Sub-marine Continuation of Peat Deposits From a Coastal Peatland in the Southern Baltic Sea and its Holocene Development

Matthias Kreuzburg,Peter Feldens,Gregor Rehder,Miriam Ibenthal,Maren Voss,Manon Janssen,Michael Naumann

doi:10.3389/feart.2018.00103

Matthias Kreuzburg, Peter Feldens + Show 5 more

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https://doi.org/10.3389/feart.2018.00103

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Abstract

Coastal low-lying areas along the southern Baltic Sea provide good conditions for coastal peatland formation. During the Holocene, the transgression of the Littorina Sea has caused coastal flooding, submergence and erosion of ancient coastlines and former terrestrial material. The present Heiligensee & Hutelmoor peatland (located near Rostock in Northern Germany) was found to continue more than 90 m in front of the coastline based on on- and offshore sediment cores and geo-acoustic surveys. The seaward areal extent of the peatland is estimated with 0.16-0.2km2. The offshore limit of the former peatland roughly coincides with the offshore limit of a dynamic coast-parallel longshore bar, with peat deposits eroded seawards. While additional organic-rich layers were found further offshore below a small sand ridge system, no connection to the former peatlands can be established based on 14C age and C/N ratios. The preserved submerged peat deposits with organic carbon contents of 37 % in front of the coastal peatland Heiligensee & Hutelmoor was radiocarbon-dated to 6725 +/- 87 and 7024 +/-73 cal yr BP, respectively, indicating an earlier onset of the peatland as presently published. The formation time of the peat layers gives information about the local sea level rise. The local sea level curve derived from our 14C-dated organic-rich layers is in general agreement to nearby sea level reconstructions (North Rugen and Fischland, Northern Germany), with differences explained by local isostatic movements.

Highlights

Shallow coastal areas and shorelines are important for social, economical, and scientific purposes, for example development of coastlines, land usage, and infrastructure, archeology, sediment dynamics, and biogeochemical fluxes (Small and Nicholls, 2003; Valiela, 2009; Wong et al, 2014)
Sub-marine Continuation of Coastal Peatland Deposits shorelines were shaped during the Littorina Sea period since ∼8,000 cal yr BP (Björck, 1995; Lemke, 1998) following the last glacial maximum (LGM)
Submerged peat detritus sampled in this study shows that the peatland development started as early as 7,024 ± 73 cal yr BP

Summary

Introduction

Shallow coastal areas and shorelines are important for social, economical, and scientific purposes, for example development of coastlines, land usage, and infrastructure, archeology, sediment dynamics, and biogeochemical fluxes (Small and Nicholls, 2003; Valiela, 2009; Wong et al, 2014). Ongoing coastal dynamic processes such as wave and current induced erosion, sediment transport and accumulation have influenced the evolution of coastlines immensely (Lehfeldt and Milbradt, 2000; Schlungbaum and Voigt, 2001; Harff et al, 2009). These processes have led to coastline displacement due to land-loss or land reclamation and changed spatial extensions of coastal ecosystems and habitats. During the post-glacial evolution of the southern Baltic Sea and the accompanying sea level rise (Lampe, 2005) sub-marine terraces of ancient shorelines developed (Kolp, 1990). The age and position of basal peat deposits, as formed in former coastal wetlands, can be used to obtain information about past sea level (Milliman and Emery, 1968; Gehrels and Anderson, 2014)

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