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| Titel |
Hydrological variability in the Northern Levant: a 250 ka multi-proxy record from the Yammoûneh (Lebanon) sedimentary sequence |
| VerfasserIn |
F. Gasse, L. Vidal, A.-L. Develle, E. Campo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 7, no. 4 ; Nr. 7, no. 4 (2011-11-24), S.1261-1284 |
| Datensatznummer |
250004686
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| Publikation (Nr.) |
 copernicus.org/cp-7-1261-2011.pdf |
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| Zusammenfassung |
The Levant is a key region in terms of both long-term hydroclimate dynamics
and human cultural evolution. Our understanding of the regional response to
glacial-interglacial boundary conditions is limited by uncertainties in
proxy-data interpretation and the lack of long-term records from different
geographical settings.
The present paper provides a 250 ka paleoenvironmental reconstruction based
on a multi-proxy approach from northern Levant, derived from a 36 m
lacustrine-palustrine sequence cored in the small intra-mountainous karstic
Yammoûneh basin from northern Lebanon. We combined time series of
sediment properties, paleovegetation, and carbonate oxygen isotopes (δc), to
yield a comprehensive view of paleohydrologic-paleoclimatic fluctuations in
the basin over the two last glacial-interglacial cycles. Integration of all
available proxies shows that Interglacial maxima (early-mid MIS 7, MIS 5.5
and early MIS 1) experienced relatively high effective moisture, evidenced
by the dominance of forested landscapes (although with different forest
types) associated with authigenic carbonate sedimentation in a productive
waterbody. Synchronous and steep δc increases can be reconciled
with enhanced mean annual moisture when changes in seasonality are taken
into account. During Glacials periods (MIS 2 and MIS 6), open vegetation
tends to replace the forests, favouring local erosion and detrital
sedimentation. However, all proxy data reveal an overall wetting during MIS
6, while a drying trend took place during MIS4-2, leading to extremely harsh
LGM conditions possibly linked to water storage as ice in the surrounding
highlands. Over the past 250 ka, the Yammoûneh record shows an overall
decrease in local effective water, coincident with a weakening of seasonal
insolation contrasts linked to the decreasing amplitude of the eccentricity
cycle.
The Yammoûneh record is roughly consistent with long-term climatic
fluctuations in the northeastern Mediterranean region (except during MIS 6).
It suggests that the role of seasonality on effective moisture, already
highlighted for MIS 1, also explains older interglacial climate. The
Yammoûneh record shares some features with speleothem isotope records of
western Israel, while the Dead Sea basin generally evolved in opposite
directions. Changes in atmospheric circulation, regional topographic
patterns and site-specific hydrological factors are invoked as potential
causes of spatial heterogeneities.
Further work is needed to refine the Yammoûneh chronology, better
understand its functioning through hydrological and climate modelling, and
acquire other long records from northern Levant to disentangle the relative
effects of local versus regional factors. |
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