TY - JOUR

T1 - Pressure Driven Poiseuille Flow

T2 - A Major Component of the Torque-Balance Governing Pacific Plate Motion

AU - Stotz, Ingo Leonardo

AU - Iaffaldano, Giampiero

AU - Davies, D. Rhodri

PY - 2018

Y1 - 2018

N2 - The Pacific plate is thought to be driven mainly by slab pull, associated with subduction along the Aleutians–Japan, Marianas–Izu–Bonin and Tonga–Kermadec trenches. This implies that viscous flow within the sub–Pacific asthenosphere is mainly generated by overlying plate motion (i.e. Couette flow), and that the associated shear–stresses at the lithosphere's base are resisting such motion. Recent studies on glacial isostatic adjustment and lithosphere dynamics provide tighter constraints on the viscosity and thickness of Earth's asthenosphere and, therefore, on the amount of shear–stress that asthenosphere and lithosphere mutually exchange, by virtue of Newton's third law of motion. In light of these constraints, the notion that subduction is the main driver of present–day Pacific plate motion becomes somewhat unviable, as the pulling force that would be required by slabs exceeds the maximum available from their negative buoyancy. Here we use coupled global models of mantle and lithosphere dynamics to show that the sub–Pacific asthenosphere features a significant component of pressure–driven (i.e. Poiseuille) flow, and that this has driven at least 50% of the Pacific plate motion since, at least, 15 Ma. A corollary of our models is that a sub–lithospheric pressure difference as high as ±50 MPa is required across the Pacific domain.

AB - The Pacific plate is thought to be driven mainly by slab pull, associated with subduction along the Aleutians–Japan, Marianas–Izu–Bonin and Tonga–Kermadec trenches. This implies that viscous flow within the sub–Pacific asthenosphere is mainly generated by overlying plate motion (i.e. Couette flow), and that the associated shear–stresses at the lithosphere's base are resisting such motion. Recent studies on glacial isostatic adjustment and lithosphere dynamics provide tighter constraints on the viscosity and thickness of Earth's asthenosphere and, therefore, on the amount of shear–stress that asthenosphere and lithosphere mutually exchange, by virtue of Newton's third law of motion. In light of these constraints, the notion that subduction is the main driver of present–day Pacific plate motion becomes somewhat unviable, as the pulling force that would be required by slabs exceeds the maximum available from their negative buoyancy. Here we use coupled global models of mantle and lithosphere dynamics to show that the sub–Pacific asthenosphere features a significant component of pressure–driven (i.e. Poiseuille) flow, and that this has driven at least 50% of the Pacific plate motion since, at least, 15 Ma. A corollary of our models is that a sub–lithospheric pressure difference as high as ±50 MPa is required across the Pacific domain.

U2 - 10.1002/2017gl075697

DO - 10.1002/2017gl075697

M3 - Letter

VL - 45

SP - 117

EP - 125

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 1

ER -