Basal Dongen Tuffite Member NLFFT

 

Premise Originally defined by NAM and RGD (1980) .
Derivatio nominis Named after its characteristic lithology and its position at the base of the Dongen Formation.
Type section Location map See figure (pdf)
  Well L02-04 (pdf)
  Location N 53°51'22.2
E 04°38'59.2
  Depth 1524 to 1532 m
  Length 8 m along hole
  Reference NAM and RGD (1980)
Definition Tuffaceous clays, blue to violet-grey in colour, alternating with dark-grey and red-brown clays.
Upper Boundary The member can be distinguished from the under- and overlying rock units by its characteristic wire-line log expression, consisting of a somewhat lower gamma-ray reading than the average clay, and by its high-velocity peaks on the acoustic log JacquƩ and Thouvenin (1975) .
Lower Boundary The member can be distinguished from the under- and overlying rock units by its characteristic wire-line log expression, consisting of a somewhat lower gamma-ray reading than the average clay, and by its high-velocity peaks on the acoustic log JacquƩ and Thouvenin (1975) .
Distribution The member occurs throughout the central and northern Netherlands and the adjacent offshore area, and is an excellent marker horizon. The unit interfingers with and locally overlies the Basal Dongen Sand Member.
Age Early Eocene (Ypresian). The member does not contain calcareous microfossils. It is characterised by an abundance of the diatom Coscinodiscus sp. 1. The volcanic ashes have originated from a source located to the north or northwest of the North Sea Morton and Knox (1990) .
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].