INERT-GASES IN GROUNDWATER FROM THE BUNTER SANDSTONE OF ENGLAND AS INDICATORS OF AGE AND PALEOCLIMATIC TRENDS

A study of the radiogenic and atmospherically derived inert gases in groundwaters from the Bunter Sandstone aquifer of Nottinghamshire, England, is described. The radiogenic gases, 222Rn and 4He, are derived by decay of the radioelements contained in the aquifer. The relationship between radioelement content of the rock and groundwater 222Rn and 4He contents is discussed. An increase in the dissolved 4He content with groundwater age is demonstrated and correlated with 14C ages. Excess 4He ages calculated from average physical properties and radioelement contents of the aquifer rock are greater than the corrected 14C ages and possible explanations for this are discussed. The dissolved Ar and Kr contents of the groundwaters indicate their temperature of air equilibration in the unsaturated zone at recharge. The recharge temperatures for groundwaters of age greater than 2·104 yr. are 5-7°C lower than those for waters recharged in the last 104 yr. This is shown to be consistent with the palaeoclimatic record for England during the late Pleistocene. © 1979.