Three piston cores, 22-26 m. long were taken in a relatively undisturbed condition during 1964 in the southern Pacific Ocean in about 5,200 meters of water by the U.S.N.S. Eltanin. All were of approximately the same siliceous-ooze lithology. Shear-strength (cohesion) measurements were made at those depths in all of the cores where samples were taken for measurement of water content, texture, mineralogy, and geochemistry. Similar measurements were made on a 6-m. core of calcareous ooze from 4,000 m. of water for comparison. Statistical analysis of 13 variables of the grouped data from the long cores shows that 41.60 per cent of the variation in cohesion is accounted for by the following, in order of their relative importance as ranked in multiple regression: depth in core 20.88%), CaCO₃ content (9.0%), silt content (3.07%), water content (5.16%), sand content (1.62%), and sorting (1.87%). In the calcareous ooze, core cohesion varies only as depth (63.91%) and the ratio chlorite: illite (24.19%). All cores show a decrease in water content and an increase in cohesion with depth. The siliceous ooze shows a progressive degeneration in its matted texture with depth, which is attributed to the solution of opaline tests and an attendant growth of the following authigenic minerals, as identified by X-ray diffraction: K-feldspar (microcline, orthoclase, and anorthoclase); Na-feldspar (albite and oligoclase); quartz; amphibole; phillipsite; clinoptilolite; dahlite (?); and wilkeite(?) and montmorillonite.

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