Mantle degassing

Direct observation of present-day mantle degassing was first reported by Clark et al. (1969) and Mamyrin et al. (1969) for the case of 3He a 3He degassing rate was subsequently determined by Craig et al. (1975). The degassing rate reported by Craig et al. is still the best available estimate of this important geochemical parameter and... 

Ozima, M., Zahnle, K. (1993) Mantle degassing and atmospheric evolution Noble gas view. Geochem. J., 27, 185-200. 

The first mantle degassing models that incorporated considerations of mantle structure were developed with the discovery of mantle noble gas isotope heterogeneities (Allegre et al, 1986, 1983 Hart et al., 1979 Kurz et al., 1982). These models, following earher interpretations of htho-phile element isotope composition variations... 

McEean D. M. (1985) Deccan traps and mantle degassing in the terminal Cretaceous marine extinctions. Cret. Res. 6, 235-259. 

There are various terrestrial reservoirs that have distinct volatile characteristics. Data from midocean ridge basalts (MORBs) characterize the underlying convecting upper mantle, and are described here without any assumptions about the depth of this reservoir. Other mantle reservoirs are sampled by ocean island basalts (OIBs) and may represent a significant fraction of the mantle (Chapter 2.06). Note that significant krypton isotopic variations due to radiogenic additions are neither expected nor observed, and there are no isotopic fractionation observed between any terrestrial noble gas reservoirs. Therefore, no constraints on mantle degassing can be obtained from krypton, and so krypton is not discussed further. Comparison between terrestrial and solar system krypton is discussed in Chapter 4.12. 

A general outline of the history of mantle degassing can be constmcted from the observations and constraints discussed above (Porcelli et ai, 2003) ... 

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