青藏高原北部新生代火山岩内下地壳岩石包体研究

Petrologic, mineralogyic and gechemical research on the lower-crust granulitic xenoliths in the Cenozoic volcanic rocks from Northern Tibetan Plateau, shows that the composition of the crust is comparatively complicated, three types of granulite are distinguished, which are two-pyroxene granulite, nortic granulite and felsic granulite. Equilibration temperature and pressure record hot state of the Northern Tibetan thicking crust. Most of the lower crust xenolith undergo retrograde metamorphism from granulitic facies to amphibole facies,whose protolith are mainly sedimentary rocks, and some metaigneous rocks. For the first time, we got Lower Prroteroic to Middle Proterozoic age of the lower crust, ~2.16Ga. As a primary result, archtectue of the lower crust of Northern Tibetan Plateau formed in early to middle Cretaceous Epoch(110-120Ma), and undergone a period of heating in Oligocene Epoch because of underplating by mantle materiall, which resulted retrograde metamorpism and crust thicking.

通过对青藏高原北部新生代火山岩中下地壳麻粒岩包体详细的岩石学、矿物学、地球化学尤其是同位素地球化学及年代学研究，建立青藏高原北部下地壳组成及岩石学模型，提供高原地壳增厚时限，结合对高原北部钾玄质火山岩地球化学研究，探讨岩石圈演化过程中壳、幔物质转化过程。.