Rheological properties of deep subducted oceanic lithosphere and their geodynamic implications  

作　　者：金振民 金淑燕 章军锋 H.W.Greenll 

机构地区：[1]Inst.Geophys.&Planet.Phys.,University of CAlifornia,Riverside

出　　处：《Science China Earth Sciences》2002年第11期969-977,共9页中国科学（地球科学英文版）

基　　金：This work was supported by the Chinese National Key Project for Basic Research (Grant No. G1999075501);the USA National Science Foundation and the Crust-Mantle Interaction Laboratory at China University of Geosciences (Wuhan)

摘　　要：According to the experimental studies on the rheology of two important mantle rocks (eclogite and harzburgite), the rheological properties of the deep subducted oceanic lithosphere are investigated by assuming a simplified harzburgite type slab model with moderate thickness of basaltic layer. When the mantle convergence rate is small or the subducting slab has been trapped in the mantle for an enough long time, the strength profile of the slab is characterized by a strong subducting crustal component lying on a weak subducting upper mantle. However, if the convergence rate is large enough, the subducting slab will be featured only by a rigid cold center. Our study suggests that the detachment of the subducting crust component from the underlying upper mantle is only likely to happen in hot slow subducting slabs, but not the cold fast subducting lithosphere. Rheological properties of the harzburgitic and the eclogitic upper mantle vary with depths. The eclogitic upper mantle is stronger than the peridotitic upper mantle across the upper mantle. Transition zone is the high strength and high viscosity layer in the upper mantle except the lithosphere.According to the experimental studies on the rheology of two important mantle rocks (eclogite and harzburgite), the rheological properties of the deep subducted oceanic lithosphere are investigated by assuming a simplified harzburgite type slab model with moderate thickness of basaltic layer. When the mantle convergence rate is small or the subducting slab has been trapped in the mantle for an enough long time, the strength profile of the slab is characterized by a strong subducting crustal component lying on a weak subducting upper mantle. However, if the convergence rate is large enough, the subducting slab will be featured only by a rigid cold center. Our study suggests that the detachment of the subducting crust component from the underlying upper mantle is only likely to happen in hot slow subducting slabs, but not the cold fast subducting lithosphere. Rheological properties of the harzburgitic and the eclogitic upper mantle vary with depths. The eclogitic upper mantle is stronger than the peridotitic upper mantle across the upper mantle. Transition zone is the high strength and high viscosity layer in the upper mantle except the lithosphere.

关 键 词：SUBDUCTION zone  MANTLE rock  high P-T  detachment  RHEOLOGICAL layering. 

分 类 号：P736[天文地球—海洋地质]