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Université de Fribourg

Early diagenetic imprint on temperature proxies in holocene corals: a case study from french polynesia

Rashid, Rashid ; Eisenhauer, Anton ; Liebetrau, Volker ; Fietzke, Jan ; Böhm, Florian ; Wall, Marlene ; Krause, Stefan ; Rüggeberg, Andres ; Dullo, Wolf-Christian ; Jurikova, Hana ; Samankassou, Elias ; Lazar, Boaz

In: Frontiers in Earth Science, 2020, vol. 8, p. -

Coral-based reconstructions of sea surface temperatures (SSTs) using Sr/Ca, U/Ca and δ18O ratios are important tools for quantitative analysis of past climate variabilities. However, post-depositional alteration of coral aragonite, particularly early diagenesis, restrict the accuracy of calibrated proxies even on young corals. Considering the diagenetic effects, we present new Mid to Late...

Université de Fribourg

Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit

Stainbank, Stephanie ; Spezzaferri, Silvia ; Boever, Eva De ; Bouvier, Anne-Sophie ; Chilcott, Colin ; Leau, Erica S.de ; Foubert, Anneleen ; Kunkelova, Tereza ; Pichevin, Laetitia ; Raddatz, Jacek ; Rüggeberg, Andres ; D.Wright, James ; M.Yu, Siyao ; Zhang, Manlin ; Kroon, Dick

In: Earth and Planetary Science Letters, 2020, vol. 545, p. 116390

Due to their large heat and moisture storage capabilities, the tropics are fundamental in modulating both regional and global climate. Furthermore, their thermal response during past extreme warming periods, such as super interglacials, is not fully resolved. In this regard, we present high-resolution (analytical) foraminiferal geochemical (δ18O and Mg/Ca) records for the last 1800 kyr from...

Université de Fribourg

Cold-water coral mound archive provides unique insights into intermediate water mass dynamics in the alboran sea during the last deglaciation

Fentimen, Robin ; Feenstra, Eline ; Rüggeberg, Andres ; Vennemann, Torsten ; Hajdas, Irka ; Adatte, Thierry ; Van Rooij, David ; Foubert, Anneleen

In: Frontiers in Marine Science, 2020, vol. 7, p. -

The Alboran Sea is widely recognized to host numerous cold-water coral ecosystems, including the East Melilla Coral Province. Yet, their development through time and response to climatic variability has still to be fully understood. Based on a combined investigation of benthic foraminiferal assemblages, foraminiferal stable isotope compositions, grain size analysis, sediment geochemistry, and...

Université de Fribourg

Ultrafast nonequilibrium evolution of excitonic modes in semiconductors

Murakami, Yuta ; Schüler, Michael ; Takayoshi, Shintaro ; Werner, Philipp

In: Physical Review B, 2020, vol. 101, no. 3, p. 035203

We study the time evolution of excitonic states after photoexcitation in the one- dimensional spinless extended Falicov-Kimball model. Several numerical methods are employed and benchmarked against each other: time-dependent mean-field simulations, the second-Born approximation (2BA) within the Kadanoff-Baym formalism, the generalized Kadanoff-Baym ansatz (GKBA) implemented with the 2BA, and...

Université de Fribourg

Solenosmilia variabilis-bearing cold-water coral mounds off Brazil

Raddatz, J. ; Titschack, J. ; Frank, N. ; Freiwald, A. ; Conforti, A. ; Osborne, A. ; Skornitzke, S. ; Stiller, W. ; Rüggeberg, Andres ; Voigt, Silke ; Albuquerque, A. L. S. ; Vertino, A. ; Schröder-Ritzrau, A. ; Bahr, A.

In: Coral Reefs, 2020, vol. 39, no. 1, p. 69–83

Cold-water corals (CWC), dominantly Desmophyllum pertusum (previously Lophelia pertusa), and their mounds have been in the focus of marine research during the last two decades; however, little is known about the mound-forming capacity of other CWC species. Here, we present new 230Th/U age constraints of the relatively rarely studied framework-building CWC Solenosmilia variabilis from a mound...

Université de Fribourg

Constraining the formation of authigenic carbonates in a seepage-affected cold-water coral mound by lipid biomarkers

Feenstra, Eline Juliette ; Birgel, Daniel ; Heindel, Katrin ; Wehrmann, Laura M. ; Jaramillo‐Vogel, David ; Grobéty, Bernard ; Frank, Norbert ; Hancock, Leanne G. ; Van Rooij, David ; Peckmann, Jörn ; Foubert, Anneleen

In: Geobiology, 2020, vol. 18, no. 2, p. 185–206

Cold‐water coral (CWC) mounds are build‐ups comprised of coral‐dominated intervals alternating with a mixed carbonate‐siliciclastic matrix. At some locations, CWC mounds are influenced by methane seepage, but the impact of methane on CWC mounds is poorly understood. To constrain the potential impact of methane on CWC mound growth, lipid biomarker investigations were combined with...

Université de Fribourg

Environmental and biological controls on Na∕Ca ratios in scleractinian cold-water corals

Schleinkofer, Nicolai ; Raddatz, Jacek ; Freiwald, André ; Evans, David ; Beuck, Lydia ; Rüggeberg, Andres ; Liebetrau, Volker

In: Biogeosciences, 2019, vol. 16, no. 18, p. 3565–3582

Here we present a comprehensive attempt to correlate aragonitic Na∕Ca ratios from Desmophyllum pertusum (formerly known as Lophelia pertusa), Madrepora oculata and a caryophylliid cold-water coral (CWC) species with different seawater parameters such as temperature, salinity and pH. Living CWC specimens were collected from 16 different locations and analyzed for their Na∕Ca ratios using...