ALBERT

Description: Bathymetry based on data recorded during MSM34-2 between 27.12.2013 and 18.01.2014 in the Black Sea. The main objective of this cruise was the mapping and imaging of the gas hydrate distribution and gas accumulations as well as possible gas migration pathways. Objectives of Cruise: Gas hydrates have been the focus of scientific and economic interest for the past 15-20 years, mainly because the amount of carbon stored in gas hydrates is much greater than in other carbon reservoirs. Several countries including Japan, Korea and India have launched vast reasearch programmes dedicated to the exploration for gas hydrate resources and ultimately the exploitation of the gas hydrates for methane. The German SUGAR project that is financed the the Ministry of Education and Research (BmBF) and the Ministry of Economics (BmWi) aims at developing technology to exploit gas hydrate resources by injecting and storing CO2 instead of methane in the hydrates. This approach includes techniques to locate and quantify hydrate reservoirs, drill into the reservoir, extract methane from the hydrates by replacing it with CO2, and monitor the thus formed CO2-hydrate reservoir. Numerical modeling has shown that any exploitation of the gas hydrates can only be succesful, if sufficient hydrate resources are present within permeable reservoirs such as sandy or gravelly deposits. The ultimate goal of the SUGAR project being a field test of the technology developed within the project, knowledge of a suitable test site becomes crucial. Within European waters only the Norwegian margin and the Danube deep-sea fan show clear geophysical evidence for large gas hydrate accumulations, but only the Danube deep-sea fan most likely contains gas hydrates within sandy deposits. The main objective of cruise MSM34 therefore is locating and characterising suitable gas hydrate deposits on the Danube deep-sea fan.

Description: Multibeam echosounder (MBES) data recorded during RV MARIA S. MERIAN cruise MSM34-2 between 27.12.2013 and 18.01.2014 in the Black Sea. The main objective of this cruise was the mapping and imaging of the gas hydrate distribution and gas accumulations as well as possible gas migration pathways. Another objective of cruise therefore was locating and characterizing 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 MSM34-2 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 observations during MSM34-1 the bathymetry of MSM34-2 mainly consists of the detailed mapping to the gas hydrate distribution area. Responsible person during this cruise / PI: Felix Gross (GEOMAR), Joerg Bialas (GEOMAR).

Description: Data for estimating heat flow in the western Black Sea are provided, based on measurements made during Expedition MSM34 (R/V Maria S. Merian). Data are located in the Bulgarian and Romanian Sector of the Black Sea in water depths ranging from 420 to 1500 m. Data were always collected with the GEOMAR-owned 6 m long heat-probe tool, consisting of 22 Thermistors (at 26 cm spacing) along a sensor-string, a reference pressure gauge and calibration thermometer (T100 sensor). Raw data are required to be calibrated relative to the T100 sensor. Calibration data for both expeditions are provided in form of temperature offsets for each thermistor. Data provided include per station all original (raw) data for each deployment (temperature as function of time, pressure/Depth) for each thermistor, as well as initial results after separating each individual measurement sequence into penetration files (pen-files) where the temperature calibration has been applied. Results report an average thermal Gradient, heat-flux and thermal conductivity over the total penetraiton Depth of 6m. Detailed information (temperature and thermal conductivity as function of depth at each location) is given in graphical form as well as ascii data per individual penetration.

Description: Seafloor pockmarks of varying size occur over an area of 50,000 km² on the Chatham Rise, Canterbury Shelf and Inner Bounty Trough, New Zealand. The pockmarks are concentrated above the flat-subducted Hikurangi Plateau. Echosounder data identifies recurrent episodes of pockmark formation at ~100,000yr frequency coinciding with Pleistocene glacial terminations. Here we show that there are structural conduits beneath the larger pockmarks through which fluids flowed upward toward the seafloor. Large negative Δ¹⁴C excursions are documented in marine sediments deposited next to these subseafloor conduits and pockmarks at the last glacial termination. Modern pore waters contain no methane and there is no negative δ¹³C excursion at the glacial termination that would be indicative of methane or mantle-derived carbon at the time the Δ¹⁴C excursion and pockmarks were produced. An ocean general circulation model equipped with isotope tracers is unable to simulate these large Δ¹⁴C excursions on the Chatham Rise by transport of hydrothermal carbon released from the East Pacific Rise as previous studies suggested. Here we attribute the Δ¹⁴C anomalies and pockmarks to release of ¹⁴C-dead CO2 and carbon-rich fluids from subsurface reservoirs, the most likely being dissociated Mesozoic carbonates that subducted beneath the Rise during the Late Cretaceous. Because of the large number of pockmarks and duration of the Δ¹⁴C anomaly, the pockmarks may collectively represent an important source of ¹⁴C-dead carbon to the ocean during glacial terminations.