Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance
Middle Neoproterozoic igneous rocks are widespread in South China, but their petrogenesis and tectonic implications are still highly controversial. The Guangfeng middle Neoproterozoic volcani-sedimentary succession was developed on a rare Sibaoan metamorphic basement (the Tianli Schists) inthe south...
| Main Authors: | , , |
|---|---|
| Format: | Journal Article |
| Published: |
Cambridge Univ Press
2008
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.11937/16324 |
| _version_ | 1848749143129849856 |
|---|---|
| author | Li, W. Li, X. Li, Zheng-Xiang |
| author_facet | Li, W. Li, X. Li, Zheng-Xiang |
| author_sort | Li, W. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Middle Neoproterozoic igneous rocks are widespread in South China, but their petrogenesis and tectonic implications are still highly controversial. The Guangfeng middle Neoproterozoic volcani-sedimentary succession was developed on a rare Sibaoan metamorphic basement (the Tianli Schists) inthe southeastern Yangtze Block, South China. This paper reports geochronological, geochemical and Nd isotopic data for the volcanic rocks in this succession. The volcanic rocks consist of alkaline basalts, andesites and peraluminous rhyolites. SHRIMP U-Pb zircon age determinations indicate that they were erupted at 827+- 14 Ma, coeval with a widespread episode of anorogenic magmatism in South China. Despite showing Nb-Ta depletion relative to La and Th, the alkaline basalts are characterized by highly positive eNd(T) values (+3.1 to +6.0), relatively high TiO2 and Nb contents and high Zr/Y and super-chondritic Nb/Ta ratios, suggesting their derivation from a slab melt-metasomatized subcontinental lithospheric mantle source in an intracontinental rifting setting. The andesites have significantly negative eNd(T) values (-9.3 to-11.1) and a wide range of SiO2 contents (57.6-65.6 %).They were likely generated by the mixing of fractionated basaltic melts with felsic melts derived from the Archaean metasedimentary rocks in the middle to lower crust. The rhyolites are highly siliceous and peraluminous. They are characterized by depletion in Nb, Ta, Sr, P and Ti and relatively high eNd(T)values (-3.0 to -4.8), broadly similar to those of the adjacent c. 820 Ma peraluminous granitoids derived from the Mesoproterozoic to earliest Neoproterozoic sedimentary source at relatively shallowlevels. We conclude that the Guangfeng volcanic suite is a magmatic response of variant levels of continental lithosphere (including lithospheric mantle and the lower-middle to upper crust) to the middle Neoproterozoic intracontinental rifting possibly caused by mantle plume activity. |
| first_indexed | 2025-11-14T07:16:15Z |
| format | Journal Article |
| id | curtin-20.500.11937-16324 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:16:15Z |
| publishDate | 2008 |
| publisher | Cambridge Univ Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-163242017-09-13T15:56:21Z Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance Li, W. Li, X. Li, Zheng-Xiang rift basin volcanic rocks South China geochemistry Neoproterozoic Middle Neoproterozoic igneous rocks are widespread in South China, but their petrogenesis and tectonic implications are still highly controversial. The Guangfeng middle Neoproterozoic volcani-sedimentary succession was developed on a rare Sibaoan metamorphic basement (the Tianli Schists) inthe southeastern Yangtze Block, South China. This paper reports geochronological, geochemical and Nd isotopic data for the volcanic rocks in this succession. The volcanic rocks consist of alkaline basalts, andesites and peraluminous rhyolites. SHRIMP U-Pb zircon age determinations indicate that they were erupted at 827+- 14 Ma, coeval with a widespread episode of anorogenic magmatism in South China. Despite showing Nb-Ta depletion relative to La and Th, the alkaline basalts are characterized by highly positive eNd(T) values (+3.1 to +6.0), relatively high TiO2 and Nb contents and high Zr/Y and super-chondritic Nb/Ta ratios, suggesting their derivation from a slab melt-metasomatized subcontinental lithospheric mantle source in an intracontinental rifting setting. The andesites have significantly negative eNd(T) values (-9.3 to-11.1) and a wide range of SiO2 contents (57.6-65.6 %).They were likely generated by the mixing of fractionated basaltic melts with felsic melts derived from the Archaean metasedimentary rocks in the middle to lower crust. The rhyolites are highly siliceous and peraluminous. They are characterized by depletion in Nb, Ta, Sr, P and Ti and relatively high eNd(T)values (-3.0 to -4.8), broadly similar to those of the adjacent c. 820 Ma peraluminous granitoids derived from the Mesoproterozoic to earliest Neoproterozoic sedimentary source at relatively shallowlevels. We conclude that the Guangfeng volcanic suite is a magmatic response of variant levels of continental lithosphere (including lithospheric mantle and the lower-middle to upper crust) to the middle Neoproterozoic intracontinental rifting possibly caused by mantle plume activity. 2008 Journal Article http://hdl.handle.net/20.500.11937/16324 10.1017/S0016756808004561 Cambridge Univ Press fulltext |
| spellingShingle | rift basin volcanic rocks South China geochemistry Neoproterozoic Li, W. Li, X. Li, Zheng-Xiang Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance |
| title | Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance |
| title_full | Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance |
| title_fullStr | Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance |
| title_full_unstemmed | Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance |
| title_short | Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance |
| title_sort | middle neoproterozoic syn-rifting volcanic rocks in guangfeng, south china: petrogenesis and tectonic significance |
| topic | rift basin volcanic rocks South China geochemistry Neoproterozoic |
| url | http://hdl.handle.net/20.500.11937/16324 |