Chemostratigraphy - A tool for understanding transport processes at the continental margin off West-Africa

Continental margins as complex interfaces between continents and ocean basins, display a variety of gravity-driven depositional environments. Understanding the interaction of external and internal control mechanisms of sediment transport processes in these environments is important in order to reconstruct their sedimentary history. This study focuses on the geochemical imprints left in the sediment material and its corresponding fluid phase by gravity-driven sediment events and transport processes. High resolution geochemical investigations of the sediments and their fluids provide a detailed characterization of the material allowing conclusions on possible changes in the depositional environment and the related processes. The chemical composition of pore water may document recent changes in the sedimentation pattern caused by slide events. Modeling fluid concentration profiles helps estimating the event age. Geochemical fingerprinting of turbidites in a chemostratigraphic approach provides a more precise characterization of sediments and corresponding sources, and help facilitate reconstruction of transport pathways

Contamination tracer testing with seabed drills: IODP Expedition 357

IODP Expedition 357 utilized seabed drills for the first time in the history of the ocean drilling program, with the aim of collecting intact sequences of shallow mantle core from the Atlantis Massif to examine serpentinization processes and the deep biosphere. This novel drilling approach required the development of a new remote seafloor system for delivering synthetic tracers during drilling to assess for possible sample contamination. Here, we describe this new tracer delivery system, assess the performance of the system during the expedition, provide an overview of the quality of the core samples collected for deep biosphere investigations based on tracer concentrations, and make recommendations for future applications of the system

Chemostratigraphie - Ein Werkzeug für das Verständnis von Transportprozessen am Kontinentalhang vor West-Afrika

Continental margins as complex interfaces between continents and ocean basins, display a variety of gravity-driven depositional environments. Understanding the interaction of external and internal control mechanisms of sediment transport processes in these environments is important in order to reconstruct their sedimentary history. This study focuses on the geochemical imprints left in the sediment material and its corresponding fluid phase by gravity-driven sediment events and transport processes. High resolution geochemical investigations of the sediments and their fluids provide a detailed characterization of the material allowing conclusions on possible changes in the depositional environment and the related processes. The chemical composition of pore water may document recent changes in the sedimentation pattern caused by slide events. Modeling fluid concentration profiles helps estimating the event age. Geochemical fingerprinting of turbidites in a chemostratigraphic approach provides a more precise characterization of sediments and corresponding sources, and help facilitate reconstruction of transport pathways

Shaping of the present-day deep biosphere at Chicxulub by the impact catastrophe that ended the Cretaceous

We report on the effect of the end-Cretaceous impact event on the present-day deep microbial biosphere at the impact site. IODP-ICDP Expedition 364 drilled into the peak ring of the Chicxulub crater, México, allowing us to investigate the microbial communities within this structure. Increased cell biomass was found in the impact suevite, which was deposited within the first few hours of the Cenozoic, demonstrating that the impact produced a new lithological horizon that caused a long-term improvement in deep subsurface colonization potential. In the biologically impoverished granitic rocks, we observed increased cell abundances at impact-induced geological interfaces, that can be attributed to the nutritionally diverse substrates and/or elevated fluid flow. 16S rRNA gene amplicon sequencing revealed taxonomically distinct microbial communities in each crater lithology. These observations show that the impact caused geological deformation that continues to shape the deep subsurface biosphere at Chicxulub in the present day