3D Shear-wave Velocity Structure of the North American Midcontinental Lithosphere
Description:
Despite being relatively stable, the interiors of global cratons preserve evidence of structural modification on geologic timescales. The North American midcontinent is the locality of a series of rifts, basins, arches, and domes. Geologic evidence suggests that these features formed throughout the Paleozoic or earlier with limited subsequent deformation. However, the mechanism(s) that drove the uplift and subsidence of these intracratonic features is poorly understood. Linking these surface tectonic features with deep crustal and upper mantle processes is important in understanding the evolution of cratons. Here we present a new 3-D shear-wave velocity model of the crust and uppermost mantle (10-100 km) of the North American midcontinent, using full-wave ambient noise tomography. Our results show a heterogeneous crustal structure across the midcontinent, with scattered low-velocity zones in the uppermost mantle. These low-velocity zones are concentrated below major rifting structures, including the Midcontinent Rift, the central Michigan Basin, the La Salle Deformation Belt within the Illinois Basin, and the Reelfoot Rift. Except for below the Reelfoot Rift, where a localized thin crust is imaged, these low velocities are imaged below a thicker crust than the regional average. These low-velocity anomalies may reflect the remnants of magmatic underplating or frozen hydrated mantle lithosphere, formed during the early rifting stage. These materials were stagnant when the rifting stopped. Below the Michigan and Illinois Basins, the relatively deep Moho may be the consequence of subsidence in the basins. These observations suggest that rifting of the midcontinent created lithospheric weak zones, serving as the pathways for magma or other hydrothermal fluids or partial melts to rise and accumulate below the crust. The findings in this study imply strong modifications within the cratonic interior that are preserved in the present-day lithospheric structure.
Session: Earthquakes, Lithospheric Structure, and Dynamics in Stable Continental Region [Poster]
Type: Poster
Date: 4/17/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Xiaotao
Student Presenter: No
Invited Presentation:
Poster Number: 74
Authors
Xiaotao Yang Presenting Author Corresponding Author xtyang@purdue.edu Purdue University |
Andrea Stevens Goddard alsg@iu.edu Indiana University, Bloomington |
Lijun Liu ljliu@mail.iggcas.ac.cn Chinese Academy of Sciences |
Haoyu Li li4897@purdue.edu Purdue University |
Kenneth Ridgway ridge@purdue.edu Purdue University |
Stephen Marshak smarshak@illinois.edu University of Illinois Urbana-Champaign |
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3D Shear-wave Velocity Structure of the North American Midcontinental Lithosphere
Category
Earthquakes, Lithospheric Structure, and Dynamics in Stable Continental Regions