Daily Report for IODP Expedition 311, October 21, 2005
LOCATION: Site U1325 (CAS-02C)
SCIENCE UPDATE: XCB coring operations in Hole U1325C continued without major interruption. One FPC pressure core was deployed at a depth of 217.6 mbsf, but it did not return with sediment under pressure. A PCS pressure core was successfully taken at a depth of 256.1 mbsf and the degassing experiment was started after X-ray scanning the core through the aluminum outer barrel. The BSR at this site was seismically predicted at a depth of ~230 mbsf. XCB coring through this interval yielded several cold spots well below the predicted BSR depth (greater than 20 m below the BSR). Extra samples for interstitial water and head-space gas analyses were taken to investigate the possibility that these cold spots may be related to gas hydrate or possibly the occurrence of free gas. The acoustic wireline logging planned for this hole will help resolve this analysis. Unlike previous Expedition 311 sites, interstitial water chloride increases with depth, reaching
constant values of ~600 mM with discrete freshening excursions that are typically associated with gas hydrate occurrence. Near midnight the DVTP tool was deployed at a depth of 275.4 mbsf to collect temperature data from a depth well below the BSR.