| LI Naisheng,YAN Quanshu,CHEN Zhihua,SHI Xuefa. 2013. Geochemistry and petrogenesis of Quaternary volcanism from the islets in the eastern Beibu Gulf: evidence for Hainan plum. Acta Oceanologica Sinica, 32(12):40－49 |
| Geochemistry and petrogenesis of Quaternary volcanism from the islets in the eastern Beibu Gulf: evidence for Hainan plum |
| Geochemistry and petrogenesis of Quaternary volcanism from the islets in the eastern Beibu Gulf: evidence for Hainan plum |
| Received:May 20, 2013 Revised:August 16, 2013 |
| DOI：10.1007/s13131-013-0386-1 |
| Key words:enriched mantle type 2 (EM2) mantle source Quaternary volcanism Hainan mantle plume eastern Beibu Gulf |
| 中文关键词: enriched mantle type 2 (EM2) mantle source Quaternary volcanism Hainan mantle plume eastern Beibu Gulf |
| 基金项目:The National Basic Research Program of China under contract No. 2013CB429705; the Public Science and Technology Research Funds Projects of Ocean, the State Oceanic Administration of the People's Republic of China under contract No. 201005003; the National Natural Science Foundation of China under contract Nos 41106051, 40906037 and 41176045; the Fundamental Research Funds of the State Oceanic Administration of the People's Republic of China under contract No. JT1001. |
| Author Name | Affiliation | E-mail | | LI Naisheng | National Oceanographic Center, Qingdao 266071, China
The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | lns@nocq.org | | YAN Quanshu | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | | | CHEN Zhihua | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | | | SHI Xuefa | The First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China | |
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| Abstract: |
| Some of the islets in the eastern Beibu Gulf are covered by Quaternary volcano strata. The rock samples from these islets mainly consist of quartz tholeiites (at Shenjiandao), olivine tholeiites (at Linshidao and Xieyangdao) and alkali basalts (at Yangpubi and Jianshidao), and basically represent four periods of the Quaternary volcanism of Hainan Island and its adjacent regions. Except for the samples from Shenjiandao, most of the Quaternary volcanics of these islets belong to alkali magma series. The trace element characteristics of all of these samples show they are OIB (oceanic island basalt) -like, which implies that their deep geodynamic setting may be related to a mantle plume. The Sr-Nd-Pb isotopic compositions show that the mantle source beneath the Quaternary strata can be regarded as a result of binary mixing between a depleted, DMM (depleted MORB mantle)-like source and an enriched mantle type 2 (EM2). The EM2 may be originated from the Hainan mantle plume, and has been metasomatized by carbonaceous fluids released from ancient recycled oceanic crust at an asthenospheric mantle level. These features, together with typical trace element ratios, reflect that the parent magma was not subjected to crustal contamination during its ascent to the surface. This study provides further petrological and geochemical evidence for the existence of the Hainan mantle plume. |
| 中文摘要: |
| Some of the islets in the eastern Beibu Gulf are covered by Quaternary volcano strata. The rock samples from these islets mainly consist of quartz tholeiites (at Shenjiandao), olivine tholeiites (at Linshidao and Xieyangdao) and alkali basalts (at Yangpubi and Jianshidao), and basically represent four periods of the Quaternary volcanism of Hainan Island and its adjacent regions. Except for the samples from Shenjiandao, most of the Quaternary volcanics of these islets belong to alkali magma series. The trace element characteristics of all of these samples show they are OIB (oceanic island basalt) -like, which implies that their deep geodynamic setting may be related to a mantle plume. The Sr-Nd-Pb isotopic compositions show that the mantle source beneath the Quaternary strata can be regarded as a result of binary mixing between a depleted, DMM (depleted MORB mantle)-like source and an enriched mantle type 2 (EM2). The EM2 may be originated from the Hainan mantle plume, and has been metasomatized by carbonaceous fluids released from ancient recycled oceanic crust at an asthenospheric mantle level. These features, together with typical trace element ratios, reflect that the parent magma was not subjected to crustal contamination during its ascent to the surface. This study provides further petrological and geochemical evidence for the existence of the Hainan mantle plume. |
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