Newly collected multibeam swath bathymetry data herald a new phase in gas-hydrate research on Lake Baikal
Naudts, L.; Khlystov, O.; Khabuev, A.; Seminskiy, I.; Casier, R.; Cuylaerts, M.; General'chenko, P.; Synaeve, J.; Vlamynck, N.; de Batist, M. A.; Grachev, M.A. (2009). Newly collected multibeam swath bathymetry data herald a new phase in gas-hydrate research on Lake Baikal. Eos, Trans. (Wash. D.C.) 90(52): OS31A-1195 In: Eos, Transactions, American Geophysical Union. American Geophysical Union: Washington. ISSN 0096-3941; e-ISSN 2324-9250, more |
| Authors | | Top | - Naudts, L., more
- Khlystov, O.
- Khabuev, A.
- Seminskiy, I.
| - Casier, R., more
- Cuylaerts, M., more
- General'chenko, P.
- Synaeve, J., more
| - Vlamynck, N., more
- de Batist, M. A., more
- Grachev, M.A.
|
| Abstract | Lake Baikal is a large rift lake in Southern Siberia (Russian Federation). It occupies the three central depressions of the Baikal Rift Zone (BRZ): i.e. the Southern, Central and Northern Baikal Basins. Rifting started ca. 30 Ma ago and is still active with a present-day average extension rate of about 4 mm/yr. With a depth of 1637 m, Lake Baikal is the deepest lake in the World. It also holds 20 % of the world’s liquid surface fresh water, which makes it the largest lake in the World in terms of volume. Lake Baikal is also the only freshwater lake in the World with demonstrated occurrences of gas hydrates in its sedimentary infill. Methane hydrates are stable at water depths below 375 m. The presence of hydrates in the sedimentary infill is evidenced by a widespread BSR. Hydrates have also been encountered locally, in the near-bottom sediments of mud-volcano-like structures. In the summer of 2009, the lake floor has been mapped with multibeam swath bathymetry for the first time during a two-month-long survey with RV Titov. Swath bathymetry data were acquired with RCMG’s mobile 50 kHz SeaBeam 1050 multibeam system. In total 12600 km of echosounder tracks were sailed covering 15000 km2, including the Academician Ridge Accommodation Zone, the Central Baikal Basin, the Selenga Delta Accommodation Zone en the South Baikal Basin. In general, the lake floor was mapped starting from water depths of about -200 m to -1637 m, with an average survey depth of -1000 m. The new bathymetric data image the lake-floor morphology in unprecedented detail, revealing many small- and large-scall morphosedimentary, morphostructural and fluid-flow-related features, many of which were hitherto unknown. Known mud-volcano provinces in the Southern and Central Baikal Basins (i.e. the Posolsky Bank mud-volcano province, the Kukuy Canyon mud volcano province and the Olkhon Gate mud-volcano province) were mapped in detail, and several new, often isolated, mud-volcano-like structures were discovered. In addition, different possible fluid-flow features were identified in front of the Selenga Delta. Also the gas-hydrate-bearing areas around the oil seeps of Gorevoi Utes and the methane seeps of Goloustnoye have been mapped in detail, revealing that these hydrate occurrences are not associated with mud-volcano-like structures. The multibeam mapping survey coincided with the 2nd season of exploration of the lake floor by manned MIR submersibles (http://baikalfund.ru/eng/projects/expedition/index.wbp). Several of the MIR dives focused on features imaged by the new bathymetry data, such as gas-hydrate occurrences at methane seeps and oil seeps and in the mud-volcano-like structures, and gas seeps and fluid-flow phenomena along active fault scarps. The multibeam mapping survey was conducted in the framework of SBRAS project 17.8 and FWO Flanders project 1.5.198.09. |
|
