Sparse wide-angle seismic profiling supported by coincident reflection imaging has been instrumental for advancing our knowledge about rifted margins. Nevertheless, features of critical importance for understanding rifting processes have been poorly resolved. We derive a high-resolution velocity model by applying full waveform inversion to the dense OETR-2009 wide-angle seismic profile crossing the northeastern Nova Scotian margin. We then create a coincident reflection image by prestack depth migrating the multichannel seismic data. This allows for the first detailed interpretation of the structures related to the final stages of continental breakup and incipient oceanic accretion at the Eastern North America Margin. Our interpretation includes a hyperextended continental domain overlying partially serpentinized mantle, followed by a 10-km-wide domain consisting of a continental block surrounded by layered and bright reflectors indicative of magmatic extrusions. A major fault, representing the continent-ocean boundary, marks a sharp seaward transition to a 16-km-wide domain characterized by smoother basement with chaotic reflectors, where no continental materials are present and a 3-km-thick embryonic oceanic crust overlying partially serpentinized mantle is created by the breakup magmatism. Further seaward, thin oceanic crust overlies the serpentinized mantle suggesting magma-poor oceanic spreading with variable magma supply as determined from variable basement topography, 2–4 km thick volcanic layer, and magnetic anomalies. Our results demonstrate that magmatism played an important role in the lithospheric breakup of the area crossed by the OETR-2009 profile. Considering that the northeastern Nova Scotian margin has been classified as amagmatic, large margin-parallel variations in magma supply likely characterize a single rift segment.

中文翻译：

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从广角地震波形反演和反射成像对跨越新斯科舍东北部边缘的裂谷到漂移过渡的新见解

由重合反射成像支持的稀疏广角地震剖面有助于推进我们对裂谷边缘的了解。然而，对于理解裂谷过程至关重要的特征还没有得到很好的解决。我们通过将全波形反演应用于穿越新斯科舍省东北部边缘的密集 OETR-2009 广角地震剖面，推导出高分辨率速度模型。然后，我们通过叠前深度偏移多道地震数据来创建重合反射图像。这允许对与北美东部边缘大陆分裂和初期海洋增生的最后阶段相关的结构进行第一次详细解释。我们的解释包括覆盖部分蛇纹石化地幔的超扩展大陆域，随后是一个 10 公里宽的区域，由一个大陆块组成，周围环绕着层状明亮的反射体，表明岩浆挤压。代表大陆 - 海洋边界的主要断层标志着向海的急剧过渡到一个 16 公里宽的区域，其特征是基底更光滑，反射体混沌，其中不存在大陆物质，3 公里厚的洋壳胚胎部分上覆蛇纹石化地幔是由岩浆分解作用形成的。进一步向海，薄的海洋地壳覆盖在蛇纹石化的地幔上，表明岩浆贫乏的海洋扩张具有可变的岩浆供应，这取决于可变的基底地形、2-4 公里厚的火山层和磁异常。我们的结果表明，岩浆作用在 OETR-2009 剖面穿过的区域的岩石圈破裂中发挥了重要作用。