Tertiary and Quaternary

 

Introduction
With the exception of the lowermost calcareous part (Danian treated in section H as part of the Chalk Group), the Tertiary in northwest Europe consists predominantly of siliciclastic rocks. A number of regional breaks in sedimentation can be used to divide the succession into three groups, i.e. the Lower, Middle and Upper North Sea Groups. The alternation of sandstones and claystones near the southern margin of the North Sea Basin forms the basis of the subdivision into formations and members used in the Netherlands.
Exploration of deeper levels in the Netherlands has yielded a large quantity of both well and seismic data on the Tertiary. These, however, have only been studied to a limited extent. A first, comprehensive overview of the geology was presented by Keizer and Letsch (1963) , later updated by Letsch and Sissingh (1983) . Lithostratigraphic descriptions have been given by Doppert et al (1975) , Kuyl (1975) and van den Bosch (1975) , and further elaborated in NAM and RGD (1980) and van den Bosch (1984) and van den Berg and Gaemers (1993) . Micropalaeontological studies have been published by Doppert (1980) and Doppert and Neele (1983) , and nannoplankton studies by Verbeek (1979) Verbeek (1988) . Regional mapping of the Tertiary and its aquifers took place in the early Eighties RGD (1982) RGD (1983) RGD (1984a) . However, a complete, modern, comprehensive, multidisciplinary synthesis of the Tertiary stratigraphy of the Netherlands is not available as yet.
The revision and update of the stratigraphy presented in the present section, focuses on the development of the onshore Paleogene and the continental Neogene. Most of the text has been written by the RGD members of the Working Group on Upper Cretaceous and Tertiary: C.L. Leyzers Vis, R.J. van Leeuwen and W.H. Zagwijn for respectively the Lower, Middle and Upper North Sea Groups.
The need exists for a multidisciplinary approach of the Tertiary stratigraphy. Awaiting this, the present revision is of a modest size and builds on the existing nomenclature. The existing stratigraphic names, though in several cases conflicting with the rules of the ‘International Stratigraphic Guide’ (Salvador (1994) ), have been retained as much as possible for the sake of continuity and to avoid a profusion of new names. For the offshore development of the Tertiary no new elements have been added.
A full sequence-stratigraphic analysis of the Tertiary succession has not been attempted in the present section. However, whenever the transgressive or regressive nature of the deposits could be evidently linked with the ‘Vail curve’ Haq (1988) , this is mentioned.
Obviously, much work still has to be done to obtain a full insight in the development of the marine Neogene, which would lead to a fundamentally new lithostratigraphy. The scope of the current revision and update project precluded this type of approach. Consequently, the existing marine Neogene nomenclature NAM and RGD (1980) is presented here virtually unchanged for completeness’ sake.
The formation descriptions end at the Tertiary-Quaternary boundary, which, in the Netherlands, is placed at the base of the Pretiglian at 2.4 Ma BP (see Section A, Chapter 2).
A selection of foraminifer and nannoplankton markers is given for the Upper Paleocene and Eocene Table 1 (see pdf) , and for the Oligocene, Table 2 (see pdf) . The nannoplankton zonation is from Martini (1971) . The foraminifer zones refer to the zonation established by Doppert (198O) and Doppert and Neele (1983) , and updated by Sliggers van Leeuwen (1987) , Beets (1992) and van Leeuwen (in press) . Correlation between the bio- and chronostratigraphy is as follows:
EpochZone PlioceneFA2 Subzone, FB Zone + FC1A Subzone MioceneFC1B Subzone, FD Zone + FE1 Subzone OligoceneFE2 Subzone, FE3 Subzone, FF Zone + FG Subzone Eocene FH Zone + FI Zone PaleoceneFJ Zone + FK Zone
Geological history
The deposition of chalky sediments, so wide-spread during the Late Cretaceous in northern Europe, continued into the Tertiary. But by the end of the Danian (Early Paleocene) it ceased because of a sudden increase in supply of siliciclastics, resulting from a thermal uplift of the British Isles and compression of the central European Alpine foreland Ziegler (1990) . These crustal movements are attributed to the Laramide phase of the Alpine orogeny. With the beginning of the Cenozoic the North Sea Basin came into being as a result of post-rift thermal relaxation of the lithosphere, isostatic adjustment and sediment loading Ziegler (1990) . For the structural setting, see also Section A, Chapter 3.
Paleogene
The Paleogene in the North Sea Basin basically reflects a deep-water stage resulting from crustal subsidence of that area combined with a general rise in sea level. Where the deepest part of the basin bordered the Shetland Platform in the northeast, turbidites developed at the base of the steep shelf edge during the Paleocene and Early Eocene (Knox et al., 1981). Towards the south, the basin shallowed gradually, allowing epineritic and littoral sands to be deposited. These interdigitate with finer-grained clastics along the southern margin in response to sea-level fluctuations. For northwest Europe a sea-level curve has been established by Vinken (1988) , which differs somewhat from the global curve of Haq (1988) , possibly because of the influence of regional tectonic movements in this area.
Explosive volcanic activity at the transition from Paleocene to Eocene, related to northern North Atlantic-Norwegian-Greenland rift zone, caused extensive, well-correlatable ash falls in the North Sea Basin Ziegler (1990) . Eocene depocentres are present in the Netherlands in the southwest (Voorne Trough) and in an area north to north-east of the Broad Fourteens area (see Section A, page 18).
Resumed inversion of the areas of the former Upper Jurassic-Lower Cretaceous basins caused significant local tectonic uplift in the western and southern Netherlands. These crustal movements occurred during the latest Eocene to earliest Oligocene, giving rise to extensive truncation of the previously deposited Eocene and Paleocene formations Letsch and Sissingh (1983) in a NW-SE-trending zone, which extended from the south-eastern and central Netherlands into the southern North Sea, and which experienced reduced subsidence as early as the Paleocene and Eocene. This tectonic element is called here the Southern Early Tertiary High. It is probably related to part of the Mid Netherlands Fault Zone (see Section A, page 19). The unconformity resulting from above-mentioned crustal movements (often called Pyrenean unconformity) marks the boundary between the Lower North Sea Group and the Middle North Sea Group.
During the Early Oligocene the sea transgressed across the uplifted and eroded areas related to this high. Sedimentation protruded towards the southeast into the Lower Rhine Embayment. Renewed differential subsidence of the Roer Valley Graben became manifest in the Late Oligocene Zagwijn (1989) .
The British Isles were uplifted again during the Late Eocene and the Oligocene. In conjunction with these movements the Artois Axis (northwest France and southwestern Belgium) emerged, cutting off the North Sea Basin from the Tethys Ocean. Further regional uplift and a global low sea level resulted in a break in sedimentation and regional erosion at the end of the Oligocene. The boundary between the Middle North Sea Group and the Upper North Sea Group is based on this break. In the deepest part of the Roer Valley Graben, however, sedimentation probably continued without major interruptions Zagwijn (1989) .
Neogene
The Neogene can be characterised as a period of fill, and consequently shallowing, of the North Sea Basin. Deltas prograded from the south and southeast, and from the Fennoscandian Borderzone into the basin Ziegler (1990) . In the areas of large sediment supply, the accumulation rate exceeded the subsidence rate, resulting in the basin filling up. The patterns of sediment accumulation and locations of the coastlines were strongly influenced by repeated glacio-eustatic sea-level fluctuations. Peat formation was wide-spread along the southeastern basin margin, particularly during the Middle Miocene and the first part of the Late Miocene. In the inner part of the Lower Rhine Embayment an exceptionally long, continuous period of over 6 Ma of peat accumulation occurred (Ville Formation), because the conditions needed for peat growth continued Zagwijn (1989) .
From the Miocene onwards, an overall regressive trend with a number of superimposed transgressions can be distinguished in the southern Netherlands. A strong regressive pulse occurred in the early Middle Miocene. This led to extended peat formation far west into the Roer Valley Graben, even past the town of Eindhoven. Renewed transgression began in the Middle Miocene and was succeeded by a major regression, which continued into the Pliocene.
Two delta systems came into being by the Middle Miocene: one from the east, pouring sediments into the German Bight Bijlsma (1981) and the adjacent part of the North Sea Basin, and one from the southeast Zagwijn (1989) , filling the Lower Rhine Embayment and the adjacent part of the basin.
Miocene depocentres existed in marine near-shore environments in front of the southeastern delta system Zagwijn and Doppert (1978) . The Zuiderzee Low was a depocentre as well. Farther away from the coast, the Miocene succession is incomplete or strongly condensed.
The Pliocene showed a continuation of delta growth in the southeast of the Netherlands (mainly primeval river Rhine) and a clear influence of a river system from the northern German and Baltic region, in the northern part of the country. This prograding development continued into the Pleistocene. With the exception of a prodelta depocentre in the Roer Valley Graben, the main sediment accumulation shifted from the Zuiderzee area towards the main axis of the North Sea Basin. The beds laid down in a near-coastal marine environment locally contain abundant shells and bryozoans, known as the (Coralline) ‘Crag facies’. Age-wise they correlate with the Coralline Crag of East Anglia and the southern North Sea Zagwijn and Doppert (1978) .
An important regional hiatus occurs at or close to the Plio-Pleistocene boundary. This break probably resulted from a eustatic drop in sea level related to the first evident glacial stage of the Quaternary (Pretiglian). Sedimentation rates in the North Sea Basin increased during the Quaternary to about ten times the rate prevailing in the Neogene Zagwijn (1989) . On the other hand, regional neotectonics towards the end of the Pliocene caused almost a twentyfold increase of the rate of uplift of the southern shoulder of the Roer Valley Graben van den Berg ( 1994) .
Correlation Litho-chronostratigraphic charts of the Tertiary for the southern and central Netherlands are shown in I.5 (see pdf) , I.7 (see pdf) and I.9 (see pdf) , reflecting the Upper Paleocene and Eocene, Oligocene, and Miocene respectively. Figure I.2 (see pdf) incorporates the legend to these charts. A schematic overview of the lithostratigraphy of the Paleocene, Eocene and Oigocene is given by Fig. I.8 (see pdf) . Fig I.1 (see pdf) shows a generalised correlation of the main Tertiary lithostratigraphical units of the southern and central Netherlands and the neighbouring countries.
Regional correlation Regional lithostratigraphic correlation chart of the Tertiary for the Netherlands and neighbouring countries Regional lithostratigraphic correlation chart of the Tertiary for the Netherlands and neighbouring countries
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Structural element Cenozoic structural elements Cenozoic structural elements
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Chrono-stratigraphy Miocene and Plicene litho-chronostratigraphic chart for the southern  Netherlands and adjacent area in Germany Miocene and Pliocene litho-chronostratigraphic chart for the southern Netherlands and adjacent area in Germany
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  Oligocene and early Miocene litho-chronostratigraphic chart for the southern  Netherlands Oligocene and early Miocene litho-chronostratigraphic chart for the southern Netherlands
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  Late Paleocene and Eocene litho-chronostratigraphic chart for the southern and central Netherlands Late Paleocene and Eocene litho-chronostratigraphic chart for the southern and central Netherlands
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References See References Tertiary

Van Adrichem Boogaert, H.A. & Kouwe, W.F.P., 1993-1997. [Stratigraphic unit]. In: Stratigraphic Nomenclature of the Netherlands.
Retrieved [Datum] from [url].