|It is well accepted
these days that the earth’s long term climate is controlled by orbital
cycles. By understanding the past cyclic climate, we might ultimately be
able to make better predictions about future climate effects.
The past climate is
recorded by sediment layers accumulating at the bottom of the sea, like
an actors movements by a series of pictures on a motion film.
In such small scale environments,
climatic effects might have more impact than in large oceanic basins. On
the other hand, local effects, caused by e.g. tectonism or biological events,
may disturb the climate signal.
Sicily, for example, one can find the Punta di Maiata, a white cliff with
beautiful beige and grey layers, representing the precessional cycles (21.000-year
period) in the Mediterranean climate.
For a different record
of the past climate, one can look at continental sediments e.g. from an
ancient lake or river bed.
was started to study these effects by comparing continental and marine
sediment layers with exactly the same age.
Scientists from different
disciplines have worked closely together in this program.
research started in the brown coal mines of Ptolemais, Northern Greece.
it is proven that the black-and-white couplets represent precession, just
like the grey-beige layers in Punta di Maiata.
By correlating the
black-and-white layers to an astronomical variable (summer-insolation),
it is now possible to compare individual continental layers from Ptolemais
with simultaneously deposited marine layers from Sicily.
To study the recording
mechanism of climate in different sedimentary environments, a cross section
through different continental and marine palaeoenvironments is made.
|The Pliocene fluviatile-
lacustrine basin fill near Apolakkia on the island of Rhodes (Greece),
for example, has distinct grey layers that might or might not represent
has been used to examine this.
||The lower Pliocene
marine deposits on Milos, Greece consist of silty marls with intercalated
sapropels (the dark layers in the picture).
and biostratigraphy indicate an age beytween ~ 4.6 and 3.8 Ma.
of the sapropel pattern confirms these ages.
Pleistocene deposits in the Megalopolis Basin (Greece), lignite seams occur
every 100.000 years.
Smaller scale cycles
divide the main lignite seams into smaller beds that probably represent
Questions that have
been addressed in all these settings are on:
1. The age and timing
of the lithological layers, and determining a possible astronomically induced
2. Bed-to-bed correlation
with sequences from the marine realm, and with other continental lacustrine
sections (e.g. in Romania).
D.J.J., Krijgsman, W., Langereis, C.G., Cornée, J.-J., Duermeijer,
C.E. and van Vugt, N., 2007, Discrete Plio-Pleistocene phases of tilting
and counterclockwise rotation in the southeastern Aegean arc (Rhodos; Greece):
early Pliocene formation of the south Aegean left-lateral strike-slip system,
of the Geological Society of London 164, 1133-1144.
Marunteanu, M., Macalet, R., Meulenkamp, J.E., Van Vugt, N. (2006). Late
Miocene to Early Pliocene chronostratigraphic framework for the Dacic Basin,
Romania, Palaeogeogr. Palaeoclimatol. Palaeoecol., 238, 107-124.
Okuda, M., Van Vugt, N., Nagakawa,
T., Ikeya, M., Hayashida, A., Yasuda, Y. and Setoguchi, T. (2000). Palynological
evidence for the astronomical origin of lignite-detritus sequence in the
Middle Pleistocene Marathousa Member, Megalopolis, SW Greece. Earth
Planet. Sci. Lett., 201, 143-157.
Van Vugt, N., Langereis, C.G.
and Hilgen, F.J. (2001). Orbital forcing in Pliocene-Pleistocene Mediterranean
lacustrine deposits: dominant expression of eccentricity versus precession,
Palaeoclimatol. Palaeoecol., 172, 193-205.
Van Vugt, N. (2000). Orbital forcing
in late Neogene lacustrine basins from the Mediterranean. A magnetostratigraphic
and cyclostratigraphic study. (PhD thesis, Utrecht University), Geologica
Ultraiectina, 189, 167 pp. [PDF
entire thesis or link
to individual chapters]
Steenbrink, J., Van Vugt,
N., Kloosterboer-Van Hoeve, M.L. and Hilgen, F.J. (2000). Refinement of
the Messinian APTS from sedimentary cycle patterns in the lacustrine Lava
section (Servia Basin, NW Greece), Earth Planet. Sci. Lett., 181,
Hilgen, F.J., Abdul Aziz, H.,
Krijgsman, W., Langereis, C.G., Lourens, L.J., Meulenkamp, J.E., Raffi,
I., Steenbrink, J., Turco, E., Van Vugt, N., Wijbrans, J.R. and Zachariasse,
W.J. (1999). Present status of the astronomical (polarity) time-scale for
the Mediterranean late Neogene, Phil. Trans. R. Soc. Lond. A, 357,
Steenbrink, J., Van Vugt, N.,
Hilgen, F.J., Wijbrans, J.R. and Meulenkamp, J.E. (1999). Sedimentary cycles
and volcanic ash beds in the lower Pliocene lacustrine succession of Ptolemais
(NW Greece): Discrepancy between 40Ar/39Ar and astronomical
Palaeogeogr. Palaeoclimatol. Palaeoecol. 152, 283-303.
Duermeijer, C.E., Van Vugt, N.,
Langereis, C.G., Meulenkamp, J.E. and Zachariasse, W.J. (1998). A major
late Tortonian rotation phase of the Crotone Basin using AMS as tectonic
tilt correction and timing of the opening of the Tyrrhenian Basin, Tectonophysics,
Van Vugt, N., Steenbrink, J.,
Langereis, C.G., Hilgen, F.J. and Meulenkamp, J.E. (1998). Sedimentary
cycles in the early Pliocene lacustrine sediments of Ptolemais (NW Greece)
correlated to insolation and to the marine Rossello section (S. Italy),
Planet. Sci. Lett.,