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对锆石微区性质、显微结构、激光Raman测试及阴极发光图像的研究结果表明,南苏鲁中国大陆科学钻探工程主孔片麻岩和退变榴辉岩中的锆石均保存了与柯石英等典型超高压矿物共存于同一变质增生锆石微区中的流体包裹体,多数为CO2(气)-H2O(液)两相,且以H2O液相为主的流体包裹体,少数为单一的H2O液相流体包裹体,表明苏鲁地体的榴辉岩及其围岩在超高压变质阶段并非处于“干体系”环境,而是处在有流体参与的相对“湿体系”环境.SHRIMP定年结果显示,含柯石英+流体包裹体的变质增生锆石微区的U-Pb年龄为233.7±4.3 Ma,可能代表了苏鲁地体超高压变质峰期阶段至峰后降压初始阶段锆石生长时间.其他锆石边的U-Pb年龄为213.2±5.2 Ma,代表角闪岩相退变质过程中锆石增生的时间.因此,苏鲁地体超高压岩石折返过程中的流体活动主要出现在中晚三叠世,不过在超高压阶段依然存在流体活动.这些结果不仅为进一步深入探讨超高压变质过程中流体性质、演化以及流体一岩石相互作用机理提供重要的信息,而且为今后在世界各地超高压岩石中准确识别原生流体包裹体提供了新的研究方法.
The results of Zircon micro-zone properties, microstructure, laser Raman test and cathodoluminescence images show that the zircons in the main gneisses and degenerated eclogites of the South Sulu Continental Scientific Drilling Project both conserved Some typical ultrahigh-pressure minerals such as Coke and quartz coexist in the fluid inclusions in the same metamorphic and accretionary zircon microstructure. Most of the fluid inclusions are CO2 (gas) -H2O (liquid) two phases and fluid inclusions dominated by H2O liquid, a few are The single H2O fluid inclusions indicate that the eclogites and their surrounding rocks in the Sulu terrain are not in a “dry system” environment during the UHP metamorphism but are in a relatively “wet system” environment with fluid participation. The results of SHRIMP dating show that the U-Pb age of the metamorphic-accretionary zircon zone containing coesite + fluid inclusions is 233.7 ± 4.3 Ma, which may represent the initial stages of UHP metamorphism during the post-peak depression Zircon U-Pb ages of 213.2 ± 5.2 Ma indicate the time of zircon accretion in the process of retrogressive metamorphism of the amphibolite, therefore, the fluid activity during the reentry of the UHP rocks in the Sulu terrane Mainly in the Middle Triassic, but in the stage of ultra-high pressure However, fluid activities exist, which not only provide important information for further exploration of fluid properties, evolution and fluid-rock interaction mechanism during the UHP metamorphism, but also provide accurate identification of primary fluid inclusions in ultrahigh-pressure rocks around the world in the future A new research method.