Effects of low temperature sea-floor weathering On the rare earth elements of tholeiitic basalts

Abstract

The study of the rare earth elements (REE) when considered relative to chondritic abundances has been considered as a very valuable diagnostic tool in a variety of investigations. The generally accepted proposition that the REE show little migration during secondary alterations (e .g. Frey et al., 1968; Philpotts et al., 1969; Schilling, 1973, 1975; Herrmann et al., 1974; Kempe and Schilling, 1974; Condie, 1976; Garcia, 1978) has recently been challenged by Ludden and Thompson (1978), who have demonstrated that a significant uptake of the light REE (La-Sm) occurs during weathering processes at low temperatures of sea-floor tholeiitic basalt. The samples studied were dredged basalts collected from the Mid-Atlantic ridge at 23° N. The ages of these samples ranged from Oto 5 Myron the basis of the magnetic anomaly pattern. From their results, geochemical and petrological inferences based on the stability of REE in tholeiitic basalts should be modified. Thus, it is pertinent to see if Ludden and Thompson's findings are present in other submarine basalts.