A NEW NANNOFOSSIL ZONATION SCHEME FOR TilE BOREAL CAMPANIAN
Jackie Bumett, Dept. of Geological Sciences, University College London.
IN1RODUCTION
In 1975, the Institute of Geological Sciences (now the British Geological Survey) drilled theTrunch Borehole (located in north-eastern Norfolk, eastern England) in order to sample ascomplete a section of the Upper Cretaceous on the British mainland as possible, to be used asa standard section for correlation purposes in the northern English and southern North Sea area
(Gallois & Morter, 1975). Approximately 220m of the borehole are Campanian in age.
As part of an extensive correlation project between macrofossil and nannofossil zonation
schemes, approximately 260m of Campanian chalk from the Lagerdorf and Kronsmoor Quarries,
located near Hamburg, north-western Germany, were examined for their nannofloral content.
It became apparent that the Campanian nannofloras of the two areas are comparable, bothcontaining a number of Boreal-restricted forms, with a number of characteristically Tethyanzonal marker species being absent. The application of Sissingh's (1977, 1978) standard numbered
zonation scheme, supplemented by Perch-Nielsen's nannofossil event observations (1979, 1983,
summarised in Bolli et al., 1985) fails between NF Zones CC18 and CC22B, due to the non-,or very rare and stratigraphically sporadic occurrences of Bukryaster hayii, Ceratolithoides
verbeekii, Marthasterites furcatus spp., Ceratolithoides aculeus, Quadmm sissinghii, Quadmm
trifuium and Lithastrinus grillii. Additionally, in northern chalks, where calcitic overgrowth on
nannofossil specimens tends to obscure fine detail, it is sometimes very difficult to differentiate
between Reinhardtites levis and R. anthophoms when routinely dating by light-microscope, thus
the identification of the bases of standard NF Zones CC22C and CC23A can be less than
precise.
Correlation between the identifiable Campanian NF zones of the Trunch Borehole and theGerman quarries revealed a number of interstitial nannofloral events which bridge the gap in
Sissingh's (1977) scheme and provide a workable alternative for the Boreal region, possibly
including the North Sea area. The new zones are fitted within the framework of Sissingh's
scheme (but are distinguished from his zones by the prefix B, for Boreal), in order that theirrelative positions, with respect to the standard cosmopolitan events, are continuous. Integrated
macro- and microbiostratigraphical data on the sections involved will be published elsewhere.
NANNOFOSSIL BIOZONATIONNew NF Zones CC/B18 to CC/B22 replace Sissingh's (1977) NF Zones CC18 to CC22, whilst
Sissingh's Zone CC17 is divided into Subzones CC/B 17a, CC!B 17b and CC/B 17c, and his
Subzone CC23A is subdivided into CC/B23Aa, CC/B23Ab and CC/B23Ac, herein. The zones
are defined in Appendix 2.
Figure 1 shows the correlation between the English and German nannofossil events used todefine the new (sub-)zones. The stage and macrofossil zonation of the Trunch Borehole isattributed to Morter (1984, unpublished B.G.S. data). Stage and macrofossil data was taken from
Schulz et al. (1984) for the German material. Age definitions for the new (sub-)zones are
estimated from the German scale, as this has a more refined macrofossil zonation control thanhas the Trunch Borehole.
Sissingh's (1977) standard nannofossil zones are correlated with the new Boreal zones and,for interest, with the Campanian part o.f the Sr-isotope curve of McArthur et al. (in press:
based on the Trunch Borehole) in Figure 2. A high degree of age-refinement was not possible
in the Trunch Borehole, with which to correlate the Sr-isotope curve. From the correlation of
nannofossil data between England and Germany, more refined age-assignments can beextrapolated for the curve. A nannofossil species index is given in Appendix 1.
DISCUSSION
A number of industry-orientated Boreal nannofossil zonation schemes have been produced for
the Late Cretaceous, based on North Sea well samples. These schemes suffer from having little,
or no, biostratigraphical control with- which to correlate onshore material, and from thenannofloras being generally much less well preserved than in onshore material. Mortimer (1987)
produced a Cenomanian to Maastrichtian scheme for the southern Norwegian and Danish
North Sea area, and equated his zones to Sissingh's (1977) scheme by extrapolation. In
INA Newsletter 12/3 - 1990

67

particular, he divided the uppermost Hod and lowermost Tor Formations (representing theLower and Upper Campanian, respectively) into four nannofossil zones, based on the LOs(=
first downhole occurrences) of Orastmm campanensis, Helicolithus trabeculatus, Cylindralithus
asymmetricus ( = C. biarcus?), Broinsonia enormis and Phanulithus ( =Calculites) obscurus. In mystudy, 0. campanensis was found not to have a correlatable LO between Germany and England,
whilst H trabeculatus, C.biarcus and B. enormis were found to range beyond the limits definedby Mortimer (probably due to preservation). Varol (1989) used Mortimer's (1987) scheme withsome additional events, one of which (the LO of Tortolithus caistorensis) approximates to thefindings of this study.
CONCLUSIONS
It is hoped that the extensive geographical application of this new biozonation already evincedby this study is applicable to the North Sea area (although I appreciate that the new scheme
uses mostly FOs, whereas LOs are of more use, industrially), where correlation of nannofloral
events with macrofossil/stage data would prove useful for industrial and research purposes.
ACKNOWLEDGEMENTS
The nannofloras of the Trunch Borehole were first investigated as part of a Ph.D. study fundedby the N.E.R.C. in collaboration with B.P. Research plc., the material kindly being madeavailable by the B.G.S .. Supplementary investigation of Trunch Borehole material and of theGerman material was undertaken as part of a post-doctoral study, funded by the N.E.R.C.
(Research Grant No. GR3/6767). Collection of the German material was aided by Dr. Joachim
Schonfeld (Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover), Prof. Jake Hancock,
Mr. Ray Parrish and Mr. Graeme Burnett, permission to sample most kindly being givenby the Alsen-Breitenburg Cement Company. Thank yous to Dr. K. von Salis Perch-Nielsen
and Dr. AR. Lord for critically assessing the text.
REFERENCES
Gallois R.W. & Morter, AA 1975: East Anglia and South-East England District. Mundesley (132) sheet. Trunch
Borehole (TG 2933 3455).1.G.S. boreholes 1975,Inst. GeoL Sci. Rep. 16/10, 8-10.
McArthur J.M., Thirlwall M. F., Kennedy W J., Burnett, J.A, Gale, AS., Lord, AR. & Mattey, D. 1990: A Strontium
Isotope Stratigraphy for the Upper Cretaceous. Nature, in press.
Mortimer C.P. 1987: Upper Cretaceous Calcareous Nannofossil Biostratigraphy of the Southern Norwegian andDanish North Sea Area. Abh. Geol B.-A., 39, 143-175.
Perch-Nielsen K. 1979: Calcareous nannofossils from the Cretaceous between the North Sea and the Mediterranean.
JUGS Series A, 6, 223-272.
Perch-Nielsen K. 1983: Recognition of Cretaceous stage boundaries by means of calcareous nannofossils. In:
Birkelund T., Bromley R., Christensen W.K., Hakansson E. & Surlyk F. (Eds.). "Abstracts - Symposium on
Cretaceous Stage Boundaries, Copenhagen, October 18-21, 1983", 152-156.
Perch-Nielsen K. 1985: Mesozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. & Perch-Nielsen, K.
"Plankton Stratigraphy", 329-426.
Schulz M.-G., Ernst G., Ernst H. & Schmid F. 1984: Coniacian to Maastrichtian stage boundaries in the standard
section for the Upper Cretaceous white chalk of NW Germany (Lagerdorf-Kronsmoor-Hemmoor): Definitions andproposals. BulL geoL Soc. Denmark, 33(l!l), 203-215.
Sissingh W. 1977: Biostratigraphy of Cretaceous calcareous nannoplankton. GeoL Mijnbouw, 56(1), 37-65.
Sissingh W. 1978: Microfossil biostratigraphy and stage-stratotypes of the Cretaceous. GeoL Mijnbouw, 57(3),433-440.
Varol 0. 1989: Quantitative analysis of the Arkhangelskiella cymbiformis Group and Biostratigraphic usefulness in
the North Sea Area. J. MicropalaeontoL, 8(2), 131-134.

APPENDIX 1: NANNOFOSSIL TAXONOMICAL INDEX
References for, and illustrations of, these species can be found in Perch-Nielsen (1985).

Biscutum dissimilis Wind & Wise in Wise & Wind, 1977
B. magnum Wind & Wise in Wise & Wind, 1977
Broinsonia parca (Stradner, 1963) Bukry, 1969
Calculites obscurus (Deflandre, 1959) Prins & Sissingh in Sissingh, 1977
Heteromarginatus bugensis (Gorka, 1963) Crux in Crux et al., 1982
Monomarginatus quaternarius Wind & Wise in Wise & Wind, 1977
Neocrepidolithus cohenii (Perch-Nielsen, 1968) Perch-Nielsen, 1984a
Orastrum campanensis (Cepek, 1970) Wind & Wise in Wise & Wind, 1977
Prediscosphaera stoveri (Perch-Nielsen, 1968) Shafik & Stradner, 1971
Reinhardtites anthophorus (Deflandre, 1959) Perch-Nielsen, 1968
R. levis Prins & Sissingh in Sissingh, 1977
Staurolithites mielnicensis (Gorka, 1957) Perch-Nielsen, 1968sensu Crux in Lord, 1982

68

INA Newsletter 12/3 - 1990

Tortolithus caistorensis Crux in Crux et al., 1982
Tranolithus orionatus (Reinhardt, 1966a) Reinhardt, 1966

APPENDIX 2: FORMAL DESCRIPTION OF ZONESCALCULITES OBSCURUS PARTIAL RANGE (P.R.) ZONE (CC17)
Sissingh (1977).
Definition: FO of Calculites obscurus to the FO of Broinsonia parea.
Age: Late Santonian to early Campanian.
CALCULITES OBSCURUS P.R. SUBZONE (CC/B 17a)
New subzone
Definition: FO of Calculites obscurus to the FO of Orastrum campanensis.
Age: Late late Santonian to early early Campanian. Type locality: Lagerdorf Quarry.
ORASTRUMCAMPANENSISP.R. SUBZONE (CC/B17b)
New subzone
Definition: FO Orastrum campanensis to the FO of Biscutum magnum.
Age: Early early Campanian. Type locality: Lagerdorf Quarry.
BISCUTUMMAGNUMP.R. SUBZONE(CC/B17c)
New subzone
Definition: FO of Biscutum magnum to the FO of Broinsonia parca.
Age: Early early Campanian. Type locality: Lagerdorf Quarry.
BROINSONIAPARCA P.R. ZONE (CC/B18)
New zone
Definition: FO of Broinsonia parca to the FO of Staurolithites mielnicensis.
Age: Early early Campanian. Type locality: Lagerdorf Quarry.
STAUROLITHITESMIELNICENSISP.R. ZONE (CC/B19)
New zone
Definition: FO of Staurolithites mielnicensis to the FO of Monomarginatus quaternarius.
Age: Early to middle early Campanian.
Type locality: Lagerdorf Quarry.
MONOMARGINATUSQUATERNARIUSP.R. ZONE (CC/B20)
New zone
Definition: FO of Monomarginatus quaternarius to the FO of Reinhardtites levis.
Age: Middle early to early late Campanian. Type locality: Lagerdorf Quarry.
Remarks: Prediscosphaerastoveri FOs around the CC22B/CC22C boundary, probably within this zone, and may be
useful in cases where the FO of Reinhardtites levis is difficult to distinguish.
BISCUTUMDISSIMILISP.R. ZONE (CC/B21)
New zone
Definition: FO of Reinhardtites levis to the LO of Biscutum dissimilis.
Age: Early late Campanian. Type locality: Lagerdorf Quarry.
EIFFELLITHUSEXIMIUS P.R. ZONE (CC/B22)
New subzone
Definition: LO of Biscutum dissimilis to the LO of Reinhardtites anthophoms (or LO E. eximizlS).
Age: Early to late late Campanian. Type locality: Lagerdorf and Kronsmoor Quarries.
TRANOLITHUSORIONATUS (= PHACELOSUS) P.R. ZONE (CC23)
Sissingh 1977
Definition: LO of Reinhardtites anthophorus to the LO of Tranolithus orionatus.
Age: Latest Campanian to early Maastrichtian.
TRANOLITHUSORIONATUS P.R. SUBZONE (CC23A)
Perch-Nielsen 1985
Definition: LO Reinhardtites anthophorus to the LO of Broinsonia parea.
Author: Figured but not defined in Perch-Nielsen (in Bolli et al., 1985).
Age: Latest Campanian to earliest Maastrichtian.
HETEROMARGINATUSBUGENSIS P.R. SUB-SUBZONE (CC/B23Aa)
New sub-subzone
Definition: LO Reinhardtites anthophorus to the LO of Heteromarginatus bugensis.
Age: Late late Campanian. Type locality: Kronsmoor Quarry.
TORTOLITHUSCAISTORENSIS P.R. SUB-SUBZONE (CC/B23Ab)
New sub-subzone
Definition: LO of Heteromarginatus bugensis to the LO of Tortolithus caistorensis.
Age: Latest Campanian to earliest Maastrichtian. Type locality: Kronsmoor Quarry.
NEOCREPIDOLITHUSCOHENII P.R. SUB-SUBZONE (CC/B23Ac)
New sub-subzone
Definition: LO of Tortolithus caistorensis to the LO of Broinsonia parca.
Age: Early early Maastrichtian. Type locality: Kronsmoor Quarry.

INA Newsletter 12/3 - 1990

69

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Figure 2: New Boreal zonation scheme correlated with thestandard nannofossil zones of Sissingh (1977, 1978) andPerch-Nielsen (1979, 1983, 1985) and the Sr-isotope curve for
the Campanian of northern England (after McArthur ~ ~. inpress).

INA Newsletter 12/3 - 1990