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  • 1
    Publication Date: 2019-02-01
    Description: Brachiopod shells are the most widely used geological archive for the reconstruction of the temperature and the oxygen isotope composition of Phanerozoic seawater. However, it is not conclusive whether brachiopods precipitate their shells in thermodynamic equilibrium. In this study, we investigated the potential impact of kinetic controls on the isotope composition of modern brachiopods by measuring the oxygen and clumped isotope compositions of their shells. Our results show that clumped and oxygen isotope compositions depart from thermodynamic equilibrium due to growth rate-induced kinetic effects. These departures are in line with incomplete hydration and hydroxylation of dissolved CO2. These findings imply that the determination of taxon-specific growth rates alongside clumped and bulk oxygen isotope analyses is essential to ensure accurate estimates of past ocean temperatures and seawater oxygen isotope compositions from brachiopods.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 2
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    In:  Földtani Közlöny, 147 (2). pp. 177-194.
    Publication Date: 2019-02-01
    Description: Clumped isotope geochemistry is a new, dynamically developing field of research, which is based on the temperature-dependent clumping of the 13C and 18O isotopes within one molecule. Using the clumped isotope thermometer, the temperature of the carbonate precipitating fluids can be determined with high precision, based on solely the clumped isotope value (∆47) of carbonates. Besides palaeoclimatology, the method can be used in several research fields in geology, including palaeoceanography, atmospheric research, reservoir geology, geomorphology, structural geology, diagenesis, biogeochemistry, low temperature metamorphic processes, meteorite research, etc. Due to continuous developments, the number of applications is still significantly increasing. This paper briefly introduces the reader to the principles of clumped isotope geochemistry, reviewing its theoretical basis, its possible applications, available calibrations and reviews the current state of the art.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 3
    Publication Date: 2019-02-01
    Description: Results of clumped isotope, oxygen isotope and elemental (Mg/Ca, Sr/Ca) analyses of exceptionally well-preserved belemnite rostra and ammonite shells from the uppermost Callovian–Upper Kimmeridgian (Lamberti–Mutabilis zones) of the Russian Platform are presented. Despite a significant decrease in belemnite δ18O values across the Upper Oxfordian–Lower Kimmeridgian, the clumped isotope data show a constant seawater temperature (ca. 16 °C) in the studied interval. The decrease in belemnite δ18O values and lower δ18O values measured from ammonite shells are interpreted as a result of the salinity decline of the Middle Russian Sea of ca. 12‰, and salinity stratification of the water column, respectively. The postulated secular palaeoenvironmental changes are linked to the inflow of subtropical, saline waters from the Tethys Ocean during a sea-level highstand at the Middle–Late Jurassic transition, and progressive isolation and freshening of the Middle Russian Sea during the Late Oxfordian–Kimmeridgian. The obtained clumped isotope data demonstrate relative stability of the Late Jurassic climate and a paramount effect of local palaeoceanographic conditions on carbonate δ18O record of shallow epeiric seas belonging to the Subboreal Province. Variations in Mg/Ca and Sr/Ca ratios of cylindroteuthid belemnite rostra, which are regarded by some authors as temperature proxies, are, in turn, interpreted to be primarily dependent on global changes in seawater chemistry. The paleoenvironmental variations deduced from clumped and oxygen isotope records of the Russian Platform correspond well with changes in local cephalopod and microfossil faunas, which show increasing provincialism during the Late Oxfordian and the Early Kimmeridgian. Based on the review of literature data it is suggested that the observed salinity decrease and restriction of Subboreal basins during the Late Jurassic played a major role in the formation of periodic bottom water anoxia and sedimentation of organic rich facies.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 4
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    PANGAEA
    In:  Supplement to: Bajnai, David; Pálfy, József; Martinez, Mathieu; Price, Gregory D; Nyerges, Anita; Fözy, István (2017): Multi-proxy record of orbital-scale changes in climate and sedimentation during the Weissert Event in the Valanginian Bersek Marl Formation (Gerecse Mts., Hungary). Cretaceous Research, 75, 45-60, https://doi.org/10.1016/j.cretres.2017.02.021
    Publication Date: 2019-09-09
    Description: The Valanginian positive carbon isotope excursion and associated environmental changes, known as the Weissert Event, is the first in the series of Cretaceous Earth system perturbations. Here, we develop a multiproxy cyclostratigraphy from a 31.2-m-thick Upper Valanginian to lowermost Hauterivian section of the Bersek Marl Formation in Gerecse Mountains, Hungary, comprising alternating marlstone layers of varying clay and carbonate content. The bulk carbonate d13C signal shows sustained, elevated values (up to 2.7 per mil) up to 19.2 m, followed by a decreasing trend upsection. Together with biostratigraphic data, this suggests that the lower part of the section was deposited during the plateau phase of the Valanginian Weissert Event. Spectral analyses of the multiproxy dataset, including magnetic susceptibility measurements and gamma-ray spectroscopy on the lower part of the section led to the identification of precession, obliquity, long and short eccentricity signals. A mean sedimentation rate of 14 m/Myr was calculated based on astronomical tuning. The cyclicity in the proxy signals reflects dilution cycles by detrital inputs in the basin, which supports the idea that orbitally-forced humid-arid cycles controlled the pelagic alternating sedimentation during the Early Cretaceous throughout the Tethyan area.
    Type: Dataset
    Format: text/tab-separated-values, 1074 data points
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  • 5
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    PANGAEA
    In:  Supplement to: Wierzbowski, Hubert; Bajnai, David; Wacker, Ulrike; Rogov, M A; Fiebig, Jens (2018): Clumped isotope record of salinity variations in the Subboreal Province at the Middle-Late Jurassic transition. Global and Planetary Change, 167, 172-189, https://doi.org/10.1016/j.gloplacha.2018.05.014
    Publication Date: 2019-10-08
    Description: Here, we provide the results of the clumped isotope analyses of 24 biogenic carbonate samples, along with the results of carbonate reference materials (ETH1–4, Carrara, MuStd, Strauss) and equilibrated gases (25 °C and 1000 °C). Carbonate digestion at 90 °C and subsequent CO2 purification was done on an automated line connected to a ThermoFisher MAT 253 isotope ratio mass spectrometer. We present the raw isotope values calculated using both the [Gonfiantini/Santrock] and the [Brand]/IUPAC isotopic parameters. The raw data is projected onto the carbon dioxide equilibrium scale (CDES) using the equilibrated gases and without applying any acid fractionation factor to the final values. The origin of sample material, sample preparation methods, and mass spectrometry procedures are further detailed in the associated files and the linked article: Wierzbowski et al. (2018).
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 6
    Publication Date: 2019-10-08
    Description: Here, we provide the results of the clumped isotope analyses of 24 biogenic carbonate samples, along with the results of carbonate reference materials (ETH1–4, Carrara, MuStd, Strauss) and equilibrated gases (25 °C and 1000 °C). Carbonate digestion at 90 °C and subsequent CO2 purification was done on an automated line connected to a ThermoFisher MAT 253 isotope ratio mass spectrometer. We present the raw isotope values calculated using both the [Gonfiantini/Santrock] and the [Brand]/IUPAC isotopic parameters. The raw data is projected onto the carbon dioxide equilibrium scale using the equilibrated gases and without applying any fractionation factor to the final values. Preparation methods and mass spectrometry analytics are further detailed in the associated files and the linked article.
    Type: Dataset
    Format: application/octet-stream, 785.0 kBytes
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  • 7
    Publication Date: 2019-10-08
    Type: Dataset
    Format: text/tab-separated-values, 20231 data points
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  • 8
    Publication Date: 2019-10-29
    Type: Dataset
    Format: application/octet-stream, 340.0 kBytes
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  • 9
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    PANGAEA
    In:  Supplement to: Vickers, Madeleine L; Bajnai, David; Price, Gregory D; Linckens, Jolien; Fiebig, Jens (2019): Southern high-latitude warmth during the Jurassic-Cretaceous: New evidence from clumped isotope thermometry. Geology, 47(8), 724-728, https://doi.org/10.1130/G46263.1
    Publication Date: 2019-11-06
    Description: Here, we present the results of the clumped isotope measurements of 11 latest Jurassic to Early Cretaceous belemnites from DSDP Site 511, along with the results of carbonate reference materials (ETH1-4, Carrara, MuStd) and equilibrated gases (25 °C and 1000 °C). Carbonate digestion at 90 °C and subsequent CO2 purification was done on an automated line connected to a ThermoFisher MAT 253 isotope ratio mass spectrometer. We present the raw isotope values calculated using both the [Gonfiantini/Santrock] and the [Brand]/IUPAC isotopic parameters. The raw data is projected onto the carbon dioxide equilibrium scale (CDES) using the equilibrated gases and without applying any acid fractionation factor to the final values. The origin of sample material, sample preparation methods, and mass spectrometry procedures are further detailed in the associated files and the linked article: Vickers et al. (2019).
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 10
    Publication Date: 2019-11-06
    Type: Dataset
    Format: text/tab-separated-values, 8110 data points
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