软流层的地球膨胀成因及其形成时间  

The Earth Expansion Generated the Asthenosphere and Its fFormation Time

作　　者：陈志耕[1] 

机构地区：[1]河北地质学院地球动力与应用研究所,河北石家庄050031

出　　处：《地球科学进展》2013年第7期834-846,共13页Advances in Earth Science

摘　　要：地球的软流层(圈)堪称全球构造、岩浆与成矿作用动力之源。以往人们虽然认识到软流层的重要作用,但其形成机制的定量研究还不够。最近20多年来,对地球半径变化的检验研究结果表明,地球膨胀已经有了较多的直接证据。而且,即使按照地球膨胀晚期0.1 mm/a的半径增长率计算,所产生的地球膨胀构造动力事件,也将是一个全球性超级构造动力事件。根据地球的非线性有限膨胀演化,所提出的软流层成因是:源于原始地球深部的膨胀内压,推挤原始地幔顶部物质做功并转化为原始岩石圈球壳围限下的地幔顶部物质的压缩能A,当压缩能的积累超过原始地幔顶部物质局部熔融所需要的热能Ω时,地幔顶部物质便开始熔融并逐渐形成地球的原始软流层。据此,按照地球非线性膨胀演化初期的半径增长率1.08 mm/a、原始地幔顶部物质以15%的局部熔融和绝热等压过程估算,地球开始膨胀后仅19.2 Ma,地球的原始软流层(圈)便可形成。The Earth’s asthenosphere may refer to the dynamic source of global tectonics,magmatism and mineralization.Although people have recognized the importance of the asthenosphere’s tectonic dynamic,magmatism and mineralization,there is little in-depth study of its formation mechanism in specific and quantitative tools.In recent twenty years,a series of research results in the radius change of the Earth show that the expansion of the Earth has much direct evidence.Accordingly,even calculated by inflation rate（0.1 mm/a） of the radius of the late Earth expansion,the result of the Earth expansion will also be a global super tectonic event.According to the nonlinear limited expansion evolution of the Earth,the asthenosphere cause model is that,the expansion internal pressure from the original deep Earth pushes the top of the primitive mantle acting and is converted into compression energy A acting on the top mantle material under confined by original lithosphere shell.When the accumulating compression energy exceeded the thermal energy Ω required to melt the part of material on top original mantle,the uppermost mantle material began to melt and gradually formed the Earth’s primitive asthenosphere.Accordingly,assuming that the radial growth rate of nonlinear limited expansion at the beginning expansion period of the Earth is 1.08 mm/a,the meltdown rate of the top material of primitive mantle is 15%,under the condition of adiabatic isobaric process,it will only need 19.2 Ma to form the Earth’s original asthenosphere after the Earth began to expand.

关 键 词：地球膨胀 地球膨胀检验 软流层成因 软流层形成时间 全球超级构造动力事件 

分 类 号：P542[天文地球—构造地质学]