好问题!地球化学家和地球物理学家同意各自保留不同意见,有时相当强烈。也有分歧在每组两组之间。这不仅仅是铀。有四个同位素的半衰期是足够长的时间,它们可以被原始的半衰期不这么长时间,他们不产生热量。这四个同位素铀235,半衰期为07.03亿年,——钾40,半衰期为12.77亿年,铀238,半衰期为44.68亿年,232年-钍,半衰期为140.56亿年。一致认为地球化学家之间是很少有,如果有的话,这些同位素在地球的核心。钾、钍和铀化学活跃。他们很容易氧化。事实上,他们很容易把化学和许多其他元素——但不是铁。 They are strongly lithophilic elements. Moreover, all three are "incompatible" elements. In a partial melt, they have a strong affinity to stay in the molten state. This means that relative to solar system abundances, all three of these elements should be strongly enhanced in the Earth's crust, slightly depleted in the Earth's mantle, and strongly depleted in the Earth's core. Geophysicists look at the amount of heat needed to drive the Earth's magnetic field, and at the recent results from neutrino observations. From their perspective, the amount of residual heat from the Earth's formation is not near enough to drive the geomagneto. The growth of the Earth's inner core creates some heat, but not near enough to sustain the geodynamo. Geophysicists want a good amount of heat flux across the core mantle boundary to sustain the geodynamo, and to them the only viable source is radioactivity. Recent geoneutrino experiments appear to rule out uranium or thorium in the Earth's core, but not potassium 40. The neutrinos generated from the decay of potassium 40 are not detectable using current technology.