ALBERT

Description: The continental slopes of the Black Sea show abundant manifestations of gas seepage in water depth of

Description: In the eastern Black Sea, we determined methane (CH4) concentrations, gas hydrate volumes, and their vertical distribution from combined gas and chloride (Cl−) measurements within pressurized sediment cores. The total gas volume collected from the cores corresponded to concentrations of 1.2–1.4 mol CH4 kg−1 porewater at in-situ pressure, which is equivalent to a gas hydrate saturation of 15–18% of pore volume and amongst the highest values detected in shallow seep sediments. At the central seep site, a high-resolution Cl− profile resolved the upper boundary of gas hydrate occurrence and a continuous layer of hydrates in a sediment column of 120 cm thickness. Including this information, a more precise gas hydrate saturation of 22–24% pore volume could be calculated. This volume was higher in comparison to a saturation calculated from the Cl− profile alone, resulting in only 14.4%. The likely explanation is an active gas hydrate formation from CH4 gas ebullition. The hydrocarbons at Batumi Seep are of shallow biogenic origin (CH4 〉 99.6%), at Pechori Mound they originate from deeper thermocatalytic processes as indicated by the lower ratios of C1 to C2–C3 and the presence of C5.

Description: The nature of the Ionian Sea crust has been the subject of scientific debate for more than 30 years, mainly because seismic imaging of the deep crust and upper mantle of the Ionian Abyssal Plain (IAP) has not been conclusive to date. The IAP is sandwiched between the Calabrian and Hellenic subduction zones in the central Mediterranean. To univocally confirm the proposed oceanic nature of the IAP crust as a remnant of the Tethys ocean and to confute its interpretation as a strongly thinned part of the African continental crust, a NE-SW oriented 131 km long seismic refraction and wide-angle reflection profile consisting of eight ocean bottom seismometers and hydrophones was acquired in 2014. A P-wave velocity model developed from travel time forward modelling is refined by gravimetric data and synthetic modelling of the seismic data. A roughly 6km thick crust with velocities ranging from 5.1km/s to 7.2km/s, top to bottom, can be traced throughout the IAP. In the vicinity of the Medina Seamounts at the southern IAP boundary, the crust thickens to about 9km and seismic velocities decrease to 6.8km/s at the crust-mantle boundary. The seismic velocity distribution and depth of the crust-mantle boundary in the IAP document its oceanic nature, and support the interpretation of the IAP as a remnant of the Tethys oceanic lithosphere formed during the Permian and Triassic period.

Description: Multibeam echosounder (MBES) data recorded during RV METEOR cruise M111 between 10.10.2014 and 01.11.2014 in the eastern Mediterranean Sea. The aim of the cruise was to quantify the deep geometry and architecture of the Calabria subduction zone and Ionian Sea lithosphere and to shed light on the nature of the Ionian Sea with OBS/OBH and deep sea seismics. Additionally the M111 cruise formed the core of an ambitious investigation covering the Ionian Sea and island of Sicily. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Description of processed data sources: During the cruise M111 the Kongsberg EM122 multibeam echosounder with a nominal sounding frequency of 12 kHz was utilized. 288 beams (and up to 864 soundings in equidistant and dual swath mode) are formed for each ping with a 1°(Tx)/2°(Rx) footprint while the seafloor is detected using amplitude and phase information for each beam sounding. For further information consult https://www.km.kongsberg.com/. The EM122 was recording during the deployment of the OBH/OBS, during seismic surveys and during transits. Responsible person during this cruise / PI: Ingo Klaucke (iklaucke@geomar.de). Chief Scientist: H. Kopp hkopp@geomar.de CR: https://www.tib.eu/de/suchen/id/awi%3Adoi~10.2312%252Fcr_m111/ CSR: http://www.bsh.de/aktdat/dod/fahrtergebnis/2014/20140277.htm Responsible person for data delivery and approval: Paul Wintersteller (seafloor-imaging@marum.de) A special thanks goes to to the watch keeper during M111: Marzia Rovere, Ingo Klaucke, Anne Krabbenhoeft, Marc-André Gutscher

Description: The backscatter data were collected during R/V SONNE Cruise SO244. For processing of the backscatter information, all data recorded during turns of the ship were eliminated before gridding to a 20 m cell size throughout the study area.

Description: Bathymetry based on data recorded during MSM34-1 between 09.12.2013 and 27.12.2013 in the Black Sea. The main objective of this cruise was the localization and characterization of suitable gas hydrate deposits on the Danube deep-sea fan.

Description: Multibeam echosounder (MBES) data recorded during RV MARIA S. MERIAN cruise MSM34-1 from 09.12.2013 - 27.12.2013. The main objective of this cruise was the localization and characterization of suitable gas hydrate deposits on the Danube deep-sea fan. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Description of the data source: During the RV MARIA S. MERIAN cruise MSM34-1 Kongsberg EM122 multibeam echosounder with a nominal sounding frequency of 11.5 to 12.5 kHz was utilized. 288 beams (and up to 864 soundings in equidistant and dual swath mode) are formed for each ping with a 2°(Tx)/2°(Rx) footprint while the seafloor is detected using amplitude and phase information for each beam sounding. For further information consult https://www.km.kongsberg.com/. Based on the acquisition of 2D seismic lines sufficient overlapping of the outer beams between adjacent profiles was possible. Thus the generation of a very detailed 25 m by 25 m bathymetric survey was possible. Responsible person during this cruise / PI: Jasper Hoffmann (jhoffmann@geomar.de), Ingo Klaucke (GEOMAR). Chief Scientist: Ingo Klaucke CR: https://www.tib.eu/de/suchen/id/awi%3Adoi~10.2312%252Fcr_msm34/ CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2013/20130125.htm

Description: Multibeam bathymetric data were acquired during R/V SONNE Cruises SO104, SO244, and R/V Marcus G. Langseth Cruise MGL1610. The datasets were individually processed and gridded with grid cell sizes of 75 m. For the combined grid, depth information from SO244 was used wherever possible. If no SO244 data were available, MGL1610 data were preferred over SO104 data. The backscatter data were collected during R/V SONNE Cruise SO244. For processing of the backscatter information, all data recorded during turns of the ship were eliminated before gridding to a 20 m cell size throughout the study area.