Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite
Garnet xenocrysts ( n = 386) and associated mineral inclusions and intergrowths from the diamond-free Zagadochnaya kimberlite (Daldyn field, Yakutia) were studied to provide new insights into mantle processes beneath the central Siberian Craton. Electron microprobe analyses indicate that the great m...
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fthighwire:oai:open-archive.highwire.org:petrology:54/11/2379 2023-05-15T18:45:09+02:00 Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite Ziberna, Luca Nimis, Paolo Zanetti, Alberto Marzoli, Andrea Sobolev, Nikolai V. 2013-11-01 00:00:00.0 text/html http://petrology.oxfordjournals.org/cgi/content/short/54/11/2379 https://doi.org/10.1093/petrology/egt051 en eng Oxford University Press http://petrology.oxfordjournals.org/cgi/content/short/54/11/2379 http://dx.doi.org/10.1093/petrology/egt051 Copyright (C) 2013, Oxford University Press Original Papers TEXT 2013 fthighwire https://doi.org/10.1093/petrology/egt051 2015-02-28T17:53:03Z Garnet xenocrysts ( n = 386) and associated mineral inclusions and intergrowths from the diamond-free Zagadochnaya kimberlite (Daldyn field, Yakutia) were studied to provide new insights into mantle processes beneath the central Siberian Craton. Electron microprobe analyses indicate that the great majority of the garnets follow the ‘lherzolitic’ trend in the CaO vs Cr 2 O 3 diagram (Cr 2 O 3 = 0·5–9·3 wt %, CaO = 3·2–10·3 wt %), with <10% falling in the wehrlitic field and <3% falling in a transitional region between the lherzolitic and harzburgitic fields. A representative subset of the garnets ( n = 28) was further analysed for trace elements by laser ablation inductively coupled plasma mass spectrometry. Based on both major and trace element data, three main compositional groups are distinguished: Group A garnets (Cr 2 O 3 = 1·3–5·2 wt %) may contain inclusions of chromian diopside and are characterized by progressively increasing, chondrite (CI)-normalized rare earth element (REE) abundances from La to Lu; Group B garnets (Cr 2 O 3 = 5·4–8·6 wt %) are less depleted in light REE (LREE) and show nearly flat patterns from Sm to Lu; Group C garnets (Cr 2 O 3 = 7·3–8·4 wt %) are characterized by humped to strongly sinusoidal REE patterns, with Yb between 0·5 and 3·0 × CI. Numerical simulations of melt–rock interactions show that the wide spectrum of garnet REE compositions can be produced by a unique episode of melt injection and percolation through a refractory mantle column, whereby the melt progressively changes its composition owing to chromatographic ion exchange, fractional crystallization, and assimilation of peridotitic minerals, under decreasing melt/rock ratios. The calculated composition of the metasomatizing melt has a kimberlitic affinity, but is distinct from the composition of the host Zagadochnaya kimberlite. Most of the Group B and C garnets show replacement by a secondary mineral assemblage of (Ca, Cr)-poor garnet, chromian diopside, and chromite (± phlogopite ± amphibole). The (Ca, ... Text Yakutia HighWire Press (Stanford University) Journal of Petrology 54 11 2379 2409 |
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Original Papers Ziberna, Luca Nimis, Paolo Zanetti, Alberto Marzoli, Andrea Sobolev, Nikolai V. Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite |
topic_facet |
Original Papers |
description |
Garnet xenocrysts ( n = 386) and associated mineral inclusions and intergrowths from the diamond-free Zagadochnaya kimberlite (Daldyn field, Yakutia) were studied to provide new insights into mantle processes beneath the central Siberian Craton. Electron microprobe analyses indicate that the great majority of the garnets follow the ‘lherzolitic’ trend in the CaO vs Cr 2 O 3 diagram (Cr 2 O 3 = 0·5–9·3 wt %, CaO = 3·2–10·3 wt %), with <10% falling in the wehrlitic field and <3% falling in a transitional region between the lherzolitic and harzburgitic fields. A representative subset of the garnets ( n = 28) was further analysed for trace elements by laser ablation inductively coupled plasma mass spectrometry. Based on both major and trace element data, three main compositional groups are distinguished: Group A garnets (Cr 2 O 3 = 1·3–5·2 wt %) may contain inclusions of chromian diopside and are characterized by progressively increasing, chondrite (CI)-normalized rare earth element (REE) abundances from La to Lu; Group B garnets (Cr 2 O 3 = 5·4–8·6 wt %) are less depleted in light REE (LREE) and show nearly flat patterns from Sm to Lu; Group C garnets (Cr 2 O 3 = 7·3–8·4 wt %) are characterized by humped to strongly sinusoidal REE patterns, with Yb between 0·5 and 3·0 × CI. Numerical simulations of melt–rock interactions show that the wide spectrum of garnet REE compositions can be produced by a unique episode of melt injection and percolation through a refractory mantle column, whereby the melt progressively changes its composition owing to chromatographic ion exchange, fractional crystallization, and assimilation of peridotitic minerals, under decreasing melt/rock ratios. The calculated composition of the metasomatizing melt has a kimberlitic affinity, but is distinct from the composition of the host Zagadochnaya kimberlite. Most of the Group B and C garnets show replacement by a secondary mineral assemblage of (Ca, Cr)-poor garnet, chromian diopside, and chromite (± phlogopite ± amphibole). The (Ca, ... |
format |
Text |
author |
Ziberna, Luca Nimis, Paolo Zanetti, Alberto Marzoli, Andrea Sobolev, Nikolai V. |
author_facet |
Ziberna, Luca Nimis, Paolo Zanetti, Alberto Marzoli, Andrea Sobolev, Nikolai V. |
author_sort |
Ziberna, Luca |
title |
Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite |
title_short |
Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite |
title_full |
Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite |
title_fullStr |
Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite |
title_full_unstemmed |
Metasomatic Processes in the Central Siberian Cratonic Mantle: Evidence from Garnet Xenocrysts from the Zagadochnaya Kimberlite |
title_sort |
metasomatic processes in the central siberian cratonic mantle: evidence from garnet xenocrysts from the zagadochnaya kimberlite |
publisher |
Oxford University Press |
publishDate |
2013 |
url |
http://petrology.oxfordjournals.org/cgi/content/short/54/11/2379 https://doi.org/10.1093/petrology/egt051 |
genre |
Yakutia |
genre_facet |
Yakutia |
op_relation |
http://petrology.oxfordjournals.org/cgi/content/short/54/11/2379 http://dx.doi.org/10.1093/petrology/egt051 |
op_rights |
Copyright (C) 2013, Oxford University Press |
op_doi |
https://doi.org/10.1093/petrology/egt051 |
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Journal of Petrology |
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54 |
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11 |
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2379 |
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2409 |
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1766236124797206528 |