About 286 m of Pliocene-Pleistocene sediments separated from the metadolerite basement by a 6-m-thick tectonic breccia were drilled in Hole 1114A (Fig. F3). Seven lithologic units were identified within the rift-related, mostly volcaniclastic turbidite sediments (see fig. F1 in Shipboard Scientific Party, 1999c).
Despite the very poor core recovery at Site 1114, structural analysis on cores from the sedimentary section reveals different features of the deformation (Shipboard Scientific Party, 1999c). Deformation is characterized by highly inclined bedding, the presence of faults, and scaly fabrics that increase with depth (Fig. F3).
Bedding measurements show a wide range of dips, from horizontal to 80°, with a majority of dips at 15°. Even if some of the inclined strata may be linked to early soft-sediment deformation, their consistent development throughout the recovered section favors their tectonic origin deformation (Shipboard Scientific Party, 1999c). The increase of the bedding dips with depth is mainly marked from ~110 m deep downward, at the top of the FMS data interval.
Fractures are present all along the cored interval (Fig. F3). Dips range from 0° to 90°, with an average of 30°-40°. Most are dip-slip faults (normal and locally reverse), but oblique and strike-slip faults are also present in the sedimentary section. One of the most characteristic features of the sediments from 64.6 meters below seafloor (mbsf) downward is the presence of scaly fabrics involving fine-grained clay-rich material of various thicknesses. The intensity of fabric development increases with depth. Their origin maybe tectonic or coring induced, but they were interpreted to result mainly from tectonic deformation (Shipboard Scientific Party, 1999c).
However, this core analysis is limited by the poor recovery (~12%) and by the fact that the dip direction of the observed bedding and faults cannot be determined because the cores are not oriented.