Bromine content of English Zechstein Cycle 3 chloride salts on Teesside and in the Staithes area of Co. Cleveland, N.E. England

Abstract

SUMMARY We present profiles of the vertical distribution of bromine in cores of the late Permian (Zechstein) Boulby Halite Formation (EZ3 Na) from lower Teesside and from the potash field around Boulby Mine, Staithes, North Yorkshire. The profile for the Teesside core shows that the bromine content of the halite there (and therefore the salinity of the originating brine) lies in the lower part of the range regarded as normal for marine-derived brines throughout deposition of the formation and increases only slightly near the top. The bromine content of the Boulby Halite in the potash field core is generally slightly greater than that in the Teesside core, but, as predicted by conventional theory, increases sharply in the Boulby Potash Member near the top of the formation. Comparison of the two bromine concentration profiles suggests a close correlation. This suggested correlation needs to be tested against other bromine profiles but, if correct, implies (a) that closely sampled bromine profiles are a useful tool in the correlation of salt deposits, and (b) the Boulby Potash is entirely, or almost entirely, younger than the Boulby Halite of Teesside, possibly indicating basin-shrinkage.