Carbon dating granite

carbon dating granite

Can you use radiocarbon dating on sedimentary rocks?

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. Assume that a feldspar crystal from the granite shown in Figure 8.15 was analyzed for 40 K and 40 Ar. The proportion of 40 K remaining is 0.91.

Can you use radiocarbon dating on rocks older than 60 ka?

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. Assume that a feldspar crystal from the granite shown in Figure 8.15 was analyzed for 40 K and 40 Ar.

How can carbon dating be used to date glacial sediments?

Fragments of wood incorporated into young sediments are good candidates for carbon dating, and this technique has been used widely in studies involving late Pleistocene glaciers and glacial sediments.

Which igneous rocks are suitable for K-Ar dating?

[SE] In order to use the K-Ar dating technique, we need to have an igneous or metamorphic rock that includes a potassium-bearing mineral. One good example is granite, which normally has some potassium feldspar (Figure 8.15).

Why is it difficult to date sedimentary rocks using radiometric dating?

Why is it difficult to date sedimentary rocks using radiometric dating techniques? Because the elements used for dating need to be re-set by volcanism. Radioactive elements decay at a certain constant rate and this is the basis of radiometric dating.

Why can’t we use radioactive elements for dating?

Because the elements used for dating need to be re-set by volcanism. Radioactive elements decay at a certain constant rate and this is the basis of radiometric dating. But, the decay elements need to be set, much like you would re-set a stop watch for a runner, to ensure an accurate measurement.

How is the decay rate of radioactive elements used in radiometric dating?

Radioactive elements decay at a certain constant rate and this is the basis of radiometric dating. But, the decay elements need to be set, much like you would re-set a stop watch for a runner, to ensure an accurate measurement.

How do geologists determine the age of a rock?

When minerals get subducted into the Earth and come back as volcanic magmas or ash, this essential re-sets the radiometric clock back to zero and therefore a reliable age date is possible.

What type of rocks can be radioactive dated?

Radioactive dating is a method of dating rocks and minerals using radioactive isotopes. This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks. Over 300 naturally-occurring isotopes are known.

What rocks can be dated with potassium argon?

The following rocks which are igneous and/or metamorphic minerals, can also be dated by Potassium-Argon: Sanidine, anorthoclase, plagioclase, leucite, nepheline, muscovite, phlogopite, and lepidolite. Whole rock basalt (lava) and some report that ash can also be used.

What is the potassium-argon isotopic dating method for lavas?

The potassium-argon (K-Ar) isotopic dating method is especially useful for determining the age of lavas. Developed in the 1950s, it was important in developing the theory of plate tectonics and in calibrating the geologic time scale . Potassium occurs in two stable isotopes ( 41 K and 39 K) and one radioactive isotope ( 40 K).

Why are quickly cooled lavas used for K Ar dating?

The quickly cooled lavas that make nearly ideal samples for K–Ar dating also preserve a record of the direction and intensity of the local magnetic field as the sample cooled past the Curie temperature of iron. The geomagnetic polarity time scale was calibrated largely using K–Ar dating.

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