Results from Lithosphere Imaging of the Southern Oklahoma Aulacogen Using Magnetotellurics

Abstract:

The EarthScope continent wide seismic and magnetotelluric (MT) experiments revealed many unexpected geophysical anomalies in the USA interior, often associated with large paleo-tectonic features. These discoveries have advanced our understanding of the North American tectonic evolution, seismic hazards, and processes related to tectonic reactivation. The Southern Oklahoma Aulacogen (SOA) is one such tectonic features. The SOA is a Cambrian failed rift associated with Rodinian disassembly, which underwent later structural inversion during the Pennsylvanian Ancestral Rocky Mountain (ARM) orogeny. The SOA is perhaps the ideal feature to study the tectonic episodes which shaped North America given it is readily accessible and has been spared subsequent tectonic activity and deep burial. However, the lithospheric structure of the SOA is poorly constrained below the upper crust, and there is a critical lack of deeper imaging datasets. From winter 2018 to spring 2019 13 long period MT stations were collected across the SOA with the goal to image the entire lithospheric column. The objective is to investigate how initial rifting and ARM inversion modified the lithosphere in the region. Additionally, this project seeks to understand how modification by the initial rifting may have influenced the localization of ARM deformation. We expect the results from the MT data currently undergoing processing and inversion will help to answer these questions.