Please Note:

The Open Access Repository has moved to a new authentication system as of the 1st of November.

Account holders will now be able to login using their University of Tasmania credentials.
If you have trouble logging in please email us on E.Prints@utas.edu.au so we can assist you.

Public users can still access the records in this repository as normal

Open Access Repository

Metal saturation in the upper mantle

Downloads

Downloads per month over past year

Rohrbach, A and Ballhaus, C and Golla-Schindler, U and Ulmer, P and Kamenetsky, VS and Kuzmin, DV (2007) Metal saturation in the upper mantle. Nature, 449 (7161). pp. 456-458. ISSN 00280836

[img] PDF
Nature-2007_fO2...pdf | Request a copy
Full text restricted
Available under University of Tasmania Standard License.

Abstract

The oxygen fugacity (f)(O2) of the Earth's mantle is one of the fundamental variables in mantle petrology. Through ferric-ferrous iron and carbon-hydrogen-oxygen equilibria, (f)(O2) influences the pressure-temperature positions of mantle solidi and compositions of small-degree mantle melts(1-3). Among other parameters, (f)(O2) affects the water storage capacity and rheology of the mantle(4,5). The uppermost mantle, as represented by samples and partial melts, is sufficiently oxidized to sustain volatiles, such as H2O and CO2, as well as carbonatitic melts(6,7), but it is not known whether the shallow mantle is representative of the entire upper mantle. Using high-pressure experiments, we show here that large parts of the asthenosphere are likely to be metal-saturated. We found that pyroxene and garnet synthesized at >7 GPa in equilibrium with metallic Fe can incorporate sufficient ferric iron that the mantle at >250 km depth is so reduced that an (Fe,Ni)-metal phase may be stable. Our results indicate that the oxidized nature of the upper mantle can no longer be regarded as being representative for the Earth's upper mantle as a whole and instead that oxidation is a shallow phenomenon restricted to an upper veneer only about 250 km in thickness.

Item Type: Article
Keywords: ferric iron, oxidation-state, experimental calibration, oxygen barometer, transition zone, core formation, spectroscopy, metallic iron, olivine
Journal or Publication Title: Nature
Page Range: pp. 456-458
ISSN: 00280836
Identification Number - DOI: 10.1038/nature06183
Additional Information:

Publisher - Nature Publishing Group

Date Deposited: 12 Dec 2007 03:04
Last Modified: 18 Nov 2014 03:25
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page
TOP