摘要：The lowest of the five bentonites in the German Turonian tephrostratigraphic framework, TC, can be correlated for the first time from the Rotpläner (red limestone) standard section in the Söhlde-Loges Quarry (Lower Saxony) to highly condensed, near-swell successions of the nearby Woltwiesche Quarry and the Hoppenstedt Quarry (Saxony-Anhalt). A second bentonite, TC2, only recently recognised at Söhlde-Loges, is now identified at Woltwiesche and in the distal/expanded white limestone successions of the Salzgitter-Salder Quarry and the Flöteberg road-cutting (both Lower Saxony). TC2 can easily be located a short distance above a major lithofacies change (herein termed the Basal Upper Turonian Facies Turnover), making it an isochronous marker permitting correlation between condensed nearswell and expanded basinal sections. On this basis, a bentonite, previously identified as TC at Hoppenstedt must be reassigned as TC2. Examination of the major, trace, and rare-earth element (REE) data of all the five bentonites identified in Lower Saxony and Saxony-Anhalt shows that it is possible to discriminate between them to some extent. Bentonites TC and TC2 are geochemically similar and separable from TD, which is itself distinct from TE and TF.
关键词：Bentonite;Tuff;Upper Cretaceous;Turonian;Lower Saxony;Saxony-Anhalt;Rare-earth elements;Trace elements
