Measurements of the extension required for crustal breakup on the magma-poor Iberia-Newfoundland conjugate margins

A kinematic reconstruction of Iberia using intracontinental strike‐slip corridors

“…For the Atlantic, between 112 and 83 Ma, we use the extensional template of Gómez‐Romeu et al. (2020), which provides extension values for FL and NAM relative to IB, in strong agreement with independently obtained values proposed by Sutra et al. (2013).…”

“…Since the strike-slip corridors do not represent in reality simple linear plate boundaries, the motion is hypothetically assumed orthogonal to rift necking lines in orthogonal settings and parallel to the corridors borders where strike slip dominates (Figure 2). For the Atlantic, between 112 and 83 Ma, we use the extensional template of Gómez-Romeu et al (2020), which provides extension values for FL and NAM relative to IB, in strong agreement with independently obtained values proposed by Sutra et al (2013).…”

Structural analysis and measured extension in fault complexes along the Lofoten‐Vesterålen margin, offshore Norway, in the context of crustal‐scale rifting towards breakup in NE Atlantic

“…However, the behaviour of the faults at larger values of heaves in the data censoring area appears to be mostly above the predicted (exponential) frequency curve, and not below as expected by the method. Thus, the misfit suggest that a power‐law frequency distribution needs to be considered (Gómez‐Romeu et al, 2020). As a result, the value of the slope (red‐line in Figure 9b,c), or the fractal dimension obtained for both the WRHFC and NURFC is approximately −0.8.…”

“…The lack in definition of a precise COB in that area is expected to potentially attenuate the measurements of crustal extension compared to the amount of extension observed in the conjugate side in Norway (e.g., Figure 7a). An increment in the magnitude of extension can be expected if the COB position is moved towards the south‐eastern part of the Foster Basin (Figure 6a) because of an increment in the location of the distal limit of contiguous continental crust (e.g., Gómez‐Romeu et al, 2020). Thus, the wider the margin, the greater the magnitude of calculated extension.…”

“…The current study also tests through a simplified version of fault population analysis whether brittle extension measured from the seismic interpretation on fault complexes along the Lofoten‐Vesterålen margin is representative to the amount of extension experienced in the rifted conjugate margin setting (e.g., Reston & McDermott, 2014). The analysis (following methodologies described in Ackermann et al, 2001; Gómez‐Romeu et al, 2020; Pickering et al, 1996; Walsh et al, 1991) determines the proportion of faults which have too small displacements to be imaged by conventional seismic reflection data. Extensional faults with larger throws (>0.2–0.5 s twt) are one of the most direct means by which continental lithosphere extends because they are readily visible on seismic data.…”