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<meta content="Ballhaus, C." name="eprints.creators_name" />
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<meta content="ferric iron, oxidation-state, experimental calibration, oxygen barometer, transition zone, core formation, spectroscopy, metallic iron, olivine" name="eprints.keywords" />
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<meta content="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." name="eprints.abstract" />
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<meta content="Taylor, W. R. & Green, D. H. in Magmatic Processes: Physicochemical Principles (ed.
Mysen, B. O.) 121–138 (Geochemical Society USA Special Publication 1, University
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caused by carbon dioxide. Nature 440, 659–662 (2006).
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gamma phases of (Mg,Fe)2SiO4. Contrib. Mineral. Petrol. 123, 345–357 (1996).
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6. Matveev, S., Ballhaus, C., Fricke, K., Trunckenbrodt, J. & Ziegenbein, D. CHO
volatiles under upper mantle conditions. I. Experimental results. Geochim.
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olivine–orthopyroxene–spinel oxygen barometer—implications for oxygen
fugacity in the Earth’s upper mantle. Contrib. Mineral. Petrol. 107, 27–40 (1991).
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relationship to tectonic environment and fluid speciation. Science 248, 337–345
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post-perovskite. Geophys. Res. Lett. 33, L12S13, doi:10.1029/2006GL025858
(2006).
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(Mg,Fe)(Si,Al)O3 majorite with implications for the transition zone. Phys. Chem.
Miner. 30, 206–216 (2003).
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& Manghnani, M. H.) 237–250 (Center Academic, Tokyo, 1982).
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in garnets from polycrystalline diamond aggregates. Contrib. Mineral. Petrol. 146,
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diamonds from Mwadui, Tanzania. Contrib. Mineral. Petrol. 132, 34–47 (1998).
31. Bellis, A. J. & Canil, D. Ferric iron in CaTiO3 perovskite as an oxygen barometer for
kimberlitic magmas. I: Experimental calibration. J. Petrol. 48, 219–230 (2007).
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kimberlite magmas. II: Applications. J. Petrol. 48, 231–252 (2007).
" name="eprints.referencetext" />
<meta content="Rohrbach, A. and Ballhaus, C. and Golla-Schindler, U. and Ulmer, P. and Kamenetsky, V.S. and Kuzmin, D.V. (2007) Metal saturation in the upper mantle. Nature, 449 (7161). pp. 456-458. ISSN 00280836" name="eprints.citation" />
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<meta content="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." name="DC.description" />
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<h1 class="ep_tm_pagetitle">Metal saturation in the upper mantle</h1>
<p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Rohrbach, A.</span> and <span class="person_name">Ballhaus, C.</span> and <span class="person_name">Golla-Schindler, U.</span> and <span class="person_name">Ulmer, P.</span> and <span class="person_name">Kamenetsky, V.S.</span> and <span class="person_name">Kuzmin, D.V.</span> (2007) <xhtml:em>Metal saturation in the upper mantle.</xhtml:em> Nature, 449 (7161). pp. 456-458. ISSN 00280836</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/2608/1/Nature-2007_fO2.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" class="ep_doc_icon" border="0" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/2608/1/Nature-2007_fO2.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />569Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input accept-charset="utf-8" value="3417" name="docid" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.1038/nature06183">http://dx.doi.org/10.1038/nature06183</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">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.</p></div><table style="margin-bottom: 1em" cellpadding="3" class="not_ep_block" border="0"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Additional Information:</th><td valign="top" class="ep_row">Publisher - Nature Publishing Group</td></tr><tr><th valign="top" class="ep_row">Keywords:</th><td valign="top" class="ep_row">ferric iron, oxidation-state, experimental calibration, oxygen barometer, transition zone, core formation, spectroscopy, metallic iron, olivine</td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/260300.html">260000 Earth Sciences > 260300 Geochemistry</a><br /><a href="http://eprints.utas.edu.au/view/subjects/260100.html">260000 Earth Sciences > 260100 Geology</a></td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">2608</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Prof Vadim Kamenetsky</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">12 Dec 2007 14:04</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">09 Jan 2008 02:30</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=2608;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&eprintid=2608">item control page</a></p>
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