Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors
Abstract The world’s largest current Cu resource is volcanic arc-hosted, porphyry copper deposits. Whether unusual parental magmas or fortuitous combinations of processes accompanying emplacement of common parental arc magmas (e.g., basalt) is required for ore deposit formation, remains unclear. Spa...
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2023-03-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-023-31736-z |
| _version_ | 1797853957390860288 |
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| author | Timothy S. J. Leong John A. Mavrogenes Richard J. Arculus |
| author_facet | Timothy S. J. Leong John A. Mavrogenes Richard J. Arculus |
| author_sort | Timothy S. J. Leong |
| collection | DOAJ |
| description | Abstract The world’s largest current Cu resource is volcanic arc-hosted, porphyry copper deposits. Whether unusual parental magmas or fortuitous combinations of processes accompanying emplacement of common parental arc magmas (e.g., basalt) is required for ore deposit formation, remains unclear. Spatial and tectonic associations of adakite (andesite with high La/Yb, Sr/Y) with porphyries exist, but genetic links are debated. Delayed saturation with Cu-bearing sulfides consequent to elevated redox state seems essential for late-stage exsolution of Cu-bearing hydrothermal fluids. Partial melting of igneous layers of subducted, hydrothermally altered oceanic crust in the eclogite stability field are invoked to account for andesitic compositions, residual garnet signatures, and the putative oxidised character of adakites. Alternative petrogeneses include partial melting of lower crustal, garnet-bearing sources and extensive intra-crustal amphibole fractionation. Here we demonstrate mineral-hosted, adakite glass (formerly melt) inclusions in lavas erupted subaqueously in the New Hebrides arc are oxidised relative to island arc (and mid-ocean ridge) basalts, are H2O-S-Cl-rich, and moderately enriched in Cu. Polynomial fitting of chondrite-normalised, rare earth element abundance patterns shows the precursors of these erupted adakites were unequivocally derived from partial melting of subducted slab, and represent optimal porphyry copper progenitors. |
| first_indexed | 2024-04-09T19:58:07Z |
| format | Article |
| id | doaj.art-f448bcf02f004ca68678c101f5adc5ba |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-04-09T19:58:07Z |
| publishDate | 2023-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-f448bcf02f004ca68678c101f5adc5ba2023-04-03T05:22:13ZengNature PortfolioScientific Reports2045-23222023-03-011311810.1038/s41598-023-31736-zWater-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitorsTimothy S. J. Leong0John A. Mavrogenes1Richard J. Arculus2Research School of Earth Sciences, Australian National UniversityResearch School of Earth Sciences, Australian National UniversityResearch School of Earth Sciences, Australian National UniversityAbstract The world’s largest current Cu resource is volcanic arc-hosted, porphyry copper deposits. Whether unusual parental magmas or fortuitous combinations of processes accompanying emplacement of common parental arc magmas (e.g., basalt) is required for ore deposit formation, remains unclear. Spatial and tectonic associations of adakite (andesite with high La/Yb, Sr/Y) with porphyries exist, but genetic links are debated. Delayed saturation with Cu-bearing sulfides consequent to elevated redox state seems essential for late-stage exsolution of Cu-bearing hydrothermal fluids. Partial melting of igneous layers of subducted, hydrothermally altered oceanic crust in the eclogite stability field are invoked to account for andesitic compositions, residual garnet signatures, and the putative oxidised character of adakites. Alternative petrogeneses include partial melting of lower crustal, garnet-bearing sources and extensive intra-crustal amphibole fractionation. Here we demonstrate mineral-hosted, adakite glass (formerly melt) inclusions in lavas erupted subaqueously in the New Hebrides arc are oxidised relative to island arc (and mid-ocean ridge) basalts, are H2O-S-Cl-rich, and moderately enriched in Cu. Polynomial fitting of chondrite-normalised, rare earth element abundance patterns shows the precursors of these erupted adakites were unequivocally derived from partial melting of subducted slab, and represent optimal porphyry copper progenitors.https://doi.org/10.1038/s41598-023-31736-z |
| spellingShingle | Timothy S. J. Leong John A. Mavrogenes Richard J. Arculus Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors Scientific Reports |
| title | Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors |
| title_full | Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors |
| title_fullStr | Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors |
| title_full_unstemmed | Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors |
| title_short | Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors |
| title_sort | water sulfur rich oxidised adakite magmas are likely porphyry copper progenitors |
| url | https://doi.org/10.1038/s41598-023-31736-z |
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