Spinel peridotites from the Nui Nua and Ba Ria volcanic suites of southern Vietnam were investigated to interpret mantle processes and geochemical evolution of the lithospheric mantle beneath southern Vietnam. Spinel peridotites from both study areas consist of lherzolites and harzburgites displaying porphyroclastic textures. The spinel peridotites may have experienced a low degree (1–13%) of fractional melting. The variation of light rare earth elements (LREEs) and other incompatible elements in clinopyroxenes indicates that most of the spinel peridotites have undergone silicate metasomatism. The spinel peridotite xenoliths of both areas originated at depths between 35 and 52 km with equilibrium temperatures ranging from 714–1211 °C (±15 °C). Correlations between Sr, Nd, and Pb isotopic compositions of the clinopyroxenes suggest that the spinel peridotites originated from mixing of depleted (DM) and enriched (EM2) mantle sources. The spinel peridotites from Nui Nua gave a Pb-Pb isochron age of 3.6 ± 0.3 Ga which suggests the formation time of lithospheric mantle beneath southern Vietnam due to initial melt extraction.

中文翻译：

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越南南部Nui Nua和Ba Ria地区以下岩石圈地幔的岩石学特征

对越南南部Nui Nua和Ba Ria火山岩层的尖晶石橄榄岩进行了研究，以解释越南南部下方岩石圈地幔的地幔过程和地球化学演化。来自两个研究区域的尖晶石橄榄岩均由具有杂碎碎屑质地的锂铁矿和哈兹伯格岩组成。尖晶石橄榄岩的熔融度可能较低（1-13％）。斜辉石中轻稀土元素（LREE）和其他不相容元素的变化表明，大多数尖晶石橄榄石都经历了硅酸盐交代作用。这两个地区的尖晶石橄榄岩异岩都起源于35至52 km的深度，平衡温度范围为714-1211°C（±15°C）。Sr，Nd，斜辉石的Pb和Pb同位素组成表明，尖晶石橄榄岩源自贫化（DM）和富集（EM2）地幔源的混合。Nui Nua的尖晶石橄榄岩的Pb-Pb等时年龄为3.6±0.3 Ga，这表明由于最初的熔体提取，越南南部下方岩石圈地幔的形成时间。