Details

Autor(en) / Beteiligte

• Yu, Mengming
• Yan, Yi
• Huang, Chi‐Yue
• Zhang, Xinchang
• Tian, Zhixian
• Chen, Wen‐Huang
• Santosh, M.

Titel

Opening of the South China Sea and Upwelling of the Hainan Plume

Ist Teil von

• Geophysical research letters, 2018-03, Vol.45 (6), p.2600-2609

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2018

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Opening of the South China Sea and upwelling of the Hainan Plume are among the most challenging issues related to the tectonic evolution of East Asia. However, when and how the Hainan Plume affected the opening of the South China Sea remains unclear. Here we investigate the geochemical and isotopic features of the ~25 Ma mid‐ocean ridge basalt (MORB) in the Kenting Mélange, southern Taiwan, ~16 Ma MORB drilled by the IODP Expedition 349, and ~9 Ma ocean island basalt‐type dredged seamount basalt. The ~25 Ma MORBs reveal a less metasomatic depleted MORB mantle‐like source. In contrast, the Miocene samples record progressive mantle enrichment and possibly signal the contribution of the Hainan Plume. We speculate that MORBs of the South China Sea which could have recorded plume‐ridge source mixing perhaps appear since ~23.8 Ma. On the contrary, the Paleocene‐Eocene ocean island basalt‐type intraplate volcanism of the South China continental margin is correlated to decompression melting of a passively upwelling fertile asthenosphere due to continental rifting. Plain Language Summary The upwelling of mantle plume can assist continental breakup and seafloor spreading. Opening of the South China Sea and upwelling of the Hainan Plume are among the most challenging issues related to the tectonic evolution of East Asia. However, whether the upwelling of Hainan Plume had contributed to the opening of the South China Sea remains unclear. In this research, we investigate the geochemical and isotopic features of late Oligocene and middle Miocene mid‐ocean ridge basalts of the South China Sea. We find the middle Miocene mid‐ocean ridge basalts record progressive mantle enrichment and possibly signal the contribution of the Hainan Plume. Integrating with other tectonics, we speculate that the head of Hainan Plume impinged the lithosphere of the South China continental margin at the middle Oligocene, and the arriving of Hainan Plume has contributed to the latest Oligocene/earliest Miocene ridge jump and propagation. On the contrary, the Paleocene and Eocene ocean island basalt‐type volcanism in South China continental margin was derived from the passively upwelling of enriched asthenosphere due to continental rifting. This finding can contribute to a better understanding on roles of a starting mantle plume in continental breakup and seafloor spreading. Key Points Depleted and less metasomatic MORB mantle fed the late Oligocene seafloor spreading of the South China Sea MORBs and OIBs of the South China Sea record a Miocene MORB mantle enrichment and possibly signal contributions of the Hainan Plume