Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Heincke	HE569	04.02.2021 - 26.02.2021		North Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Keil Hanno	Fachbereich Geowissenschaften der Universitat Bremen	Bremerhaven	Bremerhaven

Ziel der Reise / Objectives of Cruise:

The repeated glacial-interglacial reshaping of the Quaternary landscape of the south-eastern North Sea resulted in a complex stratigraphy with large-scale to small-scale morphological structures. Intense commercial acoustic surveying during the last decades established a valuable data base of the Pleistocene facies in deeper strata, however, a good understanding of the upper ~100 m of the sediments is still lacking. Based on and extending findings from former cruises HE405 and HE463 the actual cruise He569 was carried out to address three major objectives: (1) to understand on a larger scale the interplay between Pleistocene glacial and interglacial periods in the south-eastern North Sea and related small scaled structural patterns, (2) to test the controversially discussed late Weichselian ice-dammed lake hypothesis in the context of the Elbe Paleovalley, and (3) to analyze the eastern Dogger Bank drainage systems and their relation to the Elbe Paleovalley. For this purpose a mixture of acoustic measurement systems were used throughout the cruise. 2D-multichannel seismic data with the University of Bremen special high resolution shallow water equipment were acquired on a limited set of long overview transects spanning the German EEZ in total from south-west to north-east to address objective (1) in providing a regional overview and distribution of near surface Pleistocene sedimentation structures. Several shorter transects were inspected in North-South and east-west direction in the area of the southern ducks beak in the northern German and the adjacent south-eastern Danish EEZ to investigate the extension as well as internal structural variations of a ~20 m thick acoustic facies attributed to potentially consist of glaciolacustrine sediments. Here the emphasis was on SES 2000 subbottom profiler data, however, several 2D-multichannel seismic lines were also acquired to allow proper imaging and tracing of the base reflector of this unit. In total 4 vibrocores with a length of 5.5 m each were taken from the top of the unit and revealed very homogeneous and stiff clay sediments, a rather untypical sediment type for the south-eastern North Sea. In the Danish sector of the North Sea a total of 60 working hours could be spent to acquire a 3D-seismic data cube of ca. 2000 x 8500 m using the P-Cable system of the University of Aarhus. This cube covered a section of a previously discovered buried river and drainage system and the data will help to better understand the genesis and infill history as well as the linkage to the Elbe-Palaeovaley drainage system. For logistical reasons the cruise was split into two legs with a mid-term port call in Esbjerg / Denmark. This port call was necessary to exchange some scientific personnel but mostly to exchange the Fraunhofer IWES HR3D 3D-seismic system with the P-Cable. The whole cruise program suffered severely from very difficult weather conditions with a total of five full downtime days due to storm situations but also a general very high mean wind speed of 6 Bft. While these conditions directly affected the data quality of all acoustic measurements it prevented most of the planned coring activities and several parts of the original scientific program had to be skipped or abandoned. This mostly affected the planned set of overview transects in the German and Danish sectors, where only 50% of the program was possible and a second 3D-seismic survey in the German EEZ which had to be canceled completely. Nonetheless, the cruise provided very valuable new data and information for the abovementioned scientific targets. In total 3400 km of acoustic profiles, 1310 km of which with multichannel seismic data, were acquired.

Messungen / Measurements