An impact melt origin for Earth’s oldest known evolved rocks
Earth’s oldest evolved (felsic) rocks, the 4.02-billion-year-old Idiwhaa gneisses of the Acasta Gneiss Complex, northwest Canada, have compositions that are distinct from the felsic rocks that typify Earth’s ancient continental nuclei, implying that they formed through a different process. Using pha...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
| Published: |
Nature Publishing Group, Macmillan Publishers Ltd
2018
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| Online Access: | http://purl.org/au-research/grants/arc/DP170102529 http://hdl.handle.net/20.500.11937/71426 |
| _version_ | 1848762476786614272 |
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| author | Johnson, Tim Gardiner, Nicholas Miljkovic, Katarina Spencer, Christopher Kirkland, Chris Bland, Phil Smithies, H. |
| author_facet | Johnson, Tim Gardiner, Nicholas Miljkovic, Katarina Spencer, Christopher Kirkland, Chris Bland, Phil Smithies, H. |
| author_sort | Johnson, Tim |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Earth’s oldest evolved (felsic) rocks, the 4.02-billion-year-old Idiwhaa gneisses of the Acasta Gneiss Complex, northwest Canada, have compositions that are distinct from the felsic rocks that typify Earth’s ancient continental nuclei, implying that they formed through a different process. Using phase equilibria and trace element modelling, we show that the Idiwhaa gneisses were produced by partial melting of iron-rich hydrated basaltic rocks (amphibolites) at very low pressures, equating to the uppermost ~3 km of a Hadean crust that was dominantly mafic in composition. The heat required for partial melting at such shallow levels is most easily explained through meteorite impacts. Hydrodynamic impact modelling shows not only that this scenario is physically plausible, but also that the region of shallow partial melting appropriate to formation of the Idiwhaa gneisses would have been widespread. Given the predicted high flux of meteorites in the late Hadean, impact melting may have been the predominant mechanism that generated Hadean felsic rocks. |
| first_indexed | 2025-11-14T10:48:11Z |
| format | Journal Article |
| id | curtin-20.500.11937-71426 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:48:11Z |
| publishDate | 2018 |
| publisher | Nature Publishing Group, Macmillan Publishers Ltd |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-714262022-10-27T06:55:26Z An impact melt origin for Earth’s oldest known evolved rocks Johnson, Tim Gardiner, Nicholas Miljkovic, Katarina Spencer, Christopher Kirkland, Chris Bland, Phil Smithies, H. Earth’s oldest evolved (felsic) rocks, the 4.02-billion-year-old Idiwhaa gneisses of the Acasta Gneiss Complex, northwest Canada, have compositions that are distinct from the felsic rocks that typify Earth’s ancient continental nuclei, implying that they formed through a different process. Using phase equilibria and trace element modelling, we show that the Idiwhaa gneisses were produced by partial melting of iron-rich hydrated basaltic rocks (amphibolites) at very low pressures, equating to the uppermost ~3 km of a Hadean crust that was dominantly mafic in composition. The heat required for partial melting at such shallow levels is most easily explained through meteorite impacts. Hydrodynamic impact modelling shows not only that this scenario is physically plausible, but also that the region of shallow partial melting appropriate to formation of the Idiwhaa gneisses would have been widespread. Given the predicted high flux of meteorites in the late Hadean, impact melting may have been the predominant mechanism that generated Hadean felsic rocks. 2018 Journal Article http://hdl.handle.net/20.500.11937/71426 10.1038/s41561-018-0206-5 http://purl.org/au-research/grants/arc/DP170102529 Nature Publishing Group, Macmillan Publishers Ltd fulltext |
| spellingShingle | Johnson, Tim Gardiner, Nicholas Miljkovic, Katarina Spencer, Christopher Kirkland, Chris Bland, Phil Smithies, H. An impact melt origin for Earth’s oldest known evolved rocks |
| title | An impact melt origin for Earth’s oldest known evolved rocks |
| title_full | An impact melt origin for Earth’s oldest known evolved rocks |
| title_fullStr | An impact melt origin for Earth’s oldest known evolved rocks |
| title_full_unstemmed | An impact melt origin for Earth’s oldest known evolved rocks |
| title_short | An impact melt origin for Earth’s oldest known evolved rocks |
| title_sort | impact melt origin for earth’s oldest known evolved rocks |
| url | http://purl.org/au-research/grants/arc/DP170102529 http://hdl.handle.net/20.500.11937/71426 |