Deutsches Ozeanographisches
Datenzentrum Inventur der Poseidon-Reise POS439/1 (DOD-Ref-No.20120298)
Inventory of Poseidon Cruise POS439/1 (DOD-Ref-No.20120298)

Working area
Poseidon POS439/1 30.09.2012 - 02.10.2012   The Little Belt Baltic Sea Kiel Bight Flensburger Forde  

Chief Scientist
Port of departure
Port of return
Station map
Spielhagen Robert GEOMAR Helmholtz-Zentrum fur Ozeanforschung Kiel Kiel Kiel   

Ziel der Reise / Objectives of Cruise:

Cruise objectives The major goal of cruise POS439-1 was to obtain long large-volume sediment cores from three areas: (1) the Early Holocene "Lake Kiel" (north of the present Kiel Fjord/Kieler Forde), (2) the inner Flensburg Fjord (Flensburger Forde), and (3) the Little Belt. Scientific objectives The cores from "Lake Kiel" will be used to reveal the early Holocene environmental history of the southwestern Baltic Sea at a time when this area was mostly above sea level while the so-called "Ancylus Lake" existed in the eastern Baltic Sea area. "Lake Kiel" was a small (ca. 20 km long) freshwater lake which is documented by carbonate-rich freshwater deposits overlain by younger marine sediments deposited during and after the Littorina Transgression which occurred ca. 8,000 years before present. The cores from the inner Flensburg Fjord were obtained as potential archives of the large-scale wind systems in the NW European realm. These wind systems are expected to exhibit a significant influence on the water mass exchange at the surface and at the sea floor of the Flensburg Fjord. The cores from the Little Belt were obtained to supplement the drilling campaign of leg 347 of the Integrated Ocean Drilling Project (performed in Sept.-Nov. 2013). Cruise narrative RV Poseidon left the GEOMAR pier in the afternoon of September 30th, 2012, and sailed directly to the first coring site in the area where the "Lake Kiel" had existed in former times. Several attempts were necessary to obtain cores of the uppermost ca. 50 cm of soft sediment with a 100 cm long Rumohr corer. Coring with a 550 cm square-barrel kasten corer (15x15 cm diameter) was only semi-sucessuful because the corer hit a fossil tree trunk at ca. 250 cm sediment depth and was bended. Opening and sampling of the core took several hours while the ship headed north to the Flensburg Fjord. In the early morning of October 1st, a survey with an SES 96 Parametric Sediment Echosounder was performed off the Murwik Navy School near the south coast of the inner Flensburg Fjord. A highly variable subbottom topography with equally variable thicknesses of the uppermost sediment layers was revealed and two sites for sediment coring were selected. Five Rumohr cores (38-54 cm recovery) and two kasten cores (185 and 2.75 cm recovery) were obtained. The sediment sequences were dark gray and muddy in the upper part and sandy below. Occasionally bivalves were found. RV Poseidon left the Flensburg Fjord around lunchtime of October 1st and sailed northward into Danish waters of the Little Belt. Following a sediment echosounder survey a core site at ca. 55.0?N, 10.1?E was selected which promised a thick sequence of postglacial sediments. Following the retrieval of three short Rumohr cores, a kasten core with 441 cm sediment recovery could be obtained. Opening of the core revealed an upper part of 240 cm olive gray deposits with abundant dark mottles, underlain by two meters of lighter, more sandy sediments characterized by an internal layering every 2-4 cm. All recovered Rumohr cores were stored upright, while the kasten cores were sampled with large 50-100 cm long plastic archive boxes. After the cruise storage occurred at the GEOMAR core storage facilities under cool conditions (4?C). RV Poseidon returned to the GEOMAR east shore pier in the morning of October 2nd. Weather conditions were fine during the cruise, with only light winds and a few very minor rain showers.

Messungen / Measurements

Typ der Messungen
Type of measurements
Daten im DOD
Data in DOD
GEOMAH Spielhagen Robert 4 cores G04
Core-soft bottom (no. of cores)
Square-barrel kasten cores (5.5 or 11 m long, 15x15 cm diameter) - see station list for recovery. 01.10.2012 no
GEOMAH Spielhagen Robert 4 stations G04
Core-soft bottom (no. of cores)
Station selection based on results from sediment echosounding. 01.10.2012 no
GEOMAH Spielhagen Robert 11 cores G04
Core-soft bottom (no. of cores)
Rumohr cores (1 m long, 10 cm diameter) - see station list for recovery. 01.10.2012 no
GEOMAH Spielhagen Robert 3 profiles G74
Multi-beam echosounding
Sediment echosounding profiles in areas of potential core sites. 01.10.2012 no