The sapropel record of the eastern Mediterranean Sea
óresults of Ocean Drilling Program Leg 160

Kay-Christian Emeis^a, Tatsuhiko Sakamoto^b, Rolf Wehausen^c, Hans-Jürgen Brumsack^c

a Institut für Ostseeforschung Warnemünde, Seestrasse 15, D-18119 Warnemünde, Germany
b Department of Earth and Planetary Sciences, Hokkaido University, Sapporo, Japan
c ICBM, University of Oldenburg, Oldenburg, Germany

Abstract

Research on sediments recovered during Ocean Drilling Leg 160 has concentrated on two issues: the first concerned
the stratigraphy of sapropel formation, the second was oriented to clarify specific processes that explain sapropel
origin. Progress has been made in the construction of stratigraphic composites out of sedimentary sequences from
individual holes at each of the palaeoceanographic sites. On the composites, initial work has resulted in the
establishment of high-resolution and intermediate-resolution stratigraphies for three sites (963, 964, 967); correlation
of sedimentary cycles to astronomical (insolation) cycles extends the stratigraphies to Sites 969 and 966. The sapropel
occurrences in the marine and land sequences over the entire Eastern Mediterranean are correlated; with the resolution
that can be obtained from isotope studies, groups of sapropels occurred simultaneously over the entire basin. In
detail, however, the temporal and facies patterns of sapropel sequences differ between individual sites and depositional
basins. The differences may be related to effects of water depth, diagenesis, and post-depositional tectonic attenuation
of sequences. Studies on the geochemistry and facies of sapropels agree that anoxic conditions favoured preservation
of organic matter in sapropels, caused the enrichment of trace metals associated with sapropels, and helped to preserve
primary sedimentary structures. Besides, all evidence is consistent with elevated fluxes of organic matter and associated
elements during sapropel events.