Publication Date:
2022-10-26
Description:
Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 125(12),(2020): e2020JB020040, https://doi.org/10.1029/2020JB020040.
Description:
We model the magnetic signature of rift‐related volcanism to understand the distribution and volume of magmatic activity that occurred during the breakup of Pangaea and early Atlantic opening at the Eastern North American Margin (ENAM). Along‐strike variations in the amplitude and character of the prominent East Coast Magnetic Anomaly (ECMA) suggest that the emplacement of the volcanic layers producing this anomaly similarly varied along the margin. We use three‐dimensional magnetic forward modeling constrained by seismic interpretations to identify along‐margin variations in volcanic thickness and width that can explain the observed amplitude and character of the ECMA. Our model results suggest that the ECMA is produced by a combination of both first‐order (~600–1,000 km) and second‐order (~50–100 km) magmatic segmentation. The first‐order magmatic segmentation could have resulted from preexisting variations in crustal thickness and rheology developed during the tectonic amalgamation of Pangaea. The second‐order magmatic segmentation developed during continental breakup and likely influenced the segmentation and transform fault spacing of the initial, and modern, Mid‐Atlantic Ridge. These variations in magmatism show how extension and thermal weakening was distributed at the ENAM during continental breakup and how this breakup magmatism was related to both previous and subsequent Wilson cycle stages.
Description:
Thanks to Anne Bécel, Dan Lizarralde, Collin Brandl, Brandon Shuck, and Mark Everett for beneficial discussion and assistance in compiling the archived data used in this study. We thank Debbie Hutchinson (USGS Woods Hole Coastal and Marine Science Center) for passing along her vast breadth of knowledge on the ENAM through numerous constructive suggestions to greatly strengthen our manuscript. We greatly appreciate the insightful comments from two reviewers, the Associate Editor, and the Editor that significantly improved the manuscript. Thanks to Maurice Tivey for providing codes that aided our magnetic modeling efforts. Project completed as part of J.A.G.'s Ph.D. dissertation at Texas A&M University.
Description:
2021-05-16
Keywords:
ENAM
;
Rifted margin
;
Breakup magmatism
;
Magnetic modeling
;
Continental breakup
;
Atlantic Ocean
Repository Name:
Woods Hole Open Access Server
Type:
Article
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