The tephra record from the sea of marmara for the last ca. 70 ka and its palaeoceanographic implications

M. Namik Çağatay*, Sabine Wulf, Ümmühan Sancar, Asli Özmaral, Laurence Vidal, Pierre Henry, Oona Appelt, Luca Gasperini

*Corresponding author for this work

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Abstract

We report the results of tephrochronological studies on marine cores from the eastern and western part of the Sea of Marmara extending back to early MIS-4. Glass shard compositions using electron probe microanalyses (EPMA) and stratigraphic analysis assigned three distinct tephra layers to the eruption of Avellino (Somma-Vesuvius/Italy, 3.9. ka), Cape Riva (Thera/Santorini, 22. ka) and the Campanian Ignimbrite (Phlegrean Fields/Italy, 39.3. ka), respectively. Tephra layers are important chronostratigraphic markers for the refining of age-depth models of cores and thus for the reconstruction of the palaeoceanographic evolution of the Sea of Marmara. Accordingly, a continuous sedimentary record for the last ca. 67. ka in core MD01-2430, located at -. 580. m on the Western High, shows only one lacustrine-marine transition at 12.55. ±. 0.35. cal. ka BP, which indicates that the Sea of Marmara was under lacustrine conditions disconnected from the Mediterranean Sea from early MIS-4 to early MIS-1. High lake levels and oxic bottom water conditions prevailed especially during the MIS-3 stadials. This implies that the sill depth of the Çanakkale Strait (Dardanelles) was probably higher during MIS-3 time than the present sill depth of -. 65. m. Alternatively, strong fresh water discharges from the Black Sea during the interstadials might have kept the Sea of Marmara stratified with a relatively thick layer of fresh waters above a weak Mediterranean inflow filling only deeper parts of the basins.Based on the radiocarbon and tephra-integrated age model the marine transgression at 12.55. ±. 0.35. cal. ka BP was followed by the deposition of the main lower Holocene sapropel between ca. 12.3 and 5.7. cal. ka BP, and in the shallow shelf areas (<~100. m depth) such as the Gemlik Gulf, by the formation of the upper Holocene sapropel between ca. 5.4 and 2.7. cal. ka BP.

Original languageEnglish
Pages (from-to)96-110
Number of pages15
JournalMarine Geology
Volume361
Early online date15 Jan 2015
DOIs
Publication statusPublished - 1 Mar 2015
Externally publishedYes

Keywords

  • Lacustrine-marine transition
  • Palaeoceanography
  • Sapropel
  • Sea of marmara
  • Tephrochronology

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