Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks
Rb-Sr, Sm-Nd and U-Th-Pb isotopic data for Precambrian granitoids (i.e. granites and intermediate calc-alkaline plutonic rocks) from Greenland, Scotland and Zimbabwe are used to assess the relative contributions to magma genesis of various source materials. Ancient continental crustal contributions...
Published in: | Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences |
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Online Access: | http://dx.doi.org/10.1098/rsta.1984.0010 https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.1984.0010 |
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crroyalsociety:10.1098/rsta.1984.0010 2024-09-15T18:09:04+00:00 Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks 1984 http://dx.doi.org/10.1098/rsta.1984.0010 https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.1984.0010 en eng The Royal Society https://royalsociety.org/journals/ethics-policies/data-sharing-mining/ Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences volume 310, issue 1514, page 605-625 ISSN 0080-4614 2054-0272 journal-article 1984 crroyalsociety https://doi.org/10.1098/rsta.1984.0010 2024-07-29T04:23:23Z Rb-Sr, Sm-Nd and U-Th-Pb isotopic data for Precambrian granitoids (i.e. granites and intermediate calc-alkaline plutonic rocks) from Greenland, Scotland and Zimbabwe are used to assess the relative contributions to magma genesis of various source materials. Ancient continental crustal contributions are identified by negative e N d values in the magmas at time of formation. Initial 87 Sr/ 86 Sr (Sr 1 ,) values identify crustal contributions as derived from deep (low Rb/Sr) or upper (high Rb/Sr) crust. Pb isotopic data, expressed as model ( 238 U / 204 Pb) values, permit the distinction between deep (low U/Pb) and upper (high U/Pb) crustal contributions. However, it is not usually possible to distinguish between mantle (low Rb/Sr) and deep crustal sources using Sr 1 values. In contrast, Nd and Pb isotopic data permit such a distinction to be made. The granitoids isotopically analysed for the present study range from calc-alkaline types with mantle or mixed mantle-crust isotopic characteristics (for example, late Archaean orthogneisses from west Greenland) to true granites probably produced solely by anatexis of ancient sialic crust (for example, Badcall Quay red granite, northwest Scotland; Qorqut granite, west Greenland; Mont d’Or granite, Zimbabwe). Article in Journal/Newspaper Greenland The Royal Society Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences 310 1514 605 625 |
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Open Polar |
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The Royal Society |
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crroyalsociety |
language |
English |
description |
Rb-Sr, Sm-Nd and U-Th-Pb isotopic data for Precambrian granitoids (i.e. granites and intermediate calc-alkaline plutonic rocks) from Greenland, Scotland and Zimbabwe are used to assess the relative contributions to magma genesis of various source materials. Ancient continental crustal contributions are identified by negative e N d values in the magmas at time of formation. Initial 87 Sr/ 86 Sr (Sr 1 ,) values identify crustal contributions as derived from deep (low Rb/Sr) or upper (high Rb/Sr) crust. Pb isotopic data, expressed as model ( 238 U / 204 Pb) values, permit the distinction between deep (low U/Pb) and upper (high U/Pb) crustal contributions. However, it is not usually possible to distinguish between mantle (low Rb/Sr) and deep crustal sources using Sr 1 values. In contrast, Nd and Pb isotopic data permit such a distinction to be made. The granitoids isotopically analysed for the present study range from calc-alkaline types with mantle or mixed mantle-crust isotopic characteristics (for example, late Archaean orthogneisses from west Greenland) to true granites probably produced solely by anatexis of ancient sialic crust (for example, Badcall Quay red granite, northwest Scotland; Qorqut granite, west Greenland; Mont d’Or granite, Zimbabwe). |
format |
Article in Journal/Newspaper |
title |
Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks |
spellingShingle |
Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks |
title_short |
Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks |
title_full |
Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks |
title_fullStr |
Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks |
title_full_unstemmed |
Isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of Precambrian granitoid rocks |
title_sort |
isotopic assessment of relative contributions from crust and mantle sources to the magma genesis of precambrian granitoid rocks |
publisher |
The Royal Society |
publishDate |
1984 |
url |
http://dx.doi.org/10.1098/rsta.1984.0010 https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.1984.0010 |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences volume 310, issue 1514, page 605-625 ISSN 0080-4614 2054-0272 |
op_rights |
https://royalsociety.org/journals/ethics-policies/data-sharing-mining/ |
op_doi |
https://doi.org/10.1098/rsta.1984.0010 |
container_title |
Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences |
container_volume |
310 |
container_issue |
1514 |
container_start_page |
605 |
op_container_end_page |
625 |
_version_ |
1810446458595311616 |