@article {349,
	title = {Numerical models, geochemistry and the zero-paradox noble-gas mantle},
	journal = {Philos Transact A Math Phys Eng Sci},
	volume = {360},
	year = {2002},
	note = {id: 1579; Ballentine, Chris J Van Keken, Peter E Porcelli, Don Hauri, Erik H England Philos Transact A Math Phys Eng Sci. 2002 Nov 15;360(1800):2611-31.},
	pages = {2611-31},
	abstract = {Numerical models of whole-mantle convection demonstrate that degassing of the mantle is an inefficient process, resulting in ca. 50\% of the (40)Ar being degassed from the mantle system. In this sense the numerical simulations are consistent with the (40)Ar mass balance between the atmosphere and mantle reservoir. These models, however, are unable to preserve the large-scale heterogeneity predicted by models invoking geochemical layering of the mantle system. We show that the three most important noble-gas constraints on the geochemically layered mantle are entirely dependent on the (3)He concentration of the convecting mantle derived from the (3)He flux into the oceans and the average ocean-crust generation rate. A factor of 3.5 increase in the convecting-mantle noble-gas concentration removes all requirements for: a (3)He flux into the upper mantle from a deeper high (3)He source; a boundary in the mantle capable of separating heat from helium; and a substantial deep-mantle reservoir to contain a hidden (40)Ar rich reservoir. We call this model concentration for the convecting mantle the {\textquoteright}zero-paradox{\textquoteright} concentration. The time-integrated flux of (3)He into the oceans is a robust observation, but only representative of the ocean-floor activity over the last 1000 years. In contrast, ocean-floor generation occurs over tens of millions of years. We argue that combining these two observations to obtain the (3)He concentration of the mantle beneath mid-ocean ridges is unsound. Other indicators of mantle (3)He concentration suggest that the real value may be at least a factor of two higher. As the zero-paradox concentration is approached, the noble-gas requirement for mantle layering is removed. We further consider the role that recycled material plays in ocean-island-basalt generation and show that a source with high (3)He and (3)He/(4)He must exist within the mantle. Nevertheless, only a small amount of this material is required to generate both the observed ocean-island (3)He/(4)He ratios and the concentrations inferred from basalt samples for this mantle source.},
	issn = {1364-503X (Print) 1364-503X (Linking)},
	doi = {10.1098/rsta.2002.1083},
	author = {Ballentine, C. J. and Van Keken, P. E. and Porcelli, D. and Hauri, E. H.}
}
@article {631,
	title = {Vapour undersaturation in primitive mid-ocean-ridge basalt and the volatile content of Earth{\textquoteright}s upper mantle},
	journal = {Nature},
	volume = {419},
	year = {2002},
	note = {Saal, Alberto EHauri, Erik HLangmuir, Charles HPerfit, Michael RengEngland2002/10/09 04:00Nature. 2002 Oct 3;419(6906):451-5.},
	month = {Oct 03},
	pages = {451-5},
	abstract = {The analysis of volatiles in magmatic systems can be used to constrain the volatile content of the Earth{\textquoteright}s mantle and the influence that magmatic degassing has on the chemistry of the oceans and the atmosphere. But most volatile elements have very low solubilities in magmas at atmospheric pressure, and therefore virtually all erupted lavas are degassed and do not retain their primary volatile signatures. Here we report the undersaturated pre-eruptive volatile content for a suite of mid-ocean-ridge basalts from the Siqueiros intra-transform spreading centre. The undersaturation leads to correlations between volatiles and refractory trace elements that provide new constraints on volatile abundances and their behaviour in the upper mantle. Our data generate improved limits on the abundances of carbon dioxide, water, fluorine, sulphur and chlorine in the source of normal mid-ocean-ridge basalt. The incompatible behaviour of carbon dioxide, together with the CO(2)/Nb and CO(2)/Cl ratios, permit estimates of primitive carbon dioxide and chlorine to be made for degassed and chlorine-contaminated mid-ocean-ridge basalt magmas, and hence constrain degassing and contamination histories of mid-ocean ridges.},
	issn = {0028-0836 (Linking)},
	doi = {10.1038/nature01073},
	author = {Saal, A. E. and Hauri, E. H. and Langmuir, C. H. and Perfit, M. R.}
}
