JA Daily Science Report for Expedition 308, 10 June 2005
LOCATION: Site U1320
SCIENCE UPDATE: The lithologies between Core U1320A-11X and Core U1320A-15X consist of mud mixed with meter-scaled intervals of sandy turbidites. The lithologies become progressively finer-grained downhole, mainly consisting of mud with minor intercalations of silt from Core U1320A-15X to Core U1320A-17X (193 mbsf), and then dominated by clays and mud below 193 mbsf. The coarsening-upward sequence in Hole U1320A is interpreted as an increase in the frequency of sandy turbidites through time and is tentatively linked to periods of lower sea-level. Downhole logging of Hole U1320A was undertaken with 3 tool strings: the triple combo, FMS-sonic, and well seismic tool (WST). All tools reached the bottom of the hole, and the logs obtained were good. A contact between the turbidite fan sediments and the stiffer hemipelagic mud unit was clearly identified at 174 mbsf. Logs in the shallower part of the section (turbidite fan) show alternations between sand and mud, whereas the trends are monotonous in the hemipelagic mud unit. This confirms sedimentologic observations and seismic interpretations. Well seismic measurements were undertaken, but in accordance to the IODP Marine Mammal Safety protocols, these operations were interrupted when a bottle nosed dolphin was spotted. After no more marine mammal sightings were reported for 45 minutes, the soft start protocol was started again and 12 WST stations were completed without further incidents.