Published in

European Geosciences Union, Climate of the Past, 4(7), p. 1395-1414, 2011

DOI: 10.5194/cp-7-1395-2011

European Geosciences Union, Climate of the Past Discussions, 1(7), p. 635-675

DOI: 10.5194/cpd-7-635-2011

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Tracking climate variability in the western Mediterranean during the Late Holocene: A multiproxy approach

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Climate variability in the western Mediterranean is reconstructed for the last 4000 yr using marine sediments recovered in the west Algerian-Balearic Basin, near the Alb-oran Basin. Fluctuations in chemical and mineralogical sedi-ment composition as well as grain size distribution are linked to fluvial-eolian oscillations, changes in redox conditions and paleocurrent intensity. Multivariate analyses allowed us to characterize three main groups of geochemical and miner-alogical proxies determining the sedimentary record of this region. These three statistical groups were applied to recon-struct paleoclimate conditions at high resolution during the Late Holocene. An increase in riverine input (fluvial-derived elements – Rb/Al, Ba/Al, REE/Al, Si/Al, Ti/Al, Mg/Al and K/Al ratios), and a decrease in Saharan eolian input (Zr/Al ratio) depict the Roman Humid Period and the Little Ice Age, while drier environmental conditions are recognized during the Late Bronze Age-Iron Age, the Dark Ages and the Me-dieval Climate Anomaly. Additionally, faster bottom cur-rents and more energetic hydrodynamic conditions for the former periods are evidenced by enhanced sortable silt (10-63 µm) and quartz content, and by better oxygenated bottom waters – as reflected by decreasing redox-sensitive elements (V/Al, Cr/Al, Ni/Al and Zn/Al ratios). In contrast, oppo-site paleoceanographic conditions are distinguished during the latter periods, i.e. the Late Bronze Age-Iron Age, the Dark Ages and the Medieval Climate Anomaly. Although no Ba excess was registered, other paleoproductivity indicators Correspondence to: V. Nieto-Moreno (vanesanieto@ugr.es) (total organic carbon content, Br/Al ratio, and organometal-lic ligands such as U and Cu) display the highest values dur-ing the Roman Humid Period, and together with increasing preservation of organic matter, this period exhibits by far the most intense productivity of the last 4000 yr. Fluctuations in detrital input into the basin as the main process managing deposition, reflected by the first eigenvector defined by the Principal Component Analyses, point to solar irradiance and the North Atlantic Oscillation variability as the main driving mechanisms behind natural climate variability over decadal to centennial time-scales for the last 4000 yr.