretan Straits; being recognized as a particularly
important area for both regional and global climate changes. Numerous major
rivers from the surrounding areas of the Balkans and Turkey flow into the
Aegean Sea, providing the 75% of the North Aegean sediment influx, and they
collectively constitute an important source of land-derived organic matter to
the study area. The location site of gravity core M-4 (length 2.53 m) is
affected by the Black Sea water influx through the Dardanelles Straits. Special
feature of this core is the thickness of sapropel S1 layer (96 cm). The species
Globobulimina affinis, Uvigerina mediterranea, Bulimina aculeata, Bolivina
spathulata, Cassidulina carinata were found below the base of S1, marking
conditions of low oxygen availability and high content of organic matter. The
species Globobulimina affinis marks the lower part of S1 (9.6-7.9 ka BP),
showing permanently dysoxic conditions. Due to the influence of the cold global
climate event (8.2 ka), an interruption of the sapropelic conditions is
following (7.9-7.6 ka BP), which is mainly characterized by the presence of
Uvigerina mediterranea. The species which has low tolerance to dysoxic
conditions continues to participate in the concentrations of benthic
foraminifera, throughout the duration of the upper part of sapropel S1 (7.6-6.5
ka BP). These data combined with low abundances of Globobulimina affinis in the
assemblages, reflect the drastic reduction of dysoxic conditions in the basin
of South Limnos, in this period, due to the opening of Dardanelles Straits (8-7
ka) and the relevant influx of Black Sea waters to the northern Aegean Sea in
correlation with abrupt climate changes (after 7.5 Ka).
Keywords:
benthic foraminifera, dysoxic conditions, sapropel S1, Dardanelles Strait, Black Sea
