Revisiting the longest European paleoenvironmental archive

Lead Research Organisation: University of Leeds
Department Name: Sch of Geography

Abstract

Long marine, ice core and terrestrial archives spanning multiple glacial-interglacial cycles provide a unique perspective into the evolution of Quaternary climates. Firstly, they reveal a more complete view of the range of climate variability and associated biotic responses, and secondly, they allow us to observe long-term trends in the character of this variability. Among these archives, Tenaghi Philippon, NE Greece, has continued to occupy a prominent position despite the fact that pollen analyses were initiated as early as the 1960s. This is a function of (i) its temporal length, containing a record of vegetation changes of the last 1.35 million; and (ii) its completeness, as demonstrated by its close correspondence with global deep-sea records. However, the lower part of the record had low sampling resolution and, moreover, the original core is no longer curated. A new high-quality core of the upper 60m was recently obtained by a team led by Prof. J. Pross (Frankfurt), while a further coring campaign to reach a depth of 150m is currently being organized for Autumn 2007. This application seeks to obtain funding to extend the coring in 2007 from 150m to 200m (from about 0.9 to 1.35 million years ago [Ma]), reaching the base of the polleniferous deposits. The new core will be curated in Germany, where whole-core logging and palaeomagnetic analyses will initially be undertaken. This will form the basis of several future research grant proposals in association with German and Dutch colleagues. In the context of the current application, I propose to undertake a high-resolution pollen analysis of an early Pleistocene glacial-interglacial cycle around 0.95 Ma, an interval characterized by 41 thousand year (kyr) climate periodicity. More specifically, by examining the vegetation response within a 41-kyr glacial-interglacial cycle, it may be possible to test whether 'cryptic' precessional (23-kyr) variations in ice volume occurred, as recently suggested by Raymo et al. (2006) who pointed out that because precession is out of phase between hemispheres, changes in ice volume in each hemisphere would cancel out in globally integrated reconstructions of sea level. While the Raymo et al. hypothesis is difficult to test using palaeoceanographic or sea level proxies, changes in local vegetation may retain a memory of hemispheric ice expansion. Thus, if northern ice sheets did expand in the middle of the 41-kyr cycle in response to precession, that should, in principle, be reflected in a contraction of S. European tree populations.
 
Description The fen of Tenaghi Philippon (TP), NE Greece (41°10'N, 24°20'E; 40m a.s.l.), has furnished the longest continuous European pollen record, spanning approximately the last 1.35 million years. However, the record had low sampling resolution and, moreover, the original core is no longer curated. A campaign to obtain a new core was organized by a team led by Prof. J. Pross (Goethe University Frankfurt). The small NERC grant aimed to contribute towards the drilling costs and to undertake a small self-contained palynological project. The main achievements of the research as they relate to the specific objectives were:



(1) To obtain a new complete sequence from TP that will form the basis of several future research projects: The operation was entirely successful and reached the planned depth of 200m with >99% recovery. The cores were transported to Germany, and are stored at the Bremen core repository. The cores have been logged and palaeomagnetic analyses are being planned. This means that we now have a complete core of the longest European Quaternary sediment sequence, spanning the last 1.35 million years. This will prove an invaluable resource, providing material for numerous projects over the next decade and the opportunity for the UK participation in them.



(2) To undertake a detailed palynological investigation of a glacial-interglacial (G-IG) cycle within the 41-kyr world: A detailed palynological investigation of a G-IG cycle, corresponding to Marine Isotope Stages (MIS) 24 and 25 (~ 915-960 thousand years ago [ka]) has been completed. This has revealed the presence of a long interglacial vegetation succession (~15 kyr), characterized by the sequential expansion of mediterranean, sub-mediterranean and mesophilous forest communities. This was followed by a second shorter and less extensive forest phase dominated by deciduous oaks. The IG-G transition and most of the glacial period were characterized by millennial-scale oscillations in vegetation cover. Of particular interest is the presence of a number of taxa, which are now extinct in Europe, but have extant relatives in Asia and North America. Compared to present, the palynological assemblage underscores the higher floristic diversity that characterized the early Pleistocene, especially before the onset of major glaciation at MIS 22. These results have important implications for understanding biodiversity changes and the record of species extinction.

In terms of the climatic signal, the pollen record reveals significant variations in mid-latitude hydrological balance. These bear a striking resemblance to high-resolution records from the North Atlantic (e.g. Ferretti et al. 2005), and reflect changes in the coupled ocean-air system on both orbital and millennial-timescales. This has important implications for monitoring the tempo of climate variability over the transition from the Early Pleistocene, dominated by 41 kyr glacial cycles, to the Middle Pleistocene (dominated by 100 kyr cycles).
Exploitation Route The core obtained will prove an invaluable resource, providing material for numerous projects over the next decade and the opportunity for the UK participation in them.
Sectors Environment
 
Description Tenaghi Philippon Consortium 
Organisation Goethe University Frankfurt
Country Germany 
Sector Academic/University 
PI Contribution Collaboration with Goethe University Frankfurt
Start Year 2008