Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Heincke	HE499	16.10.2017 - 26.10.2017		German Bight North Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Hepp Daniel A.	Universitat Bremen, Zentrum fur Marine Umweltwissenschaften	Bremerhaven	Bremerhaven

Ziel der Reise / Objectives of Cruise:

HE499:The Palaeo-Ems, the drowned paleo course of the Ems River, is an important link between the modern Ems River and the ancient Elbe-Palaeovalley. The understanding of the development of the drainage and infill history of the valley provides new insights into the latest glacial and postglacial dewatering system as well as the effect of sea level rise on ancient and modern river systems. Targets of expedition HE499 were the seismic mapping and the sediment sampling of the Palaeo-Ems valley: the seismic mapping was planned to (1) densify the already existing seismic grid with single channel seismic (Boomer) and echosounding systems (sediment echosounder SES 2000 and Multibeam EM710), and (2) to locate the so far unknown river courses in the southern part and to study the area of the estuary to the Elbe Palaeovalley. The sampling of the valley infill was planned (3) as transect of sediment cores (vibrocorer) to understand the effect of the Holocene transgression on the fluvial system. Bad weather conditions in October on the North Sea (many storm fronts in the Irish and Celtic Seas) in combination with strong tidal currents and shallow water depths (14 m) made proper vibrocorer operations nearly impossible. One single attempt to operate the vibrocorer failed (11% core recovery) and there was no chance to repeat the coreing. Thus, the saved time was successfully used to intensify the seismic mapping and a clear wider area were mapped than originally proposed. Only with the SES2000 we achieved 166 seismic track lines with a total length of about 1200 km. As preliminary result the fluvial system Paleo-Ems can be divided into three sections base on its morphologic character: the southern part ("upper course") is characterized, against expectation, by a complex fluvial system of several multiple displaced, South-North running river valleys. The dominant direction of this replacement is from West to East. In its middle part the fluvial system changes its character to a wide meandering main valley, probably accompanied by a few smaller rivers. In the northern part ("lower course") the South-North running fluvial system turns toward North-East and flows into the Elbe-Palaeovalley. In the area of the estuary to the Elbe Palaeovalley we observe a complex delta-like dentritic channel system. In the southern part of the study area the former palaeo-landscape is intensively eroded by morphodynamic processes, so that Holocene and glacial valley structures seems to occur in the same depth level. Nevertheless, we are able to distinguish relative stratigraphically and morphologically the Holocene from the older glacial structures. In some cases it seems that the Holocene valleys had reactivated the glacial valleys. Due to bad weather conditions and forecasts (with waves up 7 m and winds up to 9 Bft) we decided to finish the expedition one day earlier than proposed. Even if the sampling target was missed the expedition HE499 was a great success, since the seismic mapping provides us new, unexpected and amazing findings on the development of the fluvial system Paleo-Ems in the course of the Holocene transgression.

Messungen / Measurements