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采用新生代玄武岩中地幔岩捕掳体的矿物、岩石天然样品进行尖晶石与石榴石的相转变实验研究,结果发现尖晶石二辉橄榄岩与石榴石二辉橄榄岩相转变条件(T=1100℃和P=1.8～2.0GPa)与中国东部五相共存的尖晶石/石榴石二辉橄榄岩P-T平衡条件一致.提出中国东部大陆上地幔55～70km深处存在几公里至十几公里厚的尖晶石二辉橄榄岩与石榴石二辉橄榄岩相转变带.尖晶石辉石岩向石榴石辉石岩相转变深度小于55km.实验结果还揭示水促使地幔交代作用,但又抑制了相转变.同时讨论了矿物成分分带现象.
The phase transition of spinel and garnet was studied by using the natural samples of minerals and rocks of the mantle rock entrapped in the Cenozoic basalts. The results show that the phase transformation of spinel lherzolite and garnet lherzolite (T = 1100 ℃ and P = 1.8 ~ 2.0GPa) coincides with the PT equilibrium conditions of spinel / garnet lherzolites coexisting in the five phases of eastern China, and the spinel two-hui Peridotite and garnet lherzolite facies.The transition depth of spinel pyroxene to garnet pyroxenite is less than 55km.The experimental results also reveal that water can promote mantle metasomatism but inhibit phase transformation.Meanwhile, Component zoning phenomenon.