New Cretaceous Index Foraminifera from Northern Alaska 



By Helen Tappan ' 



Introduction 



STUDY OF ROCK SAMPLES from Naval Petroleum 

 Reserve No. 4, northern Alaska, over a period of about 

 8 years has shown that among the microfossils occurmg 

 in the Cretaceous strata are several new species which 

 because of their stratigraphic importance should be 

 described. Possibly because the strata here considered 

 are of a facies distinct from that of the better known 

 Cretaceous horizons (Tappan, 1951, pp. 3-4), certain 

 of these new species do not fit into any previously 

 described genera and hence new genera are here 

 described to include them. 



This paper describes 3 new genera and 34 new 

 species, two-thirds of which are agglutinated forms. 

 The calcareous species described are in large part 

 Nodosariidae and rotaliform genera. 



Some reports that are in press or in preparation by 

 other members of the U. S. Geological Survey describe 

 the stratigraphy and structure of northern Alaska as 

 deduced from field study and from information derived 



I U. S. Geological Survey and Research Associate, Smithsonian Institution. Pub- 

 lication authorized by the Director, U. S. Geological Survey. 



by drilling in connection with the petroleum explor- 

 ation in this region. Further information on the 

 foraminiferal zonation in the surface and subsurface 

 material, as well as foraminiferal range charts for the 

 various wells, is presented in those reports. 



The Foraminifera discussed in this paper have been 

 obtained from rocks ranging from Neocomian to 

 Campanian in age. A correlation chart (text-fig. 29) 

 shows how these Alaskan rocks are interrelated and 

 how they fit into the European time scale. 



All type specimens of the species described in the 

 presedt paper are deposited in the U. S. National 

 Museima. 



Acknowledgments 



The writer is indebted to many of the geologists of 

 the U. S. Geological Survey for collecting the samples 

 from which these Foraminifera were obtained and for 

 supplying the necessary geographic and stratigraphic 

 data. The field geologists are acknowledged by name 

 under the locality data in the descriptions of species. 



No known outcrop 



Prtdominantly nonmarlne 



Figure 29. — Cretaceous strata of Northern Alaska and correlation with European time scale (modified after Gryc and others, 19S6, and Imlay 

 and Reeside, 1954). 



201 



