Abstract
AbstractLitMod2D integrates geophysical and petrological data sets to produce the thermal, density, and seismic velocity structure of the lithosphere and upper mantle. We present a new LitMod2D_2.0 package with improvements focused on (i) updated anelastic attenuation correction for anharmonic seismic velocities, (ii) chemical composition in the sublithospheric mantle, and (iii) incorporation of sublithospheric mantle anomalies. Sublithospheric mantle anomalies can be defined with different chemical composition, temperature, seismic velocities, and a combination of them, allowing the application of LitMod2D_2.0 to regions affected by mantle upwelling, subduction, delamination, and metasomatism. We demonstrate the potential application of LitMod2D_2.0 to such regions and the sensitivity of thermal and compositional anomalies on density and seismic velocities through synthetic models. Results show nonlinearity between the sign of thermal and seismic velocity anomalies, and that S wave velocities are more sensitive to temperature whereas P wave velocities are to composition. In a synthetic example of subduction, we show the sensitivity of sublithospheric mantle anomalies associated with the slab and the corner flow on surface observables (elevation, geoid height, and gravity anomalies). A new open‐source graphic user interface is incorporated in the new package. The output of the code is simplified by writing only the relevant physical parameters (temperature, pressure, material type, density, and seismic velocities) to allow the user using predefined post‐processing codes from a toolbox (flexure, mineral assemblages, synthetic passive seismological data, and tomography) or designing new ones. We demonstrate a post‐processing example calculating synthetic seismic tomography, Rayleigh surface‐wave dispersion curves, and P wave receiver functions from the output file of LitMod2D_2.0.
Highlights
The characterization of the present day physical state and architecture of the lithosphere and sublithospheric upper mantle is a fundamental prerequisite for understanding their evolution and underpins large‐scale exploration programs
These approaches have provided a great deal of knowledge about the physical state of the lithosphere and shallow upper mantle, significant discrepancies in the predictions from these methods are common in the literature (e.g., Afonso et al, 2008)
Since deviations with respect to the ak135 model are always negative below ~250 km, we avoid this systematic misfit by using the above reference model (35‐km thick crust and 120‐km lithosphere‐asthenosphere boundary (LAB) depth; Figure 5) to correct our predictions when calculating synthetic tomography results
Summary
The characterization of the present day physical state (pressure, temperature, and chemical composition) and architecture of the lithosphere and sublithospheric upper mantle is a fundamental prerequisite for understanding their evolution and underpins large‐scale exploration programs (cf. Afonso, Moorkamp, & Fullea, 2016; Hoggard et al, 2020). In this context, information about the density and temperature fields within the lithospheric and sublithospheric mantle typically comes from modeling of geophysical and/or geochemical data (e.g., Afonso et al, 2008; Deen et al, 2006; Fullea et al, 2007; Goes et al, 2000; Griffin et al, 1999; Lachenbruch & Morgan, 1990; Priestley & McKenzie, 2006; Ritzwoller et al, 2004; Zeyen et al, 2005). We assess the sensitivity of surface observables to sublithospheric mantle anomalies through a synthetic model of a subduction zone setting and compute Rayleigh surface‐wave dispersion curves and synthetic P wave receiver functions to show the post‐processing possibilities (Section 6)
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