Description: Between 14.03.2006 and 25.04.2006, bathymetric data based on the KONGSBERG EM710 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 EM710 was utilized to perform bathymetric mapping in shallower areas. It allows to conduct surveys in water depths of up to 2,000 m, however it operates best in shallower water depths under 500 m. Two transducer arrays transmit frequency coded acoustic signals (70 to 100 kHz). Data acquisition is based on continuous wave pulses in shallower depths and FM (chirp) pulses in greater depths. The beam footprint has a dimension of 1° by 1°. 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, while the EM710 was only used in few parts of the research area. 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

Description: In the Campeche Knolls, in the southern Gulf of Mexico, lava-like flows of solidified asphalt cover more than 1 square kilometer of the rim of a dissected salt dome at a depth of 3000 meters below sea level. Chemosynthetic tubeworms and bivalves colonize the sea floor near the asphalt, which chilled and contracted after discharge. The site also includes oil seeps, gas hydrate deposits, locally anoxic sediments, and slabs of authigenic carbonate. Asphalt volcanism creates a habitat for chemosynthetic life that may be widespread at great depth in the Gulf of Mexico.

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

Description: Between 01.10.2003 and 12.11.2003, bathymetric data was acquired in the Gulf of Mexico during the R/V SONNE cruise SO174. The expedition was dedicated to the types and structures of near-surface marine methane hydrates and the environmental conditions required for their formation. Furthermore, the cruise aimed at the assessment of microbiological turnover and deployments of long-term observatories for examination of the mechanisms controlling the formation and dissociation of gas hydrate. Bathymetric mapping with the multibeam echosounder (MBES) SIMRAD EM120 was utilized to conduct high-quality seafloor maps in water depths between 500 and 1000 m, covering an area of 350 km² and notably improving the resolution of existing bathymetry. Sub-bottom profiling and plume imaging, visual seafloor observation, lander deployments, sediment coring, CT scanning and biological sampling complemented the research programme. 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 SO174 cruise, the hull-mounted multibeam echosounder (MBES) SIMRAD 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). Data acquisition is based on successive emission-reception cycles of the signal. 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°. The beam spacing can be set to equidistant or equiangular. For further information on the system, consult: https://www.km.kongsberg.com/ Depth is estimated from each beam by using the two-way travel time and the beam angle known from each beam, and taking into account the ray bending due to refraction in the water column by sound speed variations. Combining phase and amplitude is used to provide measurement accuracy practically independent of the beam pointing angle. A sound velocity for the calibration of the SIMRAD EM120 profile was obtained through a CTD cast. Responsible persons during this cruise / PI: Gerhard Bohrmann (gbohrmann@marum.de) & Florian Meier (florian.meier@iwes.fraunhofer.de) Chief Scientist: Gerhard Bohrmann (gbohrmann@marum.de) CR: http://oceanrep.geomar.de/13539/1/GEOMAR_Rep_117_SO174.pdf CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2003/20040025.htm

Description: This 2D multi-channel seismic data set was acquired during SONNE cruise SO241 offshore Mexico in the Guaymas Basin in June 2015. MCS data were collected using a Geometrics GeoEel streamer of variable active lengths, such as 150, 162, 175, and 187 m with 96, 104, 112, and 120 channels, respectively. The hydrophone group spacing was 1.56 m. The seismic source signal was generated by two generator-injector (GI) air guns, each with a volume of 210 cubic inches or 3.44 l (1.72 l generator and 1.72 l injector). The air guns were operated in harmonic mode at a tow depth of 2 m. The shot interval was 7 s, resulting in a mean shot point distance of 12 m. The recording time was 4 s, and the sampling rate was 1 ms. Navigation is based on ship GPS and lay backs. Locations are given in UTM zone 12N. Seismic data processing was funded by VBPR AS and carried out with RadExPro. It included common mid-point (CMP) binning with a CMP bin spacing of 3.125 m; band pass filtering using an Ormsby filter with corner frequencies of 20, 45, 250, and 400 Hz; normal move-out correction (NMO); and true amplitude recovery. The NMO-corrected gathers were stacked, and subsequently, a post-stack Stolt migration with 1500 m/s velocity was carried out. Detailed information on the data acquisition can be found in the SO241 cruise report (https://doi.org/10.3289/CR_S241).

Description: Highlights • In cold seeps of Guaymas Basin, aragonite, barite and pyrite precipitated from modified seawater. • Aragonite is highly depleted in 13C suggesting formation via anaerobic oxidation of methane. • Barite formed through mixing of reducing, Ba-rich seep fluids with a 34S-rich sulfate pool. • Pyrite framboids formed under anoxic-sulfidic water via microbial sulfate reduction. Abstract Authigenic carbonate crusts, surface muds and bivalve shell fragments have been recovered from inactive and active recently discovered cold seep sites in central Guaymas Basin. In this study, for first time, redox conditions and fluid sources involved in mineral precipitation were investigated by analyzing the mineralogy and textures of surface samples, along with skeletal contents, and C, O and S isotopes variations. The δ13C values of aragonitic bivalve shells and non-skeletal carbonate from some surface muds (1‰ to −3.7‰ V-PDB) suggest that carbonate precipitated from ambient dissolved inorganic carbon, whereas fibrous aragonite cement and non-skeletal carbonate from other sites are highly depleted in 13C (down to −47.6‰ V-PDB), suggesting formation via anaerobic oxidation of methane, characteristic of methane seepage environments. δ18O in most of the carbonates varies from +1.4‰ to +3.2‰ V-PDB, indicating that they formed from slightly modified seawater. Some non-skeletal carbonate grains from surface muds have lower δ18O values (−12.5‰ to −8.2‰ V-PDB) reflecting the influence of 18O-depleted pore water. Size distribution of pyrite framboids (mean value: 3.1 μm) scattered within diatomaceous sinter suggests formation from anoxic-sulfidic bottom waters. δ34S in pyrite is of −0.3‰ V-CDT compared to +46.6‰ V-CDT in barite, thus implying a fluid sulfate−sulfide fractionation of 21.3‰ that argues in favor of microbial sulfate reduction as the processes that mediated pyrite framboid formation, in a semi-closed system. Barite formation occurred through the mixing of reducing and Ba-rich seep fluids with a 34S-enriched sulfate pool that resulted from microbial sulfate reduction in a semi-closed system. The chemical composition of aragonite cement, barite and pyrite suggest mineral precipitation from modified seawater. Taken together, our data suggest that mineralization at the studied seep sites is controlled by the mixing of seawater with minor amounts of hydrothermal fluids, and oxygen-depleted conditions favoring anaerobic microbial processes.