THE LOWER ANHYDRITE SEAMS OF THE TEES AREA

Abstract

Recent drilling by the D’Arcy Exploration Co. and by Imperial Chemical Industries Ltd. (Wilton Works) in the Wilton area (fig. 2) has provided considerable information as to the nature and distribution of the anhydrite seams, particularly of those lower members which lie at the top of, and within, the main mass of the Permian Magnesian Limestone. This information can be used, to a certain extent, in the correlation of strata in the boreholes put down in the Billingham area. Wilton - Guisborough Area The only boreholes to reach the Carboniferous were Kirkleatham Nos. 1 and 2. However, the Tocketts bore, in the south-east of the area, though apparently just failing to reach Carboniferous strata, showed such a strong similarity to Kirkleatham No. 1 that it has been thought reasonable to consider the section of the latter as being typical of the area as a whole. Considering this section then (fig. 3), the Carboniferous beds are overlain by a conglomerate which passes upwards into the Magnesian Limestone. The outstanding feature of the latter is the presence of two anhydrite zones, apparently similar in character, lying at 277 to 406 feet and at 478 to 611 feet below the Main Anhydrite. The upper zone, cored throughout, consists of dolomite with blebs of pale blue anhydrite at the base, but, passing upwards, the pro-portion of dolomite with blebs of pale blue anhydrite at the base, but, passing upwards, the proportion of anhydrite gradually increases until a homogeneous mass of anhydrite containing dolomitic stringers …