New improvements on LitMod2D package: A tool for integrated geophysical-petrological modelling of the lithosphere and upper mantle

LitMod2D is an integrated geophysical-petrological forward modelling tool developed ten years ago at ICTJA-CSIC to study the thermal, compositional, density and seismological structure of lithosphere and sublithospheric mantle. LitMod2D integrates data from petrology, mineral physics and geophysical observables in a self-consistent framework. We present improvements on the different modules of the current version of the LitMod2D package focused on, the graphic user interface (GUI), the average composition of the upper mantle, and the incorporation of sublithospheric anomalies in terms of composition, temperature and seismic velocities. A new GUI has been developed in Python programming language to gain versatility and compatibility with different platforms. We tested several changes in the sublithospheric mantle composition (DMM vs. PUM) and in the attenuation parameters (grain size and frequency dependence) to fit the calculated seismic velocities with those from the ak135 global reference model. None of these changes produces significant variations in the calculated velocity values below 200 km depth, and hence, the calculated synthetic tomography from LitMod2D shows a redshift below this depth. The most exciting improvement is the possibility to incorporate sublithospheric mantle anomalies with different chemical compositions, and either anomalous velocities (Vp or Vs) or temperatures, observed in independent studies for each target region. To this end, we increased the range of temperatures up to 2200 ºC in calculating the mineral assemblages, and anelasticity is incorporated in calculating the bulk rock seismic velocities and their partial derivatives, such that we can translate temperature anomalies into seismic velocities and vice-versa. Additionally, this new tool allows computing coupled-uncoupled elevation to estimate the effects of sublithospheric mantle anomalies on topography giving an upper bound for dynamic topography under isostatic equilibrium. This is a SUBITOP (674899-SUBITOP-H2020-MSCA-ITN-2015) contribution.