GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    In: Radiocarbon, Tucson, Ariz. : Dept., 1959, 50(2008), 1, Seite 99-118, 0033-8222
    In: volume:50
    In: year:2008
    In: number:1
    In: pages:99-118
    Description / Table of Contents: Accelerator mass spectrometry (AMS) radiocarbon dating of ostracod and gastropod shells from the southwestern Black Sea cores combined with tephrochronology provides the basis for studying reservoir age changes in the lateglacial Black Sea. The comparison of our data with records from the northwestern Black Sea shows that an apparent reservoir age of ~1450 14C yr found in the glacial is characteristic of a homogenized water column. This apparent reservoir age is most likely due to the hardwater effect. Though data indicate that a reservoir age of ~1450 14C yr may have persisted until the Bølling-Allerød warm period, a comparison with the GISP2 ice-core record suggests a gradual reduction of the reservoir age to ~1000 14C yr, which might have been caused by dilution effects of inflowing meltwater. During the Bølling-Allerød warm period, soil development and increased vegetation cover in the catchment area of the Black Sea could have hampered erosion of carbonate bedrock, and hence diminished contamination by oldʺ carbon brought to the Black Sea basin by rivers. A further reduction of the reservoir age most probably occurred contemporary to the precipitation of inorganic carbonates triggered by increased phytoplankton activity, and was confined to the upper water column. Intensified deep water formation subsequently enhanced the mixing/convection and renewal of intermediate water. During the Younger Dryas, the age of the upper water column was close to 0 yr, while the intermediate water was ~900 14C yr older. The first inflow of saline Mediterranean water, at ~8300 14C yr BP, shifted the surface water age towards the recent value of ~400 14C yr.
    Type of Medium: Online Resource
    Pages: graph. Darst., Kt
    ISSN: 0033-8222
    Language: English
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1157
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Detailed 14C AMS data and isotope based stratigraphies from high-resolution paleoceanographic records for the last 22 ka of cores from the upper continental slope off NE Brazil reveal sedimentation rates of up to 100 cm per 1000 yr. Variations in the sediment composition relate to changes in the input of terrigenous material. The sedimentation is controlled by sea level and by the climatic regime of the hinterland. Short-term changes in the tropical wind field may act as a climatic trigger. The zonality of the SE trades was probably increased and the monsoonal activity over Africa reduced during the Younger Dryas period.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 6 (1974), S. 651-656 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a calculé les paramètres cinétiques de la décomposition thermique de CaCO3 en suivant la méthode de Coats et Redfern et en utilisant 15 courbes thermogravimétriques publiées dans la littérature. L'énergie d'activation varie entre 26 et 377 kcal/mol, les fac teurs préexponentiels entre 102 et 1069, suivant les conditions opératoires. On a observé l'effet de compensation cinétique et les résultats peuvent être décrits par la loi empirique suivante: logZ=0.195E − 1.86.
    Abstract: Zusammenfassung Fünfzehn, in der Literatur veröffentlichte thermogravimetrische Kurven der thermischen Zersetzung des CaCO3 wurden analysiert und kinetische Parameter unter Anwendung der Methode von Coats und Redfern abgeleitet. Die Aktivierungsenergie schwankt zwischen 26 und 377 kcal/Mol, die prä-exponentiellen Faktoren zwischen 102 und 1069, je nach den Arbeitsbedingungen. Der kinetische Kompensationseffekt wurde beobachtet und die Ergebnisse lassen sich mit dem folgenden empirischen Kompensationsgesetz gut beschreiben: logZ=0.195E− 1.86.
    Notes: Abstract Fifteen thermogravimetric curves of the thermal decomposition of CaCO3 reported in the literature have been analysed and kinetic parameters have been derived by means of Coats and Redfern's method. The activation energy varies between 26 and 377 kcal/mole, and the pre-exponential factors between 102 and 1069, as functions of the working conditions. The kinetic compensation effect has been observed, and the results are well described by the following empirical compensation law: logZ=0.195E− 1.86.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2021-02-08
    Description: Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to 〉100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to 〉30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since ~15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    Unknown
    Department of Geosciences, University of Arizona
    In:  Radiocarbon, 50 (1). pp. 99-118.
    Publication Date: 2016-09-15
    Description: Accelerator mass spectrometry (AMS) radiocarbon dating of ostracod and gastropod shells from the southwestern Black Sea cores combined with tephrochronology provides the basis for studying reservoir age changes in the late-glacial Black Sea. The comparison of our data with records from the northwestern Black Sea shows that an apparent reservoir age of ∼1450 14C yr found in the glacial is characteristic of a homogenized water column. This apparent reservoir age is most likely due to the hardwater effect. Though data indicate that a reservoir age of ∼1450 14C yr may have persisted until the Bølling-Allerød warm period, a comparison with the GISP2 ice-core record suggests a gradual reduction of the reservoir age to ∼1000 14C yr, which might have been caused by dilution effects of inflowing meltwater. During the Bølling-Allerød warm period, soil development and increased vegetation cover in the catchment area of the Black Sea could have hampered erosion of carbonate bedrock, and hence diminished contamination by “old” carbon brought to the Black Sea basin by rivers. A further reduction of the reservoir age most probably occurred contemporary to the precipitation of inorganic carbonates triggered by increased phytoplankton activity, and was confined to the upper water column. Intensified deep water formation subsequently enhanced the mixing/convection and renewal of intermediate water. During the Younger Dryas, the age of the upper water column was close to 0 yr, while the intermediate water was ∼900 14C yr older. The first inflow of saline Mediterranean water, at ∼8300 14C yr BP, shifted the surface water age towards the recent value of ∼400 14C yr.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2015-11-04
    Description: The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through this gateway is,...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2012-02-01
    Description: The supply of nutrients to the low-latitude thermocline is largely controlled by intermediate-depth waters formed at the surface in the high southern latitudes. Silicic acid is an essential macronutrient for diatoms, which are responsible for a significant portion of marine carbon export production. Changes in ocean circulation, such as those observed during the last deglaciation, would influence the nutrient composition of the thermocline and, therefore, the relative abundance of diatoms in the low latitudes. Here we present the first record of the silicic acid content of the Atlantic over the last glacial cycle. Our results show that at intermediate depths of the South Atlantic, the silicic acid concentration was the same at the Last Glacial Maximum (LGM) as it is today, overprinted by high silicic acid pulses that coincided with abrupt changes in ocean and atmospheric circulation during Heinrich Stadials and the Younger Dryas. We suggest these pulses were caused by changes in intermediate water formation resulting from shifts in the subpolar hydrological cycle, with fundamental implications for the nutrient supply to the Atlantic.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...