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文章拟通过分析南海中央次海盆海山火山岩样品的岩石学及地球化学资料来审视研究区的岩浆过程及其构造背景.综合位于南海中央次海盆的中南、珍贝-黄岩、涨中、宪北、玳瑁、尖峰这6条海山链的火山岩资料及最新分析结果,将来自各条海山链的洋岛型碱性玄武岩、具有过渡性质的拉斑玄武岩,以及粗面岩、粗面安山岩、流纹英安岩等纳入统一的岩浆分异体系进行地球化学特征检验.相关参数表明,中央次海盆海山火山岩岩浆具有连续的演化关系但源区性质并不均一,属于EMⅠ和DMM双端员混合.根据分析样品的Mg#值、分异指数DI以及主、微量元素的分布特征,初步判定原始岩浆在上地幔经历了橄榄石、辉石分离结晶作用后继续演化,产生包括拉斑玄武岩、碱性玄武岩、粗面岩等在内的岩石组合.其中,富集型OIB的多项地化参数特征表明,岩浆在演化过程中似有陆壳成分的加入,这可能是被动大陆边缘破裂留给南海海盆的最重要的遗产之一.
This paper intends to examine the magmatism and tectonic setting of the study area by analyzing the petrological and geochemical data of seamounts in the central sub-sea basin of the South China Sea.Comprehensive analysis of the magmatism and its tectonic setting in the Central South China Sea, Zhabei-Huangyan, Hawksbill, and spikes of the six seamounts volcanic rock data and the latest analysis results, from the seamounts of the oceanic island basaltic basalts, with transitional nature of tholeiite, as well as the rough, rough andesite, rhyolite Anan and so on into a unified magmatic differentiation system for geochemical characteristics of the test.Related parameters show that the central sub-sea seamount volcanic rocks have a continuous evolution of magmatic evolution but the nature of the source area is not uniform, belonging to the EMⅠ and DMM double-end member mix .According to the analysis The Mg # value, diurnal differentiation index DI and the distribution characteristics of major and minor trace elements of the samples indicate that the original magma continued to evolve after the upper mantle experienced the separation and crystallization of olivine and pyroxene, Rough rock, etc. Among them, the characteristics of a number of geochemical parameters of enriched OIB indicate that the magma seems to be in the evolutionary process Added ingredients, which may be one of the most important legacy left to break the passive continental margin of the South China Sea basin.