Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland
Discontinuous chains of ultramafic rock bodies form part of the 3800–3700 Ma Isua Supracrustal Belt (ISB), hosted in the Itsaq Gneiss Complex of southwestern Greenland. These bodies are among the world’s oldest outcrops of ultramafic rocks and hence an invaluable geologic record. Ultramafic rocks fr...
Published in: | Geoscience Frontiers |
---|---|
Main Authors: | , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Elsevier
2022
|
Subjects: | |
Online Access: | https://doi.org/10.1016/j.gsf.2021.101298 https://doaj.org/article/4a2795ae8c3546e19053698b5926a43e |
id |
ftdoajarticles:oai:doaj.org/article:4a2795ae8c3546e19053698b5926a43e |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:4a2795ae8c3546e19053698b5926a43e 2023-10-01T03:56:20+02:00 Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland Juan Miguel Guotana Tomoaki Morishita Ikuya Nishio Akihiro Tamura Tomoyuki Mizukami Kenichiro Tani Yumiko Harigane Kristoffer Szilas D. Graham Pearson 2022-01-01T00:00:00Z https://doi.org/10.1016/j.gsf.2021.101298 https://doaj.org/article/4a2795ae8c3546e19053698b5926a43e EN eng Elsevier http://www.sciencedirect.com/science/article/pii/S1674987121001626 https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2021.101298 https://doaj.org/article/4a2795ae8c3546e19053698b5926a43e Geoscience Frontiers, Vol 13, Iss 1, Pp 101298- (2022) Titanian chondrodite Titanian clinohumite Isua supracrustal belt UHP Deserpentinization Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.1016/j.gsf.2021.101298 2023-09-03T00:37:17Z Discontinuous chains of ultramafic rock bodies form part of the 3800–3700 Ma Isua Supracrustal Belt (ISB), hosted in the Itsaq Gneiss Complex of southwestern Greenland. These bodies are among the world’s oldest outcrops of ultramafic rocks and hence an invaluable geologic record. Ultramafic rocks from Lens B in the northwestern limb of ISB show characteristics of several stages of serpentinization and deserpentinization forming prograde and retrograde mineral assemblages. Ti-rich humite-group minerals such as titanian chondrodite (Ti-Chn) and titanian clinohumite (Ti-Chu) often occur as accessory phases in the metamorphosed ultramafic rocks. The Ti-rich humite minerals are associated with metamorphic olivine. The host olivine is highly forsteritic (Fo96-98) with variable MnO and NiO contents. The concentrations of the rare-earth elements (REE) and high-field strength elements (HFSE) of the metamorphic olivine are higher than typical mantle olivine. The textural and chemical characteristics of the olivine indicate metamorphic origin as a result of deserpentinization of a serpentinized ultramafic protolith rather than primary assemblage reflecting mantle residues from high-degrees of partial melting. The close association of olivine, antigorite and intergrown Ti-Chn and Ti-Chu suggests pressure condition between ∼1.3–2.6 GPa within the antigorite stability field (<700 °C). The overall petrological and geochemical features of Lens B ultramafic body within the Eoarchean ISB indicate that these are allochthonous ultramafic rocks that recorded serpentine dehydration at relatively lower temperature and reached eclogite facies condition during their complex metamorphic history similar to exhumed UHP ultramafic rocks in modern subduction zone channels. Article in Journal/Newspaper Greenland Directory of Open Access Journals: DOAJ Articles Greenland Geoscience Frontiers 13 1 101298 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Titanian chondrodite Titanian clinohumite Isua supracrustal belt UHP Deserpentinization Geology QE1-996.5 |
spellingShingle |
Titanian chondrodite Titanian clinohumite Isua supracrustal belt UHP Deserpentinization Geology QE1-996.5 Juan Miguel Guotana Tomoaki Morishita Ikuya Nishio Akihiro Tamura Tomoyuki Mizukami Kenichiro Tani Yumiko Harigane Kristoffer Szilas D. Graham Pearson Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland |
topic_facet |
Titanian chondrodite Titanian clinohumite Isua supracrustal belt UHP Deserpentinization Geology QE1-996.5 |
description |
Discontinuous chains of ultramafic rock bodies form part of the 3800–3700 Ma Isua Supracrustal Belt (ISB), hosted in the Itsaq Gneiss Complex of southwestern Greenland. These bodies are among the world’s oldest outcrops of ultramafic rocks and hence an invaluable geologic record. Ultramafic rocks from Lens B in the northwestern limb of ISB show characteristics of several stages of serpentinization and deserpentinization forming prograde and retrograde mineral assemblages. Ti-rich humite-group minerals such as titanian chondrodite (Ti-Chn) and titanian clinohumite (Ti-Chu) often occur as accessory phases in the metamorphosed ultramafic rocks. The Ti-rich humite minerals are associated with metamorphic olivine. The host olivine is highly forsteritic (Fo96-98) with variable MnO and NiO contents. The concentrations of the rare-earth elements (REE) and high-field strength elements (HFSE) of the metamorphic olivine are higher than typical mantle olivine. The textural and chemical characteristics of the olivine indicate metamorphic origin as a result of deserpentinization of a serpentinized ultramafic protolith rather than primary assemblage reflecting mantle residues from high-degrees of partial melting. The close association of olivine, antigorite and intergrown Ti-Chn and Ti-Chu suggests pressure condition between ∼1.3–2.6 GPa within the antigorite stability field (<700 °C). The overall petrological and geochemical features of Lens B ultramafic body within the Eoarchean ISB indicate that these are allochthonous ultramafic rocks that recorded serpentine dehydration at relatively lower temperature and reached eclogite facies condition during their complex metamorphic history similar to exhumed UHP ultramafic rocks in modern subduction zone channels. |
format |
Article in Journal/Newspaper |
author |
Juan Miguel Guotana Tomoaki Morishita Ikuya Nishio Akihiro Tamura Tomoyuki Mizukami Kenichiro Tani Yumiko Harigane Kristoffer Szilas D. Graham Pearson |
author_facet |
Juan Miguel Guotana Tomoaki Morishita Ikuya Nishio Akihiro Tamura Tomoyuki Mizukami Kenichiro Tani Yumiko Harigane Kristoffer Szilas D. Graham Pearson |
author_sort |
Juan Miguel Guotana |
title |
Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland |
title_short |
Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland |
title_full |
Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland |
title_fullStr |
Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland |
title_full_unstemmed |
Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland |
title_sort |
deserpentinization and high-pressure (eclogite-facies) metamorphic features in the eoarchean ultramafic body from isua, greenland |
publisher |
Elsevier |
publishDate |
2022 |
url |
https://doi.org/10.1016/j.gsf.2021.101298 https://doaj.org/article/4a2795ae8c3546e19053698b5926a43e |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Geoscience Frontiers, Vol 13, Iss 1, Pp 101298- (2022) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S1674987121001626 https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2021.101298 https://doaj.org/article/4a2795ae8c3546e19053698b5926a43e |
op_doi |
https://doi.org/10.1016/j.gsf.2021.101298 |
container_title |
Geoscience Frontiers |
container_volume |
13 |
container_issue |
1 |
container_start_page |
101298 |
_version_ |
1778525775708815360 |