Middle Neoproterozoic syn-rifting volcanic rocks in Guangfeng, South China: petrogenesis and tectonic significance
MetadataShow full item record
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.
© Cambridge University Press 2008
Showing items related by title, author, creator and subject.
Amalgamation between the Yangtze and Cathaysia Blocks in South China: Constraints from SHRIMP U-Pb zircon ages, geochemistry and Nd-Hf isotopes of the Shuangxiwu volcanic rocksLi, X.; Li, W.; Li, Zheng-Xiang; Lo, C.; Wang, J.; Ye, M.; Yang , Y. (2009)South China was formed through the amalgamation of the Yangtze Block with the Cathaysia Block, but the timing of this amalgamation is controversial, ranging from Mesoproterozoic to Mesozoic. We report here SHRIMP U-Pb ...
Variable involvements of mantle plumes in the genesis of mid-Neoproterozoic basaltic rocks in South China: A reviewWang, Xuan-ce; Li, X.; Li, W.; Li, Zheng-Xiang (2009)Ca. 825-720 Ma global continental intraplate magmatism is generally linked to mantle plumes or a mantle superplume that caused rifting and fragmentation of the supercontinent Rodinia. Widespread Neoproterozoic igneous ...
Initial breakup of supercontinent Rodinia as recorded by ca 860–840 Ma bimodal volcanism along the southeastern margin of the Yangtze Block, South ChinaLyu, P.; Li, W.; Wang, Xuan-Ce; Pang, C.; Cheng, J.; Li, X. (2017)Abstract It is considered that mantle plumes play an important role in the breakup of supercontinents, but continental rifting and associated bimodal volcanism often predate mantle-plume magmatism and the major stage of ...