T. Andersen et B. Sundvoll, NEODYMIUM ISOTOPE SYSTEMATICS OF THE MANTLE BENEATH THE BALTIC SHIELD- EVIDENCE FOR DEPLETED MANTLE EVOLUTION SINCE THE ARCHEAN, Lithos, 35(3-4), 1995, pp. 235-243
More than 300 published and unpublished Nd isotopic analyses of mantle
derived rocks from the Baltic shield have been compiled. The rocks ra
nge in age from Archaean to Phanerozoic. Within any given age-interval
, the mantle derived rocks range in epsilon(Nd)(t) from depleted mantl
e values at or above the growth curves of the global depleted mantle r
eservoirs of DePaolo ( 1981) and DePaolo et al. (1991) to negative val
ues. Initial neodymium isotopic compositions below the De Paolo curve
are best explained by interaction between depleted mantle derived magm
as and local crustal contaminants. The data now available lend no supp
ort to the existence of isolated, less depleted or undepleted mantle d
omains beneath the Baltic Shield, as was suggested by Mearns et al. (1
986) and Valbracht (1991a, b).