Temperature and productivity changes off the western Iberian margin during the last 150 ky

Salgueiro, Emı́lia; Voelker, Antje H L; Abreu, Lucia de; Abrantes, Fatima F; Meggers, Helge; Wefer, Gerold

doi:10.1016/j.quascirev.2009.11.013

Cited by 140 publications

(154 citation statements)

References 95 publications

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“…Because the MD01-2443 record, located just about one degree further to the south, reveals less cold temperatures (Fig. 6), subtropical AzC waters probably still influenced the southern margin, similar to the stadials and Heinrich events of the last glacial cycle (Salgueiro et al, 2010), and their presence might have enhanced iceberg melting near site MD03-2699. The arrival of IRD at the Iberian margin and thus the southernmost position of the Polar Front in the eastern North Atlantic coincided with the strongest reduction in the AMOC as indicated by the benthic δ 13 C minima in the IODP Site U1313 and MD01-2446 records (Figs.…”

Section: Hydrographic Conditions Off Portugalmentioning

confidence: 98%

Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation

Voelker¹,

Rodrigues²,

et al. 2010

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Abstract. Stable isotope and ice-rafted debris records from three core sites in the mid-latitude North Atlantic (IODP Site U1313, MD01-2446, MD03-2699 are combined with records of ODP Sites 1056/1058 and 980 to reconstruct hydrographic conditions during the middle Pleistocene spanning Marine Isotope Stages (MIS) 9-14 (300-540 ka). Core MD03-2699 is the first high-resolution mid-Brunhes record from the North Atlantic's eastern boundary upwelling system covering the complete MIS 11c interval and MIS 13. The array of sites reflect western and eastern basin boundary current as well as north to south transect sampling of subpolar and transitional water masses and allow the reconstruction of transport pathways in the upper limb of the North Atlantic's circulation. Hydrographic conditions in the surface and deep ocean during peak interglacial MIS 9 and 11 were similar among all the sites with relative stable conditions and confirm prolonged warmth during MIS 11c also for the mid-latitudes. Sea surface temperature (SST) reconstructions further reveal that in the mid-latitude North Atlantic MIS 11c is associated with two plateaus, the younger one of Correspondence to: A. Voelker (antje.voelker@lneg.pt) which is slightly warmer. Enhanced subsurface northward heat transport in the eastern boundary current system, especially during early MIS 11c, is denoted by the presence of tropical planktic foraminifer species and raises the question how strongly it impacted the Portuguese upwelling system. Deep water ventilation at the onset of MIS 11c significantly preceded surface water ventilation. Although MIS 13 was generally colder and more variable than the younger interglacials the surface water circulation scheme was the same. The greatest differences between the sites existed during the glacial inceptions and glacials. Then a north -south trending hydrographic front separated the nearshore and offshore waters off Portugal. While offshore waters originated from the North Atlantic Current as indicated by the similarities between the records of IODP Site U1313, ODP Site 980 and MD01-2446, nearshore waters as recorded in core MD03-2699 derived from the Azores Current and thus the subtropical gyre. Except for MIS 12, Azores Current influence seems to be related to eastern boundary system dynamics and not to changes in the Atlantic overturning circulation.

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Section: Hydrographic Conditions Off Portugalmentioning

confidence: 98%

Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation

Voelker¹,

Rodrigues²,

et al. 2010

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“…This time period was characterized by high to medium sea-levels ( Fig. 17) and warm to mild climatic conditions (Salgueiro et al, 2010). The Carregueira Formation is an aeolian sand unit represented in several reaches of the Lower Tejo valley and can be related to the cold and dry climatic conditions that occurred between ca.…”

Section: Pp Cunha Et Al / Quaternary Science Reviews XXX (2016) 1ementioning

confidence: 99%

New data on the chronology of the Vale do Forno sedimentary sequence (Lower Tejo River terrace staircase) and its relevance as a fluvial archive of the Middle Pleistocene in western Iberia

Cunha

Martins

Buylaert

et al. 2017

Quaternary Science Reviews

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a b s t r a c tThe Vale do Forno archaeological sites (Alpiarça, central Portugal) document the earliest human occupation in the Lower Tejo River, well established in geomorphological and environmental terms, within the Middle Pleistocene. In a staircase of six fluvial terraces, the Palaeolithic sites were found on the T4 terrace (þ24 m, above river bed) which is made of a basal Lower Gravels unit (LG) and an overlying Upper Sands unit (US). Geomorphological mapping, coupled with lithostratigraphy, sedimentology and luminescence dating (quartz-OSL and K-feldspar post-IRIR 290 ) were used in this study. The oldest artefacts found in the LG unit show crude bifacial forms that can be attributed to the Acheulian. In contrast, the US unit has archaeological sites stratigraphically documenting successive phases of an evolved Acheulian. Luminescence dating and correlation with the Marine Isotopic Stages suggest that the LG unit has a probable age of ca. 335 to 325 ka and the US unit an age of ca. 325 to 155 ka. This is in contrast to previous interpretations ascribing this terrace (and lithic industries) to the Last Interglacial and early phases of the Last Glacial. The VF3 site (Milhar os), containing Micoquian (Final Acheulian) industries (with fine and elaborated bifaces), found in a stratigraphic level located between the T4 terrace deposits and a colluvium associated with Late Pleistocene aeolian sands, is younger than 155 ka but much older than 32 ka.© 2016 Elsevier Ltd. All rights reserved. IntroductionUnderstanding of the Palaeolithic occupation of Northern Europe has been substantially based on evidence from rivers (e.g. Bridgland et al., 2006). For Western Europe and specifically in Iberia, insights into the Palaeolithic occupation is similarly derived from its major rivers (from north to south: Douro, Tejo/Tagus, Guadiana, Guadalquivir) (e.g. Santonja and Villa, 2006). Within this context, the Vale do Forno archaeological sites (Alpiarça, in central Portugal; Fig. 1) provide the earliest and most well documented human occupation in the Lower Tejo (the Portuguese part of the Tejo basin). Lower Palaeolithic bifacial sites are common, often well represented by lithic industries. Their local stratigraphy and technological characteristics indicate successive phases of what is commonly named as the Acheulian. However, they were chronologically poorly constrained.From the Spanish border to the Atlantic coast, the Tejo crosses major faults which provide a natural geomorphological subdivision of the river into a series of valley reaches (I to V;Cunha et al., 2005). * Corresponding author.E-mail addresses: pcunha@dct.uc.pt (P.P. Cunha), aam@uevora.pt (A.A. Martins), jabu@dtu.dk (J.-P. Buylaert), anmu@dtu.dk (A.S. Murray), 3raposos@sapo.pt (L. Raposo), paolo.mozzi@unipd.it (P. Mozzi), m.stokes@plymouth.ac.uk (M. Stokes).

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“…Nannofossil and planktonic foraminifer assemblages can be used as indicators for surface water conditions, like sea-surface temperature and productivity (e.g., Colmenero-Hidalgo et al, 2004;Baumann et al, 2005;Narciso et al, 2006;Kucera, 2007;Salgueiro et al, 2010), to identify past surface water variations. Aragonitic pteropod shells are preserved in sediments during specific time intervals (Herman, 1971), such as the layer dated at 19.1 calendar k.y.…”

Section: Biostratigraphy Paleontologymentioning

confidence: 99%

Methods

2013

Proceedings of the IODP

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Temperature and productivity changes off the western Iberian margin during the last 150 ky

Cited by 140 publications

References 95 publications

Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation

Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation

New data on the chronology of the Vale do Forno sedimentary sequence (Lower Tejo River terrace staircase) and its relevance as a fluvial archive of the Middle Pleistocene in western Iberia

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