Sediments collected on Leg 7 were sampled for geochemical analysis at sea. Some samples were analyzed for pH, Eh and salinity at sea; the remainder were delivered to shore-based laboratories for further work. This report summarizes the sampling and handling procedures used at sea and presents the results of the shipboard analyses. Handling procedures used were still in the development stage, and results should be used with caution. Results of shore-based geochemical analyses are presented elsewhere in this report. SAMPLING PROCEDURESGenerally, samples for geochemical analysis were taken after the core had been split, and most sections were split after they had been standing at room temperature for many (8 or more) hours. Sections 1,3,4 and 5 of most cores taken from Hole 62.1 were stored at 4°C many days before they were processed. In a few cases, prior to splitting the core, the core liner was drilled and a needle inserted. A sample of interstitial gases were obtained in one or more vacuum containers. The containers were sealed and stored under refrigeration. As soon as possible after the sections were split, generally within 5 minutes, three or four 25 to 30-cubic centimeter samples for major elements, carbon dioxide, C-isotope and shipboard analyses were collected at 20 meter intervals at each site. One sample was stored, unsqueezed, for shore analysis. The remainder were squeezed as soon after sampling as possible. Four 25 to 30-cubic centimeter additional samples were collected for carbon dioxide and C-isotope analysis. All samples were sealed in glass bottles with polyseal caps and stored under refrigeration. Two samples (and, where carbon dioxide and C-isotope samples were collected, three samples) of 25 to 30 cubic centimeters of sediment were combined and squeezed to provide interstitial solutions (about 5 cubic centimeters) for analysis for major dissolved chemical species [O^/O^, H/D] and shipboard analysis (about 2.5 cubic centimeters). The squeezed solutions and residue were stored at 4°C.
The velocity of the compressional wave was measured with a shipboard velocimeter at three intervals along whole core sections 1.5 meters long for almost all sections of nonindurated and semi-indurated sediments recovered on Leg 7 of the D/V Glomar Challenger in the Western Equatorial Pacific. In addition, the compressional wave velocity was measured on selected samples of indurated materials with a velocimeter at the University of Hawaii. Disturbance by the coring process renders measurements on some core sections as unrepresentative of in situ conditions, but other measurements appear to approach the compressional wave velocity of in situ materials closely.Measurements of compressional wave velocity, measurements of saturated bulk density and porosity reported in Chapter 25, and estimates of bulk modulus are used to compute impedance, rigidity, Lame's constant, Poisson's ratio, and the velocity of the shear wave for almost all core sections recovered on Leg 7.Holes at Sites 62, 63 and 64 penetrated sequences of nannofossil ooze, chalk and limestone as deep as 960 meters beneath the sea floor, and range in age from Eocene to Recent.The calcareous ooze-chalk sequences at these sites show an irregular exponential increase in compressional wave velocities with depth. The rates of increase at a given depth are greatest at Site 63 and least at Site 64. Compressional wave velocities at all three sites are about 1.45 to 1.50 km/sec at the surface. At 500 meters the compressional wave velocity is about 1.7 km/sec at Site 64, 2.1 km/sec at Site 62, and 2.3 km/sec at Site 63. A silicified limestone from 950 meters at Site 64 had a compressional wave velocity of 4.5 km/sec.Shear wave velocities at these sites also increase with depth, but the rate of increase decreases with depth. Shear wave velocities at Site 64 are lower throughout than those at Sites 62 and 63.Insufficient reliable data were collected on this leg to determine velocity gradients in either radiolarian ooze or pelagic clay.The upper 20 to 30 meters of the calcareous ooze at Sites 62, 63 and 64 has a compressional wave velocity less than in seawater. Near surface sediments at Sites 65 and 66 also have compressional wave velocities less than that in seawater. Thus, a low velocity channel exists in these upper sediments.The velocity at the compressional wave decreases as the fraction clay size increases where other parameters are the 1105 same. Cementation at Sites 62, 63 and 64 tends to obliterate this relationship.
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