Announcement of Union Session, Fall AGU Meeting 2000

PLATE-MANTLE INTERACTION AND FORCES THAT MOVE PLATES

In its original form, plate tectonics describes the motion of rigid plates over the deeper mantle. Plates were assumed to be essentially decoupled from the deeper mantle by the asthenosphere, driven mainly by slab pull and ridge push (i.e., forces acting on the sides of the plates) and resisted slightly by basal drag. This assumption recently has attained increased attention with the suggestion that basal drag may be an important plate driving mechanism. This session focuses on the kinematic and dynamic nature of the coupling between lithospheric plates and underlying mantle, and on which forces drive the plates.

Conveners: Götz Bokelmann, Department of Geophysics, Stanford University, Stanford, CA 943025-2215, tel. (650) 725-9181, fax (650) 725-7344, goetz@alumni.princeton.edu; Eugene Humphreys, Department of Geology, University of Oregon, Eugene, OR 97403, tel. (503) 346-5575, fax (503) 346-4692, gene@newberry.uoregon.edu.

The sessions will be held on Sunday, December 17, 2000, with an oral session in the morning (U71a), and a poster session in the afternoon (U72a).

Program Session Union U71A (Sunday Morning)

"Plate-Mantle Interaction and Forces That Move Plates", I Oral Part, Room MC 135, Conveners: G. Bokelmann, E. Humphreys

0830 How Well do we Understand Plate-driving Forces? *R J O'Connell, T W Becker (Harvard U.) INVITED
0850 Mantle Flow and Plate Driving Forces *C Lithgow-Bertelloni (U. of Michigan) INVITED
0905 Stress Field Constraints on Forces Acting on the Plates *M L Zoback, (USGS, Menlo Park), M D Zoback (Stanford U.) INVITED
0925 Evidence from North America for low resisting basal drag and a weak sub-asthenospheric layer *E D Humphreys (U. of Oregon), D Coblentz (U. of Graz), D Schutt (U. of Oregon)
1005 Seismic Anisotropy and Plate Tectonics *J Montagner (Institut de Physique du Globe, Paris) INVITED
1025 Asymmetric Mantle Dynamics in the MELT Region of the East Pacific Rise: Evidence for Asthenospheric Return Flow *D R Toomey (U. of Oregon), W S Wilcock (U. of Washington), J A Conder (Brown U.), D W Forsyth (Brown U.), J Blundy (U. of Bristol), E M Parmentier (Brown U.), W C Hammond (U. of Oregon) INVITED
1040 Mineral and Rock Physics Observations Pertinent to the Rheology of the Upper Mantle *S Karato (U. of Minnesota) INVITED
1100 Thick Shields and Plate-Mantle Interaction *G H Bokelmann (Stanford U.)
1120-1200 DISCUSSION

Session Program U72A (Sunday Afternoon)

"Plate-Mantle Interaction and Forces That Move Plates II Posters",Location MC Hall D, Conveners: G. Bokelmann, E. Humphreys

Modeling Plate Tectonics and Mantle Convection as a Single, Integrated System *P J Tackley (UCLA)
On the driving forces of plate tectonics *T W Becker , R J O'Connell (Harvard U.)
Lithospheric and Mantle Contributions to the Global Stress Field *J Guynn, C Lithgow-Bertelloni (U. of Michigan)
Earth/Moon Double-Planet, III: Slab-Pull, Ridge-Push and the Bias in Mantle Circulation *R C Bostrom (U. of Washington)
Forces Driving Plate Motion: Constraints from Large Scale Geoid Anomalies O Cadek (Charles U., Prague), *L Fleitout (Ecole Normale Superieure, Paris)
Amplitude of temperature variations and surface velocity during avalanche-like events in a multiphase temperature and pressure dependent mantle. *P L Machetel (U. of Montpellier), E Humler (CNRS, Paris)
Plate Reorganization Events Triggered by Radiogenic Mantle Heating *C W Gable (Los Alamos), J P Lowman (U. of Leeds), S D King (Purdue U.)
The Influence of Grain Size Evolution on Coupling of Plate Motions to Convective Instabilities *C Hall , E M Parmentier (Brown U.)
The Role of Gravitational Slab Work in Mantle Energetics *J Phipps Morgan (GEOMAR, Kiel)
Thin Spherical Shell Model of Global Asthenosphere Flow *W J Morgan (GEOMAR, Kiel), J P Morgan (Princeton U.)
On the Interaction Between Small-scale Convection and Plate-scale Flow *J Korenaga (MIT), T H Jordan (USC)
Ridge Push and Plume Push *W R Jacoby , H Wallner (U. of Mainz)
Shear-Wave Splitting Around Hawaii: Testing Kinematic Models of Lithosphere/Asthenosphere Interaction for a Plume *K T Walker, G H Bokelmann (Stanford U.)
Evidence for Recently Induced Deformation in the Mantle Beneath the Eifel Volcanic Fields (Germany) from Shear Wave Splitting Analysis *G Bock (GFZ, Potsdam), T Eifel-Plume Team
Evidence for Lithospheric Coupling in Anisotropic Body Wave Polarizations *V Schulte-Pelkum, D K Blackman (Scripps)
Does Seismic Anisotropy at the Base of the Lithosphere Reflect Lithospheric Drag? *M Cara, E Debayle, J J Leveque (U. of Strasbourg)
Mantle Flow at a Slab Edge: Seismic Anisotropy in the Kamchatka Region *J Park, V Levin (Yale U.), V I Peyton (USGS, Albuquerque), M T Brandon (Yale U.), J M Lees (U. of North Carolina), E Gordeev, A Ozerov (R. Academy of Sc., Kamchatka)
Lithospheric 'Schlieren' and Plate Mantle Interaction *K Fuchs (U. of Karlsruhe), M Tittgemeyer (Max-Planck-Inst. Leipzig), T Ryberg (GFZ, Potsdam), F Wenzel (U. of Karlsruhe)
Base of Craton Lithosphere *N H Sleep (Stanford U.)
The Role of Ocean-Continent Contrast and Continental Keels on Plate Motion, Net Rotation of Lithosphere, and the Geoid *S Zhong (U. of Colorado)
The off-Axis Manifestation of a Near-Ridge Cold Anomaly *S Lin, L Chiao (Nat. Taiwan U.)
Continental Rifting Parallel to Ancient Collisional Belts: An Effect of the Mechanical Anisotropy of the Lithospheric Mantle *A Tommasi, A Vauchez (U. of Montpellier)
The Influence of the Olivine-Spinel Transition on Shallow Flat Subduction *J van Hunen, A P van den Berg, N J Vlaar (U. Utrecht)
The Thermomechanical Effects of Variable Thermal Conductivity and Variable Viscosity on Eroding The Thermal Signatures in Descending Slabs in the Lower Mantle *A P Van den Berg (U. Utrecht), D A Yuen (U. of Minnesota)
Three-Dimensional Dynamic Response Functions for Instantaneous Input of Localized and Large-Scale Zonal Thermal Anomalies Into the Static Layered Mantle *T Eguchi (Nat. Defense Acad., Japan), K Matsubara (Fuji Res. Inst.), M Ishida (Nat. Res. Inst., Tsukuba)
Mantle Deformation Beneath Southern Africa *P G Silver (DTM, CIW, Washington), S S Gao (U. of Kansas), K Seismic Group

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