摘要
利用三维地幔对流模型计算了在当今板块构造运动的驱动下地幔对流的形态和演化过程,并由此分析对流作用下地幔物质的混合程度。模拟发现:1)地幔的混合程度主要受板块驱动作用的影响;2)上地幔的混合程度高于下地幔。极型场加环形场的情况下,有80%左右的上地幔区域经受过两条以上的对流轨迹曲线穿入,同时下地幔相应的穿入率也达到60%以上;3)混合程度受对流时间影响较明显。时间越长,混合程度越高,但混合程度的增长速率随时间增加逐渐减小,这使得全地幔对流情况下地幔物质保持各向不均一性成为可能;4)地幔混合还与流场类型有关,环形场的存在很大程度上增加了地幔的混合程度。
This paper simulated the pattern of mantle convection and its evolution force from modem plate tectonic motion based on a 3-D mantle convection model and then process under the driven analyzed the mantle mixture effect further. The results show four main characteritics of mantle mixture： 1 ） Degree of mantle mixture is mainly controlled by tectonic driven forces. 2） The degree of material mixture in the upper mantle is higher than that in the lower mantle. About 80% elements in the upper mantle and 60% in the lower mantle have been past through by at least two curves. 3） The degree of mantle mixture also depends on the convection time. The longer the time, the higher the degree of mixture, but the trend of mixture increase is getting downward, that makes the existence of mantle heterogeneities under the full mantle convection environment possible. 4） Mantle convection type can affect the mantle mixture in quite a deal. The existence of toroidal convections can make the material travel much longer distance than spheroidal convections, thus increase the mixture effect efficaciously.
出处
《大地测量与地球动力学》
CSCD
北大核心
2009年第1期46-51,共6页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金(40774053)
中国科学院知识创新重点方向性项目(KZCX3-SW-153)
关键词
地幔对流
混合
不均一性
板块运动
流场类型
mantle convection
mixture
heterogeneity
plate movement
mantle convection type
