Description: As an update to the RTopo-2.0.1 data set (https://doi.org/10.1594/PANGAEA.856844), RTopo-2.0.4 contains new original bathymetry data for the Northeast Greenland continental shelf. In the Southern Ocean, we added the Rosier et al. (JGR Oceans, 2018) bathymetry grid below Filchner Ice Shelf. This work was supported in part through the Deutsche Forschungsgemeinschaft (DFG) within the Special Priority Program (SPP) 1889 "Regional Sea Level Change and Society" (grant OGreen79), the German Federal Ministry for Education and Research (BMBF) within the GROCE project (Grant 03F0778A), the Natural Environment Research Council (NERC) large grant "Ice shelves in a warming world: Filchner Ice Shelf System" (NE/L013770/1), the NERC project "Greenland in a warmer climate: What controls the advance & retreat of the NE Greenland Ice Stream" (Grant NE/N011228/1), and the Helmholtz Climate Initiative "Regional Climate Change" (REKLIM).

Description: As an update to the Northeast Greenland - Digital Bathymetric Compilation (https://doi.pangaea.de/10.1594/PANGAEA.849313), the updated digital bathymetric model (DBM) for the Northeast Greenland (NEG) continental shelf (74°N - 81°N) contains new original bathymetry data for the Northeast Greenland continental shelf, specifically in front of the 79 North Glacier, recorded during R/V Polarstern expedition PS100. This work was supported in part through the Deutsche Forschungsgemeinschaft (DFG) within the Special Priority Program (SPP) 1889 "Regional Sea Level Change and Society" (grant OGreen79), the German Federal Ministry for Education and Research (BMBF) within the GROCE project (Grant 03F0778A), and the NERC project "Greenland in a warmer climate: What controls the advance & retreat of the NE Greenland Ice Stream" (Grant NE/N011228/1).

Description: This dataset consists of three high-resolution multi-channel seismic reflection (MCS) profiles from the southeastern North Sea between Amrum and Heligoland shown in the corresponding publication. These data were acquired during expedition AL496 with R/V Alkor in July 2017 and during expedition MSM98/2 with R/V Maria S. Merian in February 2021 to image buried glacial landforms (tunnel valleys and a glacitectonic complex). All data have been processed to produce full seismic reflection profiles in the time-domain with an emphasis on the suppression of multiple reflections (shallow water artefacts). The raw seismic data (including navigation) is included in this dataset.

Description: Summary The Bathymetrists Seamounts (BSM) are located north of the volcanic Sierra Leone Rise in the eastern Atlantic between 6° and 9°N. The three W-E, N-S and NE-SW striking directions of the seamounts indicate a clear structural control for the emplacement of these volcanoes. The origin of the melts, their relationship to the Sierra Leone Rise and the role of the faults in the formation of the melts are unknown as the BSM could be explained by plume related volcanism or decompression melting beneath deep (transform) faults. The SEDIS-cruise M152/2 of RV METEOR strove for a better understanding of the life cycle of submarine volcanoes and their effect on the oceanic lithosphere in the oceanic intraplate setting of the BSM and the relationship to the Sierra Leone Rise. The aims were: 1) to understand the interaction between crustal thickness, tectonics and volcanic phases, 2) to investigate the structural, chronological and petrological evolution of individual seamounts and seamount chains, 3) to review slope failures and resulting mass flow processes. We addressed these objectives by more than 4000 km highresolution reflection seismic and more than 5000 km of parametric echosounder, multi-beam, and gravity and magnetic profiles. Rock samples for ground truthing and geochemical research have been collected during 14 dredge stations. We further determined the concentrations in surface seawater and air and the state of air-sea exchange of a number of nowadays globally banned pesticides, polychlorinated biphenyls, brominated flame retardants, polycyclic aromatic hydrocarbons and their derivatives. Zusammenfassung Die Bathymetrists Seeberge liegen nördlich der Sierra Leone Schwelle, einer vulkanischen Plattform im östlichen Atlantik zwischen 6° und 9° N. Diese submarinen Vulkane gruppieren sich entlang W-E, N-S und NE-SW Trends, was eine strukturelle Kontrolle der Vulkanentstehung indiziert. Die Schmelzentstehung sind unbekannt und können mit PlumeVulkanismus oder Dekompressionsschmelzen unter bisher nicht untersuchten Störungen und tiefen Transformstörungen zusammenhängen. Der Bezug zur Sierra Leone Schwelle ist ebenfalls unbekannt. Im Zuge der SEDIS-Expedition M152/2 mit FS METEOR wurde der Lebenszyklus von Unterwasservulkanen und deren geochemischen Einfluss auf die ozeanische Lithosphäre der Bathymetrists Seeberge untersucht. Anhand der profilhaften geophysikalischer Messungen und Dredge-Proben wollen wir 1) die Wechselwirkung zwischen Krustenmächtigkeit, Tektonik und Vulkanismus verstehen, 2) die strukturelle, chronologische und petrologische Entwicklung von Vulkanen und Vulkanketten untersuchen, und 3) Auslösemechanismen, Transportprozesse und Volumina von Hangrutschungen studieren. Zur Bearbeitung der wissenschaftlichen Fragen sammelten wir mehr als 4000 km mehrkanal-reflexionsseismischer und mehr als 5000 km parametrische Sedimentecholot, Fächerlot, Schwere und Magnetik-Profile. Für die geochemischen Arbeiten sammelten wir an 14 Stationen Gesteinsproben unter Einsatz einer Dredge. Die regelmäßige Beprobung der Luft und des Oberflächenwassers diente der Bestimmung der Konzentration von heute weltweit verbotenen Pestiziden, polychlorierten Biphenylen, bromierten Flammschutzmitteln, polyzyklischen aromatischen Kohlenwasserstoffen und deren Derivaten und um den Austausch zwischen Luft und Meer weiter zu verstehen.

Description: The Skagerrak builds the transition from the exposed Palaeozoic basement of South Norway to thick Mesozoic to Cenozoic sediments covering Danish Jutland. It states the southern Norwegian Trench, and comprises from W to E the Mesozoic Farsund Basin, the northernmost sector of the Sorgenfrei-Tornquist Zone and the Palaeozoic Skagerrak Graben. Over the past decades, fluid escape structures at the southern Skagerrak Shelf and in the central Norwegian Trench were investigated and layer-parallel fluid migration from Mesozoic rocks was suggested. However, a fluid source or a corresponding migration system of the fluids has not been proposed yet. In this study, a joint interpretation of seismic imagery and seismic attributes reveals fluid indications and migration systems in the Farsund Basin and the central Skagerrak. We propose that source rocks of the Lower Jurassic Fjerritslev Formation generated thermogenic fluids in the Farsund Basin as well as in the Fjerritslev Trough. For the central Skagerrak, a time-structure map of the base of the F-III member of the Fjerritslev Formation shows that these fluids could migrate upward forced by buoyancy and partially bypassed by faults, and seep out in the Norwegian Trench. Furthermore, we propose that fluid escape structures on the southern shelf were likely caused by seepage of biogenic fluids under bottom current action.

Description: Laterally discontinuous subsea permafrost is present in the Arctic along the Beaufort Sea margin. Discontinuities within the permafrost include unfrozen zones from which fluids are free to migrate vertically or laterally, potentially accelerating permafrost degradation. This process releases greenhouse gases that further contribute to global warming. Generally, because of its contrasting viscoelastic properties compared to unfrozen sediments, permafrost can be easily detected by seismic methods. A discontinuity in subsea permafrost corresponds to the termination of a frozen layer. At this termination, seismic energy is diffracted rather than reflected or refracted. This condition is well suited for diffraction imaging. Here, we present a processing workflow to identify subsea permafrost discontinuities using the diffracted wavefield. This workflow aims to extract diffractions from seismic data collected on the continental shelf of the Canadian Beaufort Sea. The shallow water environment combined with the occurrence of subsea permafrost generates highly energetic free surface multiples that overprinted diffractions. Thus, preliminary steps of the processing flow focused on multiple attenuation. A recursive velocity analysis, starting with a 100 common-midpoint (CMP) interval and ending with a 5 CMP interval, is also performed to better capture lateral permafrost discontinuities. Then, the full wavefield data are migrated, collapsing the energy distributed along the hyperbolic trajectory of the diffractions at their apexes. Afterwards, reflections are adaptively subtracted from the migrated data. Finally, demigration of the residuals (i.e., collapsed diffractions) is performed. The resulting image reveals several near-surface diffractions attributed to discontinuities at the top of the subsea permafrost. Diffractions present distinct amplitude, frequency and velocity characteristics suggesting that various permafrost conditions coexist across the continental shelf.