| IODP Proceedings Volume contents Search | ||
 | ||
| Expedition reports Research results Supplementary material Drilling maps Expedition bibliography | ||
|
doi:10.2204/iodp.proc.319.102.2010 Cuttings-Core-Log-Seismic integrationDuring Expedition 319 we used information from cores and cuttings as well as several of the LWD, MWD, and wireline logging data sets to establish accurate ties to the 2006 Kumano 3-D seismic reflection data set (e.g., Moore et al., 2007, 2009). In addition, zero-offset VSP (check shot) results (see "Downhole measurements") were used to verify or adjust depths of the 3-D seismic reflection volume (see below). At Site C0009, wireline logging data, gamma ray data from MWD, cuttings from riser drilling, and a limited number of cores were available to define lithologic units. Three wireline logging runs were conducted: the first run with EMS-HRLA-PEX-gamma ray, the second run with FMI-Hostile Natural Gamma Ray Spectrometry Cartridge (HNGC)-Sonic Scanner-EMS-Power Positioning Device and Caliper Tool (PPC), and the third run with MDT-gamma ray (see "Logging" and this section for details). At Sites C0010 and C0011, only a limited suite of LWD/MWD data was available. The suite comprises data from the LWD geoVISION tool, measuring NGR and resistivity, and the MWD-PowerPulse, measuring direction and inclination, downhole torque, and WOB. For details regarding techniques, refer to "Logging," "Lithology," "Downhole measurements," and "Physical properties." Seismic reflection dataData acquisition along the NanTroSEIZE transect was contracted with Petroleum Geo-Services (PGS) in 2006, covering an area ~12 km × 56 km that extends from the Kumano Basin seaward to the frontal thrust in the dip direction and extends from ~4 km northeast to ~8 km southwest along strike of the NanTroSEIZE drilling transect (Moore et al., 2009). Preexpedition 3-D seismic processing consisted of three stages. In the first stage, PGS provided a 3-D stack and poststack migration to better understand the regional seismic reflection characteristics for choosing parameters for more detailed processing. During the second stage, the data set was processed through 3-D prestack time migration by Compagnie Générale de Géophysique (CGG) in Kuala Lumpur, Malaysia. Variable streamer feathering and strong seafloor multiples required several processing steps to fill and regularize all of the bins and provide quality imaging. The third stage consisted of 3-D prestack depth migration (PSDM) performed at the JAMSTEC-Institute for Research on Earth Evolution (IFREE). The 3-D PSDM clearly images details of faults and small-scale structures but lacks velocity resolution deeper than ~4500–5000 mbsf. Data resolution is ~5–7 m for near-surface sediments, ~10–20 m for the deepest sediments drilled so far in NanTroSEIZE, and ~90–125 m for the oceanic crust region. In order to acquire as accurate a cuttings-core-log-seismic correlation as possible, the depth-migrated data were converted back to time using the PSDM velocity field and then reconverted to depth using new velocity information based on the zero-offset VSP (check shot) (see "Downhole measurements" and "Downhole measurements" in the "Site C0009" chapter). In this way we minimized the potential differences in arrival times between these seismograms and those in the Kumano 3-D multichannel seismic data. Application to information from coring and loggingZero-offset VSP measurements did not cover the entire drilled and cored interval (see the "Site C0009" chapter). Hence, it was necessary to extrapolate the velocity structure below the lowest check shot data point based on velocity-depth profiles obtained from wireline sonic data (see "Downhole measurements"). Velocities from the sonic log were lower than those used for seismic processing prior to the expedition (see above and discussion in "Cuttings-Core-Log-Seismic integration" in the "Site C0009" chapter). For Site C0010, zero-offset VSP data were not available, so the regional velocity model used both the PSDM velocity field (see Moore et al., 2009, and above) and the zero-offset VSP information from Site C0004, located ~3.5 km to the east of Site C0010 (Kinoshita, Tobin, Ashi, Kimura, Lallemant, Screaton, Curewitz, Masago, Moe, and the Expedition 314/315/316 Scientists, 2009). Details regarding measures taken at the individual sites are found in the respective site chapters. Once the seismic data were refined using the relevant zero-offset VSP and sonic log data, intervals where complementary information from LWD, downhole logging, or coring was available were examined. For Expedition 319, this meant, explicitly,
|
||
