Newtonian versus non-Newtonian upper mantle viscosity: Implications for subduction initiation
نویسندگان
چکیده
[1] The effect of rheology on the evolution of the slab-tip during subduction initiation is analyzed using 2-D numerical flow models. Experimentally determined flow laws have both strong temperatureand stress-dependence, which leads to large local variations in viscosity with direct consequences for subduction initiation. We find that models with Newtonian viscosity lead to flat or coupled subduction due to hydrodynamic stresses that pull the slab-tip up towards the overriding plate. Non-Newtonian rheology reduces these hydrodynamic stresses by decreasing the wedge viscosity and the slab coupling to wedge-corner flow, rendering the small negative-slab buoyancy of the slab-tip sufficient to maintain its dip during the early stages of subduction. Citation: Billen, M. I., and G. Hirth (2005), Newtonian versus non-Newtonian upper mantle viscosity: Implications for subduction initiation, Geophys. Res. Lett., 32, L19304, doi:10.1029/2005GL023457.
منابع مشابه
Pulsating diapiric flows: Consequences of vertical variations in mantle creep laws
Peter van Keken a, David A. Yuen b and Arie van den Berg a Received November 21, 1991, revision accepted June 17, 1992 Recent laboratory work has suggested that the rheology of the lower mantle may be Newtonian. We have studied the time-dependent dynamics of plumes interacting with a rheological interface separating an upper non-Newtonian mantle and a Newtonian lower mantle . Pulsating diapiric...
متن کاملOn the Purpose of Toroidal Motion in a Convecting Mantle
The purpose of toroidal flow, i.e., strike-slip motion and plate spin, in the plate-tectonic style of mantle convection is enigmatic. It is a purely horizontal, dissipative flow field that makes no apparent contribution to the release of heat. However, when plate-like toroidal motion is allowed to arise as a phenomenon of non-Newtonian mantle dynamics, it in fact acts to reduce the net amount o...
متن کاملMicrofiche. Although It Is Recognized That Certain Portions Are Illegible, It Is Being Released in the Interest of Making Available as Much Information as Possible
Candidate models of the forces which oppose the sinking of slabs are all constrained to produce results consistent with the following observation: relative geoid highs, which one assumes are due to slabs, characteristically occur over subduction zones. Certain models which are otherwise plausible, such as those based on a Newtonian half-space mantle, yield geoid lows instead of highs. This stud...
متن کاملEffect of six non-Newtonian viscosity models on hemodynamic parameters of pulsatile blood flow in stenosed artery
A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with non-Newtonian models using ADINA. Blood flow was considered laminar, and the arterial wall was considered rigid. Studied stenosis severities were 30, 50, and 70% of the cross-section...
متن کاملThe Earth's Mantle: Evidence of Non-Newtonian Flow.
Recent information from experimentally deformed dunite coupled with a reanalysis of data on the Fennoscandian postglacial rebound suggest that the rheological behavior of the upper mantle is distinctly non-Newtonian, and that the shear strain rate is proportional to the shear stress raised to about the third power.
متن کامل