CORRELATION BETWEEN PHOSPHATE CONTENT AND THE FORAMINIFERAL PLANKTON/BENTHOS RATIO IN CHALKS (LATE CRETACEOUS, NORTHERN ISRAEL): PALEOENVIRONMENTAL SIGNIFICANCE?

Two environments of phosphate deposition within carbonate rocks are distinguished on the basis of the relationship between phosphate content and the foraminiferal plankton/benthos (P/B) ratio in Senonian‐Maastrichtian chalks of Galilee, Northern Israel: (1) A normal marine environment of phosphate deposition during Santonian time. This environment is characterized by a low, normal P₂O₅ content and a positive correlation between P/B ratio and P₂O₅. Since it is assumed that the P/B ratio increases with the depth of the sea, it is suggested that the phosphate content in carbonate rocks can be employed as a bathymetric indicator. (2) An “abnormal” high phosphate deposition environment, found mainly in Upper Campanian sediments and related genetically to the economic phosphorite deposits in the Negev (Central Israel). The negative correlation of P/B ratio to P₂O₅ is caused by a shallowing of the sea and a continuous increase in P₂O₅, (e.g., by upwelling currents or a terrigenous supply) throughout the Upper Campanian.