HR: 0800h
AN: T11C-1879    [Abstracts]
TI: The Caribbean plate: Pushed, pulled or dragged?
AU: * van Benthem, S
EM: benthem@geo.uu.nl
AF: Utrecht University, Budapestlaan 4, Utrecht, 3584CD, Netherlands
AU: Govers, R
EM: govers@geo.uu.nl
AF: Utrecht University, Budapestlaan 4, Utrecht, 3584CD, Netherlands
AB: Mechanical coupling between the lithosphere and the asthenosphere remains a controversial topic in the geosciences. Beneath the Caribbean plate, shear wave splitting measurements indicate EW strain in the asthenosphere, which was previously interpreted as: mantle flow significantly drives the Caribbean plate. Here, we constrain the average shear traction on the base of the Caribbean plate by balancing all torques. These torques result from body forces that act on the Caribbean (slab pull, ridge push, lateral density variations), from plate boundary friction and from basal shear tractions. We obtain a range of physically realistic torque solutions, which we examine further by computing the corresponding strain and rotations within the Caribbean plate for comparison with observations. Models that match the observations (1) have a near-zero basal shear traction (°9 0.3 MPa), (2) have (lithosphere-)averaged fault friction °9 10 MPa, (3) have Cocos Ridge indenting into the overriding Panama plate, (4) require a net pull by the Caribbean slab. We conclude that the mechanical coupling of the Caribbean plate to the underlying asthenosphere is small.
DE: 0545 Modeling (4255)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8162 Rheology: mantle (8033)
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2008 Fall Meeting