A short note on the pressure-depth conversion for geophysical interpretation

Databases of material properties based on mineral physics are rapidly becoming an essential tool for interpreting geophysical observations. The conversion of physical properties from pressure to depth is usually based on preliminary reference Earth model. We quantify the error that is introduced with this assumption. The corrected pressure profile is obtained by updating the starting one with the inferred density distribution and iterating until convergence (which is attained in few steps). We show two examples. The first is related to the interpretation of average seismic Earth models. The second refers to the interpretation of a 2-D thermal structure of the oceanic lithosphere as predicted by a half-space cooling model. The effects are overall small, nevertheless important for interpretation since they are systematic, they have a feedback with thermal interpretation and they can shift the location of predicted mineralogical phase transitions that are associated with abrupt density and seismic velocity jumps. For example, variations up to 0.6 GPa at 2500 km depth are obtained by changing the potential mantle temperature of 100 K. © 2013. American Geophysical Union. All Rights Reserved.