Consulta: subjectFacets:"Sapropel"
Registros recuperados: 8
Data/hora: 10/06/2024 14:04:50

Florisphaera profunda and the origin and diagenesis of carbonate phases in eastern Mediterranean sapropel units
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Thomson, J; Crudeli, D; De Lange, Gj; Slomp, Cp; Erba, E; Corselli, C; Calvert, Se.
High relative concentrations of the lower photic zone nannofossil Florisphaera profunda have been reported in all recent eastern Mediterranean sapropels. In the most recent sapropel (S1), high bulk sediment Sr/Ca ratios occur along with high F. profunda contents toward the base of the unit, exemplified here in four cores from 1.5-3.5 km water depth. Co-occurring biogenic carbonates contain insufficient Sr to account for these high Sr concentrations, and X-ray diffraction and selective leaching show that the high Sr/Ca ratios are due to aragonite, the CaCO3 polymorph that is rarely preserved in deep marine sediments, with similar to1 wt % Sr. The possible sources of this aragonite include ( 1) precipitation with surface ocean production, ( 2) detrital input...
Tipo: Text
Palavras-chave: Sapropel; Aragonite; Strontium.
Ano: 2004
URL: https://archimer.ifremer.fr/doc/00229/33975/32412.pdf

Organic matter isotopes reveal enhanced rainfall activity in Northwestern Mediterranean borderland during warm substages of the last 200 kyr
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pasquier, Virgil; Toucanne, Samuel; Sansjofre, Pierre; Dixit, Yama; Revillon, Sidonie; Mokeddem, Zohra; Rabineau, Marina.
In this study we use bulk sediment organic matter stable isotopes (δ13Corg and δ15N) to examine the nature and timing of preserved organic matter in borehole PRGL1-4 from Northwestern Mediterranean Sea. This region is known as a transitional zone between the North Atlantic atmospheric circulation and the North African monsoon system. In the Gulf of Lion (SE France), increased inputs of organic matter from sediment-laden rivers occurred during warm substages of the last 200 kyr (MIS 5e, 5c, and 5a; MIS 6d, and 6b). Increased terrestrial organic matter are inferred from organic carbon isotopic composition (δ13Corg), and are interpreted as resulting from enhanced rainfall over the Rhone river catchment area. Such increase in terrestrial organic carbon induced...
Tipo: Text
Palavras-chave: Mediterranean; Rainfall; North Atlantic oscillation; Organic matter; North Mediterranean borderland; Sapropel.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00473/58421/61116.pdf

The timing and evolution of the post-glacial transgression across the Sea of Marmara shelf south of Istanbul
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Eris, K; Ryan, W; Cagatay, M; Sancar, U; Lericolais, Gilles; Menot, G; Bard, E.
High-resolution reflection seismic profiles with core analyses of sedimentary sequence near the Sea of Marmara (SoM) entrance to the Strait of İstanbul (SoI, Bosphorus) provide detailed record of sealevel changes since the Late Glacial Maximum (LGM). The sequence is deposited over the LGM erosional surface at a maximum depth of -105 m. It includes seven seismic units that can be confidently correlated with 14C-dated sedimentary units in the cores. Unit 6 represents levee deposits of the paleo-SoI channel that was deposited by a Black Sea outflow during 11.2-10.6 kyr BP. The reflection surfaces at base of Unit 5 and 4 correspond to wave-cut terraces at -71and -63 m, respectively, and are estimated to be 10.6 and 9.8 kyr BP. The seismic Unit 2, overlaying a...
Tipo: Text
Palavras-chave: Sapropel; Delta; Marmara Sea; Holocene; Sea level; Seismic stratigraphy.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3574.pdf

Constraints on Black Sea outflow to the Sea of Marmara during the last glacial-interglacial transition
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Major, Candace; Ryan, William; Lericolais, Gilles; Hajdas, Irka.
New cores from the upper continental slope off Romania in the western Black Sea provide a continuous, high-resolution record of sedimentation rates, clay mineralogy, calcium carbonate content, and stable isotopes of oxygen and carbon over the last 20000 yr in the western Black Sea. These records all indicate major changes occurring at 15 000, 12 800, 8400, and 7 100 yr before present. These results are interpreted to reflect an evolving balance between water supplied by melting glacial ice and other river runoff and water removed by evaporation and outflow. The marked retreat of the Fennoscandian and Alpine ice between 15 000 and 14 000 yr is recorded by an increase in clays indicative of northern provenance in Black Sea sediments. A short return toward...
Tipo: Text
Palavras-chave: Clay mineralogy; Stable isotopes; Sapropel; Younger Dryas; Deglaciation.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-473.pdf

Tracking rainfall in the northern Mediterranean borderlands during sapropel deposition
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Toucanne, Samuel; Mintoo, Charlie Morelle Angue; Fontanier, Christophe; Bassetti, Maria-angela; Jorry, Stephan; Jouet, Gwenael.
The role of mid-latitude precipitation in the hydrological forcing leading to the deposition of sapropels in the Mediterranean Sea remains unclear. The new GDEC-4-2 borehole, East Corsica margin (northern Tyrrhenian Sea), provides the first precisely dated evidence for enhanced rainfall in the Western Mediterranean during warm intervals of interglacial periods over the last 547 kyr. Comparison of GDEC-4-2 proxy records with pollen sequences and speleothems from the central and eastern Mediterranean reveals that these pluvial events were regional in character and occurred probably in response to the intensification of the Mediterranean storm track along the northern Mediterranean borderlands in autumn/winter. Our dataset suggests that the timing of maxima...
Tipo: Text
Palavras-chave: Mediterranean; Rainfall; Interglacials; Sapropel.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00287/39804/38301.pdf

The experimental analysis on the Late Quaternary deposits of the Black Sea
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Tekiroglu, Selin Eda; Ediger, Vedat; Yemenicioglu, Semal; Kapur, Selim; Akca, Erhan.
Holocene sediments taken from the south-eastern and western Black Sea have been investigated in relation to their geochemical, sedimentological and mineralogical characteristics. Their textures are characterized by their low amount of sand, upward-increasing silt and downward-increasing clay contents. While the terrigenous materials transported from Anatolian volcanic-based sources and European alluvial sediments form the shore deposits, the deep-sea sediments mainly consist of the marine biological production. The highest amount of organic carbon was deposited following the formation of anoxic conditions at the bottom until the beginning of the still continuing carbonate-rich coccolith (Emiliania huxleyi) deposition. The high metal concentrations are...
Tipo: Text
Palavras-chave: Mer Noire; Holocène; Sapropel; Coccolithes; Black Sea; Holocene; Sapropel; Coccolith.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00323/43369/42841.pdf

New insights into upper MOW variability over the last 150 kyr from IODP 339 Site U1386 in the Gulf of Cadiz
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Kaboth, Stefanie; Bahr, Andre; Reichart, Gert-jan; Jacobs, Bram; Lourens, Lucas J.
The upper Mediterranean Outflow Water (MOW) paleo-oceanographic history in the Gulf of Cadiz is poorly constrained due to the lack of high-resolution records that pre-date the last glaciation. Existing proxy records concentrate on MOW variability along the middle slope of the Gulf of Cadiz. Here we present a continuous high-resolution benthic foraminifera delta O-18 record from the upper MOW core at IODP Expedition 339 Site U1386 in the Gulf of Cadiz of the past 150,000 years. Based on delta O-18, grain-size and Zr/AI variability comparison of our results with existing Mediterranean Sea (MD01-2472, MD95-2043), open ocean (LR04) and Gulf of Cadiz (MD99-2339) records we have gathered new insights into the evolution of the upper MOW core on glacial...
Tipo: Text
Palavras-chave: Mediterranean outflow; Glacial-interglacial variability; Sapropel; Heinrich events; Gulf of Cadiz.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00421/53235/54767.pdf

A dynamic explanation for the origin of the western Mediterranean organic-rich layers
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Rogerson, M.; Cacho, I.; Jimenez-espejo, F.; Reguera, M. I.; Sierro, F. J.; Martinez-ruiz, F.; Frigola, J.; Canals, M.
The eastern Mediterranean sapropels are among the most intensively investigated phenomena in the paleoceanographic record, but relatively little has been written regarding the origin of the equivalent of the sapropels in the western Mediterranean, the organic-rich layers (ORLs). ORLs are recognized as sediment layers containing enhanced total organic carbon that extend throughout the deep basins of the western Mediterranean and are associated with enhanced total barium concentration and a reduced diversity (dysoxic but not anoxic) benthic foraminiferal assemblage. Consequently, it has been suggested that ORLs represent periods of enhanced productivity coupled with reduced deep ventilation, presumably related to increased continental runoff, in close...
Tipo: Text
Palavras-chave: Sapropel; Mediterranean; Sea level; Paleoceanography; Circulation.
Ano: 2008
URL: https://archimer.ifremer.fr/doc/00237/34825/33303.pdf