HR: 0830h
AN: PP11A-0218    [PDF]
TI: Otolith Chemistry During Deposition of Sapropel S5 in the Mediterranean
AU: * Reichart, G
EM: greichart@awi-bremerhaven.de
AF: Carbon Group Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, D-27570 Germany
AU: * Reichart, G
EM: greichart@awi-bremerhaven.de
AF: Department of Geochemistry Faculty of Geosciences Utrecht University, P.O. Box 80021, utrecht, NL-3508TA Netherlands
AU: Jorissen, F
EM: jorissen@sciences.univ-angers.fr
AF: Laboratory for the Study of Recent and Fossil Bio-Indicators, Angers University, 2 Boulevard Lavoisier, BruxellesAngers, B-10004904 Belgium
AU: Nolf, D
EM: Dirk.Nolf@naturalsciences.be
AF: Institut royal des Sciences naturelles de Belgique, rue Vautier 29, Southampton Bruxelle, B-1000 Belgium
AU: Rohling, E
EM: E.Rohling@soc.soton.ac.uk
AF: Southampton Oceanography Centre SOC), European Way, Southampton, SO14 3ZH United Kingdom
AU: Mason, P
EM: mason@geo.uu.nl
AF: Department of Petrology Faculty of Geosciences Utrecht University, P.O. Box 80021, Utrecht, NL-3508TA Netherlands
AB: Geological evidence for periodical low oxygen bottom water conditions in the Mediterranean is known since the early sixties. Sediment layers deposited during these conditions are enriched in organic matter and known as sapropels. After more than 40 years of intensive study, controversies still exist over the mechanisms of their formation. Whereas some authors believe the water column to have been anoxic, possibly even into the photic zone, others argue that only the sediment water interface may have been oxygen depleted. According to the latter theory the higher organic carbon content in sapropelic sediments is attributed primarily to increased sea surface productivity. The proponents of the water column disoxia argue that a lower organic matter degradation rate under oxygen depleted conditions caused the higher organic matter contents. One of the reasons for this long standing controversy is that non of the methods used to reconstruct the paleoenvironment during sapropel times gives direct information on what happened in the water column. Proxies used to reconstruct bottom water conditions are valid only at the sediment water interface and reconstructed low oxygen concentrations can also be explained by a dysoxic blanket covering the sea floor. To resolve this issue information concerning higher parts of the water column is needed. We present such data for sapropel S5 found in a core from the Ionian Sea. Ten centimeter from the base of the sapropel a remarkably well preserved fish specimen was discovered parallel to the lamination of the sapropel. The fish specimen was determined as Myctophum punctatum, a mesopelagic lantern fish, and still contained both its otholiths. Over the complete depth interval corresponding to sapropel S5 several other otoliths of mesopelagic fish species were found. To reconstruct water column properties before, during and after the deposition of sapropel S5, we quantified the trace metals incorporated in the fish otoliths, using depth resolved Laser Ablation Inductively Coupled Mass Spectrometry.
DE: 1050 Marine geochemistry (4835, 4850)
DE: 1065 Trace elements (3670)
DE: 3030 Micropaleontology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting