Benthic foraminiferal assemblages of late Aptian early Albian black shale intervals in the Vocontian Basin, SE France

Benthic foraminiferal assemblages were analyzed from three black share inte rvals in the upper Aptian to lower Albian of the Vocontian Basin, SE France based on Q-mode principal component analyses. Variations in the distributi on patterns of benthic foraminifera around these events suggest differences in the origin of the black shales. Differences between faunas of bioturbar ed marry and laminated black shale facies have been observed in the Niveau Paquier, Oceanic Anoxic Event (OAE) Ib and Niveau Leenhardt. Here, the faun al composition and plankton/benthos ratios suggest eutrophic conditions dur ing the deposition of organic-rich sediments leading to black shales. No ma jor variations have been observed in black shares of the upper Aptian Nivea u Jacob. Benthic assemblages and low plankton/benthos ratios indicate mesot rophic conditions. Third order sea-level changes are believed to control ma inly the origin of the investigated black shale levels. (C) 1998 Academic P ress Limited.