Zone : Elphidium excavatum


Sequence : TB-3.9 to TB-3.10

Description :
This zone is characterised by low diversity microfaunas, dominated by elphidiums and cassidulinids, mainly Elphidium excavatum (including Elphidium excavatum selseyense and Cassidulina laevigata). In the marine setting the top occurrence of Elphidiella hannai can be used to subdivide this zone into an upper E. excavatum selseyense subzone (TB-3.10) and lower Elphidiella hannai zone (approx. TB-3.9). Other typical species include Buccella frigida and Ammonia beccarii. Middle and outer neritic faunas contain Cassidulina crassa and Neogloboquadrina pachyderma.

In lithological terms, the non-marine facies (which consists of well rounded coarse sands with minor traces of peat) is called the Maasluis Formation, whereas the marine inner to middle neritic facies (recognisable as fine sand with clay and abundant shell fragments) is called the Oosterhout Formation. For the open marine facies (grey to grey green clays with local sands) Mud Hole is sometimes used. These formations span the Pliocene to recent.

Zone : Bulimina aculeata


Sequence : TB-3.8 HS

Description :
This zone is distiguished from the above zones by the common presence of buliminids or bolivinids (Bolivina spathulata and Bulimina aculeata/marginata).
Bulimina aculeata
Cassidulinids can be common is this assemblage. Outer neritic equivalents may contain the first downhole planktics (Globigerina bulloides and Neogloboquadrina atlantica)

Zone : Cibicides lobatulus grossus


Sequence : TB-3.8 TR/LSW

Description :
The top of the zone is defined by the top of (common) Cibicides lobatulus grossus. The microfaunas are generally similar to those from the above zone, with Cibicides lobatulus grossus added to them (common to abundant).
C.lobatulus grossus
Other species which sometimes occur in this zone are Bolivina catanensis (B.spathulata) and Discorbitura cushmani. Where the outer neritic assemblages are preserved, they contain Globigerina bulloides and Neogloboquadrina atlantica.

Zone : Monspeliensina pseudotepida


Sequence : TB-3.5 to TB-3.8 TR/LSW

Description :
The zone is based on the presence of M. pseudotepida. Otherwise the microfaunas consist mainly of C. laevigata, E. excavatum (and other elphidiums), Florilus boueanus, Melonis affinis and B. aculeata. Martinotiella communis, Siphotextularia sculpturata and Textularia decrescens occur in arenaceous facies, with Sigmoilopsis schlumbergeri. Although Monspeliensina pseudotepida can occur up into the basal part TB-3.8 sequence (Praetiglian), it only occurs in great numbers from the TB-3.7 sequence down.

Zone : Trifarina bradyi


Sequence : TB-3.5 to TB-3.6

Description :
The zone is based on the presence of Trifarina bradyi. Otherwise the microfaunas are similar to that of the Monspeliensina pseudotepida zone.

Zone : Cassidulinoides bradyi


Sequence : TB-3.4

Description :
The zone is based on the presence of Cassidulinoides bradyi. Otherwise the microfaunas are similar to that of the Trifarina bradyi zone.

Zone : Uvigerina venusta deurnensis


Sequence : TB-3.3 to TB-3.4

Description :
The microfaunas of this zone are usually sparse, resembling the faunas from the overlying zone. The top of the zone is marked by the top of the nominal species. Hoeglundina elegans' top (if present) also coincides with the top of this zone. Other species added in this zone are Cancris auriculus and Bulimina elongata. An acme of Uvigerina venusta deurnensis marks the top of the Miocene.
Bulimina elongata
The inner neritic faunas contain elphidiums and Karreriella siphonella chilostoma, the middle to outer neritic faunas contain cibicidids and Neogloboquadrina acostaensis.

The inner neritic facies found in the dutch sector is called the Breda Sand member of the Breda Formation (argillaceous sands rich in glauconite and mica). The deeper water equivalent of this is the Oosterhout or Mud Hole Formation in the TB-3 super sequence and the the Breda Clay member in the TB-2 sequence, which consists of brown bituminous and glauconitic clays.

Zone : Bolboforma metzmacheri


Sequence : TB-3.1 to TB-3.2

Description :
This zone is characterised by microfaunas which are dominated by calcareous algae, to the exclusion of other planktic elements and also has very few benthic species. Those present are uvigerinids, Pullenia bulloides and Melonis affine. This facies is commonly found in the British sector, but the geographic extent in the Dutch sector seems to be limited. In other parts Globocassidulina subglobosa and Cassidulinoides bradyi occur in this zone, accompanied by Neogloboquadrina atlantica and Neogloboquadrina acostaensis.

Zone : Asterigerina staeschei

Age : EARLY to MIDDLE MIOCENE (Serravalian)

Sequence : TB-2.1 to TB-2.6

Description :
Calcareous faunas characterise this zone, the distinguishing feature being the (sometimes abundant) presence of Asterigerina staeschei.
An additional marker for the top of this zone is Elphidium inflatum. Uvigerina tenuipustulata also has its top in this zone, at the top of the TB-2.5 sequence. This fauna is characteristic of the inner to middle neritic realm. In the outer neritic realm Globigerinoides trilobus occurs in the faunas and in the bathyal realm Spiroplectammina carinata and Haplophragmoides spp have their tops.

Zone : Globorotalia praescitula

Age : EARLY to MIDDLE MIOCENE (Burdigalian to Langhian)

Sequence : TB-2.3 to TB-2.4 (MFS)

Description :
Globorotalia praescitula
characterises the faunas from this zone, which otherwise are relative rich in planktic species, mainly globigerinids.
Trifarina gracilis may have its top in this zone. The G. praescitula 'acme' correlates to the TB-2.4 MSF/HS and the very similar G. zealandica 'acme' to the TB-2.3 MFS/HS.
This zone is a deep water equivalent of part of the Asterigerina staeschei zone. It has a limited geographical distribution in the Dutch Sector.

Zone : Globigerina woodi

Age : EARLY MIOCENE (Burdigalian)

Sequence : TB-2.1

Description :
This zone is characterised by the presence of Globigerina woodi and other globigerinids.
Benthic faunas include Eponides umbonatus, Trifarina gracilis, Globocassidulina subglobosa, Pullenia bulloides, Uvigerina tenuipustulata and uvigerinids. Faunas from deeper water also contain Karreriella siphonella. This zone has a limited geographical distribution in the Dutch Sector.

Zone : Spirosigmoilinella compressa


Sequence : TB-3.4 and TB-2.1 (TR)

Description :
The presence of Spirosigmoilinella compressa characterises this zone. It is the deep water equivalent of the Plectofrondicularia seminuda (Early Miocene)
and Stainforthiana schreibersiana (Late Oligocene) zones in neritic areas. Additional components of these assemblages are Almaena osnabruegensis,
Sigmomorphina regularis and Asterigerina guerichi in the Early Miocene and Stainforthiana schreibersiana in the Late Oligocene.

In the Dutch onshore wells Late Oligocene faunas rarely occur. Where they are present, they contain Gyroidina soldanii girardanus (TB-3.3), Turrilina alsatica (TB-3.2)
Turrilina alsatica
and Gyroidina soldanii mamillata (TB-3.1)
among their constituents. In most dutch onshore wells these species are only found together with Rotaliatina bulimoides, which is evidence for a Late Oligocene hiatus. The TB-4.5 sequence is also often absent in the Dutch Sector. Where present, it is characterised by the common occurrence of Cibicides dutemplei praecincta.