近日，英国南安普顿大学Derek Keir团队研究了阿巴拉契亚北部拉布拉多海裂谷成因及相关地震异常。这一研究成果发表在2025年7月29日出版的《地质学》杂志上。

北阿巴拉契亚异常（NAA）是新英格兰（美国东北部）软流圈下一个突出的低地震速度带，直径约400公里。先前的研究将这种发生在约200公里深度的浅层特征解释为与沿北美大陆边缘驱动的对流有关的热异常。然而，这些研究认识到，鉴于被动边缘在构造上静止了约180万年，这里的上升流是非常不寻常的。

研究组提出了一种基于地质观测、大地构造重建和地球动力学模拟的替代模型，该模型认为，异常实际上代表了与遥远的拉布拉多海大陆边缘裂解相关的瑞利-泰勒不稳定性。若拉布拉多海在约8500万至8000万年前发生裂解，则意味着瑞利-泰勒不稳定性链以约22公里/百万年的速度迁移，这一速度接近地球动力学模型的预期值。异常起源于迁移不稳定性，这一观点能够解释其空间特征、深度剖面以及靠近长期不活跃大陆边缘的位置。

由此推论，作为北美异常（NAA）镜像的格陵兰中北部异常也可能起源于裂解时期。此外，如果中央阿巴拉契亚异常代表的是与拉布拉多海裂谷作用开始相关的早期不稳定性，那么它也可能符合这一模型。NAA和其他相关异常切实反映了遥远的拉布拉多海边缘大陆裂谷作用和裂解的遗迹。

附：英文原文

Title: A viable Labrador Sea rifting origin of the Northern Appalachian and related seismic anomalies

Author: Thomas M. Gernon, Sascha Brune, Thea K. Hincks, Derek Keir

Issue&Volume: 2025-07-29

Abstract: The Northern Appalachian Anomaly (NAA) is a prominent low-seismic-velocity zone, ～400 km in diameter, in the asthenosphere beneath New England (northeastern USA). Previous studies interpreted this shallow feature, occurring at a depth of ～200 km, as a thermal anomaly tied to edge-driven convection along the North American continental margins. Those studies recognized, however, that upwelling here is highly unusual given that the passive margin has been tectonically quiescent for ～180 m.y. We propose an alternative model, based on geologic observations, geotectonic reconstructions, and geodynamic simulations, that the anomaly instead represents a Rayleigh-Taylor instability linked to the breakup of the distant Labrador Sea continental margin. A Labrador Sea origin at breakup, ca. 8580 Ma, would imply the migration of a chain of Rayleigh-Taylor instabilities at a rate of ～22 km/m.y., close to expected rates from geodynamic models. A migrating-instability origin for the anomaly can reconcile its spatial characteristics, depth profile, and position near a long-inactive continental margin. A corollary is that the north-central Greenland anomaly, a mirror-image of the NAA, also potentially originated at the time of breakup. Further, The Central Appalachian Anomaly may fit this model if it represents an early-stage instability linked to rifting onset in the Labrador Sea. The NAA and other associated anomalies viably represent a legacy of continental rifting and breakup along the distant Labrador Sea margins.

DOI: 10.1130/G53588.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G53588.1/659899/A-viable-Labrador-Sea-rifting-origin-of-the