Whole mantle dynamics: Linking surface and deep processes (co-organized)
Co-Conveners: Rob Van der Voo , Clinton Conrad , Michael Gurnis 
Oral Programme
 / Thu, 07 Apr, 08:30–12:00  / Room 22
Poster Programme
 / Attendance Fri, 08 Apr, 10:30–12:00  / Display Fri, 08 Apr, 08:00–17:00  / Hall A

Three basic elements of geodynamics were recognized by the late 1960’s: Plate tectonics, mantle plumes of possibly deep origin, and the Wilson cycle of ocean opening and closing. More recently, deep-seated plumes of the past are shown to mostly rise from the edges of two Large Low Shear wave Velocity Provinces (LLSVPs) on the core-mantle boundary, which appear stable, antipodal and equatorial, persisting in their present positions for several hundreds of millions of years, and perhaps much longer.

Although links between mantle activity and plate tectonics are becoming more evident, we still lack a generally accepted mechanism that consistently explains plate tectonics in the framework of mantle convection. As such, a prime goal now is to integrate plate tectonics into mantle dynamics and develop a theory that explains plate motions quantitatively and dynamically. This requires plate kinematic models linked to the mantle with the aid of a global plate motion reference frame based on moving hotspots and on palaeomagnetic data. The resulting plate reconstructions constitute the input to subduction models, which are meant to test and refine the consistency between the reference frame and subduction histories. Linking surface and mantle processes is extremely challenging and is only now becoming feasible due to recent constraints on paleo-longitudes for plate motions before the Cretaceous, much improved subsurface tomographic images, better understanding of the dynamics of true polar wander, and recent advances in mineral physics. Dramatic increases in computational capacity, as well as the development of numerical methods that efficiently model mantle flow while incorporating surface tectonics, plumes, and subduction, have emerged to facilitate further study. We now need capitalize on these advances to generate a new time-dependent Earth model that links plate tectonics with shallow and deep mantle convection, and includes such elements as deeply subducted slabs and stable LLSVPs with plumes that mostly rise from their edges on the core-mantle-boundary.

We envision a multi-disciplinary session that reflects the diversity of fields, scales, and constraints that contribute to this problem. We welcome contributions from the fields of geology, tectonics, paleomagnetism, geodynamics, seismology, and mineral physics.

Invited speakers: B. Steinberger (GFZ), A. McNamara (Arizona), S.C. Werner (PGP)