Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence

Abstract

Abstract.We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago, a time period centred on Marine Isotope Stage (MIS) 9 and characterized by particular baseline climate states. This study enables the documentation of vegetation changes in the north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appear more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition, which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the Southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appear to be related to changes in deep water circulation and probably to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in Southern Europe.

A 0.65Ma chronology and incision rate assessment of the NW Iberian Miño River terraces based on 10Be and luminescence dating

“…It is likely that the low gradient of the terraces (0.003 to 0.007 m km − 1 ) in combination with high infiltration capacity of the terraces, prevented overland flow. Additional factors may be that the underlying granites weathered rapidly, thus preventing water stagnation, also that the Miño catchment has always been vegetated, even during the coldest spells of the glacial periods (Sanchez-Goñi et al, 2008;Desprat et al, 2009). It has also been demonstrated that fluvial systems with moderate vertical uplift rates (typically 0.08 to 0.11 m ka − 1 ) have the largest potential for alluvial terrace preservation (Veldkamp and Van den Berg, 1993).…”

“…Vandenberghe, 1995;Busschers et al, 2007;Bridgland and Westaway, 2008). The greater part of the catchment was always vegetated and relatively humid (Desprat et al, , 2009 (Lisiecki and Raymo, 2005). The Y-axis is inverted.…”

Climatic and human effects on the post-glacial dynamics of Fagus sylvatica L. in NW Iberia

“…BP) The relevant presence of Fagus pollen offshore the Iberian margin is basically focussed on the isotopic interglacials MIS 11 and MIS 9 (Desprat et al 2005(Desprat et al , 2008 although only a few grains appeared belonging to MIS-5 or younger . The local presence of F. sylvatica woodlands in NW Iberia during the final stages of the Pleistocene has recently been inferred by pollen analysis of ancient limnetic levels (Gómez-Orellana 2002;Gómez-Orellana et al 2007).…”

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

“…well into the interglacial setting MIS 9e apart from other interglacial intervals. This difference is not only evidenced by the prolonged planktic δ 13 C minimum but also by the persistent, if low presence of the polar species N. pachyderma (s) in the planktic foraminifer fauna off Iberia during the first half of the interglacial (de Abreu et al, 2005;Desprat et al, 2009) implying the advection of poorly ventilated waters into the mid-latitude North Atlantic. These waters were most likely Subarctic Intermediate Water because the record of ODP Site 982 on the northern Reykjanes ridge (57.5 • N) reveals the same δ 13 C minimum accompanied by persistent, but low input of IRD (Venz et al, 1999).…”