中文摘要：

一些在东方 Beibu 海湾的小岛被第四级的火山阶层盖住。从这些小岛的岩石样品主要由石英 tholeiites 组成(在 Shenjiandao ) ，橄榄石 tholeiites (在 Linshidao 和 Xieyangdao ) 并且碱暗岩(在 Yangpubi 和 Jianshidao ) ，并且基本上代表海南岛和它的邻近的区域的第四级的火山作用的四个时期。除了从 Shenjiandao 的样品，大多数这些小岛的第四级的 volcanics 属于碱岩浆系列。这些样品表演的所有的踪迹元素特征他们是 OIB (海洋的岛暗岩) 暗示他们的深 geodynamic 背景可能与一根披风羽毛有关的 -like, 。Sr-Nd-Pb 同位素的作文证明在第四级的阶层下面的披风来源能由于二进制混合在之间被考虑一弄空，相似来源和一个充实的披风打的 DMM (弄空的 MORB 披风) 2 (EM2 ) 。EM2 可以从海南披风羽毛被发源，并且是由在 asthenospheric 披风水平免除古老的再循环的海洋的外壳的碳的液体的 metasomatized。和典型踪迹元素比率，这些特征思考父母岩浆不受到外壳的污染在期间它的上升到表面。这研究为海南披风羽毛的存在提供进一步的 petrological 和 geochemical 证据。

英文摘要：

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 Xieyang- dao） 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 （de- pleted 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 re- cycled 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.