Late Miocene magmatism and evolution of Zhenbei-Huangyan Seamount in the South China Sea: evidence from petrochemistry and chronology

WANG Ye-jian; HAN Xi-qiu; LUO Zhao-hua; QIU Zhong-yan; DING Wei-wei; LI Jia-biao; GAO Shui-tu; CHEN Rong-hua

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Article Navigation > Haiyang Xuebao > 2009 > 31(4): 93-102

WANG Ye-jian, HAN Xi-qiu, LUO Zhao-hua, QIU Zhong-yan, DING Wei-wei, LI Jia-biao, GAO Shui-tu, CHEN Rong-hua. Late Miocene magmatism and evolution of Zhenbei-Huangyan Seamount in the South China Sea: evidence from petrochemistry and chronology[J]. Haiyang Xuebao, 2009, 31(4): 93-102.

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Late Miocene magmatism and evolution of Zhenbei-Huangyan Seamount in the South China Sea: evidence from petrochemistry and chronology

1.
Key Laboratory of Submarine Geosciences of State Oceanic Administration, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China;Depatment of Earth Sciences, College of Science, Zhejiang University, Hangzhou 310027, China
2.
Key Laboratory of Submarine Geosciences of State Oceanic Administration, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
3.
College of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China

Received Date: 2008-09-27
Rev Recd Date: 2009-02-23

Abstract

Abstract

E-W trending Zhenbei-Huangyan Seamount at about 15°N in the South China Sea Basin was considered to be ancient spreading axis.Two samples(9DG,9DG-2) were dredged from Huangyan Seamount in 2005 and detail petrological,geochemical and chronological analyses were conducted.The samples are characterized by high contents of silica,aluminium,potassium,sodium and the low content of titanium,with content of 60.3% and 63.6% for SiO₂,17.56% and 17.55% for Al₂O₃,0.48% and 0.31% for TiO₂,and the alkalinity ratios and 3.88 and 3.62.Based on petrological and petrochemical classification,the two samples are trachyte and belong to the alkaline series.Their REE and trace element distribution patterns are similar to oceanic island basalt(OIB),but with higher LREE content and lower contents of europium,srtontium,phosphorus and titanium.Strontium-neodymium-leadisotope analysis shows that the cotentratioes ⁸⁷Sr/⁸⁶Sr=0.704183,²⁰⁶Pb/^204MPb=18.68668,²⁰⁷Pb/²⁰⁴Pb=39.00261,and ¹⁴³Nd/¹⁴⁴ Nd=0.512827,respectlvely,which indicates that magm as were derived from the mixture of DM (depleted mantle) and EM Ⅱ(enriched mant leⅡ).According to potassiumarg on dating,the samples were formed (7.77±0.49) Ma ago,a bit later than the basalts[(9.1±1.29)~(10.0±1.80) Ma]from Zhenbei Seamount.Compared with geochemical and isotopic features of the basalts from Zhenbei Seamount,it is concluded that trachyte from Huangyan Seamount was originated from the same mantle source of basalts from Zhenbei Seamount,but formed at the different evolution stages.It is suggested that during the late Miocene,there was mantle plume activity probably or athenosphere mantle upwelling along Zhengbei-Huang yan Seamount.
- trachyte,
- geochemistry,
- potassium-arg on dating,
- Zhenbei Seamount,
- Huangyan Seamount,
- South China Sea Basin

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References(18)

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