Aeolian contribution to strontium and strontium isotope variations in a Tasmanian speleothem

A speleothem from south-central Tasmania shows marked secular variations in its strontium content. The element exhibits a striking bimodal distribution pattern with abrupt changes between two modal groups that is believed to be due to rapid changes in the direction of the dominant strong winds. Strontium isotope compositions in the speleothem range from 0.70865 to 0.70898, indicating derivation of Sr from at least two distinct sources; the first a persistent one from the overlying limestone, the second a higher 87Sr/86Sr component, probably representing input from terrestrial dust. The speleothem record is unusual because it indicates a greater input of radiogenic Sr dust flux during interstadial times than under full-glacial conditions. If an aeolian origin of some of the strontium contained in speleothems at other inland cave sites around the world can be confirmed, variations in strontium isotope composition will provide high-resolution records of how terrestrial dust flux has varied during the Quaternary. In near-coastal sites, significant amounts of strontium may be derived from seasalt and in those areas temporal variation of the element in speleothems may reflect, at least in part, changing distance from the coast due to changes in sealevel.