Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Maria S. Merian	MSM116 RIOGRANDERISE	03.04.2023 - 07.05.2023		South Atlantic Ocean

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Palike Heiko	Universitat Bremen, Zentrum fur Marine Umweltwissenschaften	Montevideo	Recife

Ziel der Reise / Objectives of Cruise:

Sediment coring to reconstruct Paleogene Climate: The primary objective of MSM116 was to obtain sequences of very well-preserved deposits of calcareous microfossils from relatively shallow water depths (in reach of the MeBo-200 coring device) and paleo-water depths (thus with potentially good preservation), and therefore allow the study of surface and bottom water temperatures, Delta-18O-seawater, and related paleoceanographic parameters to establish climatic boundary conditions during past "warmer worlds". The planned program consisted of coring two stations on the Rio Grande Rise (DSDP Site 72-516), each triple-cored to obtain an as complete as possible sedimentary sequence from Pliocene through at least Miocene, but possibly older, strata. Overall, the material would serve to establish a Paleogene MeBo-200 core sequence with excellent microfossil preservation and high CaCO3 content, to preserve sections that could not be recovered at DSDP 516, and to sample enough material to allow pairwise application of traditional (Mg/Ca, alkenone) and novel (clumped isotopes) proxies to answer unresolved questions about the evolution of ocean temperatures, past CO2 concentrations, and Earth System Sensitivity. The quality of previous cores at DSDP Site 516 has been variable and incomplete. In addition, the remaining partially sampled sediments are now over 35 years old and less suitable for reliable paleoproxy analysis. Future proxy reconstructions applied to these sediments include paleo-productivity, changes in faunal composition, and carbonate accumulation rates for the Pliocene, extended Miocene and possibly Oligocene horizons. The ancillary aim of the cruise, which we intend to follow to avoid idle time during MeBo-200 maintenance between deployments, or due to unfavorable weather conditions, was to obtain temperature gradient profile measurements using a short (3.6m) lance with attached temperature loggers to obtain in-situ formation temperatures, and together with measured thermal conductivity measurements, provide heat-flow measurements in the working area. An additional objective was to conduct detailed multibeam mapping and subbottom parametric profiling to enhance our understanding of the cored sediments, and the general working area. Several CTD/Rosette measurements were planned to characterize the oceanographic conditions and properties of the watermasses bathing the the relatively shallow drilling sites, and therefore establish to what extent paleoceanographic proxies to be measured from the sediment cores can be used to establish past changes in, e.g. Antarctic Intermediate Water, North-Atlantic Deep Water, and potentially surface currents. Since coring on the Rio Grande Rise was not possible due to objections from the Brazilian Navy, the cruise concentrated on Stocks Seamount in the equatorial south Atlantic, which was within reach for the MeBo-200. Here we recovered a Paleogene sequence of sediments from a succession of sedimentary pelagic foraminiferal oozes and sands with nannofossils, ranging from the Pleistocene through to the Late Paleocene in the oldest sediments on top of basalt.

Messungen / Measurements