【摘要】 主要对玻基橄辉岩和碱性橄榄玄武岩及其所含的尖晶石二辉橄榄岩包体的特征进行了详细研究描述,并根据这些岩石的化学成分和稀土元素含量讨论了它们的成因,根据二辉地质温度计和辉石地质温度计估算了它们的形成深度。研究结果表明:广西马山永州出露的这些基性-起基性小岩体多数为玻基橄辉岩,少数为碱性橄榄玄武岩,两者均属碱性玄武岩浆分异的产物。它们所含尖晶石二辉橄榄岩包体(Ⅰ型超镁铁质岩包体),为亏损地幔岩碎块,系上地幔部分熔融形成碱性玄武岩浆后残留的地幔碎块被岩浆携带上来的。尖晶石二辉橄榄岩平衡温度为1015～1114℃,压力为1.86～1.99GPa。形成深度为60～70km。玻基橄辉岩与碱性橄榄玄武岩的同位素年龄为28～51Ma。更多还原

【Abstract】 Many basic-ultrabasic rocks exposed in Yongzhou, Mashan, Guangxiare mostly limburgites and in less amount, alkali olivine basalts. Both ofthem are products of differentiation of alkalibasaltic magma. The spinel-lherzolite included in these rocks belongs to group I of ultrabasic rockinclusion. These inclusions are crushed stones of depleted mantle. Theywere carried up to the earth surface by basaitic magma from deep seat.The primary mantle was subjected to partial melting and produced basalticmagma and spinel-lherzolite remained. The equilibrium P-T conditions ofspinel-lherzolite inclusions are 1015-1114℃ and 1860～1990 Mpa. So theywere originated at a depth of 60～70 km in the upper mantle. The isotopicages of the limburgite and alkali olivine basalt in Yongzhou, Mashan were28～51 Ma.更多还原