Zone : Rotaliatina bulimoides

Age : EARLY OLIGOCENE (Rupelian)

Sequence : TA-4.4

Description :
The top of Rotaliatina bulimoides marks the top of this zone.
Rotaliatina bulimoidesRotaliatina bulimoides
The diverse assemblages from this zone include Globigerina linaperta eocaena, Globorotalia opima, Gyroidina soldanii mammillata, Heterolepa dutemplei praecincta and Svratkina perlata. In deeper water R. bulimoides is rare and the faunas are dominated by arenaceous specimens.

These faunas are characteristic of the Rupel Formation (light greenish grey and beige to brownish grey clays, glauconitic, locally calcareous and limestone beds). This lithology seems to extend into the Upper Oligocene beds as well.

Zone : Bolivina cookei

Age : LATE EOCENE (Priabonian)

Sequence : TA-4.1 and TA-4.2

Description :
The top of the zone is marked by the top of the nominal species.
Bolivina cookei Bolivina cookei
Vaginulopsis decorata has its top occurrence below that of Bolivina cookei (TB-4.2). Since these two species usually occur together in the dutch sector, the TA-4.3 seems to be absent. The shallow water equivalent of the lower part of this zone is the Nummulites germanicus zone (TB-4.1). The outer neritic equivalents are the Globorotalia cerroazulensis zone (TB-4.3) and the Globigerapsis index acme (TB-4.1 and TB-4.2), and the bathyal faunas consist of arenaceous species, including Trochammina sp.X and Reticulophragmium amplectens.

Zone : Cibicides truncana

Age : MIDDLE EOCENE (Bartonian)

Sequence : TA-3.6

Description :
The top of the zone is marked by the top of the nominal species.
Cibicides truncana Cibicides truncana
The lateral equivalents of this zone are the outer neritic Truncorotaloides rorhri zone and the deep water Ammomarginulina macrospira zone.

Zone : Spiroplectammina flexuosa

Age : MIDDLE EOCENE (Lutetian to Bartonian)

Sequence : TA-3.1 (HS) to TA-3.5

Description :
The nominal species of this zone, Spiroplectammina flexuosa, is generally found in purely arenaceous faunas, with some Cyclammina spp, Rhabdammina spp, Haplophragmoides spp or Recurvoides spp. Karreriellids are rare and a Cenodiscus spp (radiolarian) acme occurs at the base of this zone. In outer neritic faunas, this zone corresponds to the Pseudohastigerina micra (TA-3.4 to -3.5) and Acarinina pentacamerata / Pseudohastigerina wilcoxensis (TB-3.1 HS to TB-3.3) zones. In even shallower water it is, for the major part, represented by the Planulina - Cibicides sub-zone of Doppert & Neele (1983).

Zone : Bolivinopsis navarroana

Age : EARLY EOCENE (Ypresian)

Sequence : TA-2.7 to TA-3.1 (TR)

Description :
This zone is characterised by the consistent presence of arenaceous foraminifera, including Gaudryina hiltermanni and Bolivinopsis navarroana.
Bolivinopsis navarroana Bolivinopsis navarroana
It also coincides with a radiolarian (Cenodiscus spp) acme. In the neritic facies Bulimina truncana and Turrilina brevispira occur, sometimes accompanied by planktic foraminifera (Acarinina pentacamerata and Globigerina hagni).

These faunas are found in the Ieper Clay member, which consist of light greenish grey, non-calcareous silty claystones, which are reddish brown near the base.

Zone : Globigerina linaperta


Sequence : TA-2.5 (HS) to TA-2.6

Description :
The zone is characterised by the presence of (sometimes abundant) Globigerina linaperta.
Globigerina linaperta G.linaperta
Benthic species include Bulimina sp.nov. King, Turrilina brevispira, Bolivinopsis navarroana, Glomospira charoides, Ammodiscus cretaceus and Haplophragmoides walteri. Occasionally, Nuttalides truempyi is occasionally found in the faunas. The planktics are occasionally pink, reflecting the reddish brown colour of the sediment.

Zone : Coscinodiscus spp


Sequence : TA-2.4 to TA-2.5 (TR)

Description :
This zone is characterised by the presence of common pyritised diatoms, mostly Coscinodiscus sp.8 (the small version of Coscinodiscus sp.3). It can be subdivided in two sub-zones: a Coscinodiscus sp.8 sub-zone (low diversity diatom faunas with Coscinodiscus sp.8 and Triceratium sp.1) and a lower Coscinodiscus sp.1 subzone, in which these species occur together with Coscinodiscus sp.1 and the disc-shaped diatom Coscinodiscus sp.6.
Triceratium sp.01 Triceratium sp.01
Coscinodiscus sp.01 Coscinodiscus sp.01
Coscinodiscus sp.06 Coscinodiscus sp.06
The upper sub-zone represents the TA-2.4 (HS) to TA-2.5 (T) system tracks, the lower sub-zone represents the TA-2.4(TR) system track.

These faunas are characteristic of the Dongen Tuff member.

Zone : Bulimina trigonalis


Sequence : TA-2.1

Description :
The top of this zone is marked by the top of the nominal species. The assemblages from this zone are usually of low diversity, with occasionally Bulimina midwayensis and Gavelinella beccariiformis.
Bulimina trigonalis Bulimina trigonalis
The outer neritic equivalent contains globigerinids. The bathyal equivalent in the the northern areas can be subdivided into two sub-zones: a monospecific fauna of Cyclammina sp.1 (TA-2.3 to TA-2.3) and a diverse arenaceous Spiroplectammina spectabilis zone (TA-2.1). In the S. spectabilis zone, Rzehakina epigona and Spirosigmoilinella sp.1 have their tops slighly below the top of S. spectabilis. The faunas also contain common species of Trochammina spp, Haplophragmoides spp and Ammodiscus spp.

Occasionally, Globorotalia uncinata and Globorotalia compressa are found in this zone, indicating that the TA-1.4 sequence was sometimes preserved in the rock record (but subsequently eroded and reworked).

Zone : Morozovella pseudobulloides


Sequence : TA-1.3

Description :
The top of this zone is marked by the top occurrence of the nominal species together with other primitive globigerinids.
Morozovella pseudobulloides M. pseudobulloides
In its absence, the calcareous benthic faunas with Gavelinella beccariiformis, Gavelinella voltziana, Tappanina selmensis and Osangularia expansa are characteristic of this zone. Shallow water faunas contain Rotalia saxorum. The lithology is chalk with calcarenites, which contain (abundant) macrobioclasts and chert. These sediments belong to the Ekofisk Formation.

Zone : Globoconusa daubjergensis


Sequence : TA-1.2

Description :

The faunas from this zone contain high proportions of primitive planktic foraminifera, amongst which Globigerina simplicissima and Globoconusa daubjergensis.
Globoconusa daubjergensis G. daubjergensis
The chalk is usually too inundated to retrieve these planktics from the sediment, however. The geographic distribution in the Dutch sector therefore appears to be limited.