负浮力是板块运动的驱动力吗?关于岩石断裂力学的讨论

Is negative buoyancy the primary force driving plate motion during the onset of subduction?A discussion on rock fracture mechanics

本文从岩石断裂力学的角度,讨论了俯冲板块下拉牵引力(负浮力)作为板块运动初始驱动力的可能性。笔者总结已发表的岩石抗张强度的岩石力学实验结果,并和现在普遍认为的负浮力的数量级进行对比分析,结果表明大洋岩石圈上部岩石强度较低,仅有n×10 MPa。虽然随着温度和压力的增加岩石圈的强度不断增强,但是在板块俯冲的初始阶段,大洋岩石圈可能无法承受拖曳板块运动高达n×10^2 MPa的应力。此外,构造模拟、热开裂、疲劳断裂、俯冲挠曲、俯冲脱水以及熔融作用等地质现象的分析,也表明俯冲板块的负浮力作为板块运动初始驱动力是不符合客观事实的。

Based on the method of rock fracture mechanics,we discussed in this paper the possibility of pulling force(negative buoyancy)exerted by subducting plate being the driving force for plate movement.Experimental results of rock fracture indicate that the lithospheric strength is very low,only about n×10 MPa,which is unlikely to bear the necessary n×10^2 MPa stress during the onset of subduction.In addition,results from tectonic modeling,thermal cracking,fatigue fracture,flexure of subducted slabs,subduction dehydration and melting process studies reveal that the idea of negative buoyancy of subducting plate being the driving force for plate movement is inconsistent with research observations.