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对苏鲁造山带桃行地区2个代表性的花岗质超高压正片麻岩进行了综合的锆石学和岩石学研究,结果对大陆俯冲带深部变质脱水和部分熔融这2个重要地质过程发生的温压条件和时空关系提供了制约.样品1中锆石记录了大陆俯冲过程中在236±5 Ma的中温榴辉岩相变质作用和折返过程中223±3 Ma的高温深熔作用,而样品2中锆石记录了大陆俯冲过程中237±3 Ma低程度中温深熔作用和贯穿整个碰撞造山过程的低温脱水作用.2个样品中的石榴石也显示了不同的结构和组成变化,给出了与锆石一致的P-T记录,指示大陆俯冲隧道中流体活动对锆石和石榴石生长的作用.这2个样品在地表相距仅百米,具有基本一致的岩石化学组成,但在陆壳碰撞过程中具有明显不同的P-T轨迹,说明它们在陆壳俯冲和折返过程中,处在陆壳板片的不同位置,并最终导致它们变质脱水和部分熔融行为的差异.
A comprehensive zircon and petrological study of two representative granitic EHV nodules in the Taohang area of the Sulu orogenic belt has been carried out. The results show that there are two important geological processes in the deep subduction and subsidence of the continental subduction zone The occurrence of temperature and pressure conditions and space-time relationship provided a constraint.The sample 1 zircon recorded during the continental subduction at 236 ± 5 Ma medium temperature eclogite facies metamorphism and the reintegration process of 223 ± 3Ma deep-melting, While zircon 2 in sample 2 records moderate-temperature deep-melting at a low level of 237 ± 3 Ma during the continental subduction and low temperature dehydration throughout the entire orogenic collision. The garnets in the 2 samples also show different structural and compositional changes, A PT record consistent with zircon is given to indicate the effect of fluid activity on the growth of zircon and garnet in subducted tunnels in China.These two samples are only one hundred meters apart from the surface of the earth and have basically the same petrochemical composition, The strikingly different PT trajectories during the collision indicate that they are at different locations on the continental crust sheet during subduction and reentry of the continental crust, ultimately leading to differences in their metamorphic and partially melted behavior.