25Pre-existing intra-basement shear zones can induce mechanical and rheological heterogeneities 26 that may influence rifting and the overall geometry of rift-related normal faults. However, the 27 extent to which physical and kinematic interaction between pre-existing shear zones and 28 younger rift faults control the growth of normal faults is less-well understood. Using 3D 29 reflection seismic data from the northern North Sea and quantitative fault analysis, we constrain 30 the 3D relationship between pre-existing basement shear zones, and the geometry, evolution, 31 and synrift depositional architecture of subsequent rift-related normal faults. We identify NE-32 SW-and N-S-striking rift faults that define a coeval Middle Jurassic -Early Cretaceous, non-33 colinear fault network. NE-SW-striking faults are parallel to underlying intra-basement shear 34 zone. The faults either tip-out above or physically merge with the underlying shear zone. For 35 faults that merges with the basement shear zone, a change from tabular to wedge-shaped 36 geometry of the hangingwall synrift strata records a transition from non-rotational to rotational 37 extension faulting, which we attribute to the time of rift fault's linkage with the shear zone, 38 following downward propagation of its lower tip. N-S-striking faults are oblique to, and offset 39 (rather than link with) intra-basement shear zones. These observations highlight the selective 40 influence pre-existing intra-basement shear zones have on evolving rift-related normal faults. 41 42 1. 45 Phillips et al. 2016). Examples of such rift basins include the North Sea rift basin (e.g., Ziegler, 46 1975; Fossen, 2010), the East Greenland rift system (e.g., Rotevatn et al., 2018), the Malawi 47 rift system (e.g., Dawson et al., 2018), the Taranaki Basin, New Zealand (e.g., Collanega et al., 48in press), the Phitsanulok Basin, Thailand (e.g., Morley et al., 2007), and the Potiguar Basin, 3 49 NE Brazil (e.g., Kirkpatrick et al., 2013). These pre-existing intra-basement shear zones not 50 only induce lithological heterogeneity, but also thermal, mechanical and/or rheological 51 heterogeneities at crustal and lithospheric scales that impact the style and duration of rifting, 52 and the final rift geometry. In the North Sea for example, these shear zones are exposed onshore 53 and are imaged in seismic reflection data offshore (e.g., Norton, 1987; Fossen, 1992; Reeve et 54 al., 2013; Phillips et al., 2016; Fazlikhani et al., 2017; Lenhart et al., 2019). Although the 55 recognition and description of intra-basement shear zones in the field may be relatively 56 straightforward, seismic imaging of intra-basement shear zones in subsurface datasets (e.g., 2D 57 and 3D seismic) can be limited by a combination of factors (Phillips et al., 2016). For example, 58 seismic data may not image to the relatively deep depths at which crystalline basement occurs; 59 even when the seismic record length is sufficient, decreasing seismic resolution with depth due 60 to frequency attenuation may n...
