The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada)
We report detailed petrographic investigations along with Os-187/Os-188 data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation...
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2017
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ftubkoeln:oai:USBKOELN.ub.uni-koeln.de:21375 2023-05-15T18:20:28+02:00 The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) Bragagni, A. Luguet, A. Fonseca, R. O. C. Pearson, D. G. Lorand, J. -P. Nowell, G. M. Kjarsgaard, B. A. 2017 https://kups.ub.uni-koeln.de/21375/ eng eng PERGAMON-ELSEVIER SCIENCE LTD Bragagni, A., Luguet, A., Fonseca, R. O. C., Pearson, D. G., Lorand, J. -P., Nowell, G. M. and Kjarsgaard, B. A. (2017). The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada). Geochim. Cosmochim. Acta, 216. S. 264 - 286. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1872-9533 ddc:no doc-type:article publishedVersion 2017 ftubkoeln 2022-11-09T07:18:11Z We report detailed petrographic investigations along with Os-187/Os-188 data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation and evolution of the cratonic lithospheric mantle beneath the Rae craton. When devoid of alteration, BMS grains mainly consist of pentlandite + pyrrhotite +/- chalcopyrite. The relatively high BMS modal abundance of the four investigated xenoliths cannot be reconciled with the residual nature of these peridotites, but requires addition of metasomatic BMS. This is especially evident in the two peridotites with the highest bulk Pd/Ir and Pd/Pt. Metasomatic BMS likely formed during melt/fluid percolation in the Sub Continental Lithospheric Mantle (SCLM) as well as during infiltration of the host kimberlite magma, when djerfisherite crystallized around older Fe-Ni-sulfides. On the whole-rock scale, kimberlite metasomatism is visible in a subset of bulk xenoliths, which defines a Re-Os errorchron that dates the host magma emplacement. The Os-187/Os-188 measured in the twenty analysed BMS grains vary from 0.1084 to > 0.17 and it shows no systematic variation depending on the sulfide mineralogical assemblage. The largest range in Os-187/Os-188 is observed in BMS grains from the two xenoliths with the highest Pd/Ir, Pd/Pt, and sulfide modal abundance. The whole-rock T-RD ages of these two samples underestimate the melting age obtained from BMS, demonstrating that bulk Re-Os model ages from peridotites with clear evidence of metasomatism should be treated with caution. The T-RD ages determined in BMS grains are clustered around 2.8-2.7, similar to 2.2 and similar to 1.9 Ga. The 2.8-2.7 Ga T-RD ages document the main SCLM building event in the Rae craton, which is likely related to the formation of the local greenstone belts in a continental rift setting. The Paleoproterozoic T ages can be explained by addition of ... Article in Journal/Newspaper Somerset Island Cologne University: KUPS Canada Rae ENVELOPE(-116.053,-116.053,62.834,62.834) Somerset Island ENVELOPE(-93.500,-93.500,73.251,73.251) |
institution |
Open Polar |
collection |
Cologne University: KUPS |
op_collection_id |
ftubkoeln |
language |
English |
topic |
ddc:no |
spellingShingle |
ddc:no Bragagni, A. Luguet, A. Fonseca, R. O. C. Pearson, D. G. Lorand, J. -P. Nowell, G. M. Kjarsgaard, B. A. The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) |
topic_facet |
ddc:no |
description |
We report detailed petrographic investigations along with Os-187/Os-188 data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation and evolution of the cratonic lithospheric mantle beneath the Rae craton. When devoid of alteration, BMS grains mainly consist of pentlandite + pyrrhotite +/- chalcopyrite. The relatively high BMS modal abundance of the four investigated xenoliths cannot be reconciled with the residual nature of these peridotites, but requires addition of metasomatic BMS. This is especially evident in the two peridotites with the highest bulk Pd/Ir and Pd/Pt. Metasomatic BMS likely formed during melt/fluid percolation in the Sub Continental Lithospheric Mantle (SCLM) as well as during infiltration of the host kimberlite magma, when djerfisherite crystallized around older Fe-Ni-sulfides. On the whole-rock scale, kimberlite metasomatism is visible in a subset of bulk xenoliths, which defines a Re-Os errorchron that dates the host magma emplacement. The Os-187/Os-188 measured in the twenty analysed BMS grains vary from 0.1084 to > 0.17 and it shows no systematic variation depending on the sulfide mineralogical assemblage. The largest range in Os-187/Os-188 is observed in BMS grains from the two xenoliths with the highest Pd/Ir, Pd/Pt, and sulfide modal abundance. The whole-rock T-RD ages of these two samples underestimate the melting age obtained from BMS, demonstrating that bulk Re-Os model ages from peridotites with clear evidence of metasomatism should be treated with caution. The T-RD ages determined in BMS grains are clustered around 2.8-2.7, similar to 2.2 and similar to 1.9 Ga. The 2.8-2.7 Ga T-RD ages document the main SCLM building event in the Rae craton, which is likely related to the formation of the local greenstone belts in a continental rift setting. The Paleoproterozoic T ages can be explained by addition of ... |
format |
Article in Journal/Newspaper |
author |
Bragagni, A. Luguet, A. Fonseca, R. O. C. Pearson, D. G. Lorand, J. -P. Nowell, G. M. Kjarsgaard, B. A. |
author_facet |
Bragagni, A. Luguet, A. Fonseca, R. O. C. Pearson, D. G. Lorand, J. -P. Nowell, G. M. Kjarsgaard, B. A. |
author_sort |
Bragagni, A. |
title |
The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) |
title_short |
The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) |
title_full |
The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) |
title_fullStr |
The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) |
title_full_unstemmed |
The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada) |
title_sort |
geological record of base metal sulfides in the cratonic mantle: a microscale os-187/os-188 study of peridotite xenoliths from somerset island, rae craton (canada) |
publisher |
PERGAMON-ELSEVIER SCIENCE LTD |
publishDate |
2017 |
url |
https://kups.ub.uni-koeln.de/21375/ |
long_lat |
ENVELOPE(-116.053,-116.053,62.834,62.834) ENVELOPE(-93.500,-93.500,73.251,73.251) |
geographic |
Canada Rae Somerset Island |
geographic_facet |
Canada Rae Somerset Island |
genre |
Somerset Island |
genre_facet |
Somerset Island |
op_relation |
Bragagni, A., Luguet, A., Fonseca, R. O. C., Pearson, D. G., Lorand, J. -P., Nowell, G. M. and Kjarsgaard, B. A. (2017). The geological record of base metal sulfides in the cratonic mantle: A microscale Os-187/Os-188 study of peridotite xenoliths from Somerset Island, Rae Craton (Canada). Geochim. Cosmochim. Acta, 216. S. 264 - 286. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 1872-9533 |
_version_ |
1766198010402832384 |