Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt)
Mantle peridotites from the Mesoproterozoic forearc-type ophiolites in the Eastern Sayan range (Eastern Siberia) provide insights into the nature and formation processes of the supra-subduction mantle. The peridotites are represented by porphyroclastic harzburgites and dunites. The harzburgites have...
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Frontiers Media S.A.
2023-10-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2023.1270053/full |
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| author | Marina A. Gornova Vasiliy A. Belyaev Anas A. Karimov Anas A. Karimov Sergei Yu. Skuzovatov Nikolay S. Karmanov Alexander Ya. Medvedev Nikolay V. Bryanskiy Nikolay V. Bryanskiy |
| author_facet | Marina A. Gornova Vasiliy A. Belyaev Anas A. Karimov Anas A. Karimov Sergei Yu. Skuzovatov Nikolay S. Karmanov Alexander Ya. Medvedev Nikolay V. Bryanskiy Nikolay V. Bryanskiy |
| author_sort | Marina A. Gornova |
| collection | DOAJ |
| description | Mantle peridotites from the Mesoproterozoic forearc-type ophiolites in the Eastern Sayan range (Eastern Siberia) provide insights into the nature and formation processes of the supra-subduction mantle. The peridotites are represented by porphyroclastic harzburgites and dunites. The harzburgites have strongly refractory compositions recorded in high Mg# olivine (0.912-0.927) and orthopyroxene (0.916-0.935), high Cr# spinel (0.45-0.66), low Al2O3 and Cr2O3 abundances in orthopyroxene, the lack of residual clinopyroxene, low HREE abundances in orthopyroxene, clinopyroxene and whole-rocks. Some rocks are relatively enriched in SiO2, which is a common feature of supra-subduction (arc and forearc) peridotites and suggests hydrous melting, whereas the rest resemble the chemistry of residues from anhydrous melting of depleted mantle (DM). The whole-rock Al2O3 and Cr-spinel compositions reflect high degrees of partial melting, which initiated in the garnet facies. The Khara-Nur peridotites experienced modification by high-Mg, low-Ti hydrous (boninitic or tholeiitic) arc melts, which crystallized newly-formed minerals (clinopyroxene, Cr-spinel, olivine) in harzburgites. The trace-element composition of clinopyroxene (YbN = 0.5-1.0, La/YbN = 0.05-0.5) resembles that of clinopyroxene from the forearc peridotites and reflects low melt/rock ratio. In dunites, melt percolation resulted in growth of Cr-spinel hosting multiphase inclusions (olivine + clinopyroxene + orthopyroxene + amphibole + phlogopite). Clinopyroxenes from Cr-spinel-hosted inclusions exhibit considerable variations in trace element composition due to heterogeneity of parental melts. Remarkably low Fe3+/∑Fe ratios (0.02-0.12) of Cr-spinels in both harzburgites and dunites are uncommon in SSZ mantle rocks and cannot be explained in terms of the supra-subduction processes, such as partial melting and melt percolation. The whole-rock and mineral compositions of Khara-Nur peridotites, along with previously reported Paleo- to Mesoproterozoic Re-Os model ages, suggest an affinity to ultra-depleted Proterozoic subcontinental lithospheric mantle (SCLM). Overall, the Khara-Nur mantle rocks most likely represent a block of SCLM which underwent melt interaction in a supra-subduction tectonic setting that yielded boninitic and tholeiitic melts comprising now the crustal part of Eastern Sayan ophiolites. |
| first_indexed | 2024-03-11T18:18:35Z |
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| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-03-11T18:18:35Z |
| publishDate | 2023-10-01 |
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| series | Frontiers in Earth Science |
| spelling | doaj.art-dbcf4d32bcc1412eade35b04f8e412bd2023-10-16T05:06:33ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632023-10-011110.3389/feart.2023.12700531270053Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt)Marina A. Gornova0Vasiliy A. Belyaev1Anas A. Karimov2Anas A. Karimov3Sergei Yu. Skuzovatov4Nikolay S. Karmanov5Alexander Ya. Medvedev6Nikolay V. Bryanskiy7Nikolay V. Bryanskiy8Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaVinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaVinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaInstitute of the Earth’s Crust, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaVinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaSobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk, RussiaVinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaVinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaInstitute of the Earth’s Crust, Siberian Branch of Russian Academy of Sciences, Irkutsk, RussiaMantle peridotites from the Mesoproterozoic forearc-type ophiolites in the Eastern Sayan range (Eastern Siberia) provide insights into the nature and formation processes of the supra-subduction mantle. The peridotites are represented by porphyroclastic harzburgites and dunites. The harzburgites have strongly refractory compositions recorded in high Mg# olivine (0.912-0.927) and orthopyroxene (0.916-0.935), high Cr# spinel (0.45-0.66), low Al2O3 and Cr2O3 abundances in orthopyroxene, the lack of residual clinopyroxene, low HREE abundances in orthopyroxene, clinopyroxene and whole-rocks. Some rocks are relatively enriched in SiO2, which is a common feature of supra-subduction (arc and forearc) peridotites and suggests hydrous melting, whereas the rest resemble the chemistry of residues from anhydrous melting of depleted mantle (DM). The whole-rock Al2O3 and Cr-spinel compositions reflect high degrees of partial melting, which initiated in the garnet facies. The Khara-Nur peridotites experienced modification by high-Mg, low-Ti hydrous (boninitic or tholeiitic) arc melts, which crystallized newly-formed minerals (clinopyroxene, Cr-spinel, olivine) in harzburgites. The trace-element composition of clinopyroxene (YbN = 0.5-1.0, La/YbN = 0.05-0.5) resembles that of clinopyroxene from the forearc peridotites and reflects low melt/rock ratio. In dunites, melt percolation resulted in growth of Cr-spinel hosting multiphase inclusions (olivine + clinopyroxene + orthopyroxene + amphibole + phlogopite). Clinopyroxenes from Cr-spinel-hosted inclusions exhibit considerable variations in trace element composition due to heterogeneity of parental melts. Remarkably low Fe3+/∑Fe ratios (0.02-0.12) of Cr-spinels in both harzburgites and dunites are uncommon in SSZ mantle rocks and cannot be explained in terms of the supra-subduction processes, such as partial melting and melt percolation. The whole-rock and mineral compositions of Khara-Nur peridotites, along with previously reported Paleo- to Mesoproterozoic Re-Os model ages, suggest an affinity to ultra-depleted Proterozoic subcontinental lithospheric mantle (SCLM). Overall, the Khara-Nur mantle rocks most likely represent a block of SCLM which underwent melt interaction in a supra-subduction tectonic setting that yielded boninitic and tholeiitic melts comprising now the crustal part of Eastern Sayan ophiolites.https://www.frontiersin.org/articles/10.3389/feart.2023.1270053/fullsupra-subduction ophiolitesophiolitic peridotitesredox stateSCLMmantle wedgemelt-rock reaction |
| spellingShingle | Marina A. Gornova Vasiliy A. Belyaev Anas A. Karimov Anas A. Karimov Sergei Yu. Skuzovatov Nikolay S. Karmanov Alexander Ya. Medvedev Nikolay V. Bryanskiy Nikolay V. Bryanskiy Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt) Frontiers in Earth Science supra-subduction ophiolites ophiolitic peridotites redox state SCLM mantle wedge melt-rock reaction |
| title | Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt) |
| title_full | Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt) |
| title_fullStr | Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt) |
| title_full_unstemmed | Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt) |
| title_short | Supra-subduction melt modification of the fossil subcontinental lithospheric mantle: insights from ultra-depleted Khara-Nur ophiolitic peridotites (Eastern Sayan, central Asian orogenic belt) |
| title_sort | supra subduction melt modification of the fossil subcontinental lithospheric mantle insights from ultra depleted khara nur ophiolitic peridotites eastern sayan central asian orogenic belt |
| topic | supra-subduction ophiolites ophiolitic peridotites redox state SCLM mantle wedge melt-rock reaction |
| url | https://www.frontiersin.org/articles/10.3389/feart.2023.1270053/full |
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