Rigidity of the Atlantic oceanic lithosphere beneath New England seamounts

Investigation of the flexural response of the oceanic plate subject to loading of New England seamounts provides an insight into the rigidity of the lithosphere. Fourier domain analysis of the bathymetry and gravity anomalies over New England seamounts suggests that internal density perturbations exist in the crust and/or uppermost mantle. The loads due to the topography of the seamounts and density perturbations must have been supported by the lithosphere. We group the seamounts into three representative ages and adopt a 3-D thin elastic plate model over an invicid mantle to assess the rigidity of the lithosphere under these loads. The rigidity values are about 3–7×10 23 N m for lithospheric ages ranging from 30 to 60 my. The base of the elastic part of the lithosphere follows an isotherm in the range of 750–850 °C, suggesting a strong lithosphere that makes the north Atlantic Ocean difficult to initiate subduction. However, the thermal blanketing by the thick sediments at Scotian basin reduces the rigidity by one to two orders of magnitude, and may facilitate initiation of subduction of the north Atlantic oceanic lithosphere at Scotian margin.