Daily Report for IODP Expedition 311, September 29, 2005
LOCATION: Site U1329 (CAS-05D)
SCIENCE UPDATE: After coring Hole U1329C to a depth of 188.5 mbsf (106% recovery), the PCS cutting shoe was lost in the hole during the third deployment of the PCS (Core U1329C-23P). It was determined that it was not possible to advance the hole beyond 189.5 mbsf. We also decided that the hole was not deep enough to wireline log, which is now scheduled for a dedicated logging hole (i.e., U1329D). At the same time weather conditions degraded to the point that it was determined to be unsafe to conduct further coring operations. After some improvement in the weather, we pulled out of Hole U1329C to drill Hole U1329D as a dedicated logging hole. At 19:55 hr, after advancing Hole U1329D to 165.6 mbsf, the ship’s heave increased enough that we needed to suspend operations again (>6 m heave). With improving conditions we returned to drilling Hole U1329D, which had been advanced to a depth of 180 mbsf by midnight (target total hole depth is 220 mbsf). We also are scheduled to drill a spot coring and pressure-coring hole at Site U1329 with interspersed temperature measurements using the APCT and DVTP probes. Cores U1329C-1H through 16H Pleistocene gray and dark greenish gray clay. Core U1329C-17H marks an abrupt change to late Miocene age sediments. Initial interstitial water analyses suggests a very uniform pore-water salinity profile with depth, averaging about 31.5 ppt, with some evidence of additional “freshening” near the bottom of U1329C. The chemistry of headspace and void gases also appear to be generally uniform in Hole U1329C, with a slight increase in ethane and propane concentrations in Core U1329C-22X (C1/C2=3980).