Any comparison between core and FMS structural analysis results is made difficult by the very poor core recovery in Hole 1114A, the short FMS record interval, and the washout zones in the FMS data. Three fracture zones are clearly determined from FMS images analysis, whereas the distribution of fractures observed on cores shows a nearly constant density of fractures. Between FZ1 and FZ2 determined from FMS images, there is almost no core recovery, so no comparison is possible. Unfortunately, in the interval with significant shear zones evident in cores, there are no reliable FMS data because of washout zones. As for the bedding, dip is much greater below ~100 mbsf in cores, whereas there are no FMS data above. However, the FMS data analysis confirms the presence of bedding dips between ~10° and 60° as observed in cores.
Both cores and FMS data reveal the presence of highly deformed intervals with the presence of shear zones and fracture zones. Reverse faults have also been observed in both sets of data. Thus, although cores and FMS images are not directly comparable, the results of the structural analysis performed on both data are somewhat consistent. An interpretative structural log can be derived from cores and FMS analyses (Fig. F27). It summarizes the evolution of bedding dips with depth from cores and FMS measurements as well as the location of fracture zones determined from FMS images. The wide range of bedding dips observed in the logged sedimentary sequence as well as the sharp changes of bedding dip direction, associated with intense networks of steep faults, may indicate differential rotation of strata within fault-bounded compartments.
The oriented FMS images permit the determination of bed and fracture dip directions. This permits placement of the studied site in a more regional context. Fractures mainly dip north-northwestward and clearly northward in FZ2a. This may express the present north-south extension of the western Woodlark Basin. The presence of strike-slip and oblique faults observed in cores and reverse faults observed on FMS images are indicative of an oblique extensional system on Moresby Seamount that is characterized by the presence of a northeast-dipping detachment zone on its northern flank and by the presence of southwest-dipping antithetical normal faults on its southern flank.