气候变化领域集成服务门户(CCPortal): Evidence for a Prolonged Continental Breakup Resulting From Slow Extension Rates at the Eastern North American Volcanic Rifted Margin

CCPortal

DOI	10.1029/2020JB020093
	Evidence for a Prolonged Continental Breakup Resulting From Slow Extension Rates at the Eastern North American Volcanic Rifted Margin
	Bécel A.; Davis J.K.; Shuck B.D.; Van Avendonk H.J.A.; Gibson J.C.
发表日期	2020
ISSN	21699313
卷号	125 期号:9
英文摘要	When continental rifting is accompanied by localized magmatism under extensional stress, the breakup duration can be short and the continent/ocean transition sharp, as mantle melts are thought to be efficient at heating and weakening the lithosphere. This mode of rifting has been invoked for the Eastern North American Margin (ENAM) based on the existing geophysical data. Here, we present results from multichannel seismic profiles from the ENAM Community Seismic Experiment offshore North Carolina, U.S. Our survey area encompasses both the East Coast Magnetic Anomaly (ECMA) and the Blake Spur Magnetic Anomaly (BSMA), which lies ~200-km farther seaward. Our prestack depth-migrated seismic images reveal major changes in the structure of the igneous crust across the BSMA. Between the ECMA and BSMA, we image a proto-oceanic domain of rough, faulted, and thin igneous crust. The roughness of this oceanic crust is similar to modern ultraslow spreading environments which involve the continued presence of a pre-existing lithospheric lid. Seaward of the BSMA the basement is smooth, and the crust is relatively thick, which is typical for Jurassic oceanic crust. Across the BSMA, we image a step up in basement and crustal root, which we interpret to represent complete lithospheric breakup and a transition to steady-state seafloor spreading in agreement with coincident refraction results. Our results would also indicate low extension rates in the final stages of rifting that may have influenced the thermal structure of the lithosphere and could explain the delay for continental breakup. All of these observations show that although continental rifting between eastern North America and northwest Africa was assisted by magmatic activity, it did not lead to rapid localization of extensional strain as previously thought. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Central Atlantic opening; continental breakup; continental margin; proto-oceanic crust; steady-state seafloor spreading; volcanic rifted margin
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187639
作者单位	Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States; Now at Drummond Carpenter, PLLC, Orlando, FL, United States; Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States
推荐引用方式 GB/T 7714	Bécel A.,Davis J.K.,Shuck B.D.,et al. Evidence for a Prolonged Continental Breakup Resulting From Slow Extension Rates at the Eastern North American Volcanic Rifted Margin[J],2020,125(9).
APA	Bécel A.,Davis J.K.,Shuck B.D.,Van Avendonk H.J.A.,&Gibson J.C..(2020).Evidence for a Prolonged Continental Breakup Resulting From Slow Extension Rates at the Eastern North American Volcanic Rifted Margin.Journal of Geophysical Research: Solid Earth,125(9).
MLA	Bécel A.,et al."Evidence for a Prolonged Continental Breakup Resulting From Slow Extension Rates at the Eastern North American Volcanic Rifted Margin".Journal of Geophysical Research: Solid Earth 125.9(2020).