Crustal Thickness Variations in the Central Midcontinent, USA, and Their Tectonic Implications: New Constraints Obtained Using the H‐κ‐c Method

Abstract

Abstract The central midcontinent of the USA's cratonic platform is a region of low elevation and relief underlain by tectonic basins, domes, faults, and monoclines. To investigate potential correlations among shallow crustal structure and crustal thickness, we produced a high‐resolution Moho‐depth map of the region by applying the recently developed H‐κ‐c receiver‐function method to data from EarthScope Transportable‐Array and Flexible‐Array stations. Results indicate that Moho depth varies from 38 to 57 km. Changes of Moho depth and of Vp/Vs ratios do not correlate with Precambrian tectonic boundaries, suggesting that they reflect post‐accretion tectonics. Deeper Moho underlies sedimentary basins, implying a relationship between crustal thickness and lithospheric subsidence. Thicker crust may be due to rift‐related underplating, and thinner crust may have undergone delamination. Some depth changes underlie known faults and fold zones. Since short‐wavelength undulations were detected only under high‐density seismic arrays, they may occur more widely but have yet to be resolved.

Keywords

• midcontinent
• Moho
• receiver function
• Earthscope
• OIINK