Search results for "palaeoclimate"
showing 10 items of 26 documents
8.2 ka event North Sea hydrography determined by bivalve shell stable isotope geochemistry.
2019
AbstractThe abrupt 8.2 ka cold event has been widely described from Greenland and North Atlantic records. However, its expression in shelf seas is poorly documented, and the temporal resolution of most marine records is inadequate to precisely determine the chronology of major events. A robust hydrographical reconstruction can provide an insight on climatic reaction times to perturbations to the Atlantic Meridional Overturning Circulation. Here we present an annually-resolved temperature and water column stratification reconstruction based on stable isotope geochemistry of Arctica islandica shells from the Fladen Ground (northern North Sea) temporally coherent with Greenland ice core record…
Petrography and carbonate isotope stratigraphy from MIS AND-1B core, Antarctica: Evidence of the early Pliocene warming event
2011
Abstract A large portion of ANDRILL (ANtarctic geological DRILLing) core AND-1B recovered in the Western Ross Sea and spanning the early Pliocene has been investigated in order to obtain a detailed carbonate isotope record from Antarctic margin sediments through the early Pliocene warming event. Petrographic observations and mineralogical analyses reveal the authigenic nature of the carbonate and small proportions of Fe and Mg incorporated within the calcite lattice. High productivity conditions testified by ~ 80 m-thick diatomite interval (383 to 460 mbsf) well fit with the composite nature of the authigenic carbonate generally characterizing organic matter-rich sediments. As is known, sed…
Distribution of clay minerals in Early Jurassic Peritethyan seas: palaeoclimatic significance inferred from multiproxy comparisons.
2009
13 pages; International audience; A set of published, unpublished, and new clay mineral data from 60 European and Mediterranean localities allows us to test the reliability of clay minerals as palaeoclimatic proxies for the Pliensbachian–Toarcian period (Early Jurassic) by reconstructing spatial and temporal variations of detrital fluxes at the ammonite biochronozone resolution. In order to discuss their palaeoclimatic meaning, a compilation of low-latitude belemnite δ18O, δ13C, Mg/Ca, and 87Sr/86Sr values is presented for the first time for the whole Pliensbachian– Toarcian period. Once diagenetic and authigenic biases have been identified and ruled out, kaolinite content variation is cons…
SISALv2: a comprehensive speleothem isotope database with multiple age–depth models
2020
Characterizing the temporal uncertainty in palaeoclimate records is crucial for analysing past climate change, correlating climate events between records, assessing climate periodicities, identifying potential triggers and evaluating climate model simulations. The first global compilation of speleothem isotope records by the SISAL (Speleothem Isotope Synthesis and Analysis) working group showed that age model uncertainties are not systematically reported in the published literature, and these are only available for a limited number of records (ca. 15 %, n = 107/691). To improve the usefulness of the SISAL database, we have (i) improved the database’s spatio-temporal coverage and (ii) create…
Vulnerability of the North Water ecosystem to climate change
2021
High Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, l…
Osmium and lithium isotope evidence for weathering feedbacks linked to orbitally paced organic carbon burial and Silurian glaciations
2022
Abstract The Ordovician (∼487 to 443 Ma) ended with the formation of extensive Southern Hemisphere ice sheets, known as the Hirnantian glaciation, and the second largest mass extinction in Earth History. It was followed by the Silurian (∼443 to 419 Ma), one of the most climatically unstable periods of the Phanerozoic as evidenced by several large scale ( > 5 ‰ ) carbon isotope (δ13C) perturbations associated with further extinction events. Despite several decades of research, the cause of these environmental instabilities remains enigmatic. Here, we provide osmium (187Os/188Os) and lithium (δ7Li) isotope measurements of marine sedimentary rocks that cover four Silurian δ13C excursions. Osmi…
Data for: Evidence of warm and humid interstadials in central Europe during early MIS 3 revealed by a multi-proxy speleothem record
2018
Supplementary data for: Evidence of warm and humid interstadials in central Europe during early MIS 3 revealed by a multi-proxy speleothem record. By Weber, M., Scholz, D., Schröder-Ritzrau, A., Deininger, M., Spötl, C., Lugli, F., Mertz-Kraus, R., Jochum, K.P., Fohlmeister, J., Stumpf, C.F., Riechelmann, D.F.C. Quaternary Science Reviews1) Stable isotopes2) Trace elements3) Sr isotopes THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOVE
Vegetation and climate in the eastern Iberian Peninsula during the pre-evaporitic Messinian (late Miocene). Palynological data from the Upper Turolia…
2015
International audience; The present paper reports a complete palynological study of the Upper Turolian sediments outcropping at the Venta del Moro site (eastern Iberian Peninsula). The pollen assemblages observed mainly reflect the local and regional vegetation, which must have formed part of a wetland ecosystem within a general setting of open steppe, as indicated by the great abundance and diversity of herbaceous pollen. This reflects the persistence of open vegetation in the Iberian Peninsula after the Middle Miocene when it became extensive. We here report the most recent record of Disanthus for the Iberian Peninsula. This shrub played an important role in an unusual, edaphically-mediat…
Data for: Leukoma antiqua (Bivalvia) - a high-resolution marine paleoclimate archive for southern South America?
2018
Data for freshwater mixing line, Figure 2 Stable oxygen and carbon isotope data of shells, Td18O(shell) plus 1 sigma errors, instrumental SST, data for Figures 6+7 Temporal Alignment of oxygen isotope data (and temperatures reconstructed thereof), data for Figure 8
Reconstruction of the internal structure of the pore system of a complex dinosaur eggshell (Megaloolithus siruguei)
2013
Despite the many reconstructions of fossil material that have recently appeared in the literature, dinosaur eggshells have never been reconstructed using computing techniques. Using the EMAC 3-D modelling methodology, we reconstruct a section of the Late Cretaceous Megaloolithus siruguei eggshell, which has a particularly complex pore system, exhibiting an intricate network of vertical, oblique, and horizontal pores.