ALBERT

Description: Between 14.03.2006 and 25.04.2006, bathymetric data based on the KONGSBERG EM120 system (MBES) was acquired in the Gulf of Mexico during the R/V METEOR cruise M67/2. The main research goal was the investigation of asphalt volcanoes in the Campeche Bay and related sedimentary structures. The leg was split into two parts. During the first sub-leg 2a geophysical and especially hydroacoustic methods were used to explore the distribution of these asphalt volcanoes and to map knolls as well as other structures like mass wasting and asphalt flows. Using reflection seismic, sedimentary structures related to the volcanoes were also investigated. Further mapping but also sampling of vent fluids and asphalt was the research interest of sub-leg 2b. Therefore the Remotely Operating Vehicle (ROV) QUEST (Marum) as well as a TV-MUC were used. Bathymetry mapping was done using the EM120 for deeper and the EM710 for shallower regions. 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 M67/2 cruise, the hull-mounted multibeam echosounder (MBES) KONGSBERG EM120 was utilized to perform bathymetric mapping. It allows to conduct surveys in water depths of up to 11,000 m. Two transducer arrays transmit frequency coded acoustic signals (11.25 to 12.6 kHz). While the emission beam has a dimension of 150° across and 2° along track, the reception is obtained from 191 overlapping beams with widths of 2° across and 20° along track. The beam footprint has a dimension of 2° by 2°. For further information on the system, consult: https://www.km.kongsberg.com/ Due to the water depth of the research area the EM120 was permanently used. Only for shallower regions the EM710 was used too. To convert the recorded travel times into water depth, several sound velocity profiles were obtained with the shipboard CTD, providing a correction for ray bending for each beam. Depth is estimated from each beam by using the two-way travel time and the known beam angle known, and taking into account the ray bending due to refraction in the water column by sound speed variations. Responsible person during this cruise / PI: Volkhard Spieß (vspiess uni-bremen.de), Gerhard Bohrmann (gbohrmann@marum.de) Chief Scientist: : Volkhard Spieß (vspiess uni-bremen.de), Gerhard Bohrmann (gbohrmann@marum.de) CR: https://www.tib.eu/de/suchen/id/awi%3Adoi~10.2312%252Fcr_m67/ CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2006/20060077.htm