Table 1

Concentrations, isotope ratios, and ages of pore waters. Concentrations have 1σ uncertainties of 3.3% (Cl), 2.3% (Br), and 0.48% (I). Sed. age, depositional age of sediments containing hydrates; fluid age, sediment age corrected for expulsion of pore waters because of compaction; min. age, age based on decay of initial ratio of 129I/I = 1500 × 10−15; corr. age, age corrected for in situ buildup of 129I in deep sediments.

SampleDepth (mbsf)Cl(mM)Br (mM)I (mM)U (ppm)129I/I (× 10−15)Sed. age (Ma)Fluid age (Ma)Min. age (Ma)Corr. age (Ma)
997A35X275.24712.591.192.7220  ±  601.84.6543.6  ±  7.348.8
997A46X367.155002.911.493.44155  ±  202.65.9851.6  ±  3.358.2
997A52X411.254912.971.533.31181  ±  322.956.5848.1  ±  4.653.3
997B14X493.565153.231.722.69127  ±  543.637.6856.1  ±  12.863.3
997B24X572.255193.131.702.67125  ±  194.359.7656.5  ±  3.963.8
997B33X642.725163.051.632.15142  ±  295.019.6853.6  ±  5.460.1
997B39X687.655143.041.662.43214  ±  325.4610.344.3  ±  3.848.0