Atmospheric and Oceanic Circulation Patterns off Northwest Africa During the Past 25 Million Years

Sarnthein, Michael; Thiede, Jörn; Pflaumann, Uwe; Erlenkeuser, Helmut; Fütterer, Dieter K; Koopmann, B; Lange, Heinz; Seibold, Eugen

doi:10.1007/978-3-642-68409-8_24

Cited by 252 publications

(230 citation statements)

References 104 publications

Supporting

Mentioning

213

Contrasting

Order By: Relevance

“…At site 659, the terrigenous component should largely equate to the siliciclastic sediment fraction, because the South Saharan and Sahelian dust discharge contains less than 4-8% CaC03 [Sarnthein et al, 1982]. Hence the noncarbonate fraction (100% minus %CaC03 ) at this distal site on top of the Cape Verde Plateau (Figure 1) is considered to be purely eolian, because the concentrations of biogenic opal ( < 2% ), organic carbon (< 0.5%), and volcanic glass are negligible and fluvial sediment supply and turbidites cannot reach this position .…”

Section: Discussionmentioning

confidence: 99%

Astronomic timescale for the Pliocene Atlantic δ¹⁸O and dust flux records of Ocean Drilling Program Site 659

Tiedemann¹,

Sarnthein²,

Shackleton³

1994

Paleoceanography

Self Cite

675

485

View full text Add to dashboard Cite

Abstract. High-resolution benthic oxygen isotope and dust flux records from Ocean Drilling Program site 659 have been analyzed to extend the astronomically calibrated isotope timescale for the Atlantic from 2.85 Ma back to 5 Ma. Spectral analysis of the o 1 BO record indicates that the 41-kyr period of Earth's orbital obliquity dominates the Pliocene record. This is shown to be true regardless of fundamental changes in the Earth's climate during the Pliocene. However, the cycles of Sahelian aridity fluctuations indicate a shift in spectral character near 3 Ma. From the early Pliocene to 3 Ma, the periodicities were dominantly precessional (19 and 23 kyr) and remained strong until1.5 Ma. Subsequent to 3 Ma, the variance at the obliquity period (41 kyr) increased. The timescale tuned to precession suggests that the Pliocene was longer than previously estimated by more than 0.5 m.y. The tuned ages for the magnetic boundaries Gauss/Gilbert and Top Cochiti are about 6-8% older than the ages of the conventional timescale. A major phase of Pliocene northern hemisphere ice growth occurred between 3.15 Ma and 2.5Ma. This was marked by a gradual increase in glacial Atlantic o 1 BO values of 1o/oo and an increase in amplitude variations by up to 1.5o/oo, much larger than in the Pacific deepwater record (site 846). The first maxima occured in cold stages G6-96 between 2.7 Ma and 2.45 Ma. Prior to 3 Ma, the isotope record is characterized by predominantly low amplitude fluctuations(< 0.7o/oo.). When obliquity forcing was at its minimum between 4.15 and 3.6 Ma and during the Kaena interval, o 18 0 amplitude fluctuations were minimal. From 4.9 to 4.3 Ma, the o 18 0 values decreased by about 0.5o/oo, reaching a long-term minimum at 4.15 Ma, suggesting higher deepwater temperatures or a deglaciation. Deepwater cooling and/or an increase in ice volume is indicated by a series of short-term o 1 BO fluctuations between 3.8 and 3.6 Ma.

show abstract

Section: Discussionmentioning

confidence: 99%

Astronomic timescale for the Pliocene Atlantic δ¹⁸O and dust flux records of Ocean Drilling Program Site 659

Tiedemann¹,

Sarnthein²,

Shackleton³

1994

Paleoceanography

Self Cite

675

485

View full text Add to dashboard Cite

show abstract

“…Upwelling conditions also prevailed on the upper slope of the Atlantic side of the Rifian corridors during the Messinian (Gebhardt, 1993). The coastal upwellings have persisted off NW Africa up to the present day (Sarnthein et al, 1982).…”

mentioning

confidence: 95%

Messinian paleoenvironmental evolution in the lower Guadalquivir Basin (SW Spain) based on benthic foraminifera

Pérez-Asensio

Aguirre

Schmiedl

et al. 2012

Palaeogeography, Palaeoclimatology, Palaeoecology

View full text Add to dashboard Cite

Benthic foraminiferal assemblages of a drill core from the lower Guadalquivir Basin (northern Gulf of Cádiz, SW Spain) have been analysed in order to reconstruct the paleoenvironmental evolution in the vicinity of the Betic seaways during the Messinian. The core consists of marine sediments ranging from the latest Tortonian to the early Pliocene. Changes in the abundance of certain marker species, planktonic/benthic ratio (P/B ratio), paleodepth estimated with a transfer function, content of sand grains and presence of glauconitic layers indicate a complete transgressive-regressive sea-level cycle from the bottom to the top of the section. An abrupt sea-level rise, from inner-middle shelf to middle slope, is recorded at the lowermost part of the core (latest Tortonian-earliest Messinian), followed by a relatively rapid shallowing from middle slope to outer shelf. Magnetobiostratigraphic data show These assemblages are dominated by Nonion fabum and Bulimina elongata, two taxa that are able to feed from continental low-quality organic matter, most likely derived from river run-off. The paleoenviromental evolution on the Atlantic side of Betic and Rifian seaways is similar during the Messinian, with a Messinian continuous sea-level lowering driven by regional tectonic uplift and upwelling-related waters reaching the upper slope. This study will further contribute to understand the role of tectonics on the sea-level changes as well as on the closure of the Atlantic-Mediterranean gateways that led to the MSC, and on the paleoceanography on the Atlantic sides of these corridors.

show abstract

“…The CC flows southward over the continental shelf and slope along the coast (Stramma and Siedler, 1988;Mittelstaedt, 1991). Off Cape Blanc the CC starts to deflect to the west and at approximately 151N the current diverges (Sarnthein et al, 1982;Fütterer, 1983). The dominant fraction of this surface water veers, driven by the Trade Winds, from the continental shelf to the open ocean.…”

Section: Introductionmentioning

confidence: 99%

“…A minor portion of the waters from the CC continues south and southeast-wards along the African coast. The pattern of the Eastern Boundary Current (EBC) is locally influenced by the presence of the islands, by the morphology of the shelf, the location of the shelf break and by variations in intensity and direction of local winds (Sarnthein et al, 1982). Mittelstaedt et al (1975) described that occasionally enhanced southern monsoonal and other local winds can reverse the general direction of the surface water flow.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Plewa

Meggers

Kuhlmann

et al. 2012

Deep Sea Research Part I: Oceanographic Research Papers

View full text Add to dashboard Cite

a b s t r a c tOne hundred and twenty-eight surface-sediment samples collected off North-West Africa were studied geochemically to detect the expressions of different meridional climate regimes and zonal productivity gradients in the surface sediments. This geochemical multi-tracer approach, coupled with additional information on the bulk carbonate and TOC contents makes it possible to characterise the sedimentological regime in detail. Typical terrigenous elements like Al, K and Fe mirror the importance of the humid (fluvial) influence in the north of the study area and the dominance of aeolian input in the south. Furthermore, the distributions of Ti and Fe in the surface sediments serve as tracers for the supply of eolian volcanic material from the Canary Islands. The spatial variability of the TOC contents in the surface sediments closely follows the ocean surface productivity patterns, whereas the CaCO 3 contents are mainly controlled by dilution with terrigenous matter. The potential productivity proxy Ba is not a reliable tracer for productivity in this region, since it is mainly supplied by terrigenous input (coupled with aluminosilicates).

show abstract

Atmospheric and Oceanic Circulation Patterns off Northwest Africa During the Past 25 Million Years

Cited by 252 publications

References 104 publications

Astronomic timescale for the Pliocene Atlantic δ¹⁸O and dust flux records of Ocean Drilling Program Site 659

Astronomic timescale for the Pliocene Atlantic δ¹⁸O and dust flux records of Ocean Drilling Program Site 659

Messinian paleoenvironmental evolution in the lower Guadalquivir Basin (SW Spain) based on benthic foraminifera

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Contact Info

Product

Resources

About

Atmospheric and Oceanic Circulation Patterns off Northwest Africa During the Past 25 Million Years

Cited by 252 publications

References 104 publications

Astronomic timescale for the Pliocene Atlantic δ18O and dust flux records of Ocean Drilling Program Site 659

Astronomic timescale for the Pliocene Atlantic δ18O and dust flux records of Ocean Drilling Program Site 659

Messinian paleoenvironmental evolution in the lower Guadalquivir Basin (SW Spain) based on benthic foraminifera

Geochemical distribution patterns as indicators for productivity and terrigenous input off NW Africa

Contact Info

Product

Resources

About

Astronomic timescale for the Pliocene Atlantic δ¹⁸O and dust flux records of Ocean Drilling Program Site 659

Astronomic timescale for the Pliocene Atlantic δ¹⁸O and dust flux records of Ocean Drilling Program Site 659