The elemental content of Niue Island soils as an indicator of their origin

Abstract

The major and trace element contents of 241 Niue Island lateritic soils were determined, mainly by X‐ray fluorescence, to deduce soil origins. The analyses showed very low SiO2 content, and a high content of Mg, P, V, Cr, Sr, Y, Hg, and α‐counts, compared with other laterites worldwide. The distribution patterns are consistent with derivation by weathering from calcite and dolomite rather than from deposited volcanic ash. Weathering is a particularly novel explanation for the origin of the relatively high content of P in these soils. The soils contain a negative Ce anomaly, consistent with an origin from seawater or coral, but not volcanic ash. If recent results showing in situ formation of magnetite in soils are applicable, the soil mineralogy is wholly consistent with an origin from calcite/dolomite. An origin from calcite is also consistent with the relative lack of volcanic ash on the seabed nearby, and very low deposition of aeolian dust. The radioactivity content is consistent neither with calcite/dolomite weathering, nor volcanic ash origin, but may have originated, like a few of the stable elements, from rising hydrothermal solutions.

Key words:

• Niue Island
• weathering
• cerium
• phosphate
• chromium
• yttrium
• mercury
• soils