Z1 (Werra) Formation ZEZ1

 

Basin development Sub-basin development Fringe development, southern offshore Fringe development, southern onshore
Premise This formation was first described in the Netherlands by Van Waterschoot van der Gracht (1909, 1918), later in a systematic way by Visscher (1955) . It was introduced formally as Zechstein 1 Formation by NAM and RGD (1980) . Here it is renamed and amended to incorporate the lower part of the former Fringe Zechstein Formation of these authors.
Derivatio nominis Name derived from the German stratigraphic nomenclature where it is customarily applied to the oldest evaporite cycle of the Zechstein Richter-Bernburg (1955) .
Type section Location map See figure (pdf)
  Well Rossum-Weerselo-3 (pdf)
  Location N 52°21’03.5
E 06°54’38.2
  Depth 1407 to 1804 m
  Length 397 m along hole
  Reference NAM and RGD (1980) (sub-basin setting)
Additional section Location map See figure (pdf)
  Well Vries-1 (pdf)
  Location N 53°02’14.7
E 06°35’40.4
  Depth 3083 to 3122 m
  Length 39 m along hole
  Reference NAM and RGD (1980) (main-basin setting)
  Well P09-01A (pdf)
  Location N 52°32’19.4
E 03°44’52.2
  Depth 4500 to 4620 m
  Length 120 m along hole
  Reference (carbonate/sandstone facies).
  Well Q16-02 (pdf)
  Location N 52°07’05.3
E 04°07’15.3
  Depth 3851 to 3872.5 m
  Length 21.5 m along hole
  Reference (sandstone facies)
  Well Buurmalsen-1 (pdf)
  Location N 51°54’18.7
E 05°18’49.2
  Depth 2020 to 2069 m
  Length 49 m along hole
  Reference (claystone/evaporite facies)
Definition The lithological development of this formation differs markedly between the sub-basins and the main basin. The oldest evaporite cycle of the Zechstein Group, generally consists of a basal black shale, followed by carbonates - anhydrites - salts - anhydrites in the sub-basins, and carbonates - anhydrites in the main basin. Towards the fringe of the basin the unit grades progressively into a succession of carbonates - claystones and/or sandstones.
Upper Boundary The upper boundary has been placed at the base of the Z2 Carbonate Member or the Red-Brown Salt Clay Member. On the platform area in the south, the basal member of the formation varies from the Coppershale( Member to the Fringe Coppershale Member.
Lower Boundary The Z1(Werra)Formation is situated between the base of the Coppershale or the lowermost member of the formation and the base of the Z2 (Stassfurt) Formation. The lower boundary has been placed at the transgression surface of the formation on older units. In the basin, this corresponds to the Coppershale Member overlying the Lower or Upper Rotliegend Group.
Distribution This formation is recognised in the entire basin, but marked variations in the lithology and distribution occur. Salts were only deposited in sub-basins, such as the Central Netherlands Basin and the Lower Rhine Embayment. In the main basin and on intra-basinal highs, carbonates and anhydrites were deposited.
Age Thuringian, Late Permian.
Subdivision  
  In the sub-basins the formation is developed as a complete evaporite cycle. In the main basin, salt beds are missing from this cycle. In the western offshore, the formation is developed in a sandy facies, whereas in the onshore part of the Netherlands it shows a typical claystone-carbonate development. The nomenclature applied to each of these situations is: Zechstein Group ZE
  ZEZ1T Z1 (Werra) Formation
  ZEZ1W Z1 Anhydrite Member
  ZEZ1C Z1 Carbonate Member
  ZEZ1K Coppershale Member
    Z1 Upper Anhydrite Member
  ZEZ1H Z1 Salt Member
  ZEZ1A Z1 Lower Anhydrite Member
  ZEZ1C Z1 Carbonate Member
  ZEZ1K Coppershale Member
  ZEZ1S Z1 Sandstone Member
  ZEZ1M Z1 Middle Claystone Member
  ZEZ1F Z1 Fringe Carbonate Member
  ZEZ1G Z1 Lower Claystone Member
  ZEZ1E Fringe Coppershale Member
  ZEZ1M Z1 Middle Claystone Member
  ZEZ1F Z1 Fringe Carbonate Member
  ZEZ1G Z1 Lower Claystone Member
  ZEZ1E Fringe Coppershale Member
  In some instances, for example in the Central Netherlands Basin, the Z1 Carbonate Member is absent and the Z1 Anhydrite rests on the Coppershale. Some topography was still present during the Zechstein transgression, and on isolated fault blocks, mainly in the fringe area, younger sediments of the Z1 (Werra) Formation may overlie the Upper Rotliegend Group. In the Central Netherlands basin, which has a sub-basin development, there is evidence of strong synsedimentary faulting, which had died out by the time the Zechstein Upper Anhydrite Member was deposited.
References See References Permian

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