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| Titel |
Geochemical and mineralogical record of eolian input in the westernmost Mediterranean Sea since the Last Glacial Maximum |
| VerfasserIn |
M. Rodrigo-Gámiz, F. Martinez-Ruiz, F. J. Jimenez-Espejo, D. Gallego-Torres, V. Nieto-Moreno, D. Ariztegui, O. Romero |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028037
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| Zusammenfassung |
| Eolian supply has significantly contributed to terrigenous sedimentation in the Mediterranean.
Its reconstruction has further allowed the characterization of the atmospheric response to
climate oscillations. Here we present a high-resolution record of eolian input oscillations in
the westernmost Mediterranean (Alboran Sea basin) for the last 20.000 yr. The Alboran Sea
basin is a key zone for paleoclimate reconstruction because high sedimentation rates provide
excellent analysis resolution. We have analyzed marine sediments from core 293G, recovered
in the east Alboran basin during the TTR-12 cruise. Radiocarbon ages and stable oxygen
isotope record from planktonic foraminifera have provided a detailed age model for this site.
Characterization of eolian terrigenous material from the African margin has been based on
geochemical/mineralogical tracers. Sediments are composed of terrigenous materials
(mostly clays, quartz and feldspars) and biogenic carbonates. Detrital clays are mainly
dominated by illite followed by smectites, chlorite and kaolinite. Arid periods are also
characterized by enhanced palygorskite content. Geochemical profiles (e.g., Si/Al,
Ti/Al, Zr/Al) correspondingly reveal aridity oscillations during this time interval. In
particular, Zr/Al ratio records major climate fluctuations with a significant increase
during the last Heinrich event (H1). Wetter conditions at time of deposition of the
sapropel S1 in the eastern Mediterranean are also recorded by a decreasing trend in
Zr/Al ratio. Other element ratios such as Mg/Al, K/Al, Rb/Al have been used as
proxies for changes in river runoff and support rapid climate changes in the western
Mediterranean borderlands involving significant fluctuation in the fluvial input to
the marine basin. These fluctuations are also accompanied by changes in marine
productivity and reflected as changes in sedimentary organic matter. Furthermore,
Ba-based proxies, used for paleoproductivity reconstruction, point to productivity peaks
during cold periods, H1 and Younger Dryas, and a progressive decreasing trend
until present day levels. Substantial changes in oxygen conditions are similarly
related to major climate oscillations. Other than these millennial oscillations, the
analyzed geochemical and mineralogical profiles reveals brief fluctuations at shorter
time scales providing new insights into the causes, timing, and mechanisms of
atmosphere-ocean interactions in the western Mediterranean during the last 20
kyr.
Acknowledges: Projects Marcal CGL2006-13327-C04-04, Sagas CTM2005-08071-C03-01,
Ministerio MARM 200800050084447, RNM 0179, CSD2006-00041. |
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