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对苏鲁地体西部东海地区榴辉岩及其共生片麻岩内部石英脉进行了氧同位素研究。石英脉及其寄主岩石榴辉岩和片麻岩中的石英与其他矿物之间达到了氧同位素平衡,计算得到的平衡温度分别为:石英脉660～840℃,榴辉岩595～725℃,片麻岩505～665℃。石英脉的δ~(18)O值变化范围为-5.3‰～7.5‰,与寄主岩石的δ~(18)O相似。指示变质流体与寄主岩石保持氧同位素平衡,同时表明超高压变质作用期间或之后只存在内部缓冲的流体流动。片麻岩的δ~(18)O值低达-4‰,与共生榴辉岩的δ~(18)O相似。因此,片麻岩和榴辉岩的原岩在经历超高压变质作用之前均出露过大陆地壳,可能一同遭受了古大气降水的热液蚀变作用。石英脉是在同位素平衡条件下从δ~(18)O分布不均一的变质流体中沉淀出来的,这种流体则是由热液蚀变的榴辉岩原岩经脱水作用而形成,因而其δ~(18)O值受寄主榴辉岩性质所控制。这些结果为榴辉岩相变质作用期间变质流体在裂隙内部的有限流动提供了佐证。
Oxygen isotope studies of eclogite and quartz vein in the symbiotic gneiss in the East China Sea in the western Sulu terrain were carried out. Quartz and its host rock eclogite and gneiss in the quartz and other minerals to achieve the oxygen isotope balance between the calculated equilibrium temperature are: quartz veins 660 ~ 840 ℃, eclogites 595 ~ 725 ℃, Gneiss 505 ~ 665 ℃. The δ ~ (18) O values of quartz veins range from -5.3 ‰ to 7.5 ‰, similar to δ 18 O of host rocks. Indicating that the metamorphic fluid maintains the oxygen isotope balance with the host rock, indicating at the same time that there is only internal buffered fluid flow during or after the ultrahigh-pressure metamorphism. The δ 18 O value of gneiss is as low as -4 ‰, which is similar to δ 18 O of the symbiotic eclogites. Therefore, the original rocks of gneiss and eclogite have exposed continental crust before experiencing UHP metamorphism and may have suffered the hydrothermal alteration of paleo-atmospheric precipitation together. Quartz veins are precipitated from the metamorphic isotopes of metamorphic fluids with heterogeneous distribution of δ ~ (18) O. This fluid is formed by hydrothermal alteration of eclogite protoliths through dehydration, and hence δ The ~ (18) O value is controlled by the host eclogite property. These results provide evidence for the limited flow of metamorphic fluids inside the fracture during eclogitic metamorphism.