Sand-box modelling of basement-controlled transfer zones in extensional domains

The interaction modalities of transfer zones connecting rift segments may b e influenced by several factors. Amongst these, the location and architectu re of transfer zones in narrow rifts has been repeatedly associated with th e presence of inherited basement anisotropies. Sand-box models were made to investigate how the orientation, geometry and kinematics of transfer zones depend upon pre-existing basement anisotropies. Analogue models reproduced offset rift segments linked by transfer zones bordered by arcuate normal f aults. Strike-slip faults are present inside the transfer zone, provided th at angle alpha (between the extension direction and the axis of the transfe r zone) is less than 50 degrees. Narrower transfer zones, striking oblique to the extension direction, occur for angle phi (between the direction perp endicular to the extension direction and the direction of the basement anis otropy) less than 90 degrees; wider transfer zones, subparallel to the exte nsional direction, occur for phi > 90 degrees. Increasing the overstep indu ces narrower transfer zones striking subparallel to the extension direction . Similar geometrical and kinematical patterns have been found at transfer zones in narrow rifts. The comparison between experimental and natural data shows how the geometry, kinematics and orientation of natural transfer zon es depends upon the trend of inherited anisotropies: transfer zones along i nherited basement structures set at lower angles to the extension direction , and display lower aspect ratios, than transfer zones where inherited anis otropies are absent.