More than 2 km of Formation MicroScanner (FMS) electrical images were acquired during Ocean Drilling Program Leg 180 at Sites 1109, 1115, and 1118 along a north-south-trending transect across the northern margin of the western Woodlark Basin. These data are analyzed to complement the shipboard core structural observations with oriented measurements.
Unambiguous fractures are identified only in the dolerite at the bottom of Hole 1109D. Strike is mainly east-west, and dip ranges from 5° to 30°.
Only few fractures are identified in the sediments of Sites 1118, 1109, and 1115, even though they were frequently observed in cores.
Bedding orientation deviates from subhorizontal only in a few intervals. These deviations are often associated with fracturing and are compatible with horizontal axis folding. This geometry suggests two possible interpretations: gravity-driven slumping and growth faulting or tectonic-driven extension associated with folding. These two processes may result in similar structural axis orientation along the east-west strike of the Moresby detachment.
Full borehole dynamic and static FMS image coverage is also provided and is related to the lithologies described in cores. Typical dynamic image facies of sandy, calcareous, and clayey formations are shown in a catalog of larger-scale images. The static image, which is directly related to resistivity, seems to be mainly controlled by carbonate content, as also suggested by conventional logs.
1Célérier, B., Louvel, V., Le Gall, B., Gardien, V., and Huchon, P., 2002. Presentation and structural analysis of FMS electrical images in the northern margin of the Woodlark Basin. In Huchon, P., Taylor, B., and Klaus, A. (Eds.), Proc. ODP, Sci. Results, 180 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/180_SR/177/177.htm>. [Cited YYYY-MM-DD]
2ISTEEM, CNRS-Université de Montpellier II, cc MSE, 34095 Montpellier Cedex 5, France. Bernard.Celerier@dstu.univ-montp2.fr
3Laboratoire de Mesures en Forage, ODP-NEB, 13545 Aix-en-Provence Cedex 4, France. Present address: 12, Impasse Jean Giono, 13830 Roquefort-La Bedoule, France.
4Institut Universitaire Européen de la Mer, CNRS UMR 6538, 29280 Plouzané, France.
5Université Lyon I, UMR 5570, 69622 Villeurbanne Cedex, France.
6Géosciences Azur, Observatoire de Villefranche, BP 48, 06235 Villefranche sur mer, France.
Initial
receipt: 19 March 2001
Acceptance: 16 May 2002
Web publication: 28 August 2002
Ms 180SR-177