THERMAL AND RARE GAS EVOLUTION OF THE MANTLE
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dc.contributor.author | Phipps Morgan J. | |
dc.date.accessioned | 2020-12-27T12:13:43Z | |
dc.date.available | 2020-12-27T12:13:43Z | |
dc.date.issued | 1998 | |
dc.identifier | https://elibrary.ru/item.asp?id=669 | |
dc.identifier.citation | Chemical Geology, 1998, , 3, 431-445 | |
dc.identifier.issn | 0009-2541 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/21434 | |
dc.description.abstract | Present-day seismic evidence implies that the 660 km-deep seismic velocity jump is associated with neither an internal thermal boundary layer nor a strong internal barrier to flow between the upper and lower mantle. However, the generally preferred geochemical paradigm for mantle rare-gas evolution concludes that the lower mantle has remained an isolated and undegassed reservoir throughout at least the past 4.35 Ga of Earth history, as ~50% of the 40Ar produced by 40K-decay appears to still reside within the mantle. Here we reexplore this problem assuming that present-day differentiation processes have operated throughout Earth history. Present mantle overturn rates are slow (~5-10 Ga to pass a mantle volume through the mid-ocean ridge crucible). If slab subduction has been the mantle's primary heat-loss mechanism, then a simple boundary layer argument suggests that paleo-subduction and mantle overturn rates were proportional to the heat loss-squared, and thus more than twenty times faster in the Archean than at the present day. Nevertheless, simple models of Ar evolution within a convecting mantle demonstrate that whole-mantle convection can retain 25-60% of the 40Ar produced during Earth evolution without the need for postulating an isolated and undegassed lower mantle. These models suggest that the 40Ar constraint should be reinterpreted to be a constraint that ~50% of the mantle (and crust?!) has been undegassed since the 40Ar was produced within it. | |
dc.subject | EARTH HISTORY | |
dc.subject | MANTLE | |
dc.subject | ISOTOPES | |
dc.subject | ARGON | |
dc.title | THERMAL AND RARE GAS EVOLUTION OF THE MANTLE | |
dc.type | Статья |
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