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.