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| Titel |
Holocene coastal and palaeoenvironmental evolution in the surroundings of
the Rioni Delta (Kolkheti lowlands, W Georgia) |
| VerfasserIn |
Hannes Laermanns, Daniel Kelterbaum, Mikheil Elashvili, Matthias May, Stephan Opitz, Daniela Hülle, Julian Rölkens, Helmut Brückner |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125105
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| Publikation (Nr.) |
 EGU/EGU2016-4637.pdf |
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| Zusammenfassung |
| 0.0.1 The Kolkheti (Colchis) lowlands form the central part of the extensive coastal
lowlands along the Black Sea coast of Georgia. Situated between the Greater and the Lesser
Caucasus, favourable climatic conditions resulted in a constant human occupation of the
region during the Holocene. However, due to continuous deltaic sedimentation and
progradation of the Rioni River, considerable changes of the coastal configuration and the
palaeoenvironmental conditions in its hinterland are considered, which also were related
to sea-level fluctuations of the Black Sea and modifications in sediment supply.
Because there is a paucity of data regarding the Holocene coastal evolution of Western
Georgia, this study aims to (i) determine the stratigraphy of the Kolkheti lowlands;
(ii) elucidate the palaeogeographical and palaeoenvironmental changes along the
Georgian Black Sea coastline; and (iii) reconstruct the (relative) sea-level (RSL)
evolution in the study area, and compare these results with other regional studies.
0.0.2 Our research is based on ten sediment cores and two sediment outcrops which
from the northern part of the Rioni delta area, i.e. the northern part of the Kolkheti lowlands.
The sediment cores were analysed for geochemical and geophysical parameters (X-ray
fluorescence spectroscopy, granulometry, loss on ignition, CN analysis) and for their
microfaunal content (foraminifera, ostracoda), in order to deduce different depositional
environments and their succession throughout the Holocene. The chronostratigraphy is based
on 13 14C and 4 IRSL ages. Our results show that significant palaeoenvironmental changes
have taken place in the surroundings of the Rioni delta during the last eight millennia.
The sedimentary record indicates shallow marine conditions dominating most of
the research area during the 6th millennium BC. These deposits are covered by
brackish/lagoonal sediments. Lateron and floodplain-related fine-grained alluvial deposits
accumulated since the 4th millennium BC. Both the lagoonal and alluvial deposits
are intercalated by peat layers. 14C age estimates of the different peats enable the
reconstruction of the RSL evolution in the study area. The formation of the sand spit
system started during the 2nd millennium BC. Luminescence dating of the oldest
foredune ridges indicate a last mobilisation of the dunes between the 10th and 12th
centuries AD. Based on the succession of the inferred depositional environments, we
provide a valuable framework for the interpretation of the region’s archaeological
record, such as the identification of appropriate locations for the as yet “lost” city of
Phasis. |
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