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| Titel |
The distribution and utility of sea-level indicators in Eurasian sub‑Arctic salt marshes (White Sea, Russia). |
| VerfasserIn |
Daria Nikitina, Andrew Kemp, Benjamin Horton, Christopher Van, Marina Potapova, Stephen Culver, Tatyana Repkina, David Hill |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250150833
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| Publikation (Nr.) |
 EGU/EGU2017-15345.pdf |
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| Zusammenfassung |
| We investigated the utility of foraminifera, diatoms and bulk-sediment geochemistry (δ13C and parameters measured by RockEval pyrolysis) as sea-level indicators in Eurasian sub-Arctic salt marshes. At three salt marshes in Dvina Bay (White Sea, Russia), we collected surface sediment samples along transects sequentially crossing sub-tidal, tidal-flat, salt-marsh and Taiga forest environments. Foraminifera formed bipartite assemblages, where elevations below mean high higher water (MHHW) were dominated by Miliammina spp. and elevations between MHHW and the highest occurrence of foraminifera were dominated by Jadammina macrescens and Balticammina pseudomacrescens. Both assemblages existed on all three transects and we conclude that foraminifera are sea‑level indicators in Eurasian sub-Arctic salt marshes. Five, high‑diversity groups of diatoms were identified and they displayed geographic variability among the study sites (<15 km apart). RockEval pyrolysis and δ13C measurements recognized two groups (clastic-dominated environments below MHHW and organic-rich environments above MHHW). Since one group included sub-tidal elevations and the other supra-tidal elevations, we conclude that the measured geochemical parameters do not meet the criteria for being stand-alone sea-level indicators. Core JT2012 captured a regressive sediment sequence of clastic, tidal-flat sediment overlain by salt-marsh organic silt and freshwater peat. The salt‑marsh sediment accumulated at 2804 ± 52 years BP years before present and preserved foraminifera (J. macrescens and B. pseudomacrescens) with a high degree of analogy to modern assemblages indicating that relative sea level was 2.60 ± 0.47 m above present at this time. Diatoms confirm that marine influence decreased through time, but the lack of analogy between modern and core assemblages limits their utility as sea-level indicators in this setting. |
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