Geochemical Reconnaissance of the Lower Lias

Abstract

GEOCHEMICAL reconnaissance by the sampling of stream sediment has indicated patterns of high or above normal molybdenum both in the Republic of Ireland^1,2 and in several areas in England and Wales^2–4. Anomalous concentrations of molybdenum in the stream bed have usually been correlated with the underlying bedrock geology and the source of the molybdenum traced to black marine shales of varying age. Good correlations have been established between the molybdenum content of the stream sediment and that of the topsoil, though this relationship may be subject locally to variation in secondary environment, soil parent material and sediment geochemistry. Comparison of regional geochemical data with information on disease incidence in livestock has indicated that, in addition to confirming areas in which clinical molybdenum-induced hypocuprosis is already recognized, the method may also delineate areas in which the subclinical problem occurs. Highly significant relationships have been established between drainage molybdenum patterns on one hand and bovine blood copper concentrations on the other in Co. Limerick, Derbyshire and north Staffordshire^3,5. In the two latter areas animal trials over the past 2 years have shown an economic response to copper supplementation in herds where clinical symptoms of deficiency are absent.