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The Jurassic magmatism and its tectonic setting in the eastern margin of South China: Evidence from the volcanic rocks of the Maonong Formation in the SE Zhejiang
Zhang Wei1; Wu HongXiang1; Zhu KongYang; Zhang KeFeng1; Xing XinLong2; Chen DongXu3; Chen HanLin1; Zhang FengQi1
2018
Source PublicationACTA PETROLOGICA SINICA
ISSN1000-0569
Volume34Issue:11Pages:3375
AbstractIntraplate extension has been considered as a consensus to explain the setting of the interior of eastern South China during Jurassic, however, there are still arguments on the tectonic setting in the eastern margin. Therefore, analyses on the volcanic rocks of the Maonong Formation from the southeastern Zhejiang (including petrology, SHRIMP zircon U-Pb dating, zircon trace elements, bulk elements geochemistry and Sr-Nd isotope analyses) are employed to constrain the tectonic setting of the eastern margin of South China. The Maonong profile located in Songyang is a representative of the Jurassic volcanic rocks in Zhejiang Province. The volcanic rocks in this profile are mainly composed of dacitic crystal tuff and rhyolitic vitric tuff. The SHRIMP U-Pb dating shows that the age of rhyolitic vitric tuff from Maonong is at 153 +/- 2Ma. Coupled with previous researches, the Maonong Formation was probably formed at 180 similar to 148Ma. Volcanic rocks from the Maonong Formation are predominantly magnesian and talc-alkaline series and show prominent pattern of relative enrichment in LREE. Early Jurassic dacitic tuff has inconspicuous Eu negative anomalies whereas Late Jurassic rhyolitic tuff has prominent one. Tuffs in both periods are enriched in LILE (K, Rb and Th) and depleted in HFSE (Nb , Ta, Zr and Hf). Early Jurassic dacitic tuff was generated at conditions with a residual assemblage of plagioclase + hornblende + garnet, but Late Jurassic rhyolitic tuff was generated at conditions with residual assemblage of plagioclase + hornblende, presumably indicating their distinct source depths. The Sr-Nd-Hf isotope compositions of the Maonong volcanic rocks are akin to the Paleoproterozoic basement of the Cathaysia Block. Therefore, they presumably originated from the partial melting of the Paleoproterozoic basement with minor involvement of juvenile material. According to the analyses of the tectonic setting, they were formed in Andean-type subduction environment with relatively low temperature. By calculations of zircon oxygen fugacity of rocks at different ages and regions, it was found that the oxygen fugacity of the Early Jurassic magmatic rocks from sea areas of SE China was higher than that from continental margin, and oxygen fugacity of magmatic rocks from continental margin was rising from Late Triassic to Late Jurassic. The tempo-spatial variation of oxygen fugacity may suggest the impact of subducted fluids with a tendency to expand from sea areas of SE China to the continental margin. The comprehensive analyses suggest that an "Andean-type" margin arc related to the paleo-Pacific subduction was probably developed in the eastern margin of South China, which could be dated back to the early Early Jurassic and expanded in Middle-Late Jurassic. The coastal region was predominantly under a retro-arc compressive setting, in contrast to the synchronous extensional setting in the hinterland.
DepartmentOMG
KeywordVolcanic rocks of the Maonong Formation Jurassic Paleo-Pacific subduction Andean-type active continental margin Eastern South China
Document Type期刊论文
Identifierhttp://ir.scsio.ac.cn/handle/344004/17992
Collection中科院边缘海地质重点实验室
Affiliation1.Zhejiang Univ, Sch Earth Sci, Hangzhou 310027, Zhejiang, Peoples R China
2.Minist Educ, Res Ctr Struct Anal Petroliferous Basins, Hangzhou 310027, Zhejiang, Peoples R China
3.Ctr Explorat & Dev Geol & Mineral Resources Jiang, Nanchang 330030, Jiangxi, Peoples R China
4.Chinese Acad Sci, South China Sea Inst Oceanol, CAS Key Lab Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China
Recommended Citation
GB/T 7714
Zhang Wei,Wu HongXiang,Zhu KongYang,et al. The Jurassic magmatism and its tectonic setting in the eastern margin of South China: Evidence from the volcanic rocks of the Maonong Formation in the SE Zhejiang[J]. ACTA PETROLOGICA SINICA,2018,34(11):3375, 3398.
APA Zhang Wei.,Wu HongXiang.,Zhu KongYang.,Zhang KeFeng.,Xing XinLong.,...&Zhang FengQi.(2018).The Jurassic magmatism and its tectonic setting in the eastern margin of South China: Evidence from the volcanic rocks of the Maonong Formation in the SE Zhejiang.ACTA PETROLOGICA SINICA,34(11),3375.
MLA Zhang Wei,et al."The Jurassic magmatism and its tectonic setting in the eastern margin of South China: Evidence from the volcanic rocks of the Maonong Formation in the SE Zhejiang".ACTA PETROLOGICA SINICA 34.11(2018):3375.
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