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  • 1
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    Cosmogenic rare gases and 10-Be in a cross section of Knyahinya (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The concentrations of cosmogenic nuclides were studied as a function of shielding on samples from a cross section of the 293 kg main fragment of the L5 chondrite Knyahinya. The stone broke into two nearly symmetrical parts upon its fall in 1866. The planar cross section has diameters between 40 and 55 cm. He, Ne, and Ar were measured on about 20 samples by mass spectrometry and the 10-Be activities on aliquots of 10 selected samples were determined by AMS. The 10-Be data are presented and the abundances of spallogenic nuclides are compared with the model calculations reported by Reedy for spherical L chondrites. The 10-Be production rates in Knyahinya are shown versus the shielding parameter 22-Ne/21-Ne.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst. Workshop on Cosmogenic Nuclides; 1 p
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  • 2
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    Studies on cosmogenic nuclides in meteorites with regard to an application as potential depth indicators (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Measurements of stable and radioactive spallation products in meteorites allow to investigate their histories, especially with respect to the exposure to galactic cosmic ray particles and the pre-atmospheric size of the object. While the concentrations of spallation products lead to the determination of exposure and terrestrial ages, production rate ratios are characteristic for the location of the sample in the meteorite. So, one of the aims of this investigation on meteorites is to obtain depth indicators from suitable pairs of cosmogenic nuclides. Because of the different depth profiles for nuclide productions it is necessary to determine the concentrations of a larger number of spallation products in aliquots of a single small sample. Such same sample measurements of Be-10 and light noble gases were performed on 15 ordinary chondrites (7 H- and 8 L-chondrites. Be-10 was determined by accelerator mass spectrometry and the noble gases were measured by static mass spectrometry. The results are summarized and discussed.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst. Workshop on Cosmogenic Nuclides; 3 p
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  • 3
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    Age of Allan Hills 82102, a meteorite found inside the ice (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The terrestrial age of a meteorite that was recovered from below the surface of Antarctic ice is reported, and it is argued that this represents a measurement of the age of the ice itself. The cosmogenic radionuclides Be-10, C-14, Al-26, Cl-36, and Mn-53 are measured in the meteorite and Be-10 and Cl-36 in the ice. A terrestrial age of 11,000 yr is obtained for the meteorite, which suggests that the snow accumulation area where it fell was only a few tens of km away.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 340; 550-552
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  • 4
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    Cosmic ray records in Antarctic meteorites (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The cosmogenic radionuclides Be(10), Al(26), and Mn(53) and noble gases were determined in more than 28 meteorites from Antarctica by nuclear analytical techniques and static mass spectrometry, respectively. The summarized results are listed. The concentrations of Al(26) and Mn(53) are normalized to the repective main target elements and given in dpm/kg Si sub eq and dpm/kg Fe. The errors stated include statistical as well as systematical errors. For noble gas concentrations estimated errors are 5% and for isotopic ratios 1.5%. Cosmic ray exposure ages T sub 21 were calculated by the noble gas concentrations and the terrestrial residence time (T) on the basis of the spallogenic nuclide Al(26). The suggested pairing of the LL6 chondrite RKPA 80238 and RKPA 80248 and the eucrites ALHA 76005 and ALHA 79017 is confirmed not only by the noble gas data but also by the concentrations of the spallation produced radionuclides. Futhermore, ALHA 80122, clasified as an H6 chondrite, has a noble gas pattern which suggest that this meteorite belongs to the ALHA 80111 shower.
    Keywords: SPACE RADIATION
    Type: Lunar and Planetary Inst. International Workshop on Antarctic Meteorites; p 55-57
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  • 5
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    Determination of depositional Beryllium-10 fluxesin the area of the Laptev Sea and Beryllium-10 concentrations in water samples of high northern latitudes (1999)
    Springer
    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 516-532. ISBN 3-540-65676-6
    Details
    Publication Date: 2015-04-08
    Type: Book chapter , NonPeerReviewed
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  • 6
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    Similar glacial and interglacial export bioproductivity in the Atlantic sector of the Southern Ocean: Multiproxy evidence and implications for atmospheric CO2 (2000)
    AGU (American Geophysical Union)
    In:  Paleoceanography, 15 . pp. 642-658.
    Details
    Publication Date: 2019-07-02
    Description: We present time series of export productivity proxy data including 230Thex-normalized deposition rates (rain rates) of 10Be, dissolution-corrected biogenic Ba, and biogenic opal as well as authigenic U concentrations which are complemented by rain rates of total (detrital) Fe and sea ice indicating diatom abundances from five sediment cores across the Atlantic sector of the Southern Ocean covering the past 150,000 years. The results suggest that 10Be rain rates and authigenic U concentration cannot serve as quantitative paleoproductivity proxies because they have also been influenced by detrital particle fluxes in the case of 10Be and bulk sedimentation rates (sediment focussing) and deep water oxygenation in the case of U. The combined results of the remaining productivity proxies of this study (rain rates of biogenic opal and biogenic Ba in those sections without authigenic U) and other previously published proxy data from the Southern Ocean (231Pa/230Th and nitrogen isotopes) suggest that a combination of sea ice cover, shallow remineralization depth, and stratification of the glacial water column south of the present position of the Antarctic Polar Front and possibly Fe fertilization north of it have been the main controlling factors of export paleoproductivity in the Southern Ocean over the last 150,000 years. An overall glacial increase of export paleoproductivity is not supported by the data, implying that bioproductivity variations in the Southern Ocean are unlikely to have contributed to the major glacial atmospheric CO2 drawdown observed in ice cores.
    Type: Article , PeerReviewed
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  • 7
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    Measurement of carrier-free 10Be samples with AMS: the method and its potential (2004)
    Elsevier
    In:  Nuclear Instruments & Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 223-224 . pp. 247-252.
    Details
    Publication Date: 2017-02-13
    Description: A method for direct measurement of the natural 10Be/9Be ratio in a sample by AMS is presented. Samples of 100 ng of Be with 10Be concentrations orders of magnitude higher than in conventional 10Be AMS samples were produced without the addition of 9Be carrier and analysed using the accelerator secondary ion mass spectrometry (Accelerator SIMS) source of the PSI/ETH AMS facility. Special mounting techniques and the analysis procedure using a focussed Cs+ beam of up to 600 nA and beam spot diameter of 100 μm are described. The results of measurements on two test samples from Pacific ferromanganese crust D11–1 are presented and compared with similar measurements by conventional secondary ion mass spectrometry (SIMS). Background measurements at a level of ∼5 × 10−11 indicate that ratios of a few times 10−10 could be measured to a precision of ∼10%. PACS 29.17.+w; 29.30.−h; 82.80.Ms; 89.60.+x
    Type: Article , PeerReviewed
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  • 8
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    High Resolution 10Be and 230Th Profiles in DSDP Site 580 (1987)
    North-Holland
    In:  Nuclear Instruments & Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 29 . pp. 326-331.
    Details
    Publication Date: 2017-02-13
    Description: 10Be and 230Th profiles were measured at Site 580 at a depth of 20 m (230Th and 10Be) and 80 m (10Be), corresponding to 360 ka and 1.5 Ma, respectively, with a resolution of approx. 5000 a. The radiometric sediment accumulation rates of 6.2 cmka ( ± 25%) agree well with the average for the last 730 ka (via paleomagnetic stratigraphy). Age corrected concentrations of 10Be range from 2 to 7 × 109atomsg (average 3.5 ± 1). The variations of the 10Be concentrations can be explained by changes in the sediment supply during different climatic conditions. The maxima and the minima of 10Be follow the fluctuations of excess 230Th in the core section during the last 360 ka. Fluxes of both 10Be and 230Th exceed production and vary remarkably throughout time suggesting enhanced scavenging by bioproductivity. At the Brunhess-Matuyama boundary we observe a maximum of 10Be (6.0 ± 0.3.109atomsg, corresponding to 2.5 σ deviation from the average value). However, the observed large fluctuations of Be-10 throughout the core profile make it difficult to interprete this particular maximum.
    Type: Article , PeerReviewed
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  • 9
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    230 THORIUM AND 10 BERYLLIUM STRATIGRAPHY OF TWO SEDIMENT CORES FROM THE ARCTIC SEA (1992)
    In:  [Talk] In: 4. International Conference on Paleoceanography (ICP IV), 21.09.-25.09.1992, Kiel .
    Details
    Publication Date: 2014-05-26
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 10
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    The manganese nodules of the Kane Gap (East Atlantic). Indicators of sedimentation — erosion changes (1989)
    Springer
    In:  Geologische Rundschau, 78 (3). pp. 943-958.
    Details
    Publication Date: 2019-02-01
    Description: Manganese nodules from the Kane Gap (a deep sea channel connecting the Sierra Leone and Gambia Basins off West Africa) were investigated chemically and dated by10Be along cross-sections. Comparing the nodule structure with the stratigraphy of the related sediments, the following conclusions are drawn concerning the sedimentation processes during the last 4 to 6×106 years: The growth of the nodules started about 4 to 4.5 Ma before present during or near to the end of a period of erosion on a fossil-free, probably Miocene sediment. During the first phase of only a few hundred thousandyears, the nodules grew very quickly (7 to 〉18 mm/Ma). Fe-rich hydrogenetic material formed the internal sections of the nodules during this time. Slowing down of the bottom currents, resulting in deposition of thin sediment covers for short intervals, caused the character of the nodules to change to a more diagenetic composition. The growth rates were reduced to about 1 to 2 mm/Ma. The time of slowing is roughly 3 to 4 Ma BP. Probable uncertainties of the dating and growth rates resulting from supposed changes of the10Be supply to the nodules due to variations of the near bottom environment are discussed.
    Type: Article , PeerReviewed
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