Potassium argon and argon argon dating Neue freunde kennenlernen berlin
Potassium (K) is one of the most abundant elements in the Earth's crust (2.4% by mass).
One out of every 10,000 Potassium atoms is radioactive Potassium-40 (K-40).
The calcium-potassium age method is seldom used, however, because of the great abundance of nonradiogenic calcium in minerals or rocks, which masks the presence of radiogenic calcium.
On the other hand, the abundance of argon in the Earth is relatively small because of its escape to the atmosphere during processes associated with volcanism.
With 18 protons and 22 neutrons, the atom has become Argon-40 (Ar-40), an inert gas.
They are the lower mantle (below 670km), upper mantle, continental mantle lithosphere, oceanic mantle lithosphere, continental crust and oceanic crust, the latter four constituting the earth's crust. A steady-state upper mantle model has been proposed for mass transfer of rare gases, including Ar.
When rocks are heated to the melting point, any Ar-40 contained in them is released into the atmosphere.
When the rock recrystallizes it becomes impermeable to gasses again.
The potassium-argon dating method has been used to measure a wide variety of ages.
The potassium-argon age of some meteorites is as old as 4,500,000,000 years, and volcanic rocks as young as 20,000 years old have been measured by this method.
As the K-40 in the rock decays into Ar-40, the gas is trapped in the rock.