地幔柱构造理论研究若干问题及研究进展

SOME PROBLEMS AND ADVANCES IN THE THEORETICAL STUDIES OF MANTLE PLUMES

介绍了目前地幔柱构造理论研究中若干重要问题和最新进展，许多证据显示，地幔柱是来自于核幔边界附近的Ｄ″层，导致Ｄ″层发生热扰动并产生地幔柱的热动力源于外地核的不均匀加热作用；一个新启动的地幔柱在穿过整个地幔的缓慢上升过程中会形成巨大球状顶冠和狭窄尾柱；地幔柱巨大球状顶冠会导致地壳发生上隆、区域变质作用、地壳深熔作用、构造变形作用和大规模火山作用，形成大陆或大洋溢流玄武岩；地幔柱狭窄尾柱的长期活动会在上覆运动板块上形成一系列热点火山链。最后讨论了地幔柱构造与板块构造关系，并阐述了地幔柱构造在当前大地构造研究领域中的重要地位。

Many evidences indicate that mantle plumes originate from the high-temperature and low-viscosity D'layer located at the core-mantle boundary, and that the starting of mantle plumes results from the heterogenious heating of the earth's core. Recent research shows that the ascending velocity of a mantle plume is not as fast as is expected in the early research and that a mantle plume often horizontally diverges and produces a huge spherical head,and leaves a narrow tail while it ascends and encounters the cold lithosphere. The large spherical heads of mantle plumes can result in the crust's upswelling, deformation,metamorphism and volcanic eruption to form continental flood basalts, The longlived narrow tails of mantle plumes can penetrate the overlying moving plates to form oceanic island basalts. No evidences indicate that the vertical mantle plumes can be deflected by horizontal convection of the mantle,so volcanic chains formed by mantle plumes provide an absolute reference frame with respect to plate motion. The relationship between mantle plume tectonics and plate tectonics has remained a controversy since mantle plume was proposed. Although some evidences imply that mantle plumes are indenpendent of plate tectonics, some Japanese geologists recently advocated that both mantle plumes and plates are controlled by the same tectonic dynamical system of the earth.