Single reservoir degassing

The simplest case for atmosphere formation is unidirectional degassing from a single solid Earth reservoir, which is represented by the MORE source region. Early models focused on Ar isotopes (see reviews by Ozima and Podosek 1983 Turner 1989). Generally, the key assumption is that the rate of degassing is related to the total amount of Ar present in the mantle. Also, there is no return flux from the atmosphere by subdued on. Then  

Using a BSE value of 270 ppm K, a value of a = 1.82x10 ° is obtained. The equation for the average mantle Ar isotope composition at time t is 

A different perspective on °Ar degassing has been provided by Schwartzman y 973), who argued that K is likely to be transferred coherently out of the mantle with °Ar i.e., any °Ar that has been produced by K will be degassed when the K is 

Model shortcomings. The major shortcoming of the single reservoir degassing models is that mantle heterogeneities, especially for He/ He ratios, cannot be explained. Therefore, these models have been superceded by those involving a greater number of reservoirs. 

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The major shortcoming of the single reservoir degassing models is that mantle heterogeneities. 

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