GEOCHEMICAL SUBDIVISION AND CORRELATION OF CLAY-RICH BEDS IN TURONIANSEDIMENTS OF NORTHERN GERMANY

Thin, clay-rich beds form a key component of the lithostratigraphic sc heme established for Middle and Upper Turonian sediments in northern G ermany. Previously, using limited petrographic evidence, clay-rich bed s across much of this region have been classified as either containing altered volcanic ash (bentonites) or detrital clays. This paper demon strates that the use of rare-earth element (REE) data enables a rapid and reliable subdivision of clay-rich beds into those composed of bent onitic clays and those composed of detrital clays. Application of this method to the Lower Saxony region of northern Germany demonstrates th at four bentonites (T-C, T-D1, T-E and T-F) and a number of detrital b eds can be reliably identified and correlated. Three beds previously p roposed to be bentonites are reinterpreted as being composed of detrit al clays (T-O, T-D2 and T-G) and a revision of the stratigraphic nomen clature is proposed. Analysis of clay-rich beds from the Munster Basin demonstrates that it is possible to correlate individual bentonites a nd detrital beds between Lower Saxony and the Munster Basin, and betwe en shallow and deep water facies.