Argon 39 dating Now sex chat with aunty
There's a more basic explanation here: books.google.com/…Argon-Argon dating is similar to Potassium-Argon dating, but it requires less material.So with their encouragement I will attempt to explain the method and the criteria used to interpret the data generated from a Ar step-heating experiment.
Of the naturally occurring isotopes of potassium, 40K is radioactive and decays into 40Ar at a precisely known rate, so that the ratio of 40K to 40Ar in minerals is always proportional to the time elapsed since the mineral formed [ 40K is a potassium atom with an atomic mass of 40 units; 40Ar is an argon atom with an atomic mass of 40 units].
Due to the relatively heavy atomic weight of potassium, insignificant fractionation of the different potassium isotopes occurs.
However, the Argon, a noble gas, constitutes approximately 0.1-5% of the Earth's present day atmosphere.
K-Ar ages away from spreading ridges, just as we might expect, and recent volcanic eruptions yield very young dates, while older volcanic rocks yield very old dates.
Though we know that K-Ar dating works and is generally quite accurate, however, the method does have several limitations.
Therefore, mafic rocks and minerals often contain less potassium than an equal amount of silicic rock or mineral.