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  • 1
    Publication Date: 2019-02-06
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 2
    Publication Date: 2019-03-04
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  • 3
    Publication Date: 2019-02-26
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  • 4
    Publication Date: 2019-03-04
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  • 5
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    In:  [Poster] In: 16. SINA Meeting 2018, Stable Isotopes Network Austria, 22.-23.11.2018, Graz, Austria .
    Publication Date: 2019-03-06
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  • 6
    Publication Date: 2019-02-28
    Description: The Phanerozoic Eon marks the beginning of the biogenic carbonate fossil record providing information about the evolution of life, the land-ocean interaction and long term climate change. The varying chemical composition of Phanerozoic seawater also contributed to the extinction of many marine species during minor and in particular the largest five mass-extinction events. Proxy information necessary to extract quantitative information is gained mainly from major and trace element ratios as well as isotopic compositions in shells and tests of calcifying organisms like brachiopods, belemnites, bivalves, corals, foraminifera and others. However, the quality and reliability of these Phanerozoic records critically depends on the ability to recover original signals which have been in thermodynamic equilibrium with the surrounding Phanerozoic seawater. This goal cannot simply be achieved because species dependent vital effects and time dependent chemical alteration among other processes superimpose the original water signal to a certain extend making time series of trace element and isotope signals difficult to interpret. Therefore the improvement of existing and the development of new technical approaches and methods are highly desirable to improve and refine our existing knowledge on the history of the chemical composition of Phanerozoic seawater. Similar important are laboratory based culturing experiments in order to decipher the pathways and processes of trace elements from seawater to the site of calcification. In this regard we invite contributions about new and refined data and/or model based information about trace element and isotope compositions and cycling in Phanerozoic seawater. A special focus is on the marine biogeochemistry around the big five mass extension events and other important transitions characterizing changing in seawater composition. Welcome are also culturing studies on those calcifying organisms serving as archives for Phanerozoic seawater proxies. Furthermore, contributions emphasizing diagenetic processes or contributions introducing improved analytical techniques and methods for a better reconstruction of Phanerozoic seawater data are also highly welcome.
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  • 7
    Publication Date: 2019-02-28
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  • 8
    Publication Date: 2019-03-04
    Description: The boron isotope (δ11B) composition of marine calcifiers is considered to be one of the most reliable pH proxies, enabling us to reconstruct past ocean pH and infer on the associated changes in carbon budget involved (e.g. Gut- jahr et al. 2017). The application of the commonly used δ 11 B archives such as foraminifera or corals is however mostly limited to the Cenozoic due to insufficient preservation or incomplete geological records. Brachiopods have a promising potential for extending our knowledge on seawater pH evolution throughout the entire Phanerozoic considering their high abundance in the fossil record and its origin dating back to the early Cambrian. Moreover, their shell is composed of low-magnesium calcite, rendering brachiopods more resistant to post-depositional di-magenetic alteration of its primary chemical signal (e.g. Brand et al. 2012). Additionally, even today they present an extant and widespread taxa, allowing for an assessment of the controls on boron isotope incorporation into brachiopod calcite and possible distortions of the signal due to vital effects or other processes. We present a detailed exploration of boron isotope systematics in three different brachiopod species (Magellania venosa, Terebratella dorsata, Pajaudina atlantica) cultured under controlled laboratory settings for over a year. Our experimental setup includes a control (pH = 8.15) and two pH treatments (pH = 7.6 and 7.35), and we provide both bulk MC-ICP-MS as well as high spatial resolution SIMS data of the shell material. Our results indicate that boron incorporation is primarily driven by vital effects related to their ability to regulate calcifying fluid pH in response to ambient changes, which we further validate by in vivo microelectrode measurements (e.g. Stumpp et al. 2012). Despite internal buffering, the local pH at calcification sites systematically decreases with seawater pH, and hence is impacted by ocean acidification. This not only suggests that brachiopod shells serve as useful and conservative recorders of past ocean pH trends, but also provides new insights into mechanisms that may have enabled brachiopod survival throughout several major environmental crises in the past. Our findings have implications for past climate studies, as well as research on calcification processes and physio- logical adaptations to environmental change (e.g. the actual global ocean acidification). Brand, U., Posenato, R., Came, R., Affek, H., Angiolini, L., Azmy, K. and Farabegoli, E., 2012. The end-Permian mass extinction: A rapid volcanic CO2 and CH4-climatic catastrophe, Chem. Geol. 323, 121-144. Gutjahr M., Ridgewell A., Sexton P.F., Anagnostou E., Pearson P.N., Pälike H., Norris R.D., Thomas E., and Foster G.L., 2017. Very large release of mostly volcanic carbon during the Palaeocene-Eocene Thermal Maximum, Nature 548, 573-577. Stumpp M., Hu M.Y., Melzner F., Gutowska M., Dorey N., Himmerkus N., Holtmann W.C., Dupont S.T., Thorndyke M.C., and Bleich M. Acidified seawater impacts sea urchin larvae pH regulatory systems relevant for calcification, PNAS 44: 18192-18197.
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  • 9
    Publication Date: 2019-03-04
    Description: The boron isotope composition (commonly expressed as δ11B) of marine calcium carbonate is one of the most reliable pH proxies (e.g. Vengosh et al., 1991; Hemming and Hanson, 1992). In this context, brachiopods are a potential archive due to their great abundance in the geological record and their low-magnesium calcite shells that make them more resistant to diagenetic alteration (e.g. Lowenstam, 1961; Veizer et al., 1986). This study focuses on the impact of brachiopod shell biomineralization processes on the boron isotopic and elemental (B/Ca) compositions. Boron isotope analyses were performed at the micrometer scale by ion microprobe, and by laser ablation (LA) coupled to a MC-ICP-MS to create 2D images, while B/Ca was determined using LA-ICP-MS in shells of five modern brachiopods species composed of primary (PL) and secondary layer (SL) (Terebratalia transversa, Magasella sanguinea, Notosaria nigricans, Calloria inconspicua and Magellania venosa) and one species composed also with tertiary layer (TL) (Liothyrella neozelanica). Our results show that the PL is slightly depleted in 11B relative to the SL and higher in B/Ca. The SL layer does not show a specific trend of δ11B from the outermost to the innermost shell thickness. B/Ca ratio goes towards lower values in the innermost regions of the shell likely due to kinetic effects, as less boron is incorporated as growth rates slow. Values obtained here are similar to those previously published (Lécuyer et al., 2002; Penman et al., 2013). Regarding the TL, B/Ca values are lower than in PL and SL. We will further explore the mechanisms responsible for such differences in δ11B and B/Ca values between the different shell layers and its potential use as palaeo-pH proxy. Hemming, N., Hanson, G., 1992. Boron isotopic composition and concentration in modern marine carbonates. Geochim. Cosmochim. Acta 56, 537-543. Lécuyer, C., Grandjean, P., Reynard, B., Albarède, F., Telouk, P., 2002. 11B/10B analysis of geological materials by ICP-MS Plasma 54: application to the boron fractionation between brachiopod calcite and seawater. Chem. Geol. 186 (1-2), 45-55. Lowenstam, H.A., 1961. Mineralogy, O-18/O-16 ratios, and strontium and magnesium contents of recent and fossil brachiopods and their bearing on the history of the oceans. J. Geol. 69, 241-260. Penman, D.E., Hönisch B., Rasbury E.T. Hemming, N.G., Howard J.S, 2013. Boron, carbon, and oxygen isotopic composition of brachiopod shells: Intra-shell variability, controls, and potential as a paleo-pH recorder. Chem. Geol. 340, 32-39. Veizer, J., Fritz, P., Jones, B., 1986. Geochemistry of brachiopods: oxygen and carbon isotopic records of Paleozoic oceans. Geochim. Cosmochim. Acta 50, 1679-1696. Vengosh, A., Kolodny, Y., Starinsky, A., Chivas, A.R., McCulloch, M.T., 1991. Co- precipitation and isotopic fractionation of boron in modern biogenic carbonates. Geochim. Cosmochim. Acta 55, 2901-2910.
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  • 10
    Publication Date: 2019-02-05
    Description: The Phanerozoic Eon marks the beginning of the biogenic carbonate fossil record providing information about the evolution of life, the land-ocean interaction and long term climate change. The varying chemical composition of Phanerozoic seawater also contributed to the extinction of many marine species during minor and in particular the largest five mass-extinction events. Proxy information necessary to extract quantitative information is gained mainly from major and trace element ratios as well as isotopic compositions in shells and tests of calcifying organisms like brachiopods, belemnites, bivalves, corals, foraminifera and others. However, the quality and reliability of these Phanerozoic records critically depends on the ability to recover original signals which have been in thermodynamic equilibrium with the surrounding Phanerozoic seawater. This goal cannot simply be achieved because species dependent vital effects and time dependent chemical alteration among other processes superimpose the original water signal to a certain extend making time series of trace element and isotope signals difficult to interpret. Therefore the improvement of existing and the development of new technical approaches and methods are highly desirable to improve and refine our existing knowledge on the history of the chemical composition of Phanerozoic seawater. Similar important are laboratory based culturing experiments in order to decipher the pathways and processes of trace elements from seawater to the site of calcification. In this regard we invite contributions about new and refined data and/or model based information about trace element and isotope compositions and cycling in Phanerozoic seawater. A special focus is on the marine biogeochemistry around the big five mass extension events and other important transitions characterizing changing in seawater composition. Welcome are also culturing studies on those calcifying organisms serving as archives for Phanerozoic seawater proxies. Furthermore, contributions emphasizing diagenetic processes or contributions introducing improved analytical techniques and methods for a better reconstruction of Phanerozoic seawater data are also highly welcome.
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