Which allowed scientists to determine that Earth was at least 4.3 billion years old?(1 point)
Responses
chemical reactivity of zircon ions
chemical reactivity of zircon ions
the radioactive decay of uranium to lead
the radioactive decay of uranium to lead
the electrical conductivity of uranium ions
the electrical conductivity of uranium ions
magnetic field surrounding zircon
The radioactive decay of uranium to lead
This process is used in geochronology, particularly with a mineral called zircon which can be dated by the decay of uranium to lead over immense periods of time. Zircon crystals incorporate uranium atoms into their structure when they crystallize, but do not incorporate lead. Therefore, any lead found in the zircon crystals is the result of uranium decay. Since uranium decays at a known rate, scientists can measure the ratio of lead to uranium in a zircon crystal and calculate its age. This method has shown that the oldest zircon crystals, and by extension parts of the Earth's crust, are at least 4.3 billion years old.