ELSEVIER Palaeogeography, Palaeoclimatology, Palaeoecology 135 ( 1997) I --25 Pliocene sapropels in the northern Adriatic area: chronology and paleoenvironmental significance D. Rio a,*, J.E.T. Channel1 b, R. Bertoldi ‘, M.S. Poli a, P.P. Vergerio a, I. Raffi d, R. Sprovieri e, R.C. Thunell f a Department zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Geology, Paleontology and Geophysics, University of Padova, I-35137 Padova, Italy b Department of Geology, University of Floridu, Gainesville, FL 32611, USA ’ Department of Evolutive and Functional Biology, University of Parma, I-43100 Parma, Italy d Faculty of Science, University “G. d’iinnunzio”, I-66013 Chieti, Italy e Department of Geology und Geodesy, University of Palermo, I-90100 Palermo, Italy ’ Department of’ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Geological Sciences, University of South Carolina, Columbia, SC 29208, USA Received 11 June 1996; accepted 23 January 1997 Abstract A detailed stratigraphic and paleoenvironmental study was carried out on a marine section from the Marecchia Valley in the Northern Apennines. The section consists predominantly of deep-water hemipelagic clays intercalated with 15 thick, laminated sapropels (M 1 -M 15). Based on biostratigraphic (calcareous nannoplankton and planktonic foraminifera) and magnetostratigraphic results, the Marecchia Valley section is interpreted as being middle to late Pliocene in age, extending from the upper part of the Gauss Chron to the lower part of the Matuyama Chron. The high resolution stratigraphy allows us to correlate, for the first time, these northern Italian sapropels with sapropels previously described from the southern Mediterranean region. Based on this long-distance correlation, we conclude that the sapropels from throughout the Mediterranean have a common origin that is related to astronomical forcing. Specifically, these Pliocene sapropels are related to wet climatic conditions in the Mediterranean and surrounding borderlands and are linked to precession minima which are times of increased precipitation. This is consistent with our pollen data. which indicate that very wet conditions existed during sapropel formation. Additionally, the planktonic and benthic foraminiferal assemblages associated with sapropels indicate that these were periods marked by high surface productivity and low bottom water oxygen. 0 1997 Elsevier Science B.V. Keywords: stratigraphy; Pliocene: Mediterranean region; paleoclimatology 1. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Introduction The Neogene-Quaternary marine stratigraphy exposed on land in the Mediterranean region has * Corresponding author. E-mail: domenico@dmp.unipd.it 0031-0182/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. PII SOO31-0182(97)00027-S been of interest to Earth scientists since last century and has become the reference standard for the chronostratigraphy of this time interval (Berggren, 1971; Rio et al., 1991; Cita et al., in press). Recently, study of the Mediterranean Pliocene record has been given impetus by the presence of proxy indicators of the Earth climatic system which