Broom Formation (elevated)
(From NPD Bulletin no. 3)
Brent Group
Name
Named by Deegan and Scull (1977) who gave it "sub-unit" status.
Well type section
UK well 211/29-3 (Shell), from 2818 m to 2829 m, coord N61°08'06", E01'43'36.5" (Fig. 10).
Well reference section
Norwegian well 33/9-1 (Mobil), from 2664 m to 2668 m, coord N61°15'07.5", E01°50'25.8" (Fig. 11).
Thickness
11 m in the type well and 4 m in 33/9-1. In the Brent-Statfjord area it varies from a few meters to about fifteen meters in thickness.
Lithology
In the type well it is a pale grey to brown, coarse-grained poorly sorted conglomeratic sandstone containing shale clasts.
Boundaries
The Broom Formation is distinguished from the underlying Dunlin Group and the overlying Rannoch Formation by its irregular, but generally lower, gamma ray readings.
Distribution
The Broom Formation is easily identified in the Brent—Statfjord area. In parts of the East Shetland Basin a thin distal equivalent of the Broom Formation is present within the shales of the Drake Formation.
Age
Late Toarcian to Bajocian.
Depositional environment
The Broom Formation is a shallow marine deposit, and is a precursor of the regression which characterizes the overlying Rannoch Formation.
