ABSTRACT

Sediments of the sea floor of the Canada Basin and Alpha Rise, about 500 miles north of Point Barrow, Alaska, were cored to a depth of about 3 meters below the sea-sediment interface beneath Ice Island T-3 where the ocean depth varies from 3500 to 3700 meters at different locations. The sediments are lutites of average grain-size composition, 28 percent sand, 31 percent silt, and 41 percent clay. The sediments are either gray or brownish gray, the brown coloration being due in part to the oxidation of ferrus sulfide. Colloidal organic matter amounts to about 3 percent of the whole sediment. The clay fraction of the sediments consists of approximately 60 percent mica (muscovite and illite, with possibly a little biotite), 20 percent chlorite (11b polytype, and chamositic chlorite), 10 ercent mixed-layer (mica-chlorite- vermiculite), and 10 percent non-clay minerals (quartz, 1-5 percent; feldspar, <1 percent; dolomite, <5 percent). The composition of the clay is similar in all 65 samples examined, but some of the thinly bedded sediments contain a large percentage of amorphous clay. Quartz, feldspar, and clay minerals are detrital, but diagenesis has modified and increased the mixed-layering of micas, and apparently has caused the development of chlorite and vermiculite. Dolomite (mostly concentrated in the silt fraction) may be authigenic, but it could be detrital and derived from the glaciation of dolomites. The clay has been slowly deposited from mixed airborne and water (and ice) transported material in tee closed basin of the Arctic Ocean.