Wasserburg G J, Macdonald G J, Hoyle F, Fowler W A
Science. 1964 Jan 31;143(3605):465-7. doi: 10.1126/science.143.3605.465.
Data from a wide variety of igneous rock types show that the ratio of potassium to uranium is approximately 1 X 10(4). This suggests that the value of K/U approximately 1 X 10(4) is characteristic of terrestrial materials and is distinct from the value of 8 X 10(4) found in chondrites. In a model earth with K/U approximately 10(4), uranium and thorium are the dominant sources of radioactive heat at the present time. This will permit the average terrestrial concentrations of uranium and thorium to be 2 to 4.7 times higher than that observed in chondrites. The resulting models of the terrestrial heat production will be considerably different from those for chondritic heat production because of the longer half-life of U(238) and Th(238) compared with K(40).
来自各种火成岩类型的数据表明，钾与铀的比率约为1×10⁴。这表明K/U值约为1×10⁴是地球物质的特征，与球粒陨石中发现的8×10⁴的值不同。在一个K/U约为10⁴的模型地球中，铀和钍是目前放射性热的主要来源。这将使地球上铀和钍的平均浓度比在球粒陨石中观察到的浓度高2至4.7倍。由于与K⁴⁰相比，U²³⁸和Th²³⁸的半衰期更长，由此产生的地球热产生模型将与球粒陨石热产生模型有很大不同。
