Earth and Planetary Sciences ETDs

Publication Date

Spring 5-10-2017

Abstract

Magmatic addition can lead to intraplate crustal growth through plume-generated voluminous underplating of mafic material, particularly during early syn-rift processes. In addition, magmatism facilitates crustal growth and rift development by assisting extensional tectonic forces. Therefore, understanding the relationship between magmatism and rifting may help explain both these processes. In the summer of 2015 the GeoPRISMS Eastern North American Margin (ENAM) Community Seismic Experiment collected two margin-dip active source seismic refraction profiles in eastern North Carolina and southeastern Virginia using five onshore explosive shots on a northern profile and six on a southern profile (see figure). Analysis of these data resulted in 2-D P-wave velocity models of each onshore profile that reveal a crustal thickness between 36-43 km and a high velocity (7.0-7.3 km/s) layer between 5-11 km thick at the base of the crust. We interpret this feature as representing mafic magmatic addition, likely equivalent to the high velocity lower crust layer previously observed offshore at the transition between rifted continental crust and oceanic crust. Additionally, we observe slightly elevated velocities throughout the crust, which we interpret as metamorphic alteration in the mid- and upper-crust in response to magmatic addition from below. This magmatic addition could be related to Jurassic-aged syn-rift magmatism along the ENAM and/or to the voluminous Central Atlantic Magmatic Province (CAMP), and suggests that rift-related ENAM magmatism may be more voluminous than previously thought.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Dr. Lindsay Lowe Worthington

Second Committee Member

Dr. Brandon Schmandt

Third Committee Member

Dr. Mousumi Roy

Language

English

Document Type

Thesis

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