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  • 1
    Publication Date: 2023-05-12
    Keywords: Antarctica; Aurora Australis; Campaign; DATE/TIME; DDU2007; DDU2007_StC; Dumont d´Urville Station; Event label; ICE; Ice station; IO-1; IO-10; IO-11; IO-12; IO-13; IO-14; IO-2; IO-3; IO-4; IO-5; IO-6; IO-7; IO-8; IO-9; Latitude of event; Longitude of event; Sample ID; Sample thickness; Sample type; SIPEX; SNOW; Snow/ice sample; South Indian Ocean; Temperature, air; Temperature, ice/snow
    Type: Dataset
    Format: text/tab-separated-values, 181 data points
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  • 2
    Publication Date: 2023-05-12
    Keywords: Alkalinity, total; Ammonium; Antarctica; Aurora Australis; Carbon, organic, dissolved; DATE/TIME; DDU2007; DDU2007_StC; Dumont d´Urville Station; Event label; ICE; Ice station; Ikaite; IO-1; IO-10; IO-11; IO-13; IO-14; IO-2; IO-3; IO-5; IO-6; IO-7; IO-8; IO-9; Latitude of event 2; Longitude of event; Nitrate and Nitrite; Nitrite; Nitrogen, organic, dissolved; Normalized to salinity S = 35; Phosphate; Salinity, brine; Sample ID; Silicon; SIPEX; SNOW; Snow/ice sample; South Indian Ocean; Temperature, brine
    Type: Dataset
    Format: text/tab-separated-values, 184 data points
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  • 3
    Publication Date: 2023-05-12
    Keywords: Antarctica; Aurora Australis; Campaign; DATE/TIME; DDU2007; DDU2007_StC; Depth, bottom/max; DEPTH, ice/snow; Depth, top/min; Dumont d´Urville Station; Event label; ICE; Ice station; Ikaite; IO-1; IO-10; IO-11; IO-12; IO-13; IO-14; IO-2; IO-3; IO-4; IO-5; IO-6; IO-7; IO-8; IO-9; Latitude of event; Longitude of event; Sample ID; Sample type; SIPEX; SNOW; Snow/ice sample; South Indian Ocean
    Type: Dataset
    Format: text/tab-separated-values, 864 data points
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  • 4
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    PANGAEA
    In:  Supplement to: Fischer, Michael; Thomas, David N; Krell, Andreas; Nehrke, Gernot; Göttlicher, Jörg; Norman, Marc D; Meiners, Klaus M; Riaux-Gobin, C; Dieckmann, Gerhard S (2012): Quantification of ikaite in Antarctic sea ice. Antarctic Science, 25(03), 421-432, https://doi.org/10.1017/S0954102012001150
    Publication Date: 2023-10-28
    Description: Calcium carbonate precipitation in sea ice is thought to potentially drive significant CO2 uptake by the ocean. However, little is known about the quantitative spatial and temporal distribution of CaCO3 within sea ice, although it is hypothesized that high quantities of dissolved organic matter and/or phosphate (common in sea ice) may inhibit its formation. In this quantitative study of hydrous calcium carbonate as ikaite, sea ice cores and brine samples were collected from pack and land fast sea ice between September and December 2007 during two expeditions, one in the East Antarctic sector and the other off Terre Adélie. Samples were analysed for CaCO3, salinity, dissolved organic carbon/nitrogen, inorganic phosphate, and total alkalinity. No relationship between these parameters and CaCO3 precipitation was evident. Ikaite was found mostly in the uppermost layers of sea ice with maximum concentrations of up to 126 mg ikaite per litre melted sea ice being measured, although both the temporal and horizontal spatial distributions of ikaite were highly heterogeneous. The precipitate was also found in the snow on top of the sea ice at some of the sampling locations.
    Keywords: Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; SPP1158
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 5
    Publication Date: 2024-01-09
    Description: The mass accumulation rates (MARs) of aeolian dust in the ocean basins provide an important record of climate in the continental source regions of atmospheric dust and of the prevailing wind patterns responsible for dust transport in the geologic past. The incorporation of other terrigenous components such as volcanic ashes in seafloor sediments, however, often obscures the aeolian dust record. We describe a new approach which uses the delivery rate of crustal 4He to seafloor sediments as a proxy for the mass accumulation rate of old continental dust which is unaffected by the addition of other terrigenous components. We have determined the flux of crustal 4He delivered to the seafloor of the Ontong Java Plateau (OJP) in the western equatorial Pacific over the last 1.9 Myrs. Crustal 4He fluxes vary between 7.7 and 30 ncc/cm**2/kyr and show excellent correlation with global climate as recorded by oxygen isotopes, with high crustal 4He fluxes associated with glacial periods over the entire interval studied. Furthermore, the onset of strong 100 kyr glacial-interglacial climate cycling is clearly seen in the 4He flux record about 700 kyrs ago. These data record variations in the supply of Asian dust in response to climate driven changes in the aridity of the Asian dust sources, consistent with earlier work on Asian dust flux to the northern Pacific Ocean. However, in contrast to previous studies of sites in the central and eastern equatorial Pacific Ocean, there is no evidence that the Inter Tropical Convergence Zone (an effective rainfall barrier to the southward transport of northern hemisphere dust across the equator in the central and eastern Pacific) has influenced the delivery of Asian dust to the OJP. The most likely carrier phase for crustal helium in these sediments is zircon, which can reasonably account for all the 4He observed in the samples. As a first order estimate, these results suggest that the mass accumulation rate of Asian dust on the OJP over the last 1.9 Myrs varied from about 4 to 15 mg/ cm**2/kyr. In contrast, previous studies show that over the same interval the total MAR of terrigenous dust (i.e. Asian dust plus local volcanics) on OJP varied between about 34 and 90 mg/ cm**2/kyr.
    Keywords: 130-806B; Accumulation rate, mass; Age model; Calculated; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Helium-4; Helium-4, flux; Joides Resolution; Leg130; Mass spectrometer MAP215-50; North Pacific Ocean; Ocean Drilling Program; ODP; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 504 data points
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  • 6
    Publication Date: 2024-01-09
    Description: The compatibility of vanadium (V) during mantle melting is a function of oxygen fugacity (fO2): at high fO2's, V becomes more incompatible. The prospects and limitations of using the V content of peridotites as a proxy for paleo-fO2 at the time of melt extraction were investigated here by assessing the uncertainties in V measurements and the sensitivity of V as a function of degree of melt extracted and fO2. V-MgO and V-Al2O3 systematics were found to be sensitive to fO2 variations, but consideration of the uncertainties in measurements and model parameters indicates that V is sensitive only to relative fO2 differences greater than ~2 log units. Post-Archean oceanic mantle peridotites, as represented by abyssal peridotites and obducted massif peridotites, have V-MgO and -Al2O3 systematics that can be modeled by 1.5 GPa melting between FMQ - 3 and FMQ - 1. This is consistent with fO2's of the mantle source for mid-ocean ridge basalts (MORBs) as determined by the Fe3+ activity of peridotitic minerals and basaltic glasses. Some arc-related peridotites have slightly lower V for a given degree of melting than oceanic mantle peridotites, and can be modeled by 1.5 GPa melting at fO2's as high as FMQ. However, the majority of arc-related peridotites have V-MgO systematics overlapping that of oceanic mantle peridotites, suggesting that although some arc mantle may melt under slightly oxidizing conditions, most arc mantle does not. The fact that thermobarometrically determined fO2's in arc peridotites and lavas can be significantly higher than that inferred from V systematics, suggests that V retains a record of the fO2 during partial melting, whereas the activity of Fe3+ in arc peridotitic minerals and lavas reflect subsequent metasomatic overprints and magmatic differentiation/emplacement processes, respectively. Peridotites associated with middle to late Archean cratonic mantle are characterized by highly variable V-MgO systematics. Tanzanian cratonic peridotites have V systematics indistinguishable from post-Archean oceanic mantle and can be modeled by 3 GPa partial melting at ~FMQ - 3. In contrast, many South African and Siberian cratonic peridotites have much lower V contents for a given degree of melting, suggesting at first glance that partial melting occurred at high fO2's. More likely, however, their unusually low V contents for a given degree of melting may be artifacts of excess orthopyroxene, a feature that pervades many South African and Siberian peridotites but not the Tanzanian peridotites. This is indicated by the fact that the V contents of South African and Siberian peridotites are correlated with increases in SiO2 content, generating data arrays that cannot be modeled by partial melting but can instead be generated by the addition of orthopyroxene through processes unrelated to primary melt depletion. Correction for orthopyroxene addition suggests that the South African and Siberian peridotites have V-MgO systematics similar to those of Tanzanian peridotites. Thus, if the Tanzanian peridotites represent the original partial melting residues, and if the South African and Siberian peridotites have been modified by orthopyroxene addition, then there is no indication that Archean cratonic mantle formed under fO2's significantly greater than that of modern oceanic mantle. Instead, the fO2's inferred from the V systematics in these three cratonic peridotite suites are within range of modern oceanic mantle. This also suggests that the transition from a highly reducing mantle in equilibrium with a metallic core to the present oxidized state must have occurred by late Archean times.
    Keywords: 153-920; Aluminium oxide; Calcium oxide; Calculated; COMPCORE; Composite Core; DSDP/ODP/IODP sample designation; Iron oxide, FeO; Joides Resolution; Leg153; Magnesium oxide; Manganese oxide; Ocean Drilling Program; ODP; Phosphorus pentoxide; Potassium oxide; Sample code/label; Silicon dioxide; Sodium oxide; South Atlantic Ocean; Sum; Titanium dioxide; Vanadium; X-ray fluorescence (XRF)
    Type: Dataset
    Format: text/tab-separated-values, 78 data points
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  • 7
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Ocean island basalts are generally thought to be the surface expression of mantle plumes, but the nature of the components in the source regions of such mantle plumes is a subject of long-standing debate. The lavas erupted at Hawaii have attracted particular attention, as it has been proposed ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 440 (2006), S. 776-778 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Differences in isotopic abundances between meteorites and rocks on Earth leave unclear the true composition of the gas out of which the Solar System formed. The Sun should have preserved in its outer layers the original composition, and recent work has indicated that the solar wind is enriched ...
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 425 (2003), S. 605-609 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The tectonic setting in which the first continental crust formed, and the extent to which modern processes of arc magmatism at convergent plate margins were operative on the early Earth, are matters of debate. Geochemical studies have shown that felsic rocks in both Archaean high-grade ...
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In the Itsaq Gneiss Complex south of the Isua supracrustal belt (West Greenland) some areas of early Archaean tonalite and quartz-diorite are non-gneissic, free of pegmatite veins, and in rarer cases are undeformed with relict igneous textures and hence were little modified by heterogeneous ductile deformation under amphibolite facies conditions in several Archaean events. Such well-preserved early Archaean rocks are extremely rare. Tonalites are high Al, and have bulk compositions close to experimental liquids. Trace element abundances and modelling suggest that they probably originated as melts derived from basaltic compositions at sufficiently high pressures to require residual garnet + amphibolites ± clinopyroxene in the source. The major element characteristics of the quartz-diorites suggest these were derived from more mafic magmas than the tonalites, and underwent either igneous differentiation or mixing with crustal material. As in modern arc magmas, high relative abundances of Sr, Ba, Pb, and alkali elements cannot be generated simply from a basaltic source formed by large degrees of melting of a depleted mantle. This may indicate an important role for fluids interacting with mafic rocks in generating the earliest preserved continental crust. The high Ba/Th, Ba/Nb, La/Nb and low Nb/Th, Ce/Pb, and Rb/Cs ratios of these tonalites are also observed in modern arc magmas. SHRIMP U-Pb zircon geochronology was undertaken on seven tonalites, one quartz-diorite, a thin pegmatitic vein and a thin diorite dyke. Cathodoluminescence images show the zircon populations of the quartz-diorite and tonalites are dominated by single-component oscillatory-zoned prismatic grains, which gave ages of 3806 ± 5 to 3818 ± 8 Ma (2σ) (quartz-diorite and 5 tonalites) and 3795 ± 3 Ma (1 tonalite). Dating of recrystallised domains cutting oscillatory-zoned zircon indicates disturbance as early as 3800–3780 Ma. There are rare ca. 3600 Ma and 3800–3780 Ma (very high U and low Th/U) ≤ 20 μm wide partial overgrowths on the prismatic grains. Given likely Zr-undersaturation of precursor melts and evidence of zircon recrystallisation and metamorphic regrowth as early as 3800–3780 Ma, the age determinations on the prismatic oscillatory-zoned zircon populations give the igneous crystallisation age of the tonalite and quartz-diorite protoliths. When the coherency of the geochemistry is considered, these samples represent the best preserved suites of ca. 3800 Ma felsic igneous rocks yet documented.
    Type of Medium: Electronic Resource
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