Yuanzhi Zhou , Zhenjie Zhang , Jie Yang , Hanyi Wang , Molei Zhao , Qiuming Cheng
{"title":"地壳热状态控制着甘底斯带东部碰撞后富铜岩浆的形成","authors":"Yuanzhi Zhou , Zhenjie Zhang , Jie Yang , Hanyi Wang , Molei Zhao , Qiuming Cheng","doi":"10.1016/j.chemgeo.2025.122870","DOIUrl":null,"url":null,"abstract":"<div><div>The genesis of post-collisional porphyry copper deposits (PCDs) remains debated. The post-collisional magmas in the eastern Gangdese belt exhibit significant variability in copper enrichment. There is broad consensus that all these magmas originated from lower crustal partial melting, yet the mechanisms driving their Cu fertility are unclear. Quantifying the thermal state and residual mineral proportion in magma sources may provide insight into geodynamic processes and the formation conditions of Cu-fertile magmas. Here, we compiled geochemical data for Eocene and Miocene magmatic rocks and simulated the <em>P–T–</em>X(H<sub>2</sub>O) conditions and mineral proportions of magma sources by using thermodynamic and trace element modeling. Our results indicate that the Miocene magma source exhibits higher pressure and H<sub>2</sub>O content compared to the Eocene magma source. The corresponding residual mineral assemblage also shows a transition from plagioclase to garnet and from pyroxene to amphibole. This implies the deepening of crustal melting zone and extra H<sub>2</sub>O addition during the Miocene. The high-pressure and high-water conditions favored the formation of highly Cu-fertile post-collisional magmas. However, the high fertility might not be solely attributed to the effects of residual minerals (e.g., garnet and amphibole) in the lower crust but might also be partially inherited from the parent materials, which have been modified by prior subduction. These factors could be crucial for the occurrence of strong copper mineralization during the Miocene in the eastern Gangdese belt. Our findings provide quantitative constraints for formation conditions of porphyry copper deposits in post-collision settings.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"690 ","pages":"Article 122870"},"PeriodicalIF":3.6000,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Crustal thermal state controls the formation of post-collisional Cu-fertile magmas in the eastern Gangdese belt\",\"authors\":\"Yuanzhi Zhou , Zhenjie Zhang , Jie Yang , Hanyi Wang , Molei Zhao , Qiuming Cheng\",\"doi\":\"10.1016/j.chemgeo.2025.122870\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>The genesis of post-collisional porphyry copper deposits (PCDs) remains debated. The post-collisional magmas in the eastern Gangdese belt exhibit significant variability in copper enrichment. There is broad consensus that all these magmas originated from lower crustal partial melting, yet the mechanisms driving their Cu fertility are unclear. Quantifying the thermal state and residual mineral proportion in magma sources may provide insight into geodynamic processes and the formation conditions of Cu-fertile magmas. Here, we compiled geochemical data for Eocene and Miocene magmatic rocks and simulated the <em>P–T–</em>X(H<sub>2</sub>O) conditions and mineral proportions of magma sources by using thermodynamic and trace element modeling. Our results indicate that the Miocene magma source exhibits higher pressure and H<sub>2</sub>O content compared to the Eocene magma source. The corresponding residual mineral assemblage also shows a transition from plagioclase to garnet and from pyroxene to amphibole. This implies the deepening of crustal melting zone and extra H<sub>2</sub>O addition during the Miocene. The high-pressure and high-water conditions favored the formation of highly Cu-fertile post-collisional magmas. However, the high fertility might not be solely attributed to the effects of residual minerals (e.g., garnet and amphibole) in the lower crust but might also be partially inherited from the parent materials, which have been modified by prior subduction. These factors could be crucial for the occurrence of strong copper mineralization during the Miocene in the eastern Gangdese belt. Our findings provide quantitative constraints for formation conditions of porphyry copper deposits in post-collision settings.</div></div>\",\"PeriodicalId\":9847,\"journal\":{\"name\":\"Chemical Geology\",\"volume\":\"690 \",\"pages\":\"Article 122870\"},\"PeriodicalIF\":3.6000,\"publicationDate\":\"2025-05-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Chemical Geology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0009254125002608\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Geology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0009254125002608","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Crustal thermal state controls the formation of post-collisional Cu-fertile magmas in the eastern Gangdese belt
The genesis of post-collisional porphyry copper deposits (PCDs) remains debated. The post-collisional magmas in the eastern Gangdese belt exhibit significant variability in copper enrichment. There is broad consensus that all these magmas originated from lower crustal partial melting, yet the mechanisms driving their Cu fertility are unclear. Quantifying the thermal state and residual mineral proportion in magma sources may provide insight into geodynamic processes and the formation conditions of Cu-fertile magmas. Here, we compiled geochemical data for Eocene and Miocene magmatic rocks and simulated the P–T–X(H2O) conditions and mineral proportions of magma sources by using thermodynamic and trace element modeling. Our results indicate that the Miocene magma source exhibits higher pressure and H2O content compared to the Eocene magma source. The corresponding residual mineral assemblage also shows a transition from plagioclase to garnet and from pyroxene to amphibole. This implies the deepening of crustal melting zone and extra H2O addition during the Miocene. The high-pressure and high-water conditions favored the formation of highly Cu-fertile post-collisional magmas. However, the high fertility might not be solely attributed to the effects of residual minerals (e.g., garnet and amphibole) in the lower crust but might also be partially inherited from the parent materials, which have been modified by prior subduction. These factors could be crucial for the occurrence of strong copper mineralization during the Miocene in the eastern Gangdese belt. Our findings provide quantitative constraints for formation conditions of porphyry copper deposits in post-collision settings.
期刊介绍:
Chemical Geology is an international journal that publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry.
The Journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry.
Papers that are field, experimentally, or computationally based are appropriate if they are of broad international interest. The Journal generally does not publish papers that are primarily of regional or local interest, or which are primarily focused on remediation and applied geochemistry.
The Journal also welcomes innovative papers dealing with significant analytical advances that are of wide interest in the community and extend significantly beyond the scope of what would be included in the methods section of a standard research paper.