Figure 10. Interpretations of the depth section of profile LG12 between Sites 900 and 901. The eastern basement high is capped by a seismic transparent layer of prerift/pretilting sediments. Farther to the west, different tilted blocks are imaged. They are bound by fault structures (e.g., the listric structure L) and a detachment (H), which developed during different phases of rifting. A. H developed during the synrift I stage accommodating top-to-the-west motion, and was subsequently cut and rotated by L during the synrift II stage. Backrotation of H first during synrift I and subsequently during synrift II explains its current orientation. H terminates at the top of the basement high 500 m east of the drilled Site 900 (see also Figs. 11 and 12). Wedge-shaped sedimentary sequences are either of early synrift/prerift or of synrift II age. B. and C. Another interpretation involves H and L belonging to the same (C) or to the same family (B) of detachments, where normal faults and tilted blocks of the margin are rooted. (C) assumes the eastward-dipping part of H cutting across L at about 12 km depth by analogy to the Galicia Margin (e.g., Boillot et al., in press). D. This panel summarizes and extends interpretations of (B) and (C); to the west: deep lithospheric levels were tectonically unroofed as a result of conjugate, lithospheric shear zone activity during rifting (after Beslier et al., 1995).