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- Isotopes can be used as tracers - Isotopes can be used as energy source - Isotopes are used for radioactive dating - Isotopes are used…

Isotopes are used as tracers in many medical settings.

isotope dating rocks-12

Radiocarbon dating can be used on sediments or sedimentary rocks that contain carbon, but it cannot be used on materials older than about 60 ka.

K proportion of 0.95, which is equivalent to an age of approximately 96 Ma.

This is determined by drawing a horizontal line from 0.95 to the decay curve line, and then a vertical line from there to the time axis.

[SE] K-Ar is just one of many isotope-pairs that are useful for dating geological materials.

It has a half-life of 1.3 billion years, meaning that over a period of 1.3 Ga one-half of the Figure 8.14 The decay of 40K over time.

Each half-life is 1.3 billion years, so after 3.9 billion years (three half-lives) 12.5% of the original 40K will remain.

If we dated a number of individual grains in the sedimentary rock, we would likely get a range of different dates, all older than the age of the rock.

It might be possible to date some chemical sedimentary rocks isotopically, but there are no useful isotopes that can be used on old chemical sedimentary rocks.

A clastic sedimentary rock is made up of older rock and mineral fragments, and when the rock forms it is almost certain that all of the fragments already have daughter isotopes in them.

Furthermore, in almost all cases, the fragments have come from a range of source rocks that all formed at different times.

One good example is granite, which normally has some potassium feldspar (Figure 8.15).

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