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| Titel |
Late Glacial to Holocene evolution and sea-level history of Gulf of Gemlik, Sea of Marmara, Turkey |
| VerfasserIn |
Asen Sabuncu, K. Kadir Eriş, Ayse Kaslilar, M. Namik Çağatay, Luca Gasperini, Betul Filikci |
| 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 |
250121801
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| Publikation (Nr.) |
 EGU/EGU2016-649.pdf |
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| Zusammenfassung |
| The Gulf of Gemlik is an E-W elongated trans-tensional basin with a maximum depth of 113
m, located on the middle strand of the North Anatolian Fault (NAF) in the south eastern part
of the Sea of Marmara (SoM). While during the Holocene the sea level in the Gulf of Gemlik
changed in tandem with the water level changes in the SoM, it may have been different in the
late glacial when the Sea of Marmara was lacustrine. Beside the tectonic activity related to
the NAFZ, eustatic sea level changes would have controlled the basin evolution and
consequent sedimentary history during the different paleocanographic phases of the SoM.
Considering the limited studies on the late glacial-Holocene stratigraph of the Gulf of
Gemlik, this study aims to investigate the depositional units and their environments with
respect to different allogenic and autogenic controls. For these purposes, we analyzed
over 300 2 – 7 kHz bandwidth high-resolution gridded seismic sub-bottom CHIRP
profiles together with 70 kHz high resolution multibeam bathymetry with backscatter
data.
Four seismic stratigraphic units were defined and correlated with chronstratigraphic units
in five piston cores covering the last 15.8 ka BP according to radiocarbon ages (14C). The
depth-scale accuracy of chronostratigraphic units in cores is of key importance for the precise
calculation of sedimentation rates. Correlation between the seismic profiles and cores were
made by matching Multi-Sensor Core-Logger (MSCL) data and seismic reflection
coefficients and amplitudes for different stratigraphic units. The impedance data derived from
the logger were used to generate a synthetic seismogram. We used an approach to display,
estimate, and correct the depth-scale discrepancies due to oversampling affecting the upper
part of sedimentary series during piston coring. The method is based on the resynchronization
of synthetic seismograms computed from high-quality physical property logs to the
corresponding CHIRP profiles. Each sequence boundary represented by different
reflection coefficient and various amplitude values were mapped for the whole gulf area
from the pseudo-3D seismic data. Isopach and isochron maps were generated using
2-D cubic B-spline interpolation method to reconstruct basin evolution models
through late glacial to Holocene. Each map shows various depositional period with
respect to water level changes that has been controlled by sea level fluctuations in the
SoM.
The seismic units labeled as Unit S1-S4 from top to bottom display different seismic
facies and geometries. Unit S1 is a transgressive marine mud drape younger than 10.6 ka BP,
which lacustrine sediments, Unit S2 is a parallel bedded mud drape in the basin and
progradational clinoforms on the shelf edge. It is dated between 13.9-10.6 ka BP, Unit S3 is
characterized by erosional gullies and a clinoform architecture indicating a deltaic system
dated between 15.8-13.9 ka BP. Unit S4 represents mounded sediments that are truncated by
erosional gullies and dated >15.8 ka BP.
Key words: Gulf of Gemlik, Seismic Stratigraphy, Numerical Modelling, Late
Pleistocene to Holocene |
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