Lenz, O. K. ; Wilde, V. ; Riegel, W. (2011)
A unique record of cenntennial and millenial scale interaction of climate and vegetation in the Middle Eocene maar lake of Messel, Germany.
In: 5th International Limnogeology Congress 2011 / Programme and Abstract volume
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

The Middle Eocene oil shale of the Messel pit near Darmstadt (State of Hessen, Germany) is worldwide known for an exceptionally well preserved assemblage of fossils. A continuous core proved that the finely laminated oil shale was deposited in a meromictic maar lake which formed 47.8 +- 0.2 Ma ago. The core included a complete reference section of the Middle Eocene lake deposits (Messel Formation) thus representing a unique climate archive for the early Middle Eocene in Central Europe. The classical “Messel oil shale” is characterized by a continuous succession of finely laminated bituminous claystones. The lamination was caused by annual algal blooms forming light layers that were superimposed on the terrigenous background sedimentation as represented by dark layers. An average sedimentation rate of 0.14 mm/yr has been calculated from the lamination, but there are short-term fluctuations in varve thickness which can be attributed to an “Eocene ENSO”. Palynological analysis of the oil shale, which represents a time interval of ~640 kyr, with a distance of individual samples of 20 cm (about 1400 years /interval), provides an insight into the dynamics of a paratropical climax vegetation during the Middle Eocene greenhouse climate. We were able to show that short-term fluctuations in the frequency of individual taxa or pollen assemblages reflect periodicities in the range of the Milankovitch frequency band. This implies that orbital control of climate change was sufficient to impose quantitative changes in the composition of the terrestrial vegetation within the range of eccentricity, obliquity as well as long and short precession. To include the frequency range between fluctuations within the biennial to decadal ENSO-scale band and the Milankovitch frequency band, 10 m of the section were studied in 10 cm intervals (about 700 years). Furthermore, 1 m of the oil shale was examined in 1 cm intervals with a temporal resolution of ~70 years. These time series of ~70 kyr resp. ~7000 years are sufficient to detect any changes in vegetation and climate on the centennial and millennial-scale. Time series analyses of the pollen data from Messel now provide evidence of climate variability in the sub-Milankovitch frequency band. The major palynomorph elements show periodicities of 200-300 yr, 550-700 yr, ~1200 yr and ~2000 yr comparable, for instance, to De Vriess/Suess (~200 yr), Bond (~1500 yr) and Dansgaard-Oeschger (1470 yr) events of the Quaternary as well as to the millenial-scale variability of ENSO activity in the Holocene (1500/2000 yr). Thus, the recognition of these fluctuations and oscillations in the greenhouse climate of the Middle Eocene are strong evidence that these climate events are not restricted to the Quaternary.

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