JA Daily Science Report for Expedition 309, 21 July 2005
LOCATION: Site 1256
SCIENCE UPDATE: Cores 1256D-82R to 85R were cored from 792.2 to 811.4 mbsf with the following breakdown:
Core Depth Cored(m) Rec(m) Rec(%) Date Time
82R 792.20 7.0 1.20 17.1 07/21/05 0550
83R 799.20 2.6 1.38 53.1 07/21/05 0930
84R 801.80 9.6 2.04 21.2 07/21/05 1535
85R 811.40 9.6 7.11 74.1 07/22/05 0125
Rate of penetration continues at approximately 1.3 m/hr. Cores 82R to 84R are aphyric, cryptocrystalline to fine-grained, slightly altered dark grey basalt sheet flows separated by glassy chilled margins and minor hyaloclastite. Core 85R is a massive, aphyric, fine-grained basalt unlike the cores above, which explains the excellent recovery.
Initial shipboard analyses of the borehole fluid (~65 C) taken with the WSTP, indicate that the fluid is significantly different from sea water. Instead, the borehole fluid approaches the basement fluid composition for Site 1256 estimated on Leg 206 from the projection of the basal sediment porewaters. The borehole fluids have higher Ca, Sr, Li, B, Mn, and Fe concentrations but lower Mg and K when compared to sea water.