How a river submerges into the sea: a geological record of changing a fluvial to a marine paleoenvironment during early Holocene sea level rise

Abstract

Coastal seas, and in particular estuarine systems, were significantly affected by Quaternary sea level changes. Furthermore, the dynamics of shelf and coastal evolution have had a strong impact on coastal landscapes inhabited by humans. The postglacial evolution of the vast North Sea shelf with its huge drainage systems, e.g. the Elbe Paleovalley and its tributary system, is an excellent research target to understand how coastal shelf environments change in response to sea level rise. In this study, we investigate infill sediments of the Paleo‐Ems valley – a drowned extension of the modern Ems River and part of the Elbe Paleovalley drainage system. Radiocarbon‐dated transgression sequences provide several new observations regarding the mode and rate of the river system submerging due to the Holocene transgression. Thus, the Paleo‐Ems valley submerged within a short time span of~200 years since the river was not able to adjust its gradient to the rapid rising sea level. The fate of the Paleo‐Ems is exemplary for the rapid change of a former fluvial landscape into a coastal landscape and finally into a submarine seascape. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd.

Ice sheet and palaeoclimate controls on drainage network evolution: an example from Dogger Bank, North Sea

“…Numerous studies have identified Late Pleistocene to Holocene channel networks of a similar stratigraphic position to those in this study (Busschers et al, 2007;Fitch et al, 2005;Gaffney et al, 2007Gaffney et al, , 2009Hepp et al, 2017Hepp et al, , 2019Hijma and Cohen, 2011;Prins and Andresen, 2019). During this period, main channels 1 and 2 were active as proglacial channels draining the margin of the Eurasian Ice Sheet into the Late Weichselian North Sea lake, a large proglacial lake proposed to have existed to the south of Dogger Bank (Becker et al, 2018;Hjelstuen et al, 2017;Jansen et al, 1979;Murton and Murton, 2012;Roberts et al, 2018;Sejrup et al, 2016;Toucanne et al, 2010).…”

“…CPT L, CPT W; Fig. 3), as marine transgression would have modified the sedimentary environment in the sheltered estuaries to low-energy tidal mudflats, as observed elsewhere in the North Sea during Holocene marine transgression (Coughlan et al, 2018;Gaffney et al, 2009;Hepp et al, 2017Hepp et al, , 2019Prins and Andresen, 2019). The final stage of regional landscape evolution was continued marine transgression, with associated ravinement of the pre-existing topography (Figs.…”

“…Channels incised into the glaciogenic sediments formed during this period of subaerial exposure (Cotterill et al, 2017b). These channels form part of the extensive networks of post-Last Glacial Maximum North Sea channel fills mapped by the North Sea Palaeolandscape Project (Fitch et al, 2005;Gaffney et al, 2007Gaffney et al, , 2009 and other studies (Cameron et al, 1987;Coughlan et al, 2018;Hepp et al, 2017Hepp et al, , 2019van Heteren et al, 2014;Hijma et al, 2012;Prins and Andresen, 2019;Salomonsen, 1993). The channel network was buried during subsequent marine transgression which began at around 10 ka at Dogger Bank, with complete inundation occurring around 8.5-8 ka (Brooks et al, 2011;Emery et al, 2019b;Shennan et al, 2000;Sturt et al, 2013).…”

“…Postglacial drainage patterns in the North Sea have become a focus of interest in recent years since the growth in archaeological exploration of the submerged landscapes of the northwest European continental shelf (Bailey et al, 2017;Coles, 1998;Flemming et al, 2017). The adoption of seismic reflection data acquired for oil and gas exploration by the archaeological community has allowed mapping of extensive terrestrial drainage networks throughout the southern North Sea (Fitch et al, 2005;Gaffney et al, 2007Gaffney et al, , 2009Hepp et al, 2017Hepp et al, , 2019van Heteren et al, 2014;Prins and Andresen, 2019;Tappin et al, 2011). These subsurface mapping projects focused on rivers as they are likely sites of human occupation.…”

“…Previous explorations of submerged landscapes have used low-resolution 2D or 3D seismic reflection surveys designed to target deeper oil and gas reservoirs (Fitch et al, 2005;Gaffney et al, 2007Gaffney et al, , 2009 or combine oil and gas datasets with sparse high-resolution 2D seismic reflection data (Coughlan et al, 2018;Hepp et al, 2017Hepp et al, , 2019Prins and Andresen, 2019). Whilst this enables drainage networks to be identified, there is little information to constrain sedimentary and geomorphic processes and therefore the controls on landscape evolution.…”