Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Maria S. Merian	MSM84	18.06.2019 - 17.07.2019		Labrador Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Gebhardt Catalina	Alfred-Wegener-Institut fur Polar- und Meeresforschung	St. John`s	St. John`s

Ziel der Reise / Objectives of Cruise:

The Eastern Canadian margin off Labrador is a key area for paleoclimatic/-oceanographic investigations. Major ice sheets drain(ed) into this area, either directly (Laurentide Ice Sheet, LIS) or indirectly (Innuitian and Greenland ice sheets). Hudson Bay is a major source of freshwater input into the Labrador Sea. During the 8.2 ka event, a large amount of freshwater was released to the Labrador Sea by outburst events of Lake Agassiz-Objiway, causing a reduction of the Atlantic meridional overturning circulation. Many studies addressed the intercorrelations between LIS dynamics and climate variability, suggesting that repeated LIS collapses resulted in Northern Hemisphere climate instabilities. It was also shown that during the last glacial, intermediate water was not formed in the Labrador Sea as today. Hence, the dynamic behavior of the LIS is key to the understanding of climate changes during the Quaternary. MSM84 therefore had three overarching goals: (1) Reconstruction of the maximum extent of the LIS on the Labrador shelf, and its retreat history at the end of the last glacial (2) Retreat history of the LIS at the end of the last glacial inland of the present-day coastline in Lake Melville (3) Search for remnants (e.g. buried glacial features) from older glacials that overprinted the Labrador shelf and Lake Melville before the last glacial To achieve our goals, swath bathymetry, sediment echosounder, and high-resolution seismic reflection data were collected, completed by geological samples for ground-truthing and dating of glacial features. The spatial distribution of glacial features and their exact age will allow the determination of the maximum ice extent, the location and lateral extent of ice streams, the nature of sub-glacial drainage systems, as well as the locations and timing of temporal stillstands and/or re-advances during the decay of the LIS at the end of the last and possibly also previous glaciations. On June 17, 2019, all scientists and marine mammal observers embarked RV MARIA S. MERIAN. We left port on June 18, heading north to our first working area at Cartwright Saddle, which was reached on June 19. Upon arrival, we started with a hydroacoustic survey, followed by retrieval of sediment cores next morning. Our first seismic survey at Cartwright Saddle started on June 21 and continued to June 25. After all seismic equipment was on deck, we started our transit towards the interior of Lake Melville. Between June 25 and July 1, we alternated between coring and hydroacoustic mapping in Lake Melville. The bathymetry survey added ca. 1650 km² of data to the previously existing Canadian bathymetry grid. Along with the bathymetry data, we collected ca. 1720 km of PARASOUND profiles. On July 1, we left Lake Melville heading back to the Labrador Shelf where we sailed directly to our northernmost working area around Okak Bank. Upon arrival on July 2, we started our next seismic survey. On July 4, we retrieved several sediment cores and started a more detailed seismic survey with our ultrahigh-resolution streamer. Scientific work in our northernmost working area was completed with a SVP profile and a core on July 5. After transit south to Hopedale Saddle, we deployed our seismic equipment and collected seismic data from July 6 to 8. Seven sediment cores were subsequently retrieved. Due to bad weather conditions, we decided to sail southwards to Cartwright Saddle, where we started our next seismic survey on July 9. One day later, we collected 7 sediment cores. After sailing back to the Hopedale Saddle working area, we resumed our seismic work with good weather conditions on July 11 and were able to finish on July 12. One day later and after our last transit between working areas, we collected 7 cores from the Cartwright saddle before we started our last ultrahigh-resolution seismic survey. All scientific work was completed on July 15 during evening hours. St. John's was reached on July 17 shortly

Messungen / Measurements