Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia
Oxygen fugacity (fO 2 ) and temperature variations in a complete lithospheric mantle section (70-220km) of the central Siberian craton are estimated based on 42 peridotite xenoliths in the Udachnaya kimberlite. Pressure and temperature (P-T) estimates for the 70-140km depth range closely follow the...
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| Format: | Journal Article |
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Elsevier BV
2012
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| Online Access: | http://hdl.handle.net/20.500.11937/67938 |
| _version_ | 1848761698464301056 |
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| author | Goncharov, A. Ionov, D. Doucet, Luc-Serge Pokhilenko, L. |
| author_facet | Goncharov, A. Ionov, D. Doucet, Luc-Serge Pokhilenko, L. |
| author_sort | Goncharov, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Oxygen fugacity (fO 2 ) and temperature variations in a complete lithospheric mantle section (70-220km) of the central Siberian craton are estimated based on 42 peridotite xenoliths in the Udachnaya kimberlite. Pressure and temperature (P-T) estimates for the 70-140km depth range closely follow the 40mW/m 2 model conductive geotherm but show a bimodal distribution at greater depths. A subset of coarse garnet peridotites at 145-180km plots near the "cold" 35mW/m 2 geotherm whereas the majority of coarse and sheared rocks at =145km scatter between the 40 and 45mW/m 2 geotherms. This P-T profile may reflect a perturbation of an initially "cold" lithospheric mantle through a combination of (1) magmatic under-plating close to the crust-mantle boundary and (2) intrusion of melts/fluids in the lower lithosphere accompanied by shearing. fO 2 values estimated from Fe 3+ /sFe in spinel and/or garnet obtained by Mössbauer spectroscopy decrease from +1 to -4 dlog fO 2 (FMQ) from the top to the bottom of the lithospheric mantle (~0.25log units per 10km) due to pressure effects on Fe 2+ -Fe 3+ equilibria in garnet. Garnet peridotites from Udachnaya appear to be more oxidized than those from the Kaapvaal craton but show fO 2 distribution with depth similar to those in the Slave craton. Published fO 2 estimates for Udachnaya xenoliths based on C-O-H fluid speciation in inclusions in minerals from gas chromatography are similar to our results at =120km, but are 1-2 orders of magnitude higher for the deeper mantle, possibly due to uncertainties of fO 2 estimates based on experimental calibrations at =3.5GPa. Sheared peridotites containing garnets with u-shaped, sinusoidal and humped REE patterns are usually more oxidized than Yb, Lu-rich, melt-equilibrated garnets, which show a continuous decrease from heavy to light REE. This further indicates that mantle redox state may be related to sources and modes of metasomatism. © 2012 Elsevier B.V. |
| first_indexed | 2025-11-14T10:35:48Z |
| format | Journal Article |
| id | curtin-20.500.11937-67938 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:35:48Z |
| publishDate | 2012 |
| publisher | Elsevier BV |
| recordtype | eprints |
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| spelling | curtin-20.500.11937-679382018-05-18T08:05:33Z Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia Goncharov, A. Ionov, D. Doucet, Luc-Serge Pokhilenko, L. Oxygen fugacity (fO 2 ) and temperature variations in a complete lithospheric mantle section (70-220km) of the central Siberian craton are estimated based on 42 peridotite xenoliths in the Udachnaya kimberlite. Pressure and temperature (P-T) estimates for the 70-140km depth range closely follow the 40mW/m 2 model conductive geotherm but show a bimodal distribution at greater depths. A subset of coarse garnet peridotites at 145-180km plots near the "cold" 35mW/m 2 geotherm whereas the majority of coarse and sheared rocks at =145km scatter between the 40 and 45mW/m 2 geotherms. This P-T profile may reflect a perturbation of an initially "cold" lithospheric mantle through a combination of (1) magmatic under-plating close to the crust-mantle boundary and (2) intrusion of melts/fluids in the lower lithosphere accompanied by shearing. fO 2 values estimated from Fe 3+ /sFe in spinel and/or garnet obtained by Mössbauer spectroscopy decrease from +1 to -4 dlog fO 2 (FMQ) from the top to the bottom of the lithospheric mantle (~0.25log units per 10km) due to pressure effects on Fe 2+ -Fe 3+ equilibria in garnet. Garnet peridotites from Udachnaya appear to be more oxidized than those from the Kaapvaal craton but show fO 2 distribution with depth similar to those in the Slave craton. Published fO 2 estimates for Udachnaya xenoliths based on C-O-H fluid speciation in inclusions in minerals from gas chromatography are similar to our results at =120km, but are 1-2 orders of magnitude higher for the deeper mantle, possibly due to uncertainties of fO 2 estimates based on experimental calibrations at =3.5GPa. Sheared peridotites containing garnets with u-shaped, sinusoidal and humped REE patterns are usually more oxidized than Yb, Lu-rich, melt-equilibrated garnets, which show a continuous decrease from heavy to light REE. This further indicates that mantle redox state may be related to sources and modes of metasomatism. © 2012 Elsevier B.V. 2012 Journal Article http://hdl.handle.net/20.500.11937/67938 10.1016/j.epsl.2012.09.016 Elsevier BV restricted |
| spellingShingle | Goncharov, A. Ionov, D. Doucet, Luc-Serge Pokhilenko, L. Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia |
| title | Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia |
| title_full | Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia |
| title_fullStr | Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia |
| title_full_unstemmed | Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia |
| title_short | Thermal state, oxygen fugacity and C-O-H fluid speciation in cratonic lithospheric mantle: New data on peridotite xenoliths from the Udachnaya kimberlite, Siberia |
| title_sort | thermal state, oxygen fugacity and c-o-h fluid speciation in cratonic lithospheric mantle: new data on peridotite xenoliths from the udachnaya kimberlite, siberia |
| url | http://hdl.handle.net/20.500.11937/67938 |