Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Maria S. Merian	MSM37	22.03.2014 - 21.04.2014		North Atlantic Ocean

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Villinger Heinrich	Universitat Bremen - Fachbereich 5 - Geowissenschaften	Las Palmas	Cadiz

Ziel der Reise / Objectives of Cruise:

MERIAN cruise MSM37 to North Pond (23?N, 56?W) had two objectives: to conduct operations at the subseafloor observatories (CORKs) and to investigate in detail locations identified during MSm²0-5 for suspected hydrothermal discharge sites at the seafloor. These goals were achieved with the main operational tool ROV Jason II from WHOI. In addition, the night program was devoted to detailed acoustic mapping of North Pond and its close vicinity with the ship's built-in swath bathymetry system EM122. Hydrologically active ridge flanks may host a large microbial biomass that is most likely sup-ported by oxidation reactions of basalt. To investigate these processes three longterm subseafloor observatories (CORKs) were installed during IODP Expedition 336 (fall 2011) to be able to conduct in situ incubation experiments, to collect fluid samples and to measure in situ formation pressures. A first visit of the sites during MSm²0-5 with WHOI ROV Jason II showed that the observatories were fully operational. Ten dives in total were conducted with ROV Jason II during the time at North Pond. Seven of these dives were dedicated to CORK operations at IODP Site 1382, Hole U1382B and IODP Site 1383, Hole U1383B and U1383C, such as pumping crustal fluids with the help of the CORK sampling ports, recovery and installation of osmo samplers and recovery of two previously in-stalled GeoMicrob sleds. In addition, pressure data were downloaded at all CORKs. All opera-tions at all CORKs went very well and without any technical problems. Two about 36 hour long exploration dives at previously identified areas with suspected seafloor discharge did not reveal active discharge although we could identify areas using temperature gradient measurements in the sediment with values of up to 0.9 K/m. This is a clear indication for circulating warm fluids within the permeable upper crust. Diffuse discharge with temperatures just above bottom water temperature may occur but could not be detected due to the subtle temperature signal in the wa-ter column. One exploratory dive to the southern termination of a dome-like rift mountain south of North Pond yielded basalt, which may represent the break-away zone of an oceanic core complex. Acoustic mapping revealed new structures due to the increased resolution of the EM122 system compared to the previously used EM120; especially the backscatter data seem to be good enough to identify sediment cover on rough topography. Despite the fact that we lost one day to weather and one to technical problems all objectives were achieved.

Messungen / Measurements