Neogene sapropels in the Mediterranean: a review

For 50 years the existence of sapropels (organic-carbon-rich sediments) dep osited within Plio-Pleistocene sediments of the Mediterranean Sea has been known. Initially, research concentrated on material recovered in relatively short gravity/piston cores taken from the eastern basins where sequences w ere found to be well developed/preserved and had extensive spatial coverage . In the main, previous studies concentrated upon establishing a workable s tratigraphy, spatial correlation of individual layers and determining the p robable depositional mechanisms. However, despite a plethora of research pa pers, some issues still remain unresolved. This is in part due to a lack of agreement between investigators; sampling and analytical short comings, re stricted sample size and the fact that, in many instances, like was not bei ng compared with like. Recently, the limit of sapropels in the western basi n has been further extended. As a result, the palaeoceanographic/palaeoclim ate models which had previously been developed for deposition of sapropels in the eastern basin have been modified. Most recently, strong links have b een established between astronomical cyclicity and sapropel formation. This review paper provides a summary of sapropel research to date, and ongoing sapropel research in the Mediterranean, some of which appears in this thema tic issue of Marine Geology. It is fitting that this thematic issue of Mari ne Geology be dedicated to the memory of Colette Vergnaud-Grazzini and Rob Kidd who in many ways helped to initiate the resurgence in sapropel studies in the 1970s in the Mediterranean -perhaps in 50 more years we will know a ll of the answers! (C) 1999 Elsevier Science B.V. All rights reserved.