ABSTRACT

The pressure-temperature environment of the subducting slab is critical for a variety of research fields. Hence, slab thermal structure calculations are used in seismology, mineral physics, gravity, petrology, and heat flow studies. The work proposed here is a major departure from previous slab thermal structure studies because the plate and slab motion in these models will be calculated dynamically. This will enable the investigators to test the validity of one of the most critical underlying assumptions used in the majority of slab thermal structure calculations: the kinematic slab approximation. Current slab thermal structure models are not able to consider the effect of deformation within the slab. Furthermore, current models are dynamically inconsistent because the density structure of the slab does not feed back into the plate and wedge flow. With the increased resolution of seismic tomography and the ability to predict flow patterns from seismic anisotropy measurements, it appears that the resolution in the observations is reaching a point that serious reconsideration of the slab thermal structure tools is warranted. In addition, there are now much better estimates of slab rheology, both from the lab and from observational constraints, and testable models of slab density structure. In order to use these new constraints to their fullest potential, a new generation of slab thermal models is needed. With a new slab thermal modeling tool, the researchers plan to focus on two specific issues: what is the impact of slab deformation on the thermal structure of the slab; and to what extend are estimates of slab buoyancy inconsistent with the observed motion of the incoming plate and the slab itself?

The broader impact of this work will be the development of a tool for calculating a new generation of slab thermal structure models. The investigators envision that this will impact subduction zone researchers in several ways. First, they will be able to quantify a range of temperatures that bound the effect of slab deformation on thermal structure. This will give researchers temperature bounds to place on simple kinematic models. The new tool for generating slab thermal structure models will be significantly more complex and computationally intensive than current tools. However, they will also generate a set series of thermal fields for a variety of geometries approximating the major currently active subduction zones. These would be available for downloading from a website so that other researchers could work with them. In addition, they plan to make the source code for this new tool available to researchers on request and plan to create a reasonably friendly GUI front-end so that non-specialists will be able to work with it.

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