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1,119 results on '"Garbe‐Schönberg, Dieter"'

3. Native sulfur at the seafloor: Composition and origin

Author

Dekov, Vesselin M., Koschinsky, Andrea, Yamanaka, Toshiro, Petersen, Sven, Paul, Sophie A.L., Kleint, Charlotte, Pelleter, Ewan, de Lange, Gert J., Kürzinger, Victoria, Garbe-Schönberg, Dieter, Ilieva, Monika, Fouquet, Yves, and Rouxel, Olivier

Published
2024
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18. Incorporation of Dissolved Heavy Metals Into the Skeleton of Porites Corals Based on Multi‐Element Culturing Experiments.

Author

Schmidt, Sarina, Hathorne, Ed C., Schönfeld, Joachim, Gosnell, Kathleen J., and Garbe‐Schönberg, Dieter

Subjects
SCLERACTINIA, HEAVY metals, CORAL colonies, COPPER, PORITES, ECOLOGICAL risk assessment, TRACE elements in water
Abstract

Anthropogenic activities increase the level of dissolved heavy metals in some tropical near‐shore environments threatening reef ecosystems. The skeleton of stony corals like Porites species potentially provides a high‐resolution geochemical archive for past heavy metal concentrations, with potentially century long records revealing baseline values before large‐scale human disturbance. However, few data exist for heavy metal partitioning into coral skeleton aragonite. To address this, culturing experiments exposing Porites lobata and Porites lichen to a mixture of dissolved Cr, Mn, Ni, Cu, Zn, Ag, Cd, Sn, Hg, and Pb over a wide concentration range have been performed. Water samples were taken frequently to monitor changes in the heavy metal concentration. Laser ablation ICP‐MS measurements of the coral aragonite revealed metal concentrations that were positively correlated with Cr, Mn, Ni, Zn, Ag, Cd, and Pb concentrations in seawater. The DTE values for most metals appear dependent on the seawater metal content, approximating a power law, and therefore stabilize at higher seawater metal/Ca ratios. The partitioning of Pb into the coral skeleton is a notable exception, with DPb being stable around 2 to 1 across a large range of "natural" to highly polluted seawater Pb concentrations. This and the general agreement with partition coefficients estimated by previous work suggests that the reconstruction of the heavy metal concentration in seawater for ecosystem monitoring is possible. However, the high variability within and between coral colonies requires further study and suggests that multiple records from multiple coral colonies should be combined to obtain robust reconstructions. Key Points: Porites corals grow normally with increased exposure to multiple metals over >1 yearSkeletal partitioning variable within and between colonies and with seawater metal contentGood agreement with previous work, especially for Pb across a large range of metal content [ABSTRACT FROM AUTHOR]

Published
2024
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22. A sub-fossil coral Sr/Ca record documents meridional variability of the Intertropical Convergence Zone in the eastern Indian Ocean

Author

Pfeiffer, Miriam, primary, Takayanagi, Hideko, additional, Reuning, Lars, additional, Watanabe, Takaaki Konabe, additional, Ito, Saori, additional, Garbe-Schönberg, Dieter, additional, Watanabe, Tsuyoshi, additional, Wu, Chung-Che, additional, Shen, Chuan-Chou, additional, Zinke, Jens, additional, Brummer, Geert-Jan, additional, and Cahyarini, Sri Yudawati, additional

Published
2024
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23. Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean

Author

Lebrato, Mario, Garbe-Schönberg, Dieter, Müller, Marius N., Blanco-Ameijeiras, Sonia, Feely, Richard A., Lorenzonie, Laura, Molinero, Juan-Carlos, Bremer, Karen, Jones, Daniel O. B., Iglesias-Rodriguez, Debora, Greeley, Dana, Lamare, Miles D., Paulmier, Aurelien, Graco, Michelle, Cartes, Joan, e Ramosl, Joana Barcelos, de Lara, Ana, Sanchez-Leal, Ricardo, Jimenez, Paz, Paparazzo, Flavio E., Hartman, Susan E., Westernströer, Ulrike, Küter, Marie, Benavides, Roberto, da Silva, Armindo F., Bell, Steven, Payne, Chris, Olafsdottir, Solveig, Robinson, Kelly, Jantunen, Liisa M., Korablev, Alexander, Webster, Richard J., Jones, Elizabeth M., Gilg, Olivier, du Bois, Pascal Bailly, Beldowskia, Jacek, Ashjianb, Carin, Yahia, Nejib D., Twining, Benjamin, Chen, Xue-Gang, Tseng, Li-Chun, Hwang, Jiang-Shiou, Dahms, Hans-Uwe, and Oschlies, Andreas

Published
2020

30. Middle-Late Miocene to Pleistocene post-collisional magmatism in the Arabia-Eurasia collision zone, an example from northwest Iran

Author

Moghadam, Hadi Shafaii, primary, Hoernle, Kaj A, additional, Hauff, Folkmar, additional, Chiaradia, Massimo, additional, Garbe-Schönberg, Dieter, additional, Orozco-Esquivel, Teresa, additional, Bindeman, Ilya N, additional, Karsli, Orhan, additional, Ghorbani, Ghasem, additional, Mousavi, Naeim, additional, and Lucci, Federico, additional

Published
2023
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40. A sub-fossil coral Sr/Ca record documents meridional variability of the Intertropical Convergence Zone in the eastern Indian Ocean.

Author

Pfeiffer, Miriam, Takayanagi, Hideko, Reuning, Lars, Watanabe, Takaaki Konabe, Ito, Saori, Garbe-Schönberg, Dieter, Watanabe, Tsuyoshi, Wu, Chung-Che, Shen, Chuan-Chou, Zinke, Jens, Brummer, Geert-Jan, and Cahyarini, Sri Yudawati

Abstract

Sea surface temperature (SST) variability in the south-eastern tropical Indian Ocean is crucial for rainfall variability in Indian Ocean rim countries. A large body of literature has focused on zonal variability associated with the Indian Ocean Dipole (IOD), but it is unclear whether meridional shifts in the position of the Intertropical Convergence Zone (ITCZ), which at present co-vary with the IOD, may also occur independently. We have developed a new, monthly resolved Sr/Ca record from a sub-fossil coral cored at Enggano Island (Indonesia, 5° S, 102° E). Core sections containing diagenetic phases are omitted from the SST reconstruction. U/Th dating shows that the Sr/Ca-based SST record extends from 1917–1868 and from 1861–1823 with a relative age uncertainty of ±2.4 years (2σ). At Enggano Island, coastal upwelling and cooling in austral spring is coupled to the position of the ITCZ, and impacts SST seasonality. The sub-fossil coral indicates an increase in SST seasonality due to enhanced austral spring cooling between 1917 and 1855, which we attribute to stronger SE winds and a northward shift in the position of the ITCZ in austral spring. A nearby sediment core indicates SST cooling and a shallowing of the thermocline prior to ~1930. These results are consistent with an increase in the North-South SST gradient in the eastern Indian Ocean calculated from historical temperature data, that is not seen in the zonal SST gradient. We conclude that the relationship between meridional and zonal variability in the eastern Indian Ocean is non-stationary and influenced by long-term temperature trends. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Deep hydrous mantle reservoir provides evidence for crustal recycling before 3.3 billion years ago

Author

Sobolev, Alexander V., Asafov, Evgeny V., Gurenko, Andrey A., Arndt, Nicholas T., Batanova, Valentina G., Portnyagin, Maxim V., and Garbe-Schönberg, Dieter

Subjects
Hydrogeology -- Research, Geological research, Earth -- Crust, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Water strongly influences the physical properties of the mantle and enhances its ability to melt or convect. Its presence can also be used to trace recycling of surface reservoirs down to the deep mantle.sup.1, which makes knowledge of the water content in the Earth's interior and its evolution crucial for understanding global geodynamics. Komatiites (MgO-rich ultramafic magmas) result from a high degree of mantle melting at high pressures.sup.2 and thus are excellent probes of the chemical composition and water contents of the deep mantle. An excess of water over elements that show similar geochemical behaviour during mantle melting (for example, cerium) was recently found in melt inclusions in the most magnesium-rich olivine in 2.7-billion-year-old komatiites from Canada.sup.3 and Zimbabwe.sup.4. These data were taken as evidence for a deep hydrated mantle reservoir, probably the transition zone, in the Neoarchaean era (2.8 to 2.5 billion years ago). Here we confirm the mantle source of this water by measuring deuterium-to-hydrogen ratios in these melt inclusions and present similar data for 3.3-billion-year-old komatiites from the Barberton greenstone belt. From the hydrogen isotope ratios, we show that the mantle sources of these melts contained excess water, which implies that a deep hydrous mantle reservoir has been present in the Earth's interior since at least the Palaeoarchaean era (3.6 to 3.2 billion years ago). The reconstructed initial hydrogen isotope composition of komatiites is more depleted in deuterium than surface reservoirs or typical mantle but resembles that of oceanic crust that was initially altered by seawater and then dehydrated during subduction. Together with an excess of chlorine and depletion of lead in the mantle sources of komatiites, these results indicate that seawater-altered lithosphere recycling into the deep mantle, arguably by subduction, started before 3.3 billion years ago. Hydrogen isotopes and compositions of melt inclusions in olivine in komatiites indicate a hydrous source produced by recycling of seawater-altered crust into the deep mantle over 3.3 billion years ago., Author(s): Alexander V. Sobolev [sup.1] [sup.2] , Evgeny V. Asafov [sup.2] , Andrey A. Gurenko [sup.3] , Nicholas T. Arndt [sup.1] , Valentina G. Batanova [sup.1] [sup.2] , Maxim V. [...]

Published
2019
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