On the origin of Niue soils and their anomalously high natural radioactivity; revised geochemical paradigm

The origin of Niue soils and their anomalously high natural radioactivity, has been debated for about 70 years. New and improved analysis of trace elements in unpolluted coral and dolomite suggest Niue Island major soil elements cannot possibly originate from their erosion as previously argued, because of low coral Fe and Al contents, their ratio, and the limited coral depth eroded. Pumice from the nearby Endeavour seamount is the most likely origin. Sub-soil calcite has trapped older eroded soil material, whose elements including uranium, have much higher concentrations relative to Al, compared with current heavily leached surface soils. Soil Cr, Hg, P, Sc, Sr, U, Y, 230Th, 231Pa, remain anomalously high compared with basalt-derived soils from elsewhere, and Cr, Hg, U were probably deposited in reducing conditions during high Fe2+ groundwater concentrations. Radionuclides in-grew, then parent U was leached by rain. Deep coral kerogen implies ancient 25-50oC temperatures.