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Damien Guillaume - One of the best experts on this subject based on the ideXlab platform.
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Ultra-refractory mantle within oceanic plateau: Petrology of the spinel harzburgites from Lac Michèle, Kerguelen Archipelago
Lithos, 2017Co-Authors: Benjamin Wasilewski, Luc Serge Doucet, Hugues Beunon, Vinciane Debaille, Adélie Delacour, Guillaume Delpech, Bertrand Moine, Michel Grégoire, Nadine Mattielli, Damien GuillaumeAbstract:The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michele locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg# are high (0.91 to 0.93) and they have 16–29 wt.% orthopyroxene (opx) and low clinopyroxene contents (0.1–2.8 wt.%). They display a wide range of serpentinisation, which result in LOI contents ranging from 0 to 3.5 wt.%. The spinel-bearing harzburgites from Lac Michele are the most refractory Peridotites identified so far among Peridotite xenoliths available on the Kerguelen Archipelago and within the oceanic lithosphere. By contrast with most of the Peridotite xenoliths from Kerguelen, they have been more preserved from post-formation processes such as metasomatic processes. The major and trace element compositions of the least serpentinised spinel harzburgites indicate an origin by ~ 30% of polybaric decompression fractional melting between 5GPa and ≤ 1 GPa. Thus, the spinel harzburgites from Lac Michele, situated at the top of the Kerguelen lithospheric mantle, are residues of melting that took place over a broad range of depth and mostly in the garnet stability field. Our results, in comparison with published data on mantle xenoliths worldwide, show that spinel harzburgites from Lac Michele have major and modal compositions that fall in the range of cratonic Peridotites rather than abyssal Peridotites, oceanic island Peridotites, subduction zones Peridotites and off-cratonic Peridotites. This indicates (i) they formed in similar condition as for the ancient continental lithospheric mantle or (ii) they are fragment of ancient continental lithospheric mantle incorporated in the Kerguelen plateau.
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Ultra-refractory mantle within oceanic plateau: Petrology of the spinel harzburgites from Lac Michèle, Kerguelen Archipelago
Lithos, 2017Co-Authors: Benjamin Wasilewski, Luc Serge Doucet, Hugues Beunon, Vinciane Debaille, Adélie Delacour, Guillaume Delpech, Bertrand Moine, Michel Grégoire, Nadine Mattielli, Damien GuillaumeAbstract:The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michèle locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg# are high (0.91 to 0.93) and they have 16–29 wt.% orthopyroxene (opx) and low clinopyroxene contents (0.1–2.8 wt.%). They display a wide range of serpentinisation, which result in LOI contents ranging from 0 to 3.5 wt.%. The spinel-bearing harzburgites from Lac Michèle are the most refractory Peridotites identified so far among Peridotite xenoliths available on the Kerguelen Archipelago and within the oceanic lithosphere. By contrast with most of the Peridotite xenoliths from Kerguelen, they have been more preserved from post-formation processes such as metasomatic processes. The major and trace element compositions of the least serpentinised spinel harzburgites indicate an origin by ~ 30% of polybaric decompression fractional melting between 5GPa and ≤ 1 GPa. Thus, the spinel harzburgites from Lac Michèle, situated at the top of the Kerguelen lithospheric mantle, are residues of melting that took place over a broad range of depth and mostly in the garnet stability field. Our results, in comparison with published data on mantle xenoliths worldwide, show that spinel harzburgites from Lac Michèle have major and modal compositions that fall in the range of cratonic Peridotites rather than abyssal Peridotites, oceanic island Peridotites, subduction zones Peridotites and off-cratonic Peridotites. This indicates (i) they formed in similar condition as for the ancient continental lithospheric mantle or (ii) they are fragment of ancient continental lithospheric mantle incorporated in the Kerguelen plateau.
Dmitri A. Ionov - One of the best experts on this subject based on the ideXlab platform.
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The origin of coarse garnet Peridotites in cratonic lithosphere: new data on xenoliths from the Udachnaya kimberlite, central Siberia
Contributions to Mineralogy and Petrology, 2013Co-Authors: Luc Serge Doucet, Dmitri A. Ionov, Alexander V GolovinAbstract:We report new textural and chemical data for 10 garnet Peridotite xenoliths from the Udachnaya kimberlite and examine them together with recent data on another 21 xenoliths from the 80–220 km depth range. The samples are very fresh (LOI near zero), modally homogeneous and large (>100 g). Some coarse-grained Peridotites show incipient stages of deformation with
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re os isotope systematics and platinum group element fractionation during mantle melt extraction a study of massif and xenolith Peridotite suites
Chemical Geology, 2004Co-Authors: D G Pearson, Dmitri A. Ionov, F. R. Boyd, G J Irvine, G DreibusAbstract:Re–Os isotope and platinum group elements (PGE) systematics are presented for Peridotite xenoliths from N. Lesotho (on-craton), S. Namibia (circum-cratonic), the Vitim volcanic field (Baikhal Rift), plus massif Peridotites from Beni Bousera, N. Morocco. Mg–Fe variations indicate that these samples have experienced between 5% (Vitim–Beni Bousera) and 50% (Lesotho) melt extraction, providing the opportunity to examine PGE fractionation over a large melting interval. The Namibian xenoliths and Beni Bousera massif Peridotites show no variation of iridium group (Ir, Ru, Os; I-PGE) abundances or inter-element fractionations relative to melt depletion indices such as Mg number or Al2O3. Lesotho Peridotites show large variations in I-PGE abundances (Os range 0.2–13 ppb) at relatively constant Al2O3 that are not easily rationalised by melt-extraction models. Despite these abundance variations, there is no significant inter-element fractionation of I-PGE, e.g., (Os/Ir)n, showing that these elements are not fractionated by even very large degrees of melting (up to 50% melt extraction). Lesotho Peridotites are amongst the most P-PGE (Pt, Pd)-depleted mantle rocks, with highly fractionated chondrite-normalised PGE. PGE systematics for all these Peridotite suites allow a relative order of PGE compatibility to be firmly established for mantle melting: Dsolid/meltOsDsolid/meltIrDsolid/meltRu>Dsolid/meltPt>Dsolid/meltPd. Vitim Peridotite xenoliths have very low Os contents and low Os/Ir (<70% chondritic) compared to the kimberlite-borne xenoliths and massif Peridotites. The Vitim low Os/Ir is comparable with other suites of alkali-basalt-borne Peridotite xenoliths and may result from syn- or post-eruption sulphide breakdown and alteration. Chondritic (Ru/Ir)n and (Os/Ir)n ratios in Lesotho and other cratonic Peridotites show no evidence of anomalous PGE fractionations in the Archean subcontinental mantle and support the Late Veneer hypothesis. In most of the Peridotite suites, (Pd/Ir)n values show a strong correlation with Os isotopic composition that is likely the result of melt-residue interaction. The positive variation of both (Ru/Ir)n and (Pd/Ir)n with bulk rock Al2O3 and Os isotopic composition for Beni Bousera and global massif Peridotites indicates that these PGE ratios were modified by interaction with melts. Hence, we find no support for the intra-element PGE fractionation in the continental lithospheric mantle (CLM) representing primordial mantle heterogeneity. Highly unradiogenic Os isotope compositions appear characteristic of lithospheric Peridotites with the lowest (Pd/Ir)n. In these samples, bulk-rock PGE patterns suggest that Os isotope systematics should be dominated by primary, residual, P-PGE-depleted sulphides, and hence, their bulk rock Re-depletion ages should be expected to approximate the melting age of the rock.
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chemical variations in Peridotite xenoliths from vitim siberia inferences for ree and hf behaviour in the garnet facies upper mantle
Journal of Petrology, 2004Co-Authors: Dmitri A. IonovAbstract:Peridotite xenoliths in a Miocene picrite tuff from the Vitim volcanic province east of Lake Baikal, Siberia, are samples of the off-craton lithospheric mantle that span a depth range from the spinel to garnet facies in a mainly fertile domain. Their major and trace element compositions show some scatter (unrelated to sampling or analytical problems), which is not consistent with different degrees of partial melting or metasomatism. Some spinel Peridotites and, to a lesser degree, garnet-bearing Peridotites are depleted in heavy rare earth elements (HREE) relative to middle REE (MREE), whereas some garnet Peridotites are enriched in HREE relative to MREE, with Lu abundances much higher than in primitive mantle estimates. Clinopyroxenes from several spinel Peridotites have HREE-depleted patterns, which are normally seen only in clinopyroxenes coexisting with garnet. Garnets in Peridotites with similar modal and major element compositions have a broad range of Lu and Yb abundances. Overall, HREE are decoupled from MREE and Hf and are poorly correlated with partial melting indices. It appears that elements with high affinity to garnet were partially redistributed in the Vitim Peridotite series following partial melting, with few effects for other elements. The Lu---Hf decoupling may disturb Hf-isotope depletion ages and their correlations with melting indices.
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carbonated Peridotite xenoliths from spitsbergen implications for trace element signature of mantle carbonate metasomatism
Earth and Planetary Science Letters, 1993Co-Authors: Dmitri A. Ionov, M G Kopylova, C. Dupuy, Suzanne Y Oreilly, Yury S GenshaftAbstract:Abstract Peridotite xenoliths from basaltic volcanics in NW Spitsbergen contain carbonates of mantle origin. These occur as pockets of granular dolomite (Mg# 0.95–0.99) accompanied by fine-grained olivine and Al,Cr,Ti-rich clinopyroxene apparently produced by reaction of carbonate-rich fluids with the primary mineral assemblage of coarse spinel Peridotites. Accessory apatite occurs in one sample. Most commonly, however, the Spitsbergen xenoliths contain patches and veins of quenched carbonate and silicate melts [1,2]. Our observations suggest that the mantle carbonates melted shortly before or during the transport of the xenoliths to the surface, which also triggered local melting in the Peridotites to produce a Na,Al-rich silicate glass. Four carbonate-bearing Peridotite xenoliths were acid leached and the leachates, the residues after leaching and the bulk rocks were analysed for 25 trace elements by ICP-MS. The trace element inventory of the leachates is dominated by dissolved carbonate material. The leachates, and the bulk Peridotites, show marked enrichment in LREE, Sr, Ba and Rb and are relatively depleted in Zr, Hf, Nb and Ta. In-situ analyses by proton microprobe show very high contents of Sr in clinopyroxenes, primary carbonates and accessory apatite; the apatite is also very rich in LREE, U, Th and Br. Relative enrichment in LREE and Sr over HREE and HFSE appears to be characteristic of mantle carbonates and carbonate-bearing Peridotites. High Sr/Sm, Sm/Hf, La/Nb, Zr/Hf and Nb/Ta ratios in mantle Peridotites (including basalt source regions) may be a signature of carbonate-related metasomatism.
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content and isotopic composition of sulphur in ultramafic xenoliths from central asia
Earth and Planetary Science Letters, 1992Co-Authors: Dmitri A. Ionov, Jochen Hoefs, Hans K Wedepohl, Uwe WiechertAbstract:Sulphur contents and isotopic compositions have been determined in 90 fresh mantle-derived garnet and spinel Peridotite and pyroxenite xenoliths from six regions of Cenozoic alkali basaltic volcanism in southern Siberia and Mongolia. Sulphur contents in most of the Peridotite nodules fall in the range 6–25 ppm, with largely positive δ34S values clustering between −1 and +7‰ (average +2‰). By contrast, the pyroxenites are richer in sulphur (25–140 ppm), and their δ34S values are close to 0‰ (−1.5 to +1.4‰). In the Peridotite nodules, sulphur content correlates negatively with MgO, while their δ34S values correlate positively with MgO. Most of the fertile lherzolites (MgO= 37–39%, CaO= 3–4%) have δ34S values close to 0‰ (−1 to +2‰), similar to meteorite values, while in the harzburgites these values reach +3 to +5‰. These features apparently reflect sulphur depletion during partial melting of Peridotite mantle accompanied by sulphur isotopic fractionation between residual Peridotites and generated basaltic melts. Clinopyroxene-poor xenoliths from southern Mongolia yielded highest δ34S values of +5 to +7‰ accompanied by high Ba and K contents and high 87Sr/86Sr ratios; these may be a result of interaction with fluids derived from subducted oceanic crust which followed the partial melting and magmatic fractionation episodes. Low average sulphur concentrations ( < 50 ppm) and largely positive δ34S values may predominate in the continental lithospheric mantle worldwide. Sulphur isotope compositions typical of tholeiitic basalts and MORB (0 to +1‰ [1,2]) may be produced by melting of moderately depleted lherzolites. Primary melts with positive δ34S values may be generated from mantle Peridotites with larger degrees of depletion and/or from rocks metasomatised by subduction-related fluids.
Luc Serge Doucet - One of the best experts on this subject based on the ideXlab platform.
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Ultra-refractory mantle within oceanic plateau: Petrology of the spinel harzburgites from Lac Michèle, Kerguelen Archipelago
Lithos, 2017Co-Authors: Benjamin Wasilewski, Luc Serge Doucet, Hugues Beunon, Vinciane Debaille, Adélie Delacour, Guillaume Delpech, Bertrand Moine, Michel Grégoire, Nadine Mattielli, Damien GuillaumeAbstract:The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michele locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg# are high (0.91 to 0.93) and they have 16–29 wt.% orthopyroxene (opx) and low clinopyroxene contents (0.1–2.8 wt.%). They display a wide range of serpentinisation, which result in LOI contents ranging from 0 to 3.5 wt.%. The spinel-bearing harzburgites from Lac Michele are the most refractory Peridotites identified so far among Peridotite xenoliths available on the Kerguelen Archipelago and within the oceanic lithosphere. By contrast with most of the Peridotite xenoliths from Kerguelen, they have been more preserved from post-formation processes such as metasomatic processes. The major and trace element compositions of the least serpentinised spinel harzburgites indicate an origin by ~ 30% of polybaric decompression fractional melting between 5GPa and ≤ 1 GPa. Thus, the spinel harzburgites from Lac Michele, situated at the top of the Kerguelen lithospheric mantle, are residues of melting that took place over a broad range of depth and mostly in the garnet stability field. Our results, in comparison with published data on mantle xenoliths worldwide, show that spinel harzburgites from Lac Michele have major and modal compositions that fall in the range of cratonic Peridotites rather than abyssal Peridotites, oceanic island Peridotites, subduction zones Peridotites and off-cratonic Peridotites. This indicates (i) they formed in similar condition as for the ancient continental lithospheric mantle or (ii) they are fragment of ancient continental lithospheric mantle incorporated in the Kerguelen plateau.
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Ultra-refractory mantle within oceanic plateau: Petrology of the spinel harzburgites from Lac Michèle, Kerguelen Archipelago
Lithos, 2017Co-Authors: Benjamin Wasilewski, Luc Serge Doucet, Hugues Beunon, Vinciane Debaille, Adélie Delacour, Guillaume Delpech, Bertrand Moine, Michel Grégoire, Nadine Mattielli, Damien GuillaumeAbstract:The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michèle locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg# are high (0.91 to 0.93) and they have 16–29 wt.% orthopyroxene (opx) and low clinopyroxene contents (0.1–2.8 wt.%). They display a wide range of serpentinisation, which result in LOI contents ranging from 0 to 3.5 wt.%. The spinel-bearing harzburgites from Lac Michèle are the most refractory Peridotites identified so far among Peridotite xenoliths available on the Kerguelen Archipelago and within the oceanic lithosphere. By contrast with most of the Peridotite xenoliths from Kerguelen, they have been more preserved from post-formation processes such as metasomatic processes. The major and trace element compositions of the least serpentinised spinel harzburgites indicate an origin by ~ 30% of polybaric decompression fractional melting between 5GPa and ≤ 1 GPa. Thus, the spinel harzburgites from Lac Michèle, situated at the top of the Kerguelen lithospheric mantle, are residues of melting that took place over a broad range of depth and mostly in the garnet stability field. Our results, in comparison with published data on mantle xenoliths worldwide, show that spinel harzburgites from Lac Michèle have major and modal compositions that fall in the range of cratonic Peridotites rather than abyssal Peridotites, oceanic island Peridotites, subduction zones Peridotites and off-cratonic Peridotites. This indicates (i) they formed in similar condition as for the ancient continental lithospheric mantle or (ii) they are fragment of ancient continental lithospheric mantle incorporated in the Kerguelen plateau.
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The origin of coarse garnet Peridotites in cratonic lithosphere: new data on xenoliths from the Udachnaya kimberlite, central Siberia
Contributions to Mineralogy and Petrology, 2013Co-Authors: Luc Serge Doucet, Dmitri A. Ionov, Alexander V GolovinAbstract:We report new textural and chemical data for 10 garnet Peridotite xenoliths from the Udachnaya kimberlite and examine them together with recent data on another 21 xenoliths from the 80–220 km depth range. The samples are very fresh (LOI near zero), modally homogeneous and large (>100 g). Some coarse-grained Peridotites show incipient stages of deformation with
Benjamin Wasilewski - One of the best experts on this subject based on the ideXlab platform.
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Ultra-refractory mantle within oceanic plateau: Petrology of the spinel harzburgites from Lac Michèle, Kerguelen Archipelago
Lithos, 2017Co-Authors: Benjamin Wasilewski, Luc Serge Doucet, Hugues Beunon, Vinciane Debaille, Adélie Delacour, Guillaume Delpech, Bertrand Moine, Michel Grégoire, Nadine Mattielli, Damien GuillaumeAbstract:The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michele locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg# are high (0.91 to 0.93) and they have 16–29 wt.% orthopyroxene (opx) and low clinopyroxene contents (0.1–2.8 wt.%). They display a wide range of serpentinisation, which result in LOI contents ranging from 0 to 3.5 wt.%. The spinel-bearing harzburgites from Lac Michele are the most refractory Peridotites identified so far among Peridotite xenoliths available on the Kerguelen Archipelago and within the oceanic lithosphere. By contrast with most of the Peridotite xenoliths from Kerguelen, they have been more preserved from post-formation processes such as metasomatic processes. The major and trace element compositions of the least serpentinised spinel harzburgites indicate an origin by ~ 30% of polybaric decompression fractional melting between 5GPa and ≤ 1 GPa. Thus, the spinel harzburgites from Lac Michele, situated at the top of the Kerguelen lithospheric mantle, are residues of melting that took place over a broad range of depth and mostly in the garnet stability field. Our results, in comparison with published data on mantle xenoliths worldwide, show that spinel harzburgites from Lac Michele have major and modal compositions that fall in the range of cratonic Peridotites rather than abyssal Peridotites, oceanic island Peridotites, subduction zones Peridotites and off-cratonic Peridotites. This indicates (i) they formed in similar condition as for the ancient continental lithospheric mantle or (ii) they are fragment of ancient continental lithospheric mantle incorporated in the Kerguelen plateau.
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Ultra-refractory mantle within oceanic plateau: Petrology of the spinel harzburgites from Lac Michèle, Kerguelen Archipelago
Lithos, 2017Co-Authors: Benjamin Wasilewski, Luc Serge Doucet, Hugues Beunon, Vinciane Debaille, Adélie Delacour, Guillaume Delpech, Bertrand Moine, Michel Grégoire, Nadine Mattielli, Damien GuillaumeAbstract:The study presents major and trace element compositions of whole-rocks and minerals of 24 spinel harzburgite xenoliths from the Lac Michèle locality in the northern part of the Kerguelen Archipelago (South Indian Ocean). The samples are modally homogeneous and large enough to provide representative whole-rock samples. Their Mg# are high (0.91 to 0.93) and they have 16–29 wt.% orthopyroxene (opx) and low clinopyroxene contents (0.1–2.8 wt.%). They display a wide range of serpentinisation, which result in LOI contents ranging from 0 to 3.5 wt.%. The spinel-bearing harzburgites from Lac Michèle are the most refractory Peridotites identified so far among Peridotite xenoliths available on the Kerguelen Archipelago and within the oceanic lithosphere. By contrast with most of the Peridotite xenoliths from Kerguelen, they have been more preserved from post-formation processes such as metasomatic processes. The major and trace element compositions of the least serpentinised spinel harzburgites indicate an origin by ~ 30% of polybaric decompression fractional melting between 5GPa and ≤ 1 GPa. Thus, the spinel harzburgites from Lac Michèle, situated at the top of the Kerguelen lithospheric mantle, are residues of melting that took place over a broad range of depth and mostly in the garnet stability field. Our results, in comparison with published data on mantle xenoliths worldwide, show that spinel harzburgites from Lac Michèle have major and modal compositions that fall in the range of cratonic Peridotites rather than abyssal Peridotites, oceanic island Peridotites, subduction zones Peridotites and off-cratonic Peridotites. This indicates (i) they formed in similar condition as for the ancient continental lithospheric mantle or (ii) they are fragment of ancient continental lithospheric mantle incorporated in the Kerguelen plateau.
Olivier Alard - One of the best experts on this subject based on the ideXlab platform.
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Dating post-Archean lithospheric mantle: Insights from Re-Os and Lu-Hf isotopic systematics of the Cameroon Volcanic Line Peridotites
Geochimica et Cosmochimica Acta, 2019Co-Authors: Jingao Liu, D. Graham Pearson, Qiao Shu, Haraldur Sigurdsson, Emilie Thomassot, Olivier AlardAbstract:Highly depleted Archean Peridotites have proven very amenable to Re-Os model age dating. In contrast, due to the increasing heterogeneity of mantle Os isotope compositions with time, the Re-Os system has not been as effective in dating post-Archean Peridotites. The timing of depletion and accretion of post-Archean lithospheric mantle around cratons is important to understand within the context of the evolution of the continents. In an attempt to precisely date post-Archean Peridotite xenoliths, we present a study of the petrology, mineralogy and geochemistry, including whole-rock Re-Os isotopes, highly siderophile elements and clinopyroxene-orthopyroxene Sr-Nd-Hf isotopes of Peridotite xenoliths from Lake Nyos in the Cameroon Volcanic Line (CVL). Eight Nyos Peridotite xenoliths, all fresh spinel lherzolites, are characterized by low to moderate olivine Fo contents (88.9–91.2) and low spinel Cr# (8.4–19.3), together with moderate to high whole-rock Al2O3 contents (2.0–3.7%). These chemical characteristics indicate that they are mantle residues of a few percent to
