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26

Good question! Geochemists and geophysicists agree to disagree, sometimes quite strongly. There are also disagreements within each group as well as between the two groups. It's not just uranium. There are four isotopes whose half-lives are long enough that they can be primordial and whose half-lives are not so long that they don't produce much heat. These ...


20

This hypothesis has been studied here as a possible explanation of selenogenesis (formation of the Moon). (Forming the Moon from terrestrial silicate-rich material. R.J. de Meijer, V.F. Anisichkin, W. van Westrenen. 2013.) The only place cited as suitable for spontaneous criticality is the Core-Mantle Boundary (CMB). The calculations above show that ...


15

To understand why sedimentary phosphate rocks (hereafter referred to as phosphorites) have elevated uranium contents we first need to understand what are they made of and why do they form in the first place. Phosphorites are rocks that are made of apatite, a mineral with the formula $\ce{Ca5(PO4)3(F,Cl,OH)}$. This mineral (especially the OH variant) is one ...


13

The conventional explanation for the Earth's magnetic field is that some combination of differential rotation and/or convection occurs in the Earth's outer core, primarily in molten iron-nickel (+ sulphur, hydrogen etc.), which acts as a kind of dynamo. Whilst we can't prove it by direct observation, this seems an eminently plausible mechanism. If this is ...


11

According to wikipedia, there are around 5.5 million tonnes of uranium in ore deposits that are commercially viable at current prices, and perhaps 35 million tonnes that are potentially viable if prices increase. Also according to wikipedia, the Earth's crust (to 25 km depth) contains an estimated 10^14 tonnes (100 trillion tonnes), while the oceans may ...


7

I can't be entirely sure but I'll make an informed guess: That value doesn't come for a single measurement. Therefore, if the error in the age of a single sample is $\pm125$ kyr, you just need to average 16 samples to get it down to $\pm31$ kyr. The uncertainty in the addition (or substraction) of two or more quantities is equal to the square root of the ...


6

(tl;dr below) First, a correction. Siderophile elements are "iron-loving" elements, those that go in the core with the Fe-Ni liquid. Uranium is lithophile, or "rock-loving". It partitions to silicate rocky material (i.e. mantle and crust) relative to the core. Secondly, But, according to this answer, the solubility of Uranium in the Earth Core is ...


5

The question "how much" is a little unprecise for geochemical questions. Rather you should think about: -How much of the element is there per Rock-Volume (=Concentration)? The crust has a higher U-concentration than the mantle because U is drawn into the minerals that compose the crust. Or you could also say that the minerals that compose the mantle don't ...


5

No. The reason for Australia’s unique evolution is that it was relatively isolated from the rest of the world. Australia isn’t too radioactive either. The fact that it has more uranium deposits than other countries is that it’s huge.


5

There are about 3 tonnes of uranium in every cubic kilometre of seawater, but in the general circulation there is no mechanism to concentrate the uranium, except perhaps low-level adsorption on manganese nodules in some parts of the sea bed. To concentrate the uranium you need some mechanism to transport it, and some other mechanism to make it precipitate. ...


4

There is no reason you couldn't have uranium deposits in the continental shelf. Certain types of deposits wouldn't occur or be likely to persist in that environment but other types such as those in Archean metasediments likely could be found. As pure speculation, I can envision formation of deposits similar to unconformity or roll-front deposits where deep-...


3

Ahhhh, probably not. If, for example, you navigate to Marsupial at Wikipedia and click on the wonderful (it really really is!) DyMaxion map at the bottom of the info panel, you wiil see that a large part of South America, Central and North America also have these animals. FWIW, the USA does indeed have Uranium deposits although I'm not sure about Central ...


2

He's correct, there is precious little uranium or thorium in the Earth's core. He's also right that an extra source of heat is required to drive the core's magnetism. Note however that, as has been known for a long time, the Earth's core is less dense than would be the case if it was pure Ni-Fe alloy. The answer is that there is a lot of sulphur down there, ...


2

Sort answer: from what we already know, NO. A comet (or asteroid) impact can influence mineral composition near the crater (high pressure and temperature) but this impact is small and diminishes quickly in respect of the radius. There is no documented quantitative difference of a mineral deposit versus its radius from an impact crater (not in cm and meters ...


1

You can try using the locality list at MinDat. Go to places that are easily accessible to you and see what minerals have been reported there. If there's something radioactive, it will probably be listed there. I would remind you that radioactive minerals are, well, radioactive. These things are dangerous. I strongly recommend you find a different hobby. I ...


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