Pb 210 dating

As planetesimals collided, various fragments were scattered and produced meteorites.

Iron meteorites were identified as pieces of the core, while stony meteorites were segments of the mantle and crustal units of these various planetesimals.

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Patterson also analyzed terrestrial sediment collected from the ocean floor, which was believed to be representative of the Bulk Earth composition. Patterson to determine the age of the Earth in 1956.

Because the isotope composition of this sample plotted on the meteorite isochron, it suggested that earth had the same age and origin as meteorites, therefore solving the age of the Earth and giving rise to the name 'geochron'. Animation shows progressive growth over 4550 million years (Myr) of the lead isotope ratios for two stony meteorites (Nuevo Laredo and Forest City) from initial lead isotope ratios matching those of the Canyon Diablo iron meteorite.

This makes it difficult to determine the analytical uncertainty on the age.

To avoid this problem, researchers Pb ratio, corresponding to the slope of a normal Pb/Pb isochron, which yields the age.

As illustrated in figure 1, this point defines the lower (left) end of the isochron.

Therefore, troilite found in Canyon Diablo represents the primeval lead isotope composition of the solar system, dating back to 4.55 /- 0.07 Byr.

If the sample behaved as a closed system then graphing the difference between the present and initial ratios of Pb should produce a straight line.

The distance the point moves along this line is dependent on the U/Pb ratio, whereas the slope of the line depends on the time since Earth's formation. The development of the Geochron was mainly attributed to Clair Cameron Patterson’s application of Pb-Pb dating on meteorites in 1956.

Chondrules and calcium–aluminium-rich inclusions (CAIs) are spherical particles that make up chondritic meteorites and are believed to be the oldest objects in the solar system.

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