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| Titel |
Geodynamic investigation of the processes that control Lu-Hf isotopic differences between different mantle domains and the crust |
| VerfasserIn |
Rosie Jones, Peter van Keken, Erik Hauri, Jeff Vervoort, Chris J. Ballentine |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129024
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| Publikation (Nr.) |
 EGU/EGU2016-9084.pdf |
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| Zusammenfassung |
| The chemical and isotopic composition of both the Earth’s mantle and the continental crust
are greatly influenced by subduction zone processes, such as the formation of continental
crust through arc volcanism and the recycling of surface material into the deep mantle. Here
we use a combined geodynamical-geochemical approach to investigate the long term role
of subduction on the Lu-Hf isotopic evolution of the mantle and the continental
crust.
We apply the geodynamic model developed by Brandenburg et al., 2008. This model
satisfies the geophysical constraints of oceanic heat flow and average plate velocities, as well
as geochemical observations such as 40Ar in the atmosphere, and reproduces the
geochemical distributions observed in multiple isotope systems which define the HIMU,
MORB and EM1 mantle endmembers. We extend this application to investigate the
detail of terrestrial Lu-Hf isotope distribution and evolution, and specifically to
investigate the role of sediment recycling in the generation of EM2 mantle compositions.
The model has been updated to produce higher resolution results and to include a
self-consistent reorganisation of the plates with regions of up-/down-wellings. The model
assumes that subduction is initiated at 4.5 Ga and that a transition from ‘dry’ to ‘wet’
subduction occurred at 2.5 Ga. The modelling suggests that the epsilon Hf evolution
of the upper mantle can be generated through the extraction and recycling of the
oceanic crust, and that the formation of continental crust plays a lesser role. Our
future intention is to utilise the model presented here to investigate the differences
observed in the noble gas compositions (e.g., 40Ar/36Ar, 3He/4He) of MORB and
OIB.
Brandenburg, J.P., Hauri, E.H., van Keken, P.E., Ballentine, C.J., 2008. Earth and
Planetary Science Letters 276, 1-13. |
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