News
Iron deposition during recovery from Late Devonian oceanic anoxia: Implications of the geochemistry of the Kawame ferromanganese deposit, Nedamo Belt
Abstract.
"The Late Devonian, during which one of the “Big Five” Phanerozoic mass extinction events occurred, was one of the most important time intervals in Earth history. Nevertheless, the paucity of deep-sea records due to subduction has hampered elucidation of the pelagic environment during the Late Devonian in Panthalassa. However, ancient hydrothermal ferromanganese sediments, which were deposited on the abyssal seafloor and then accreted onto continental margins, are preserved as umber deposits and exposed in accretionary prisms. These sediments can provide key information to characterize the paleo-ocean. [...]".
Source: Science Direct
Authors: Yusuke Kuwahara et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.103920
Plate tectonics controls ocean oxygen levels
Abstract.
"Variations in ocean oxygen levels during Earth’s history have been linked to evolution and mass extinctions. Simulations now suggest that the configuration of the continents has a substantial impact on ocean oxygenation. [...]".
Source: Nature
Authors: Katrin J. Meissner & Andreas Oschlies
DOI: https://doi.org/10.1038/d41586-022-02187-9
Constraining marine anoxia under the extremely oxygenated Permian atmosphere using uranium isotopes in calcitic brachiopods and marine carbonates
Abstract.
"The redox chemistry change in ancient oceans has profoundly shaped the evolutionary trajectories of animals. Uranium isotopes (U) in marine carbonate sediments have widely been used to place quantitative constraints on the oxygenation state of the oceans through geological history. However, syndepositional and post-depositional diagenesis impose a positive and variable U offset in the carbonate sediments relative to contemporaneous seawater, leaving uncertainties on quantification of anoxic seafloor areas in the past. Studies from modern settings suggest that Low-Magnesium Calcite (LMC) in articulate brachiopod shells are diagenetic resistant materials that may faithfully record the U value of ancient seawater. [...]".
Source: Science Direct
Authors: Wen-qian Wang et al.
DOI: https://doi.org/10.1016/j.epsl.2022.117714
Environmental change and carbon-cycle dynamics during the onset of Cretaceous oceanic anoxic event 1a from a carbonate-ramp depositional system
Abstract.
"We report the first high-resolution sedimentological and geochemical record of the negative carbon-isotope excursion (CIE) at the onset of the early Aptian oceanic anoxic event (OAE) 1a from a carbonate-ramp depositional environment, analysed from a well core from c. 2500 m depth, 100 km offshore Abu Dhabi, United Arab Emirates. Time-series analysis of stable oxygen isotope values and concentrations of Si, Al, and Ti resulted in durations of the C3 and C4 segments of the CIE that support relative completeness of the C3 segment and high sediment preservation rates of c. 13 cm/kyr of the studied sedimentary sequence. [...]".
Source: Science Direct
Authors: Thomas Steuber et al.
DOI: https://doi.org/10.1016/j.palaeo.2022.111086
A double-edged sword: The role of sulfate in anoxic marine phosphorus cycling through Earth history
Abstract.
"Modern anoxic marine sediments release phosphorus (P) to seawater, driving feedbacks at multiple timescales. On sub-Myr timescales, anoxic P regeneration amplifies ocean deoxygenation; on multi-Myr timescales, it stabilizes atmospheric O2. Some authors have extended this thinking to the Precambrian: by analogy, widespread ocean anoxia would imply extensive P regeneration from sediments. However, this neglects the role of sulfate in P regeneration. [...]".
Source: Geophysical Research Letters
Authors: Michael A. Kipp
DOI: https://doi.org/10.1029/2022GL099817
A Depth-Transect of Ocean Deoxygenation During the Paleocene-Eocene Thermal Maximum: Magnetofossils in Sediment Cores From the Southeast Atlantic
Abstract.
"The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) presents a past analog for future global warming. Previous studies provided evidence for major loss of dissolved oxygen during the PETM, although understanding the degree and distribution of oxygen loss poses challenges. Magnetofossils produced by magnetotactic bacteria are sensitive to redox conditions in sediments and water columns, and have been used to reconstruct paleoredox conditions over a range of geological settings. [...]".
Source: JGR Solid Earth
Authors: Pengfei Xue et al.
DOI: https://doi.org/10.1029/2022JB024714
Ocean biogeochemical modelling
Abstract.
"Ocean biogeochemical models describe the ocean’s circulation, physical properties, biogeochemical properties and their transformations using coupled differential equations. Numerically approximating these equations enables simulation of the dynamic evolution of the ocean state in realistic global or regional spatial domains, across time spans from years to centuries. This Primer explains the process of model construction and the main characteristics, advantages and drawbacks of different model types, from the simplest nutrient–phytoplankton–zooplankton–detritus model to the complex biogeochemical models used in Earth system modelling and climate prediction. [...]".
Source: Nature Reviews Methods Primers
Authors: Katja Fennel et al.
DOI: https://doi.org/10.1038/s43586-022-00154-2
Impact of warming and deoxygenation on the habitat distribution of Pacific halibut in the Northeast Pacific
Abstract.
"Ocean warming and deoxygenation are already modifying the habitats of many aerobic organisms. Benthic habitat in the Northeast Pacific is sensitive to deoxygenation, as low oxygen concentrations occur naturally in continental shelf bottom waters. Here, we examine the potential impacts of deoxygenation and ocean warming on the habitat distribution of Pacific halibut (Hippoglossus stenolepis), one of the most commercially important groundfish in North America. [...]".
Source: Wiley Online Library
Authors: Ana C. Franco et al.
DOI: https://doi.org/10.1111/fog.12610
GO2NE Webinar on Ocean Deoxygenation
GO2NE Webinar on Ocean Deoxygenation.
"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!
Thursday, 20th October 2022, 16:00 h – 17:00 CEST
Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The 16th webinar will take place 20 October 2022, 16:00 h CEST. The webinar will feature presentations by a more senior and an early-career scientist, 20 minutes each followed by 10 minutes moderated discussion sessions.
If you are interested to present at one of the upcoming webinars please submit a short abstract here.
Moderation:
Grant Pitcher
Department of Forestry, Fisheries and the Environment, South Africa
Speakers:
Annette Carlson
University of Connecticut, USA
"Assessing drivers of oxygen dynamics in the southern Benguela Upwelling System through the combined application of models and observations"
Bronwen Currie
Ministry of Fisheries and Marine Resources, Namibia
"Oxygen calls the shots in the Northern Benguela Upwelling System off Namibia"
If you want to receive further information about upcoming webinars please register here."
Start Date: 10/20/22
Ventilation changes drive orbital-scale deoxygenation trends in the late Cretaceous ocean
Abstract.
"Mechanisms that drive cyclicity in marine sediment deposits during hothouse climate periods in response to Earth’s orbit variations remain debated. Orbital cycles fingerprint in the oceanographic records results from the combined effect of terrestrial (e.g. weathering-derived nutrient supply, freshwater discharge) and oceanic (e.g. productivity, oxygenation) processes, whose respective contribution remains to be clarified. [...]".
Source: Geophysical Research Letters
Authors: Anta-Clarisse Sarr et al.
DOI: https://doi.org/10.1029/2022GL099830
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