ALBERT

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.

Description: Vodyanitskii mud volcano is located at a depth of about 2070 m in the Sorokin Trough, Black sea. It is a 500-m wide and 20-m high cone surrounded by a depression, which is typical of many mud volcanoes in the Black Sea. 75 kHz sidescan sonar show different generations of mud flows that include mud breccia, authigenic carbonates, and gas hydrates that were sampled by gravity coring. The fluids that flow through or erupt with the mud are enriched in chloride (up to 650 mmol L**-1 at 150-cm sediment depth) suggesting a deep source, which is similar to the fluids of the close-by Dvurechenskii mud volcano. Direct observation with the remotely operated vehicle Quest revealed gas bubbles emanating at two distinct sites at the crest of the mud volcano, which confirms earlier observations of bubble-induced hydroacoustic anomalies in echosounder records. The sediments at the main bubble emission site show a thermal anomaly with temperatures at 60 cm sediment depth that were 0.9 °C warmer than the bottom water. Chemical and isotopic analyses of the emanated gas revealed that it consisted primarily of methane (99.8%) and was of microbial origin (dD-CH4 = -170.8 per mil (SMOW), d13C-CH4 = -61.0 per mil (V-PDB), d13C-C2H6 = -44.0 per mil (V-PDB)). The gas flux was estimated using the video observations of the ROV. Assuming that the flux is constant with time, about 0.9 ± 0.5 x 10**6 mol of methane is released every year. This value is of the same order-of-magnitude as reported fluxes of dissolved methane released with pore water at other mud volcanoes. This suggests that bubble emanation is a significant pathway transporting methane from the sediments into the water column.