Early Holocene age and provenance of a mid-shelf delta lobe south of the Strait of Bosphorus, Turkey, and its link to vigorous Black Sea outflow

A. E. Aksu*, R. N. Hiscott, C. Yaltırak

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

The chronology of an abandoned Holocene delta lobe (present water depth ~40–70 m) on the northeastern shelf of the Marmara Sea south of the Strait of Bosphorus was revised from the early Holocene (~11.0–9.7 cal ka) to the middle Holocene (6.65–3.75 cal ka) by Eriş et al. (Eriş, K.K., Ryan, W.B.F., Çağatay, M.N., Sancar, Ü., Lericolais, G., Ménot, G., Bard, E., 2007. The timing and evolution of the post-glacial transgression across the Sea of Marmara shelf south of İstanbul. Marine Geology, 243, 57–76). Three independent seismic and multibeam surveys and replotting of navigational fixes for the 1992/1993-vintage survey lines which Eriş et al. correlated to their MD04-2750 giant piston core confirm that they misplotted the location of the MD04-2750 core site on seismic profiles by a minimum of ~200 m. Because of rapid convergence of seismic reflections in this critical area, the assessment of the age of the Holocene delta proposed by Eriş et al. is incorrect. Instead, existing and new data allow the age of this delta lobe to be refined to ~11.1–10.2 cal ka (±~200–300 years each) using several dated cores and the MD04-2750 chronology itself. A dense grid of previously unpublished seismic data shows that the lobe emanates from the Strait of Bosphorus and not from any of the local small streams. Mineralogy of the very fine sand fraction of the delta excludes the Kurbağalıdere stream as a source of the detritus, as does the composition of detrital hornblendes. It is concluded that the early Holocene delta lobe indeed records a period of strong Black Sea outflow, as advocated by co-authors RNH and AEA in 2002. Re-examination of multibeam imagery from the strait itself provides support for strong southward flow that potentially coincided with accumulation of the delta lobe at the southern exit of the strait.

Original languageEnglish
Pages (from-to)113-137
Number of pages25
JournalMarine Geology
Volume380
DOIs
Publication statusPublished - 1 Oct 2016

Bibliographical note

Publisher Copyright:
© 2016 Elsevier B.V.

Funding

We thank the officers and crew of the R/V Koca Piri Reis for invaluable assistance during the 2002, 2008 and 2011 geophysical and coring operations, particularly Dr. D. Yaşar. We thank the Natural Sciences and Engineering Research Council of Canada (NSERC) for Shiptime and Discovery Grants to AEA and RNH. We acknowledge the contributions of the 1992 and 1999 sparker and multibeam data and the 1993 location map from the Turkish Navy, Office of Navigation, Hydrography and Oceanography in Istanbul (TN-ONHO). We also acknowledge the donation of the geotechnical cores by the İstanbul Büyükşehir Belediyesi Deprem ve Zemin İnceleme Müdürlüğü and Dr. Hüseyin Tur for sharing his unpublished data with us. We thank Wanda Aylward and Helen Gillespie for their assistance with the acquisition of magnetic susceptibility data, and Michael Shaffer and David Grant for SEM-MLA data acquisition and processing.

FundersFunder number
Natural Sciences and Engineering Research Council of Canada

    Keywords

    • Black Sea outflow
    • Holocene delta
    • Marmara Sea
    • Mineral liberation analysis

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