Code
    ZEZ4
          Status
    Formal (NAM & RGD 1980). Amended (Adrichem Boogaert & Kouwe 1994).
          Lithological description
    Claystone - anhydrite - salt sequence in the main basin and sub-basins, and a claystone - sandstone development along the basin margin.
Depositional setting
    Marine.
Definition of lower boundary
    Placed at the base of the Red Salt Clay Member.
Definition of upper boundary
    Formed by the top of the Z4 Salt Member or the Z4 Pegmatite Anhydrite Member.
Thickness indication
    Generally less than 130 m, up to 1642 m in L05-B-03.
          Geographical distribution
    Regional correlation
    UK: Z4 Group; GER: Aller Folge (Z4); BEL: Z4 (Aller) Formation.
          Age
    latest Wuchiapingian - earliest Changhsingian.
          
    Holostratotype
  
  Depth (thickness) AH:
  1235 - 1245 m (10 m)
      Comments:
  Sub-basin setting
      
    Hypostratotype
  
  Depth (thickness) AH:
  4036 - 4096 m (60 m)
      Comments:
  Main-basin setting
      
    Parastratotype
  
  Depth (thickness) AH:
  2194 - 2250 m (56 m)
      Comments:
  Main-basin setting
      
    Hypostratotype
  
  Origin of name
    Name derived from the German stratigraphic nomenclature, where it is used for the fourth evaporite cycle of the Zechstein Group (Richter-Bernburg 1955).
          Previous name(s)
    None.
          Reviewed by (date)
    Mark Geluk (2017).
          References
    NAM & RGD 1980. Stratigraphic nomenclature of The Netherlands. Verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap 32, 77 p.
              Van Adrichem Boogaert, H.A. & Kouwe, W.F.P. 1994. Stratigraphic nomenclature of The Netherlands; revision and update by RGD and NOGEPA, Section D, Permian. Mededelingen Rijks Geologische Dienst, 50, 1-42.
              Richter-Bernburg, G. 1955. Stratigraphische Gliederung des deutschen Zechsteins - Z. Dt. Geol. Ges., 105, 593-645.
          Cite as
    TNO-GDN ([YEAR]). Z4 (Aller) Formation. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from http://acc.dinoloket.nl/en/stratigraphic-nomenclature/z4-aller-formation.