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| Titel |
Late Holocene Environmental Reconstruction and Flood Records of Lake Bafa, Western Turkey |
| VerfasserIn |
Burak Yalamaz, Ozlem Bulkan, M. Namik Çağatay, Dursun Acar |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121512
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| Publikation (Nr.) |
 EGU/EGU2016-269.pdf |
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| Zusammenfassung |
| Lake Bafa is a significant inland lake located in the Büyük Menderes River Basin near the
Aegean Sea in the horst and graben system of western Turkey. Lake Bafa was part of
the ancient Gulf of Latmos that was gradually filled by the prograding sediments
of Büyük Menderes River during the Holocene transgression, and resulted in the
creation of the Lake in the southern part. The lake is presently located 15 km from the
shoreline, 2 m above sea level. It has a maximum depth of 21 m and surface area of 60
km2.
We used multi-proxy analyses of a 4.17 m-long core extending back to ca. 2300 years
from the central depo centre of the lake. The objectives are to reconstruct the environmental
evolution of the Lake Bafa as it changed from a marginal marine to a lacustrine environment,
and to investigate the flood records during the past 2300 yrs. The core is composed of three
units: an uppermost lacustrine unit, a unit representing marine to lacustrine conditions and a
lowermost marine unit. The uppermost lacustrine unit is 1 m-thick, homogenous
clayey silt mud layer with relatively high total organic carbon (TOC= 2.5 – 4.5
%), high total inorganic carbon (TIC = 1.8 –4.5 %) and low detrital input (Si, K,
Zr, Ti). According to AMS radiocarbon dating, it was deposited over the last 600
yrs under brackish lacustrine conditions. The underlying unit is 2 m-thick, and
consists of banded mud layers with relatively low TOC (1.2-4 %) and TIC (1.2-3.5)
contents and high detrital input. Its fossil content, with scarce Cardium sp. and
Ammonia sp., indicates that it was deposited under brackish water conditions and
represents a transition from marine to lacustrine environments. The unit was deposited
between ca. 600 and 1750 yrs BP, and includes frequent flood units ranging up to 10
cm-thick fine sand- to clay-bearing coarse silt. The lowermost unit is characterized by
relatively high TOC (2-5.5 %), TIC (1.5-3.5 %) contents and high detrital input.
With its abundant Cardium sp. and foraminiferal content, the unit was deposited
under marine conditions prior to 1750 years. The marine unit also includes records
of flood events. The coarse flood sediments in both marine and transitional units
are characterized by high magnetic susceptibility and high density, low TOC and
TIC.
The core sequence suggests that the the prograding alluvial sediments during the
late Holocene gradually closed the western mouth the intermontane Bafa Basin
in the south of the ancient Gulf of Latmos, gradually converting it into a closed
limnic environment. The frequent flood records during marine and transitional period
supports the continuing connection with Büyük Menderes River until ca. 800 yrs
BP.
Keywords: Lake Bafa, Büyük Menderes River, environmental changes, flood. |
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