The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry
The Pobei mafic-ultramafic complex in northwestern China comprises magmatic Cu-Ni sulfide ore deposits coexisting with Fe-Ti oxide deposits. The Poshi, Poyi, and Podong ultramafic intrusions host the Cu-Ni ore. The ultramafic intrusions experienced four stages during its formation. The intrusion se...
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| Format: | Article |
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Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)
2017-02-01
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| Series: | Geologica Acta |
| Subjects: | |
| Online Access: | https://revistes.ub.edu/index.php/GEOACTA/article/view/16095 |
| _version_ | 1797654575033876480 |
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| author | Y.G. LIU W.Y. LI X.B. LÜ Y.H. HUO B. ZHANG |
| author_facet | Y.G. LIU W.Y. LI X.B. LÜ Y.H. HUO B. ZHANG |
| author_sort | Y.G. LIU |
| collection | DOAJ |
| description |
The Pobei mafic-ultramafic complex in northwestern China comprises magmatic Cu-Ni sulfide ore deposits coexisting with Fe-Ti oxide deposits. The Poshi, Poyi, and Podong ultramafic intrusions host the Cu-Ni ore. The ultramafic intrusions experienced four stages during its formation. The intrusion sequence was as follows: dunite, hornblende-peridotite, wehrlite and pyroxenite. The wall rock of the ultramafic intrusions is the gabbro intrusion in the southwestern of the Pobei complex. The Xiaochangshan magmatic deposit outcrops in the magnetitemineralized gabbro in the northeastern part of the Pobei complex. The main emplacement events related to the mineralization in the Pobei complex, are the magnetite-mineralized gabbro related to the Xiaochangshan Fe deposit, the gabbro intrusion associated to the Poyi, Poshi and Podong Cu-Ni deposits, and the ultramafic intrusions that host Cu-Ni deposits (Poyi and Poshi). The U-Pb age of the magnetite-mineralized gabbro is 276±1.7Ma, which is similar to that of the Pobei mafic intrusions. The εHf(t) value of zircon in the magnetite-mineralized gabbro is almost the same as that of the gabbro around the Poyi and Poshi Cu-Ni deposits, indicating that the rocks related to Cu-Ni and magnetite deposits probably originated from the same parental magma. There is a trend of crystallization differentiation evolution in the Harker diagram from the dunite in the Cu-Ni deposit to the magnetite-mineralized gabbro. The monosulfide solid solution fractional crystallization was weak in Pobei; thus, the Pd/Ir values were only influenced by the crystallization of silicate minerals. The more complete the magma evolution is, the greater is the Pd/Ir ratio. The Pd/Ir values of dunite, the lithofacies containing sulfide (including hornblende peridotite, wehrlite, and pyroxenite) in the Poyi Cu-Ni deposit, magnetite-mineralized gabbro, and massive magnetite, are 8.55, 12.18, 12.26, and 18.14, respectively. Thus, the massive magnetite was probably the latest product in the evolution of the Pobei mafic-ultramafic intrusions. We infer that the Cu-Ni sulfide and Fe-Ti oxide ores in the Pobei area were products of a cogenetic magma at different evolutionary stages; at the late stage, the magma became iron enriched through crystallization differentiation. The magma differentiation occurred in a deep staging magma chamber emplaced in the upper magma chamber. Earlier crystallized olivine with some interstitial sulfides gathered at the bottom of the staging magma chamber because of its greater density. That is to say, the ultramafic magma hosting the Cu-Ni sulfide formed at the bottom of the staging magma chamber, while the magnetite-mineralized gabbro was in the upper part. However, the magnetite-mineralized gabbro injected into the upper magma chamber first and the ultramafic lithofacies containing the olivine and the interstitial Cu-Ni sulfides were subsequently emplaced in the upper magma chamber as crystal mush.
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| first_indexed | 2024-03-11T17:01:29Z |
| format | Article |
| id | doaj.art-9e8e8f8749fa43299153dade07089e5d |
| institution | Directory Open Access Journal |
| issn | 1696-5728 |
| language | English |
| last_indexed | 2024-03-11T17:01:29Z |
| publishDate | 2017-02-01 |
| publisher | Universitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB) |
| record_format | Article |
| series | Geologica Acta |
| spelling | doaj.art-9e8e8f8749fa43299153dade07089e5d2023-10-20T07:24:35ZengUniversitat de Barcelona (UB), Geociències Barcelona (Geo3BCN), Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), Universitat Autònoma de Barcelona (UAB)Geologica Acta1696-57282017-02-01151The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistryY.G. LIU0W.Y. LI1X.B. LÜ2Y.H. HUO3B. ZHANG4Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Ministry of Land and Resources, Xi’an Center of Geological Survey Institute of Geological Survey, China University of Geosciences, Wuhan. 388 Lumo Road, Hongshan District, Wuhan 430074, China. College of Earth Science and Resources, Chang’an University.Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Ministry of Land and Resources, Xi’an Center of Geological SurveyInstitute of Geological Survey, China University of Geosciences, Wuhan. 388 Lumo Road, Hongshan District, Wuhan 430074, China.School of Earth Science, Lanzhou University.Key Laboratory of Orogenic Belt and Crustal Evolution, Peking University. The Pobei mafic-ultramafic complex in northwestern China comprises magmatic Cu-Ni sulfide ore deposits coexisting with Fe-Ti oxide deposits. The Poshi, Poyi, and Podong ultramafic intrusions host the Cu-Ni ore. The ultramafic intrusions experienced four stages during its formation. The intrusion sequence was as follows: dunite, hornblende-peridotite, wehrlite and pyroxenite. The wall rock of the ultramafic intrusions is the gabbro intrusion in the southwestern of the Pobei complex. The Xiaochangshan magmatic deposit outcrops in the magnetitemineralized gabbro in the northeastern part of the Pobei complex. The main emplacement events related to the mineralization in the Pobei complex, are the magnetite-mineralized gabbro related to the Xiaochangshan Fe deposit, the gabbro intrusion associated to the Poyi, Poshi and Podong Cu-Ni deposits, and the ultramafic intrusions that host Cu-Ni deposits (Poyi and Poshi). The U-Pb age of the magnetite-mineralized gabbro is 276±1.7Ma, which is similar to that of the Pobei mafic intrusions. The εHf(t) value of zircon in the magnetite-mineralized gabbro is almost the same as that of the gabbro around the Poyi and Poshi Cu-Ni deposits, indicating that the rocks related to Cu-Ni and magnetite deposits probably originated from the same parental magma. There is a trend of crystallization differentiation evolution in the Harker diagram from the dunite in the Cu-Ni deposit to the magnetite-mineralized gabbro. The monosulfide solid solution fractional crystallization was weak in Pobei; thus, the Pd/Ir values were only influenced by the crystallization of silicate minerals. The more complete the magma evolution is, the greater is the Pd/Ir ratio. The Pd/Ir values of dunite, the lithofacies containing sulfide (including hornblende peridotite, wehrlite, and pyroxenite) in the Poyi Cu-Ni deposit, magnetite-mineralized gabbro, and massive magnetite, are 8.55, 12.18, 12.26, and 18.14, respectively. Thus, the massive magnetite was probably the latest product in the evolution of the Pobei mafic-ultramafic intrusions. We infer that the Cu-Ni sulfide and Fe-Ti oxide ores in the Pobei area were products of a cogenetic magma at different evolutionary stages; at the late stage, the magma became iron enriched through crystallization differentiation. The magma differentiation occurred in a deep staging magma chamber emplaced in the upper magma chamber. Earlier crystallized olivine with some interstitial sulfides gathered at the bottom of the staging magma chamber because of its greater density. That is to say, the ultramafic magma hosting the Cu-Ni sulfide formed at the bottom of the staging magma chamber, while the magnetite-mineralized gabbro was in the upper part. However, the magnetite-mineralized gabbro injected into the upper magma chamber first and the ultramafic lithofacies containing the olivine and the interstitial Cu-Ni sulfides were subsequently emplaced in the upper magma chamber as crystal mush. https://revistes.ub.edu/index.php/GEOACTA/article/view/16095Magmatic Cu-Ni sulfide depositXiaochangshan Fe depositCrystallization differentiationMagnetite-mineralized gabbroBeishanEarly Permian |
| spellingShingle | Y.G. LIU W.Y. LI X.B. LÜ Y.H. HUO B. ZHANG The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry Geologica Acta Magmatic Cu-Ni sulfide deposit Xiaochangshan Fe deposit Crystallization differentiation Magnetite-mineralized gabbro Beishan Early Permian |
| title | The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry |
| title_full | The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry |
| title_fullStr | The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry |
| title_full_unstemmed | The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry |
| title_short | The Pobei Cu-Ni and Fe ore deposits in NW China are comagmatic evolution products: evidence from ore microscopy, zircon U-Pb chronology and geochemistry |
| title_sort | pobei cu ni and fe ore deposits in nw china are comagmatic evolution products evidence from ore microscopy zircon u pb chronology and geochemistry |
| topic | Magmatic Cu-Ni sulfide deposit Xiaochangshan Fe deposit Crystallization differentiation Magnetite-mineralized gabbro Beishan Early Permian |
| url | https://revistes.ub.edu/index.php/GEOACTA/article/view/16095 |
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