Uranium isotopes dating

15-Jun-2020 19:51

8 Physicists have carefully measured the radioactive decay rates of parent radioisotopes in laboratories over the last 100 or so years and have found them to be essentially constant (within the measurement error margins).Furthermore, they have not been able to significantly change these decay rates by heat, pressure, or electrical and magnetic fields.Because of such contamination, the less than 50-year-old lava flows at Mt.Ngauruhoe, New Zealand (), yield a rubidium-strontium “age” of 133 million years, a samarium-neodymium “age” of 197 million years, and a uranium-lead “age” of 3.908 billion years!For example, with regard to the volcanic lavas that erupted, flowed, and cooled to form rocks in the unobserved past, evolutionary geologists simply assume that none of the daughter argon-40 atoms was in the lava rocks.

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New evidence, however, has recently been discovered that can only be explained by the radioactive decay rates not having been constant in the past.9 For example, the radioactive decay of uranium in tiny crystals in a New Mexico granite ( yields a uranium-lead “age” of 1.5 billion years.

6 The problems with contamination, as with inheritance, are already well-documented in the textbooks on radioactive dating of rocks.7 Unlike the hourglass, where its two bowls are sealed, the radioactive “clock” in rocks is open to contamination by gain or loss of parent or daughter isotopes because of waters flowing in the ground from rainfall and from the molten rocks beneath volcanoes.

Similarly, as molten lava rises through a conduit from deep inside the earth to be erupted through a volcano, pieces of the conduit wallrocks and their isotopes can mix into the lava and contaminate it.

To date a radioactive rock, geologists first measure the “sand grains” in the top glass bowl (the parent radioisotope, such as uranium-238 or potassium-40).

They also measure the sand grains in the bottom bowl (the daughter isotope, such as lead-206 or argon-40, respectively).

New evidence, however, has recently been discovered that can only be explained by the radioactive decay rates not having been constant in the past.9 For example, the radioactive decay of uranium in tiny crystals in a New Mexico granite ( yields a uranium-lead “age” of 1.5 billion years.

6 The problems with contamination, as with inheritance, are already well-documented in the textbooks on radioactive dating of rocks.7 Unlike the hourglass, where its two bowls are sealed, the radioactive “clock” in rocks is open to contamination by gain or loss of parent or daughter isotopes because of waters flowing in the ground from rainfall and from the molten rocks beneath volcanoes.

Similarly, as molten lava rises through a conduit from deep inside the earth to be erupted through a volcano, pieces of the conduit wallrocks and their isotopes can mix into the lava and contaminate it.

To date a radioactive rock, geologists first measure the “sand grains” in the top glass bowl (the parent radioisotope, such as uranium-238 or potassium-40).

They also measure the sand grains in the bottom bowl (the daughter isotope, such as lead-206 or argon-40, respectively).

When we look at sand in an hourglass, we can estimate how much time has passed based on the amount of sand that has fallen to the bottom.