Primary oxidation variation and distribution of uranium and thorium in a lava flow.
An Icelandic basalt lava flow has a systematic oxidation variation, formed during the initial cooling, with a resultant maximum oxidation just below the center of the lava. The ratio of thorium to uranium shows a clear dependence on this primary oxidation variation. Between-lava comparisons of thorium and uranium may be critically dependent on the position of the samples in each lava.
Watkins
N D
ND
Holmes
C W
CW
Haggerty
S E
SE