Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates?
Abstract When plate tectonics initiated remains uncertain, partly because many signals interpreted as diagnostic of plate tectonics can be alternatively explained via hot stagnant‐lid tectonics. One such signal involves the petrogenesis of early Archean phaneritic ultramafic rocks. In the Eoarchean...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2022-12-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2022GC010519 |
| _version_ | 1797638007661002752 |
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| author | Jiawei Zuo A. Alexander G. Webb Emily J. Chin Lukáš Ackerman Jason Harvey Peter J. Haproff Thomas Müller Qin Wang Arthur H. Hickman Dominik Sorger Anthony Ramírez‐Salazar |
| author_facet | Jiawei Zuo A. Alexander G. Webb Emily J. Chin Lukáš Ackerman Jason Harvey Peter J. Haproff Thomas Müller Qin Wang Arthur H. Hickman Dominik Sorger Anthony Ramírez‐Salazar |
| author_sort | Jiawei Zuo |
| collection | DOAJ |
| description | Abstract When plate tectonics initiated remains uncertain, partly because many signals interpreted as diagnostic of plate tectonics can be alternatively explained via hot stagnant‐lid tectonics. One such signal involves the petrogenesis of early Archean phaneritic ultramafic rocks. In the Eoarchean Isua supracrustal belt (Greenland), some phaneritic ultramafic rocks have been dominantly interpreted as subduction‐related, tectonically‐exhumed mantle slices or cumulates. Here, we compared Eoarchean phaneritic ultramafic rocks from the Isua supracrustal belt with mantle peridotites, cumulates, and phaneritic ultramafic samples from the Paleoarchean East Pilbara Terrane (Australia), which is widely interpreted to have formed in non‐plate tectonic settings. Our findings show that Pilbara samples have cumulate and polygonal textures, melt‐enriched trace element patterns, relative enrichment of Os, Ir, and Ru versus Pt and Pd, and chromite‐spinel with variable TiO2 and Mg#, and relatively consistent Cr#. Both, new and existing data show that cumulates and mantle rocks potentially have similar whole‐rock geochemical characteristics, deformation fabrics, and alteration features. Geochemical modeling results indicate that Isua and Pilbara ultramafic rocks have interacted with low‐Pt and Pd melts generated by sequestration of Pd and Pt into sulphide and/or alloy during magmatism. Such melts cannot have interacted with a mantle wedge. Correspondingly, geochemical compositions and rock textures suggest that Isua and Pilbara ultramafic rocks are not tectonically‐exhumed mantle peridotites, but are cumulates that experienced metasomatism by fluids and co‐genetic melts. Because such rocks could have formed in either plate or non‐plate tectonic settings, they cannot be used to differentiate early Earth tectonic settings. |
| first_indexed | 2024-03-11T12:56:26Z |
| format | Article |
| id | doaj.art-612feeb1dd3f40cd8556d85c75b69d52 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:56:26Z |
| publishDate | 2022-12-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-612feeb1dd3f40cd8556d85c75b69d522023-11-03T17:00:34ZengWileyGeochemistry, Geophysics, Geosystems1525-20272022-12-012312n/an/a10.1029/2022GC010519Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates?Jiawei Zuo0A. Alexander G. Webb1Emily J. Chin2Lukáš Ackerman3Jason Harvey4Peter J. Haproff5Thomas Müller6Qin Wang7Arthur H. Hickman8Dominik Sorger9Anthony Ramírez‐Salazar10Department of Earth Sciences and Laboratory for Space Research University of Hong Kong Hong Kong ChinaDepartment of Earth Sciences and Laboratory for Space Research University of Hong Kong Hong Kong ChinaScripps Institution of Oceanography University of California, San Diego La Jolla CA USAInstitute of Geology of the Czech Academy of Sciences Prague 6 Czech RepublicSchool of Earth and Environment University of Leeds Leeds UKDepartment of Earth and Ocean Sciences University of North Carolina Wilmington Wilmington NC USADepartment of Mineralogy Geoscience Center Georg‐August‐Universität Göttingen Göttingen GermanyState Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing University Nanjing ChinaGeological Survey of Western Australia East Perth WA AustraliaDepartment of Mineralogy Geoscience Center Georg‐August‐Universität Göttingen Göttingen GermanySchool of Earth and Environment University of Leeds Leeds UKAbstract When plate tectonics initiated remains uncertain, partly because many signals interpreted as diagnostic of plate tectonics can be alternatively explained via hot stagnant‐lid tectonics. One such signal involves the petrogenesis of early Archean phaneritic ultramafic rocks. In the Eoarchean Isua supracrustal belt (Greenland), some phaneritic ultramafic rocks have been dominantly interpreted as subduction‐related, tectonically‐exhumed mantle slices or cumulates. Here, we compared Eoarchean phaneritic ultramafic rocks from the Isua supracrustal belt with mantle peridotites, cumulates, and phaneritic ultramafic samples from the Paleoarchean East Pilbara Terrane (Australia), which is widely interpreted to have formed in non‐plate tectonic settings. Our findings show that Pilbara samples have cumulate and polygonal textures, melt‐enriched trace element patterns, relative enrichment of Os, Ir, and Ru versus Pt and Pd, and chromite‐spinel with variable TiO2 and Mg#, and relatively consistent Cr#. Both, new and existing data show that cumulates and mantle rocks potentially have similar whole‐rock geochemical characteristics, deformation fabrics, and alteration features. Geochemical modeling results indicate that Isua and Pilbara ultramafic rocks have interacted with low‐Pt and Pd melts generated by sequestration of Pd and Pt into sulphide and/or alloy during magmatism. Such melts cannot have interacted with a mantle wedge. Correspondingly, geochemical compositions and rock textures suggest that Isua and Pilbara ultramafic rocks are not tectonically‐exhumed mantle peridotites, but are cumulates that experienced metasomatism by fluids and co‐genetic melts. Because such rocks could have formed in either plate or non‐plate tectonic settings, they cannot be used to differentiate early Earth tectonic settings.https://doi.org/10.1029/2022GC010519geochemistryIsuaPilbaraultramafic rockstectonicspetrogenesis |
| spellingShingle | Jiawei Zuo A. Alexander G. Webb Emily J. Chin Lukáš Ackerman Jason Harvey Peter J. Haproff Thomas Müller Qin Wang Arthur H. Hickman Dominik Sorger Anthony Ramírez‐Salazar Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates? Geochemistry, Geophysics, Geosystems geochemistry Isua Pilbara ultramafic rocks tectonics petrogenesis |
| title | Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates? |
| title_full | Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates? |
| title_fullStr | Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates? |
| title_full_unstemmed | Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates? |
| title_short | Earth's Earliest Phaneritic Ultramafic Rocks: Mantle Slices or Crustal Cumulates? |
| title_sort | earth s earliest phaneritic ultramafic rocks mantle slices or crustal cumulates |
| topic | geochemistry Isua Pilbara ultramafic rocks tectonics petrogenesis |
| url | https://doi.org/10.1029/2022GC010519 |
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