RESULTS

Water content values obtained from incremental oven drying to 60ºC compare favorably with those obtained from drying at a constant temperature of 60ºC (Fig. 1). This suggests that incremental drying produces results that are similar to those obtained from typical constant temperature drying techniques. Approximately 80% of the water content and porosity values calculated during this study are similar to at-sea determined values (Fig. 2, Fig. 3) indicating that most samples did not lose water during storage. The progressive increase in drying temperature continually reduced the amount of water left in the sample, thereby increasing the calculated water content and resultant porosity values. However, each increase in temperature produced a relatively small change in water content. The average porosity increase with temperature change from air drying at 23ºC to oven drying at 10ºC increments to 120ºC ranged from 0.95 to 3.31 points (1.7% to 7.1%) (Table 1; Fig. 2, Fig. 3).

All sediment samples graded as clayey silt according to the shore-based technique (Table 1), whereas semiquantitative shipboard analysis typically described the sediment as nannofossil-rich silty clay or predominantly clay sized. The relatively small amount of smectite (8% to 17% of total sample mass; Table 1) occurring in only four of the samples (Hole 995A) may explain why small changes in porosities were observed with large temperature changes. However, the magnitude of porosity change is not directly related to the amount of smectite present. The northern Barbados accretionary wedge sediments studied by Brown and Ransom (1996) possessed considerably more smectite than the samples collected from the Blake Ridge on this Ocean Drilling Program (ODP) leg.

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