Some Planktonic Foraminifera of the Type Danian and Their 

 Stratigraphic Importance 



By J. C. Troelsen ' 

 Introduction 



BEFORE DISCUSSING THE biostratigraphy of the Danian 

 stage, it may be well to give a brief description of 

 the development of the stage in its type area (see 

 text-fig. 22). The Danian stage was proposed by E. 

 Desor (1846, p. 181) for the limestone deposits which 

 in Denmark lie above the Maestrichtian White Chalk. 

 The type localities are Stevns Klint and Fakse 

 (=Faxe=Fax6e), both of which are located some 40 

 miles south-southwest of Copenhagen in eastern 

 Denmark. The island of Saltholm, east of Copenhagen, 

 is sometimes cited as the tjrpe locality of the Danian, 

 but this interpretation of Desor's text seems to be 

 untenable. 



The Danian deposits are known from a belt that 

 stretches in a northwest-southeasterly direction across 

 Denmark and southern Sweden. The belt (including 

 deposits lying under the Cenozoic sediments) is now 

 about 100 miles wide, and there is evidence to suggest 

 that this is not far from the original width. The 

 Danian sediments were thus laid down in a narrow 

 sound, whose southeastern extension may be found in 

 Poland (Pozaryska, 1954). Farther to the southeast, 

 the sound may have been connected with the sea in 

 which the Danian sediments of the Crimean Peninsula 

 were laid down (Bettenstaedt and Wicher, 1956, p. 515). 



The Danian deposits in the type area may be char- 

 acterized as very pure limestones, which range from 

 calcilutites to calcirudites. Many of them may also 

 be classified as coccolithic limestones, bryozoan reef 

 limestones or coral reef limestones. The almost 

 complete absence of terrigenous detritus, which is so 

 marked a character not only of the Danian limestones 

 but also of the imderlying White Chalk, is probably 

 connected with the peneplanation of the land and the 

 consequent low gradient of the rivers in late Cretaceous 

 and early Cenozoic times. Bailey and Weir (1939, 

 pp. 462—463) infer the probability of arid conditions in 

 northwest Europe in this period of time. The latter 

 theory finds support in the fact that planktonic 

 Foraminifera occurred, although in varying numbers, 

 in the narrow Danian sea. Examples from Recent seas 

 show that Globigerinae rarely enter sounds or embay- 

 ments unless the salinity of the water is high. We may 

 therefore assume that but little fresh water flowed into 



» Curator of Invertebrate Fo.ssils, Mineralogisk-Geologisk Museum, Copenhagen, 

 Denmark. 



_p^B- 



liHiJ^lllii 



II lllll 



'ill I I II II 



ili|iiiiiiii;i 

 ^'i II II 



I nil I 



III' 

 , lllll 

 (ill 1 1 11 



:<<^M,i I 

 ;|i|i'iii 



iiii 



GEOLOGIC MAP OF DENMARK 

 THE PRE-PLEhSTOCENE ROCKS 



Sllurton a OrdovlcioM 

 SFfurlan, Ordovlcian 



I ' I eosalt 





EZ3 



Rha«tlc-J 



Olifloccn* 



iHtODO* SOMOifmi 



Figure 22. — Geological map of Denmark and south Sweden (by Th. 

 Sorgenfrei), showing the location of the exposures mentioned in the 

 text. 



the Danian sea (see also Said, 1950). The regular 

 occurrence of benthonic organisms in all parts of the 

 Danian stage further shows that the bottom waters 

 must have been well aerated. 



125 



