Shipboard Geochemical Analysis, Leg 7, Glomar Challenger

Abstract

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.

Isotopic Composition of Interstitial Fluids and Origin of Methane in Slope Sediment of the Middle America Trench, Deep Sea Drilling Project Leg 84

“…Sediment gas and interstitial water were sampled according to standard DSDP procedures (Gealy and Dubois, 1971;Manheim, 1966). Gases were analyzed by the procedures of Claypool et al (1980) and Schoell (1980), with modifications.…”

Anoxic Diagenesis and Methane Generation in Sediments of the Blake Outer Ridge, Deep Sea Drilling Project Site 533, Leg 76

“…Sediment gas and interstitial water were sampled according to standard DSDP procedures (Gealy and Dubois, 1971;Manheim, 1966). Gas pockets visible through clear plastic core liners were tapped and gas was drawn off into an evacuated sampling tube (vacutainer).…”

Interstitial Gas Analysis of Sediment Samples from Site 368 and Hole 369A

“…Samples were taken when gas expansion pockets indicated the presence of gas in the sediment. The gas pockets were sampled by puncturing the core liner and allowing the gas to flow into evacuated glass containers (Gealy and Dubois, 1971). The procedure did not allow quantitative information of gas-to-sediment-volume, thus quantities are reported on a relative volume basis.…”