Category:Foraminiferal zonation

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Northern England East Anglia Northern England
MAASTRICHTIAN B. casimirovensis 27
B. junior 26
B. occidentalis
B. lanceolata s.l. 24
CAMPANIAN B. mucronata s.l. 23
G. quadrata I. lingua Gonioteuthis Zone Post A. cretaceus 20
A. cretaceus
Hagenowia horizon
O. pilula Abundant O. pilula ? ? ?D. binodosus 19
E. depressula
U. anglicus 18
SANTONIAN M. testudinarius
U. socialis
M. coranguinum Upper H. rostrata 17
CONIACIAN Lower H. rostrata
M. cortestudinarium 13
TURONIAN S. plana 12
T. lata 11
Mytiloides spp.
CENOMANIAN N. juddii S. gracile 8
M. geslinianum
C. guerangeri H. trecensis 6
A. jukesbrownei H. subglobosus 5
A. rhotomagense T. acutus
T. costatus
C. inerme
M. dixoni 3
M. mantelli M. saxbii 1
S. schluteri
N. carcitanense


Foraminifera from the Chalk Group have been taxonomically described for many years and since the 1970’s biostratigraphical applications have also been discussed. It is becoming more evident that foraminiferal inceptions and extinctions can be tied in with lithostratigraphical markers (eg. marl seams, flint bands) and macrofaunal events (eg. sponge beds, Inoceramus-rich beds), to provide a very detailed subdivision of the Chalk Group. Unfortunately, earlier biostratigraphical accounts often failed to record detailed stratigraphical and lithological information relating to sample positions within the succession, thus limiting their usefulness.

The unpublished scheme used herein for the Chalk Group of the UK recognises a maximum of 27 foraminiferal zones, and has been compiled from a variety of published and unpublished sources (Bailey, 1978; Swiecicki, 1980; Bailey et al., 1983, 1984; Hart et al., 1989; Carter & Hart, 1977, Hart, 1982; Jarvis et al., 1988; Mortimore, 1986). Data for offshore areas (King et al., 1989) mostly relates to uncored hydrocarbon wells, and the biostratigraphical scheme for these is based on the extinction horizon (‘Last Appearance Datum’ or ‘First Downhole Occurrence’) of key taxa.; caving in these boreholes makes the first appearance uphole, or inception, an unreliable datum.

The zones, numbered 1 to 27 from oldest to youngest, are pre-fixed 'BGS' to differentiate them from previously published schemes, and where possible, they are related to the UKB zones of Hart et al. (1989), macrofaunal zones and lithostratigraphical marker horizons.

Descriptions of foraminiferal biozones in the Chalk Group[edit]

In the following account the BGS foraminiferal zones of the Chalk Group are systematically described from oldest (BGS 1) to youngest (BGS 27). Alternatively, for information about a particular zone, select it from the summary table (summary correlation of foraminiferal and macrofaunal zones)


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The number of included categories (C), pages (P) and files (F) is stated in brackets.