Seismic Evidence of Crustal Modifications Below the North American Midcontinent
Description:
Despite being relatively stable, the interiors of global cratons preserve clear evidence of modification on geologic timescales. The North American craton is the locality of a series of rifts, basins, arches, and domes, varying in size and orientation. 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 upper crustal features with deep crustal and upper mantle processes is an important step in understanding the evolution of “stable” cratons including the timing, rate, and style of cratonic modification. Here we present new results using a 3-D shear-wave velocity model from full-wave ambient noise tomography to identify compositional and structural modifications in the crust across the North American midcontinent. Our results show a heterogeneous crustal structure below major surface tectonic features, suggesting strong crustal modifications related to the formation and evolution of these surface deformations. For example, the late Mesoproterozoic Midcontinent Rift is underlain by a confined low-velocity zone along strike in the upper crust, broadening at greater depths. There is a crustal low-velocity layer across most of the study area. This low-velocity layer is shallower below basins than other regions, varying from 15-20 km deep below the Illinois and Michigan Basins (Neoproterozoic - Paleozoic) to 25-30 km in other regions. The doming of this crustal low-velocity layer below the basins may be the consequence of crustal uplift before the basin subsidence. We will discuss the implications of the velocity structure for the origin and evolution of intracratonic deformation, combining other geological and geophysical constraints.
Session: Tectonics and Seismicity of Stable Continental Interiors - II
Type: Oral
Date: 5/3/2024
Presentation Time: 11:00 AM (local time)
Presenting Author: Xiaotao
Student Presenter: No
Invited Presentation:
Authors
Xiaotao Yang Presenting Author Corresponding Author xtyang@purdue.edu Purdue University |
Andrea Stevens Goddard alsg@iu.edu Indiana University |
Lijun Liu ljliu@illinois.edu University of Illinois Urbana-Champaign |
Kenneth Ridgway ridge@purdue.edu Purdue University |
Douglas Schmitt schmitt@purdue.edu Purdue University |
Haoyu Li li4897@purdue.edu Purdue University |
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Seismic Evidence of Crustal Modifications Below the North American Midcontinent
Category
Tectonics and Seismicity of Stable Continental Interiors