Buchan Formation ORBU

 

Derivatio nominis Named after the British offshore Buchan Field in the UK block 21/1, where these sandstones constitute the principal hydrocarbon reservoir. The formation was defined in the United Kingdom by Cameron (1993a) .
Type section Location map See figure (pdf)
  Well A17-01 (pdf)
  Location N 55°01’11.4
E 03°39’29.4
  Depth 2084 to 2717 m
  Length 633 m along hole
Definition A succession of white to reddish sandstones and red to red-brown and grey claystones and siltstones. Some disseminated anhydrite occurs. A prominent acid extrusive (rhyolite) intercalation and some associated thinner volcanic beds are encountered in the upper part of the formation in the Elbow Spit region.
Upper Boundary The overlying Tayport Formation is a more argillaceous unit with a number of channel sandstones. The transition to this unit is probably gradual. The contact with the Tayport Formation has not been demonstrated in any of the Dutch offshore wells.
Lower Boundary The Buchan Formation overlies the Patch Formation conformably. The base has been placed at the first occurrence of thick sandstones.
Distribution The limited amount of data available indicate the presence of the formation in the Elbow Spit High area and part of the Mid North Sea High. It is also known from the central North Sea Cameron (1993a)
Age A Frasnian to Famennian age has been assumed for the Buchan Formation in the northern part of the Dutch continental shelf because of its stratigraphic position between the palynologically dated Patch and Tayport Formations. No distinct biomarkers have been recovered as yet from this unit in the Netherlands continental shelf area.
Depositional Setting The formation was deposited in a fluvial setting. The sandstones are stacked channel deposits of a predominantly braided river system.
Subdivision The amount of information available on the Buchan Formation in the Netherlands is meagre. A conspicuous rhyolite intercalation, meriting member status, is observed. This divides the Buchan Fomation proper into an informal lower and upper member.
  ORBUR Rhyolite Member
References See References Devonian and Lower Carboniferous

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