Calcium carbonate, organic carbon, and quartz in hemipelagic sediments off Oregon : a preliminary investigation

Graduation date: 1970An analysis of the amounts of calcium carbonate, organic carbon,\ud quartz, and the rates of sediment accumulation in hemipelagic sediments\ud off Oregon has revealed that the accumulation rates of the total\ud sediment, organic carbon, and quartz were at least twice as high in\ud the late Pleistocene as they were during the Holocene. The accumulation rate of calcium carbonate was at least 8 times as high. There\ud may have been a short transition period at the end of the last glacial\ud stage from about 14,000 to 12,500 years B.P. when the sedimentation\ud rate was very high up to 75 cm/l000 years.\ud There is evidence that the amount of organic carbon in deep-sea\ud sediments is a function of terrigenous influx, of preservation, and\ud possibly of depth of burial in the sediment. Turbidite sequences in\ud the deep-sea environment off Oregon contain much higher amounts of\ud organic carbon in the upper fine-grained portion of the sequence than in the coarser basal sediment of the sequence, indicating that organic\ud carbon is concentrated in the finer and slower settling parts of the\ud flow. In lower continental slope sediments, the greatest amounts of\ud organic carbon are found in the