Difference between revisions of "Category:Foraminiferal zonation"

From Earthwise
Jump to navigation Jump to search
Line 46: Line 46:
| rowspan="3" | ''G. quadrata''
| rowspan="3" | ''G. quadrata''
| rowspan="4" | ''I. lingua''
| rowspan="4" | ''I. lingua''
| rowspan="4" | '''Gonioteuthis ''Zone'
| rowspan="4" | '''Gonioteuthis '''Zone
| Post ''A. cretaceus''
| Post ''A. cretaceus''
| rowspan="3" | '''20'''
| rowspan="3" | '''20'''
| ''A. cretaceus''
| ''A. cretaceus''
| ''Hagenowia '' horizon
| ''Hagenowia '' horizon

Revision as of 16:00, 26 September 2013

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

The foraminifera of the Chalk Group in the North Sea Basin were outlined by Wilkinson et al. (1993, 1994). The biomarkers were selected for borehole samples collected by open-hole methods and those chosen were well known, easily identified and based on those commonly used by industry. Definitions were based on the first down-hole occurrences (i.e. extinctions) and a pragmatic approach was taken; a refined or detailed biostratigraphical subdivision of the Chalk Group was not attempted. As the biomarkers offshore were based on 'tops', they do not fit exactly with the onshore biozonation outlined by Wilkinson (2000), which was based on inceptions, extinction and acmes (biomarkers or bioevents within the zones were also recognised). Nevertheless, the biomarkers of the North Sea succession can be related to the onshore biozones, and the purpose of this report is to relate the two schemes.

The biomarkers identified for offshore sequences were, by necessity, defined from the top down. Each biomarker represents a single event and no attempt was made to place them into a zonal scheme. The biomarkers of the Chalk Group in the North Sea Basin are placed, herein, within the context of the biozones recognised in southern and eastern England.

Descriptions of offshore foraminiferal biomarkers in the Chalk Group

The foraminifera biomarkers recognised in the Upper Cretaceous Shetland Group are not included in this synthesis. Being based on First Downhole Occurrences (FDOs), the highest possible stratigraphical positions for the Biomarkers are given here. However, in some cases, similar faunas may be found lower compared to the foraminiferal zones. Distributions are related to the species ranges of southern and eastern England.

In the following account Biomarkers in the offshore UK Chalk Group are systematically described from youngest (Biomarker 1) to oldest (Biomarker 15). Alternatively, for information about a particulat Biomarker, select it from the summary table (summary correlation of offshore foraminiferal biomarkers and BGS foraminiferal zones).


This category has only the following subcategory.
The number of included categories (C), pages (P) and files (F) is stated in brackets.