02236nas a2200337   4500000000100000000000100001008004100002260000800043653006800051653005900119653001400178653001300192653001700205653007300222653004900295653001400344653001700358653004000375653001300415653002300428653001300451100001700464700001500481700000900496245010300505856004300608300001100651490000700662520121500669020001401884       2006                            d  bAGU10a4802 Oceanography: Biological and Chemical: Anoxic environments10a4815 Oceanography: Biological and Chemical: Ecosystems10astructure10adynamics10aand modeling10a4850 Oceanography: Biological and Chemical: Marine organic chemistry10a4912 Paleoceanography: Biogeochemical cycles10aprocesses10aand modeling10a4950 Paleoceanography: Paleoecology10aisotopes10aorganic biomarkers10asapropel1 aE.J. Rohling1 aE. Hopmans1 aJ. e00aWater column dynamics during the last interglacial anoxic event in the Mediterranean (sapropel S5)  uhttp://dx.doi.org/10.1029/2005PA001237  aPA20180 v213 aMarine organic-rich sediments are important for long-term carbon sequestration, and as a source of fossil hydrocarbons, but the processes underlying their formation remain elusive. We present a multiproxy analysis of a relatively recent, well-preserved Mediterranean organic-rich deposit known as sapropel S5, which formed 124\textendash119 thousand years ago (ka B.P., where B.P. references year 1950). Combining planktonic foraminiferal abundance records with stable isotope and organic biomarker data, we reconcile the apparently contradicting coexistence of deep-dwelling foraminiferal faunas with green sulphur bacteria that indicate photic zone euxinia. S5 started with a rapid freshwater-induced increase of density stratification that inhibited vertical mixing and deepwater ventilation. Through the first 900 years, anoxic to euxinic deepwater conditions developed and extended up to roughly 200 m water depth. Then followed a 4100-year period of variability in the depth/intensity of winter mixing with a roughly 1400-year periodicity, coincident with fluctuations in water column stability. S5 terminated with a marked decrease in density stratification and consequently renewed convective overturn.  a0883-8305