Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide
Olivine is the dominant component in kimberlites (~40–60 vol%), where it occurs as individual grains of variable size (>1 cm to <100 μm) of xenocrystic and magmatic origin. Understanding the processes governing its compositional variations will provide unique insights into the genesis and evol...
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2018
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Online Access: | https://researchers.mq.edu.au/en/publications/ced59c3d-d41a-479c-8880-205e855bd38c https://doi.org/10.1016/j.lithos.2018.04.029 http://www.scopus.com/inward/record.url?scp=85047636269&partnerID=8YFLogxK http://purl.org/au-research/grants/arc/DE150100009 |
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ftmacquarieunicr:oai:https://researchers.mq.edu.au:publications/ced59c3d-d41a-479c-8880-205e855bd38c 2024-06-23T07:53:24+00:00 Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide Giuliani, Andrea 2018-07 https://researchers.mq.edu.au/en/publications/ced59c3d-d41a-479c-8880-205e855bd38c https://doi.org/10.1016/j.lithos.2018.04.029 http://www.scopus.com/inward/record.url?scp=85047636269&partnerID=8YFLogxK http://purl.org/au-research/grants/arc/DE150100009 eng eng info:eu-repo/semantics/closedAccess Giuliani , A 2018 , ' Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide ' , Lithos , vol. 312-313 , pp. 322-342 . https://doi.org/10.1016/j.lithos.2018.04.029 Olivine Zoning Kimberlite Metasomatism Mantle article 2018 ftmacquarieunicr https://doi.org/10.1016/j.lithos.2018.04.029 2024-06-12T23:47:22Z Olivine is the dominant component in kimberlites (~40–60 vol%), where it occurs as individual grains of variable size (>1 cm to <100 μm) of xenocrystic and magmatic origin. Understanding the processes governing its compositional variations will provide unique insights into the genesis and evolution of kimberlites. The results reviewed here include >2700 major and minor element analyses of olivine from 17 kimberlite localities from southern Africa, Canada, Greenland and Russia. These data show that the large majority of olivine grains in coherent kimberlites are compositionally zoned regardless of size and shape. The zonation typically includes a core of variable composition (e.g., Mg# = 100 × Mg/(Mg + Fe) = 78–95) that is overgrown by a rim characterised by relatively restricted Mg# (typically ≤1 "unit'; predominantly 88–92), decreasing Ni and Cr, and increasing Mn, Ca and Ti contents. One or more internal zones of variable composition occur between core and rim of some grains. The internal zones can be euhedral, diffuse or partially resorbed (i.e. embayments). Low-Ni, high Mg-Ca rinds (Mg# up to 96–98) commonly fringe olivine rims in fresh (i.e. minimally serpentinised) kimberlites. A comparison between the compositions of olivine cores and olivine from mantle xenoliths (including megacrysts) entrained by kimberlites, demonstrates that olivine cores are xenocrysts derived from disaggregation of mantle wall-rocks. This interpretation is consistent with the inclusion of mantle phases (i.e., orthopyroxene, clinopyroxene, garnet and Cr-spinel) in olivine cores, and evidence of resorption (i.e. embayments) and abrasion (e.g., rounded shapes) of these cores. A variable proportion of olivine cores is sourced from the products of kimberlite metasomatism at mantle depths (e.g., sheared peridotites, megacrysts, 'defertilised dunites'), which implies variable extent of kimberlite activity in the mantle before kimberlite emplacement at surface. Olivine rims host inclusions of groundmass minerals (e.g., spinel, ... Article in Journal/Newspaper Greenland Macquarie University Research Portal Canada Greenland Wall Rocks ENVELOPE(-129.312,-129.312,52.728,52.728) Lithos 312-313 322 342 |
institution |
Open Polar |
collection |
Macquarie University Research Portal |
op_collection_id |
ftmacquarieunicr |
language |
English |
topic |
Olivine Zoning Kimberlite Metasomatism Mantle |
spellingShingle |
Olivine Zoning Kimberlite Metasomatism Mantle Giuliani, Andrea Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
topic_facet |
Olivine Zoning Kimberlite Metasomatism Mantle |
description |
Olivine is the dominant component in kimberlites (~40–60 vol%), where it occurs as individual grains of variable size (>1 cm to <100 μm) of xenocrystic and magmatic origin. Understanding the processes governing its compositional variations will provide unique insights into the genesis and evolution of kimberlites. The results reviewed here include >2700 major and minor element analyses of olivine from 17 kimberlite localities from southern Africa, Canada, Greenland and Russia. These data show that the large majority of olivine grains in coherent kimberlites are compositionally zoned regardless of size and shape. The zonation typically includes a core of variable composition (e.g., Mg# = 100 × Mg/(Mg + Fe) = 78–95) that is overgrown by a rim characterised by relatively restricted Mg# (typically ≤1 "unit'; predominantly 88–92), decreasing Ni and Cr, and increasing Mn, Ca and Ti contents. One or more internal zones of variable composition occur between core and rim of some grains. The internal zones can be euhedral, diffuse or partially resorbed (i.e. embayments). Low-Ni, high Mg-Ca rinds (Mg# up to 96–98) commonly fringe olivine rims in fresh (i.e. minimally serpentinised) kimberlites. A comparison between the compositions of olivine cores and olivine from mantle xenoliths (including megacrysts) entrained by kimberlites, demonstrates that olivine cores are xenocrysts derived from disaggregation of mantle wall-rocks. This interpretation is consistent with the inclusion of mantle phases (i.e., orthopyroxene, clinopyroxene, garnet and Cr-spinel) in olivine cores, and evidence of resorption (i.e. embayments) and abrasion (e.g., rounded shapes) of these cores. A variable proportion of olivine cores is sourced from the products of kimberlite metasomatism at mantle depths (e.g., sheared peridotites, megacrysts, 'defertilised dunites'), which implies variable extent of kimberlite activity in the mantle before kimberlite emplacement at surface. Olivine rims host inclusions of groundmass minerals (e.g., spinel, ... |
format |
Article in Journal/Newspaper |
author |
Giuliani, Andrea |
author_facet |
Giuliani, Andrea |
author_sort |
Giuliani, Andrea |
title |
Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
title_short |
Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
title_full |
Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
title_fullStr |
Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
title_full_unstemmed |
Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
title_sort |
insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide |
publishDate |
2018 |
url |
https://researchers.mq.edu.au/en/publications/ced59c3d-d41a-479c-8880-205e855bd38c https://doi.org/10.1016/j.lithos.2018.04.029 http://www.scopus.com/inward/record.url?scp=85047636269&partnerID=8YFLogxK http://purl.org/au-research/grants/arc/DE150100009 |
long_lat |
ENVELOPE(-129.312,-129.312,52.728,52.728) |
geographic |
Canada Greenland Wall Rocks |
geographic_facet |
Canada Greenland Wall Rocks |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Giuliani , A 2018 , ' Insights into kimberlite petrogenesis and mantle metasomatism from a review of the compositional zoning of olivine in kimberlites worldwide ' , Lithos , vol. 312-313 , pp. 322-342 . https://doi.org/10.1016/j.lithos.2018.04.029 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1016/j.lithos.2018.04.029 |
container_title |
Lithos |
container_volume |
312-313 |
container_start_page |
322 |
op_container_end_page |
342 |
_version_ |
1802645018595295232 |