The Cenomanian-Turonian Boundary Event: sedimentary, faunal and geochemical criteria developed from stratigraphic studies in NW- Germany.

'Oceanic Anoxic Events' are time envelopes of increased organic carbon burial, rich in carbon-12 by biogenic fractionation, accompanied by a strong positive shift of the DELTA carbon-13 values of the carbonate in the late Cenomanian-early Turonian. The return to lower values reflects erosion and reoxidation of the carbon-12 rich organic material during times of tectonic activity. The evolution and diversity of planktonic foraminifera is closely bound to the event. The diversity is inversely correlated to DELTA carbon-13 and the occurrence of distinct species in the stratigraphical record provides evidence of changes of the Mid- Water Oxygen Minimum Zone.-Authors