Upper Cenozoic Organic-Rich Sequences Offshore and Onshore the South Aegean Sea

George Anastasakis

The upper Cenozoic sedimentary column of the south Aegean Sea is composed mostly of marine sediments which have been deposited after the Seravallian breakup of the south Aegean landmass.

Extensive submarine coring has revealed the frequent occurrence of Quaternary dark, organic-rich layers in the cores retrieved from water depths greater than 180 m. Moreover, deep-sea drilling (DSDP leg 42A) in the south Aegean basin recovered organic-rich layers as old as late Miocene.

Onshore the south Aegean Sea islands, organic-rich sediments are found at the north and south territories of the region, on Milos and Crete islands. Especially on the island of Crete and south of it, on the smaller islands of Gavdos and Koufonisi, these organic-rich sediments represent a considerable portion of the widespread upper Cenozoic sediments. Stratigraphically they cover the interval between upper Seravallian and lower Pleistocene.

The organic carbon content of all these mostly calcareous lithofacies, the so-called sapropels, ranges mostly between 0.5 and 6.5%. The most reliably chronostratigraphically correlated upper Pleistocene sapropels display similar compositional characteristics across the entire basin. Certain Pleistocene and older organic-rich layers contain increased proportions of siliceous tests. However the entire range of sapropels in the region (except those within the Messinian evaporites) can be described adequately by the same lithofacies association. To demonstrate this we compare the lower Tortonian Faneromeni Formation on Crete with the upper Quaternary sediments from the south Aegean Sea.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.