A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China
Abstract Cenozoic volcanic rocks in the East Asian continental margin usually form because of asthenosphere upwelling and resultant decompression melting, and their origins are important in deciphering mantle geodynamics attributed to intraplate volcanism. In this study, Oligocene basanite‐tephrite...
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American Geophysical Union (AGU)
2021
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oai:doaj.org-article:fa246919c3b547409ec9f5b65116dc522021-11-23T21:03:08ZA Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China2333-508410.1029/2020EA001324https://doaj.org/article/fa246919c3b547409ec9f5b65116dc522021-11-01T00:00:00Zhttps://doi.org/10.1029/2020EA001324https://doaj.org/toc/2333-5084Abstract Cenozoic volcanic rocks in the East Asian continental margin usually form because of asthenosphere upwelling and resultant decompression melting, and their origins are important in deciphering mantle geodynamics attributed to intraplate volcanism. In this study, Oligocene basanite‐tephrite rocks were found in continental interior outcrops, and Miocene to Pliocene basanite, alkaline basalt, and olivine tholeiite were abundant in coastal areas in Zhejiang, Southeast China. Episodic magmatic activities appeared to migrate oceanward with an ∼100‐km spatial gap, which was temporally and spatially synchronized with repeated retreat and rollback of the Tertiary westward subducting Pacific slab. All rocks had OIB‐like trace‐element patterns, but the basanite‐tephrite rocks contained higher LILE, HFSE, and LREE than the alkaline basalt and olivine tholeiite. Geochemical modeling indicated the basanite‐tephrite and the alkaline and olivine tholeiite basalts had low‐degree (7%–15%) and slightly higher degree (20%–30%) partial melting of heterogeneous pyroxenite sources, respectively. In addition, their magma sources showed a progressive weakening of carbonatite metasomatism and decreasing melting depths. Those features were tightly associated with punctuated upwelling of asthenospheric materials, most likely metasomatized by the stagnant Pacific slab‐derived silica/carbonatite melts. A plate‐mantle convection system is proposed in which asthenosphere materials pulled by the subducting Pacific slab explain the intraplate volcanism in East Asia as asthenospheric upwelling, which formed by escaping from either slab tears or slab front edges in the mantle transition zone.Fa‐Bin PanChong JinXiaobo HeLu TaoBao‐Jian JiaAmerican Geophysical Union (AGU)articleintraplate volcanismasthenosphere upwellingsubducting Pacific slabepisodic slab retreatrecycled crustal materialsmantle geodynamicsAstronomyQB1-991GeologyQE1-996.5ENEarth and Space Science, Vol 8, Iss 11, Pp n/a-n/a (2021) |
| institution |
DOAJ |
| collection |
DOAJ |
| language |
EN |
| topic |
intraplate volcanism asthenosphere upwelling subducting Pacific slab episodic slab retreat recycled crustal materials mantle geodynamics Astronomy QB1-991 Geology QE1-996.5 |
| spellingShingle |
intraplate volcanism asthenosphere upwelling subducting Pacific slab episodic slab retreat recycled crustal materials mantle geodynamics Astronomy QB1-991 Geology QE1-996.5 Fa‐Bin Pan Chong Jin Xiaobo He Lu Tao Bao‐Jian Jia A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China |
| description |
Abstract Cenozoic volcanic rocks in the East Asian continental margin usually form because of asthenosphere upwelling and resultant decompression melting, and their origins are important in deciphering mantle geodynamics attributed to intraplate volcanism. In this study, Oligocene basanite‐tephrite rocks were found in continental interior outcrops, and Miocene to Pliocene basanite, alkaline basalt, and olivine tholeiite were abundant in coastal areas in Zhejiang, Southeast China. Episodic magmatic activities appeared to migrate oceanward with an ∼100‐km spatial gap, which was temporally and spatially synchronized with repeated retreat and rollback of the Tertiary westward subducting Pacific slab. All rocks had OIB‐like trace‐element patterns, but the basanite‐tephrite rocks contained higher LILE, HFSE, and LREE than the alkaline basalt and olivine tholeiite. Geochemical modeling indicated the basanite‐tephrite and the alkaline and olivine tholeiite basalts had low‐degree (7%–15%) and slightly higher degree (20%–30%) partial melting of heterogeneous pyroxenite sources, respectively. In addition, their magma sources showed a progressive weakening of carbonatite metasomatism and decreasing melting depths. Those features were tightly associated with punctuated upwelling of asthenospheric materials, most likely metasomatized by the stagnant Pacific slab‐derived silica/carbonatite melts. A plate‐mantle convection system is proposed in which asthenosphere materials pulled by the subducting Pacific slab explain the intraplate volcanism in East Asia as asthenospheric upwelling, which formed by escaping from either slab tears or slab front edges in the mantle transition zone. |
| format |
article |
| author |
Fa‐Bin Pan Chong Jin Xiaobo He Lu Tao Bao‐Jian Jia |
| author_facet |
Fa‐Bin Pan Chong Jin Xiaobo He Lu Tao Bao‐Jian Jia |
| author_sort |
Fa‐Bin Pan |
| title |
A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China |
| title_short |
A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China |
| title_full |
A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China |
| title_fullStr |
A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China |
| title_full_unstemmed |
A Plate‐Mantle Convection System in the West Pacific Revealed by Tertiary Ultramafic‐Mafic Volcanic Rocks in Southeast China |
| title_sort |
plate‐mantle convection system in the west pacific revealed by tertiary ultramafic‐mafic volcanic rocks in southeast china |
| publisher |
American Geophysical Union (AGU) |
| publishDate |
2021 |
| url |
https://doaj.org/article/fa246919c3b547409ec9f5b65116dc52 |
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