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  • 1
    Electronic Resource
    Electronic Resource
    Salty brines on the Mediterranean sea floor (1997)
    [s.l.] : Macmillan Magazines Ltd
    Nature 387 (1997), S. 31-32 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In this communication, we report on brines from the Discovery Basin in the eastern Mediterranean which have the highest salin- ity ever found in the marine environment They were formed by the dissolution of bischofite (MgCl2.6H2O) and filled the basin during the past 2,000 years. The ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/387031a0
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Synchronous volcanic eruptions and abrupt climate change ∼17.7 ka plausibly linked by stratospheric ozone depletion (2017)
    National Academy of Sciences
    In:  PNAS Proceedings of the National Academy of Sciences of the United States of America, 114 (38). pp. 10035-10040.
    Details
    Publication Date: 2020-02-06
    Description: Significance: Cold and dry glacial-state climate conditions persisted in the Southern Hemisphere until approximately 17.7 ka, when paleoclimate records show a largely unexplained sharp, nearly synchronous acceleration in deglaciation. Detailed measurements in Antarctic ice cores document exactly at that time a unique, ∼192-y series of massive halogen-rich volcanic eruptions geochemically attributed to Mount Takahe in West Antarctica. Rather than a coincidence, we postulate that halogen-catalyzed stratospheric ozone depletion over Antarctica triggered large-scale atmospheric circulation and hydroclimate changes similar to the modern Antarctic ozone hole, explaining the synchronicity and abruptness of accelerated Southern Hemisphere deglaciation. Abstract: Glacial-state greenhouse gas concentrations and Southern Hemisphere climate conditions persisted until ∼17.7 ka, when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the Southern Hemisphere, with many changes ascribed to a sudden poleward shift in the Southern Hemisphere westerlies and subsequent climate impacts. We used high-resolution chemical measurements in the West Antarctic Ice Sheet Divide, Byrd, and other ice cores to document a unique, ∼192-y series of halogen-rich volcanic eruptions exactly at the start of accelerated deglaciation, with tephra identifying the nearby Mount Takahe volcano as the source. Extensive fallout from these massive eruptions has been found 〉2,800 km from Mount Takahe. Sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface UV radiation indicate that the eruptions led to stratospheric ozone depletion. Rather than a highly improbable coincidence, circulation and climate changes extending from the Antarctic Peninsula to the subtropics—similar to those associated with modern stratospheric ozone depletion over Antarctica—plausibly link the Mount Takahe eruptions to the onset of accelerated Southern Hemisphere deglaciation ∼17.7 ka.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1073/pnas.1705595114
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Fluid venting in the eastern Aleutian subduction zone (1998)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Solid Earth, 103 (B2). pp. 2597-2614.
    Details
    Publication Date: 2018-04-25
    Description: Fluid venting has been observed along 800 km of the Alaska convergent margin. The fluid venting sites are located near the deformation front, are controlled by subsurface structures, and exhibit the characteristics of cold seeps seen in other convergent margins. The more important characteristics include (1) methane plumes in the lower water column with maxima above the seafloor which are traceable to the initial deformation ridges; (2) prolific colonies of vent biota aligned and distributed in patches controlled by fault scarps, over‐steepened folds or outcrops of bedding planes; (3) calcium carbonate and barite precipitates at the surface and subsurface of vents; and (4) carbon isotope evidence from tissue and skeletal hard parts of biota, as well as from carbonate precipitates, that vents expel either methane‐ or sulfide‐dominated fluids. A biogeochemical approach toward estimating fluid flow rates from individual vents based on oxygen flux measurements and vent fluid analysis indicates a mean value of 5.5±0.7 L m−2 d−1 for tectonics‐induced water flow [Wallmann et al., 1997b]. A geophysical estimate of dewatering from the same area [von Huene et al., 1997] based on sediment porosity reduction shows a fluid loss of 0.02 L m−2 d−1 for a 5.5 km wide converged segment near the deformation front. Our video‐guided surveys have documented vent biota across a minimum of 0.1% of the area of the convergent segment off Kodiak Island; hence an average rate of 0.006 L m−2 d−1 is estimated from the biogeochemical approach. The two estimates for tectonics‐induced water flow from the accretionary prism are in surprisingly good agreement.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/97JB02131
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Concentration, accumulation rates, Th fluxes, focusing factors, and productivity proxies on core PS97/093-2 over the past 400,000 years (2021)
    PANGAEA
    Details
    Publication Date: 2023-03-24
    Description: Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization and enhanced the efficiency of the biological pump during glacials. However, past export production in the subantarctic Southeast Pacific is poorly documented, and its connection to Fe fertilization, potentially related to Patagonian Ice Sheet dynamics is unknown. We report biological productivity changes over the past 400 ka, based on a combination of 230Thxs-normalized and stratigraphy-based mass accumulation rates of biogenic barium, organic carbon, biogenic opal, and calcium carbonate as indicators of paleo-export production in a sediment core upstream of the Drake Passage (57.5º S; 70.3º W). In addition, we use fluxes of iron and lithogenic material as proxies for terrigenous input, and thus potential micronutrient supply. Stratigraphy-based mass accumulation rates are strongly influenced by bottom-current dynamics, which result in variable sediment focussing or winnowing at our site. Carbonate is virtually absent in the core, except during peak interglacial intervals of the Holocene, and Marine Isotope Stages (MIS) 5 and 11, likely caused by transient decreases in carbonate dissolution. All other proxies suggest that export production increased during most glacial periods, coinciding with high iron fluxes. Such augmented glacial iron fluxes at the core site were most likely derived from glaciogenic input from the Patagonian Ice Sheet promoting the growth of phytoplankton. Additionally, glacial export production peaks are also consistent with northward shifts of the Subantarctic and Polar Fronts, which positioned our site south of the Subantarctic Front and closer to silicic acid-rich waters of the Polar Frontal Zone. However, glacial export production near the Drake Passage was lower than in the Atlantic and Indian sectors of the Southern Ocean, which may relate to complete consumption of silicic acid in the study area. Our results underline the importance of micro-nutrient fertilization through lateral terrigenous input from South America rather than aeolian transport, and exemplify the role of frontal shifts and nutrient limitation for past productivity changes in the Pacific entrance to the Drake Passage.
    Keywords: Drake Passage; glacial-interglacial changes; iron fertilization; Mass accumulation rates; paleoproductivity; Southern Ocean; Subantarctic zone; thorium normalization
    Type: Dataset
    Format: application/zip, 3 datasets
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    DATA PANGAEA
  • 5
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    Th fluxes on core PS97/093-2 (2021)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: 230Th normalization; AGE; ANT-XXXI/3; Barium; Barium excess; Barium excess, flux; Barium excess, flux, standard deviation; Calcium carbonate; Calcium carbonate, flux; Calcium carbonate, flux, standard deviation; Calculated; calculated, 1 sigma; Carbon, organic, total; Carbon, organic, total, flux; Carbon, organic, total, flux, standard deviation; Carbon-Sulfur Determinator; DEPTH, sediment/rock; Drake Passage; glacial-interglacial changes; ICP-MS, Thermo Fisher Scientific, Element 2; ICP-OES; Iron, flux; Iron, flux, standard deviation; Iron, total; iron fertilization; Lithogenic, flux; Lithogenic, flux, standard deviation; Mass accumulation rates; Normalization based on 3 oxygen; Opal, biogenic silica; Opal, flux; Opal, flux, standard deviation; paleoproductivity; PC; Piston corer; Polarstern; PS97; PS97/093-2; Southern Ocean; South Pacific Ocean; Subantarctic zone; Thorium-230, flux normalized; Thorium-230, flux normalized, standard deviation; Thorium-232, flux normalized; Thorium-232, flux normalized, standard deviation; thorium normalization; Titanium
    Type: Dataset
    Format: text/tab-separated-values, 1403 data points
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    DATA PANGAEA
  • 6
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    Focusing factor of sediment core PS97/093-2 (2021)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: AGE; ANT-XXXI/3; Density, dry bulk; DEPTH, sediment/rock; Drake Passage; Focusing factor; glacial-interglacial changes; iron fertilization; Mass accumulation rates; paleoproductivity; PC; Piston corer; Polarstern; PS97; PS97/093-2; Southern Ocean; South Pacific Ocean; Subantarctic zone; Thorium-230 excess, decay-corrected; thorium normalization
    Type: Dataset
    Format: text/tab-separated-values, 36 data points
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    DATA PANGAEA
  • 7
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    Accumulation rates of sediment core PS97/093-2 (2021)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: Accumulation rate, mass; AGE; ANT-XXXI/3; Density, dry bulk; DEPTH, sediment/rock; Drake Passage; glacial-interglacial changes; iron fertilization; Mass accumulation rates; paleoproductivity; PC; Piston corer; Polarstern; PS97; PS97/093-2; Sedimentation rate; Southern Ocean; South Pacific Ocean; Subantarctic zone; thorium normalization
    Type: Dataset
    Format: text/tab-separated-values, 99 data points
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    DATA PANGAEA
  • 8
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    Geochemical results for 〈5 µm size fraction sediments of core PS75/056-1 (2022)
    PANGAEA
    Details
    Publication Date: 2023-08-22
    Description: This dataset contains the geochemical results for the dust fraction (〈5 µm size fraction) of sediment core PS75/056-1 from the South Pacific Subantarctic Zone (55.16°S, 114.78°W; 3581 m water depth) collected during R/V Polarstern expedition ANT-XXVI/2 (PS75 BIPOMAC) in 11/2009-01/2010 (Gersonde, 2011, doi:10.2312/BzPM_0632_2011). The original lithogenic dust provenance signal was extracted from a total of 108 samples (incl. 13 full replicates) between 0.03 and 9.93 m core depth covering the period from ~8,000 to ~260,000 years before present. The age model is from van der Does et al. (2021, doi:10.1016/j.quascirev.2021.106978). All samples were analyzed for their trace element content using a ThermoFinnigan Element II ICP-MS and their radiogenic isotope composition (Nd, Pb, Sr) was analyzed with a ThermoScientific Neptune Plus MC-ICP-MS at the ICBM in Oldenburg, Germany
    Keywords: Adopted from van der Does et al. (2021); AGE; ANT-XXVI/2; Barium; Calculated, PAAS-normalized (Taylor and McLennan, 1985); Cerium; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Dust provenance; Dysprosium; Erbium; Europium; Europium anomaly; Gadolinium; Gravity corer (Kiel type); Holmium; ICP-MS, Thermo Finnigan, Element 2; Iron fluxes; Laboratory code/label; Lanthanum; Lanthanum/Ytterbium ratio; Lead; Lead-206/Lead-204 ratio; Lead-206/Lead-204 ratio, standard deviation; Lead-206/Lead-204 ratio, standard error; Lead-207/Lead-204 ratio; Lead-207/Lead-204 ratio, standard deviation; Lead-207/Lead-204 ratio, standard error; Lead-207/Lead-206 ratio; Lead-207/Lead-206 ratio, standard deviation; Lead-207/Lead-206 ratio, standard error; Lead-208/Lead-204 ratio; Lead-208/Lead-204 ratio, standard deviation; Lead-208/Lead-204 ratio, standard error; Lead-208/Lead-206 ratio; Lead-208/Lead-206 ratio, standard deviation; Lead-208/Lead-206 ratio, standard error; Lutetium; Multi-collector ICP-MS (MC-ICP-MS), Neptune Plus, Thermo; Neodymium; Neodymium-143/Neodymium-144 ratio; Neodymium-143/Neodymium-144 ratio, standard error; Polarstern; Praseodymium; PS75/056-1; PS75 BIPOMAC; Radiogenic isotopes; Rare earth elemets; Samarium; Sample comment; SL; Southern Hemisphere Westerly Winds; Southern Ocean; South Pacific Ocean; Strontium; Strontium-87/Strontium-86 ratio; Strontium-87/Strontium-86 ratio, standard deviation; Strontium-87/Strontium-86 ratio, standard error; Terbium; Thulium; Ytterbium; Zirconium; ε-Neodymium; ε-Neodymium, standard deviation; ε-Neodymium, standard error
    Type: Dataset
    Format: text/tab-separated-values, 5019 data points
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    DATA PANGAEA
  • 9
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    Source apportionment results for 〈5 μm size fraction sediments of core PS75/056-1 (2022)
    PANGAEA
    Details
    Publication Date: 2023-08-22
    Description: This dataset contains the source apportionment results for the dust fraction (〈5 µm size fraction) of sediment core PS75/056-1 from the South Pacific Subantarctic Zone (55.16°S, 114.78°W; 3581 m water depth) collected during R/V Polarstern expedition ANT-XXVI/2 (PS75 BIPOMAC) in 11/2009-01/2010 (Gersonde, 2011, doi:10.2312/BzPM_0632_2011). The original lithogenic dust provenance signal was extracted from a total of 108 samples (incl. 13 full replicates) between 0.03 and 9.93 m core depth covering the period from ~8,000 to ~260,000 years before present. The age model is from van der Does et al. (2021, doi:10.1016/j.quascirev.2021.106978). The source apportionment was calculated using PS75/056-1 dust fraction radiogenic isotope compositions (doi:10.1594/PANGAEA.947018) and the Bayesian mixing model MixSIAR (Longman et al, 2018, doi:10.1038/s41598-018-24474-0; Stock et al., 2018, doi:10.7717/peerj.5096). Mean values of dust grain size reported together with the source apportionment results were previously published by van der Does et al. (2021, doi:10.1016/j.quascirev.2021.106978)). Iron (Fe) and Fe(II) flux data for PS75/056-1 (Shoenfelt et al., 2018, doi:10.1073/pnas.1809755115) were interpolated linearly to obtain values for the depths sampled for dust provenance work. The source-specific fluxes were calculated based on the relative contributions of the individual dust source regions to the total Fe input.
    Keywords: Adopted from van der Does et al. (2021); AGE; ANT-XXVI/2; Calculated; Comment; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Dust, aeolian; Dust provenance; Grain size, mean; Gravity corer (Kiel type); interpolated; Iron, flux; Iron fluxes; Iron II, flux; Polarstern; PS75/056-1; PS75 BIPOMAC; Radiogenic isotopes; Rare earth elemets; Sample comment; Sample ID; SL; Southern Hemisphere Westerly Winds; Southern Ocean; South Pacific Ocean
    Type: Dataset
    Format: text/tab-separated-values, 2675 data points
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    DATA PANGAEA
  • 10
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    (Fig. 2) Iron content of sediment core PS75/076-2 (2014)
    PANGAEA
    Details
    Publication Date: 2023-10-19
    Keywords: AGE; ANT-XXVI/2; AWI_Paleo; DEPTH, sediment/rock; Iron; KL; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Piston corer (BGR type); Polarstern; PS75/076-2; PS75 BIPOMAC; South Pacific Ocean; X-ray fluorescence core scanner (XRF), AWI
    Type: Dataset
    Format: text/tab-separated-values, 2560 data points
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    DATA PANGAEA
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