The last interglacial in Monticchio

Lago Grande di Monticchio is the larger of two adjacent maar lakes (Laghi di Monticchio) that formed ca. 132 ± 12 ka ago within a caldera on the western slopes of the Monte Vulture stratovolcano (1326 m a.s.l., 40°56'N, 15°35'E) in the Basilicata region of southern Italy. The lake surface of the eutrophic to hypertrophic lake is at 656 m a.s.l. A number of sediment cores have been retrieved since 1990 from different parts of the basin. Owing to improved coring techniques and expertise it was possible to successively penetrate deeper into the sediments. The first cores (B/D) taken in 1990 reached ca 52 m depth representing the last 76 kyrs, the second core (J) in 1994 has been extended by ca 20 m (the last 102 kyrs), and the latest cores (M/O) in 2000 of ca 102 m length reach the base of lacustrine sediments thus extending the sediment record back into the penultimate glaciation.

The chronology for the Monticchio record is based on multiple dating and independent of palynostratigraphic, marine isotope event or ice-core interstadial correlations. The backbone of the Monticchio time scale has been obtained from varve counting and robust sedimentation rate estimates based on measuring annual deposition rates in varved sections. This calendar year chronology is complemented by tephrochronology and a series of radioisotopic ages. A total of 345 tephra layers have been recorded in the entire record, the more distinctive of which have been labelled as 'marker tephras' (MT).

The present project aims particularly on rapid climate changes at the onset and end of the last interglacial and in the early glacial period. A multiproxy approach includes varve micro-facies, pollen, diatom, pigment, geochemical and palaeomagnetic techniques. Varve counting in combination with tephrochronology will provide a solid base for dating climatic fluctuations and determining their duration. In addition, the already existing varve-based time scale for the last 102 kyrs is under revision.

Partner: A. Lücke (stabile Isotope, FZ Jülich), J. R. M. Allen & B. Huntley (Pollenanalyse, University of Durham), P. Guilizzoni & A. Marchetto (Diatomeen, CNR Verbania Pallanza), B. Narcisi (tephrochronology, ENEA Roma)