A formula describing both magnetic and isotopic blocking temperatures

The following new theorem is proved: the equation E/RT_B =ln(1.781 k₀τ), where E = activation energy, R = the molar gas constant and T_B = blocking temperature, applies equally well to both the isotopic and the magnetic systems in rocks from a cooling orogen. The isotopic model involves first-order loss of daughter, while the magnetic model applies to an assemblage of single-domain grains with constant E. Dodson supplied the original proof that the equation applied to isotopic systems. The well-known superficial similarity between the concepts of isotopic and magnetic blocking is thus given quantitative expression.