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High-resolution Seismic Imaging of Crustal and Upper Mantle Structures Across the Southern Eastern North American Passive Margin

Description: 

The southern portion of the Eastern North American margin (ENAM) is an archetypical volcanic passive margin formed during Mesozoic rifting. How past syn- and post-rifting deformations, along with related magmatic events, had affected the southern ENAM lithospheric structures remains an open question of fundamental importance. Seismic data from the onshore and offshore deployment in this region offer a unique opportunity to investigate these questions. In this study, we present high-resolution lithospheric velocity models across the southern ENAM based on multimodal Rayleigh wave inversion and full-wave ambient noise tomography.

Our tomographic results reveal a ~70 km-wide transitional crust at the ocean-continent boundary. Beneath this transitional crust, we identify a lower-than-average mantle anomaly, interpreted as a remnant of enriched mantle underplated during early rifting stages. Additionally, a columnar low-velocity anomaly beneath the Virginia volcanic region suggests localized lithospheric delamination and asthenospheric upwelling. Within the crust, we identify three high-velocity anomalies that likely represent solidified plutons related to the Virginia volcanoes and the Central Atlantic Magmatic Province. These findings provide new insights into the tectonic and magmatic evolution of the southern ENAM lithosphere.

Session: Earthquakes, Lithospheric Structure, and Dynamics in Stable Continental Region - I

Type: Oral

Date: 4/17/2025

Presentation Time: 08:45 AM (local time)

Presenting Author: Cong

Student Presenter: No

Invited Presentation: Yes

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Authors