板块构造学说面临的挑战

PLATE TECTONIC THEORY: A SERIOUS CHALLENGE

板块构造学说揭示了海底扩张和板块的水平运动现象,阐明了与板块边界相联系的岩浆活动。但大量资料表明地球历史上岩石圈板块与软流圈是同步耦合运动的,而不是在软流圈上滑移。全球扩张与俯冲的不对称性现象也是不吻合于板块构造理论所期望的。安第斯弧作为洋陆俯冲的典范在地球物理和地球化学上均缺少证据。对于与俯冲带相关的弧后引张、大陆增生、地壳物质返回地幔和成矿作用方面均存在较多的问题。大火成岩省所揭示的岩浆活动现象超越了板块构造的格局,并发生在整个地质历史时期和更广泛的地域范围。大火成岩省学说所解释的大陆增长、地壳物质返回地幔和成矿作用过程完全不同于板块构造学说。驱动地幔柱的深地幔对流假说允许岩石圈板块与下伏软流圈一起运动,吻合铅同位素所揭示的岩石圈与软流圈长期耦合的规律。

The plate tectonic theory reveals the seafloor spreading and plate lateral movement, and illustrates magmatism related to plate boundaries. However, a great number of studies indicate that plate movement is tightly coupled with asthenosphere, instead of sliding on asthenosphere. Globally, an asymmetrical system of spreading and subduction is not expected from the plate tectonic theory, since evidences are rather scarce from geophysics and geochemistry for the Andes arc to be taken as a paradigm for ocean-continent subduction. Problems also arise from geologic phenomena that are associated with subduction zones including back arc opening, continental growth, recycling of crustal materials and metallogenesis. Magma activation involved in large igneous provinces surpasses the network established by the plate tectonic theory, and occurs during the entire earth history and in more extensive areas than those covered by plate tectonic theory. The academic opinions related to large igneous provinces propose a set of mechanisms to explain continental growth, recycling of crustal materials and metallogenesis, and these mechanisms are entirely different from those of the plate tectonic theory. The hypothesis of mantle plume driven by deep mantle convection holds lateral movement of lithosphere in coupling relationship with its underlying asthenosphere, and this is in agreement with the opinion of long term coupling between lithosphere and asthenosphere as was revealed by Pb isotope study.