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  • 1
    Electronic Resource
    Electronic Resource
    Fossil bacterial magnetite in deep-sea sediments from the South Atlantic Ocean (1986)
    [s.l.] : Nature Publishing Group
    Nature 320 (1986), S. 611-615 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Functional dependence of Lowrie-Fuller test parameter ALF (ALF s MDFARM -MDFIRM) on a, IRM; b, ARM/IRM ratio and c, MDFIRM. All measurements were performed on whole-rock samples from DSDP sediment cores (Sites 519, 521, 522 and 523; middle Eocene to Quarternary). The IRMs were generated in a ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/320611a0
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Mapping seafloor massive sulfides with the Golden Eye frequency-domain Em profiler (2018)
    EAGE
    In:  First Break, 36 (10). pp. 61-67.
    Details
    Publication Date: 2018-12-17
    Description: Since the early discovery of a black-smoker complex in 1978 on the East Pacific Rise at 21°N, speculations and expectations have been driven about the potential and perspectives of mining seafloor massive sulfide (SMS) deposits in the deep-ocean. With a worldwide accelerating industrialization, emerging markets, increased commodity prices and metal demand, and advance¬ments in deep-water mining and extraction technologies, mining of SMS may become economically feasible in the near future (Kowalczyk, 2008). However, we still know little about the resource potential of SMS deposits, and the development of geophysical methods for an assessment of their spatial extent, composition, and inner structure is crucial to derive a proper assessment of their economic value. Novel geophysical mapping techniques and exploration strategies are required to locate extinct and buried clusters of SMS deposits, away from the active vent fields and of larger economic potential, but are difficult to find and sample by conventional methods. In 2015 the International Seabed Authority (ISA) assigned an exploration license for polymetallic sulfide deposits to the German Federal Institute for Geosciences and Natural Resources (BGR) in a specified area comprising 100 patches, each 10 . 10 km in size, distributed along the Central and Southeastern Indian Ridge. The challenge to acquire high resolution near-surface electromagnetic (EM) data in such geologically and morphologically complex mid-ocean ridge environments has been addressed by our recent development of the deep-sea profiler Golden Eye that utilizes a frequency-domain electromagnetic (FDEM) central loop sensor, of 3.3 m diameter (Müller et al., 2016). This system has been used in 2015 and 2017 to map active and relict hydrothermal vent fields in the SMS licensing areas. Aside from technological developments, this paper discusses new data processing routines and methods to unravel the conductivity-depth-distribution, induced polarization and magnetic susceptibility, and joint interpretation with geochem¬istry as key elements to map and evaluate SMS deposits.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Dating North Pacific Abyssal Sediments by Geomagnetic Paleointensity: Implications of Magnetization Carriers, Plio-Pleistocene Climate Change, and Benthic Redox Conditions (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Non-carbonaceous abyssal fine-grained sediments cover vast parts of the North Pacific’s deep oceanic basins and gain increasing interests as glacial carbon traps. They are, however, difficult to date at an orbital-scale temporal resolution and still rarely used for paleoceanographic reconstructions. Here, we show that sedimentary records of past geomagnetic field intensity have high potential to improve reversal-based magnetostratigraphic age models. Five sediment cores from Central North Pacific mid-latitudes (39–47°N) and abyssal water depths ranging from 3,900 to 6,100 m were cube-sampled at 23 mm resolution and analyzed by automated standard paleo- and rock magnetic methods, XRF scanning, and electron microscopy. Relative Paleointensity (RPI) records were determined by comparing natural vs. anhysteretic remanent magnetization losses during alternating field demagnetization using a slope method within optimized coercivity windows. The paleomagnetic record delivered well interpretable geomagnetic reversal sequences back to 3 Ma. This age span covers the climate-induced transition from a biogenic magnetite prevalence in the Late Pliocene and Early Pleistocene to a dust-dominated detrital magnetic mineral assemblage since the Mid-Pleistocene. Volcaniclastic materials from concurrent eruptions and gravitational or contouritic sediment re-deposition along extinct seamount flanks provide a further important source of fine- to coarse-grained magnetic carriers. Surprisingly, higher proportions of biogenic vs. detrital magnetite in the late Pliocene correlate with systematically lowered RPI values, which seems to be a consequence of magnetofossil oxidation rather than reductive depletion. Our abyssal RPI records match the astronomically tuned stack of the mostly bathyal Pacific RPI records. While a stratigraphic correlation of rock magnetic and element ratio logs with standard oxygen isotope records was sporadically possible, the RPI minima allowed to establish further stratigraphic tie points at ∼50 kyr intervals. Thus, this RPI-enhanced magnetostratigraphy appears to be a major step forward to reliably date unaltered abyssal North Pacific sediments close to orbital-scale resolution.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: image
    Format: image
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Magnetostratigraphic effects and artifacts of an inverse redox zonation in bottom-up oxygenated East Pacific mid-ocean ridge flank sediments (2021)
    In:  EPIC3EGU 2021, virtual, 2021-04
    Details
    Publication Date: 2021-05-05
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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    PAPER (OA)
  • 5
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    Cyclic magnetite dissolution in Pleistocene sediments of the abyssal northwest Pacific Ocean: Evidence for glacial oxygen depletion and carbon trapping (2016)
    Wiley
    In:  EPIC3Paleoceanography, Wiley, 31, pp. 600-624, ISSN: 0883-8305
    Details
    Publication Date: 2018-08-10
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    PAPER (OA)
  • 6
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    Predictive modelling of grain-size distributions from marine electromagnetic profiling data using end-member analysis and a radial basis function network (2018)
    Oxford University Press
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2018. This article is posted here by permission of The Royal Astronomical Society for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 215 (2018): 460–473, doi:10.1093/gji/ggy152.
    Description: In this work, we present a new methodology to predict grain-size distributions from geophysical data. Specifically, electric conductivity and magnetic susceptibility of seafloor sediments recovered from electromagnetic profiling data are used to predict grain-size distributions along shelf-wide survey lines. Field data from the NW Iberian shelf are investigated and reveal a strong relation between the electromagnetic properties and grain-size distribution. The here presented workflow combines unsupervised and supervised machine-learning techniques. Non-negative matrix factorization is used to determine grain-size end-members from sediment surface samples. Four end-members were found, which well represent the variety of sediments in the study area. A radial basis function network modified for prediction of compositional data is then used to estimate the abundances of these end-members from the electromagnetic properties. The end-members together with their predicted abundances are finally back transformed to grain-size distributions. A minimum spatial variation constraint is implemented in the training of the network to avoid overfitting and to respect the spatial distribution of sediment patterns. The predicted models are tested via leave-one-out cross-validation revealing high prediction accuracy with coefficients of determination (R2) between 0.76 and 0.89. The predicted grain-size distributions represent the well-known sediment facies and patterns on the NW Iberian shelf and provide new insights into their distribution, transition and dynamics. This study suggests that electromagnetic benthic profiling in combination with machine learning techniques is a powerful tool to estimate grain-size distribution of marine sediments.
    Description: This work was funded through DFG Research Center/Cluster of Excellence ‘The Ocean in the Earth System’ and was part of MARUM Research Area SD
    Keywords: Neural networks ; Fuzzy logic ; Statistical methods ; Electrical properties ; Magnetic properties ; Marine electromagnetics ; Controlled source electromagnetics (CSEM)
    Repository Name: Woods Hole Open Access Server
    Type: Article
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    PAPER (OA)
  • 7
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    Dating North Pacific Abyssal Sediments by Geomagnetic Paleointensity: Implications of Magnetization Carriers, Plio-Pleistocene Climate Change, and Benthic Redox Conditions (2021)
    Frontiers Media S.A.
    In:  EPIC3Frontiers in Earth Science, Frontiers Media S.A., 9, pp. 683177, ISSN: 2296-6463
    Details
    Publication Date: 2021-08-30
    Description: Non-carbonaceous abyssal fine-grained sediments cover vast parts of the North Pacific’s deep oceanic basins and gain increasing interests as glacial carbon traps. They are, however, difficult to date at an orbital-scale temporal resolution and still rarely used for paleoceanographic reconstructions. Here, we show that sedimentary records of past geomagnetic field intensity have high potential to improve reversal-based magnetostratigraphic age models. Five sediment cores from Central North Pacific mid-latitudes (39–47°N) and abyssal water depths ranging from 3,900 to 6,100 m were cube-sampled at 23 mm resolution and analyzed by automated standard paleo- and rock magnetic methods, XRF scanning, and electron microscopy. Relative Paleointensity (RPI) records were determined by comparing natural vs. anhysteretic remanent magnetization losses during alternating field demagnetization using a slope method within optimized coercivity windows. The paleomagnetic record delivered well interpretable geomagnetic reversal sequences back to 3 Ma. This age span covers the climate-induced transition from a biogenic magnetite prevalence in the Late Pliocene and Early Pleistocene to a dust-dominated detrital magnetic mineral assemblage since the Mid-Pleistocene. Volcaniclastic materials from concurrent eruptions and gravitational or contouritic sediment re-deposition along extinct seamount flanks provide a further important source of fine- to coarse-grained magnetic carriers. Surprisingly, higher proportions of biogenic vs. detrital magnetite in the late Pliocene correlate with systematically lowered RPI values, which seems to be a consequence of magnetofossil oxidation rather than reductive depletion. Our abyssal RPI records match the astronomically tuned stack of the mostly bathyal Pacific RPI records. While a stratigraphic correlation of rock magnetic and element ratio logs with standard oxygen isotope records was sporadically possible, the RPI minima allowed to establish further stratigraphic tie points at ∼50 kyr intervals. Thus, this RPI-enhanced magnetostratigraphy appears to be a major step forward to reliably date unaltered abyssal North Pacific sediments close to orbital-scale resolution.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 8
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    (Fig 3) Acoustic, hydrographic, and electromagnetic maps of the southern bay slope survey area. Links to data files (2011)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Center for Marine Environmental Sciences; Comment; Eckernfoerder Bay, Western Baltic Sea; MARUM; Mittelgrund; MULT; Multiple investigations; Uniform resource locator/link to graphic; Uniform resource locator/link to raw data file
    Type: Dataset
    Format: text/tab-separated-values, 32 data points
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    DATA PANGAEA
  • 9
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    (Fig 3) Acoustic, hydrographic, and electromagnetic raw data of the southern bay slope survey area (2011)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Center for Marine Environmental Sciences; Class; Conductivity; CTD; Depth, bathymetric; DEPTH, sediment/rock; Depth of reflector; Eckernfoerder Bay, Western Baltic Sea; Electromagnetic sensor (Aeroquest Sensortech Ltd. GEM-3); LATITUDE; Line; LONGITUDE; Magnetic susceptibility, volume; Magnetization; Magnetometer, GSM-19M, Marine Overhauser; MARUM; Mittelgrund; MULT; Multiple investigations; Sub-bottom profiler, StrataBox 10 kHz, SyQuest; Thickness; UTM Easting, Universal Transverse Mercator; UTM Northing, Universal Transverse Mercator; UTM Zone, Universal Transverse Mercator
    Type: Dataset
    Format: text/tab-separated-values, 424252 data points
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    DATA PANGAEA
  • 10
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    (Fig 5) Geochemistry and rock magnetic parameters of sediment cores K2, K3, K5 (2011)
    PANGAEA
    Details
    Publication Date: 2023-03-03
    Keywords: Anhysteretic remanent magnetization/saturation isothermal remanent magnetization ratio; ARM, Intensity, per unit volume; Carbon, organic, total; Center for Marine Environmental Sciences; Chloride; DEPTH, sediment/rock; Eckernfoerder Bay, Western Baltic Sea; Elevation of event; Event label; GC; Gravity corer; Iron; Latitude of event; Longitude of event; Magnetic susceptibility, volume; MARUM; Mittelgrund_K2; Mittelgrund_K3; Mittelgrund_K5; S-ratio (hematite/magnetite); Sulfate
    Type: Dataset
    Format: text/tab-separated-values, 472 data points
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    DATA PANGAEA
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