TO: Tom Davies
FM: Trevor Williams
JA Daily Science Report for Expedition 307, 7 May 2005
LOCATION: Site U1316 (PORC-4A)
SCIENCE UPDATE: After completing downhole logging operations at Hole 1317D, we returned to Site U1316 to recover the lower part of the section by RCB coring (40.0-143.1 mbsf, 68% recovery). Core U1316C-2R contained the coral rudstone and mound-base-equivalent horizon previously seen in the first two holes at the site. Cores U1316C-3R to 11R are bioturbated calcareous green-grey siltstones.
Cores U1317C-1H to 5H were split with the saw after being frozen to approximately -50：C for 2 days. This resulted in a good preservation of the internal core structure (coral floatstone and rudstone) and a marked improvement over orthodox core splitting. Short ice expansion cracks (<1cm long) were observed in many of the cores.
Methods: After splitting, the half-cores had to be lifted into new liners because, despite the use of core patches, the liners were shattered and fragile from the freezing process. They were then placed in the walk-in freezer to equilibrate to approximately -10：C, after which the split-core surface could be cleaned by scraping. From previous experience among the science party with non-IODP cores, a saw blade with a fine diamond edge produces a cleaner cut-surface than the notched saw blade in the corelab core splitting room.