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Eurofleets-2 Cruise Summary Report Bottom Currents in a Stagnat Environment (BURSTER project)

Authors:
  • National Institute of Oceanography and Applied Geophysics-OGS

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Eurofleets 2- BURSTER cruise was conducted onboard the German icebreaker RV Polarstern (Expedition PS99-1a) during June 13–23, 2016 (Bremerhaven-Longyearbyen) having the principal objective of investigating the hydrographic and bio-geochemical conditions of the Kveithola glacial trough (south of Svalbard), and to uncover the possible existence of gas seepage activity in the area. Although the BURSTER research was intended as a preparatory study for the writing of a major research project, the amount of planned activities onboard was really ambitious. Thanks to a tireless, enthusiastic group formed by 13 students out of 23 scientists, a Teacher at Sea (GIFT, EU programme), and a technician from a small-medium enterprise operating with a transportable electron microscope (Nanovision Srl,), 89 multi-cores (22.50 m of sediments and 830 sub-samples), 265 water samples, 28 CTD casts along 7 transects and 2.57 km of benthic camera survey (OFOS), were collected during only 48 hours. In addition, according to the project work program, 24 hours were dedicated to the maintenance/recovery of two moorings that were deployed west of Svalbard during the Eurofleets 2- PREPARED project (RV G.O. Sars, June 2014). BURSTER group was actively supported by 4 scientists of the Italian PNRA project DEFROST, 4 AWI scientists of expedition PS99-1 and the Chief scientist, T. Soltwedel. The cruise successfully recovered evidences of chemosynthetic activity in the Kveithola Trough with the presence of benthic fauna and large tabular and/or irregular-shaped rocks that share the same characteristics of methanogenic environments observed in gas seepage areas. The promising preliminary results obtained from this initial survey of the area will represent the base for the writing of a major project for a detailed investigation of the microbial, biologic and oceanographic system of the Kveithola Trough.
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... These deposits are covered by several drift units (the "Kveithola Drift"), that are also associated to a field of pockmarks in the innermost part of the trough (Bjarnadóttir et al., 2013;Lantzsch et al., 2017;Rebesco et al., 2011Rebesco et al., , 2016Rüther et al., 2012). Very recently, geophysical and geochemical data acquired by Lucchi et al. (2016) and Mau et al. (2017) in occasion of two surveys conducted along the northwestern Barents Sea margin indicated the presence of a few single gas flares along the northern edge of the Kveithola trough. Furthermore, Weniger et al. (2019) reported high concentrations of bound gases with thermogenic origin (e.g., CH 4 ranging between 340 and 642 ng g −1 ) in near-surface sediments collected at different sites inside the trough, thus suggesting that mature petroleum systems are likely to be present in the study area. ...
... As often observed in continental shelves and slopes, factors favouring AVS preservation are rapid deposition rates and low oxygen to euxinic conditions in the overlying waters (Rickard and Morse, 2005). The Kveithola trough is today crossed by persistent, high-energy and well oxygenated dense bottom currents, rearranging the sedimentary sequences (like the Kveithola Drift) deposited in the trough during the Holocene (Lantzsch et al., 2017;Lucchi et al., 2016;Rebesco et al., Fig. 4. Depth profiles along sediment core PS99/21-5 of A) total reduced inorganic sulphur content (tRIS, black horizontal axis) and its stable isotope composition (δ 34 S tRIS , red horizontal axis); B) total organic carbon (TOC) content (black horizontal axis) and the pyritic sulphur to total organic carbon ratio (S py /TOC, red horizontal axis); C) As and D) Mo content (black horizontal axis) and the relative enrichment factors (EF X , red horizontal axis). The pink and the green areas on the trace element plots highlight the enrichment factor intervals corresponding to detectable (3 < EF < 10) and moderate to strong (EF > 10) enrichments, respectively. ...
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