Chapter 5, Problem 1TC

To determine

Whether the thickness of ooze has always been an accurate indication of the biological productivity of surface water in a given area.

Answer to Problem 1TC

The accretion of any kind of ooze depends on a subtle balance between the profusion of organisms at the ocean surface, the dissolution rate at after they reach the ocean bottom, and the rate of accumulation of terrigenous materials. Other factors that contribute to the accretion at the bottom are scouring currents and temperature, and pH conditions in the overlying water column through which the hard parts fall.

Explanation of Solution

An ooze is a deep-ocean sediment that contain at least 30% of biogenous material. Oozes originate from the remnants of organisms that settle on the bottom of the ocean floor. The organisms that contribute their remnants to the deep-ocean oozes are small, single-celled, migratory, plant-like organisms and the single-celled animals that feed on them. Once these organisms dies, their hard parts slowly settle down on the bottom, blends with fine-grained terrigenous clays and silts, and accumulate as ooze.

Oozes accumulate gradually, and the rate at which it accumulates is about 1 to 6 centimeters (1⁄2–21⁄2 inches) per thousand years. However, they accumulate more than 10 times as fast as deep-ocean terrigenous clays. Therefore, the accretion of any kind of ooze depends on a subtle balance between the copiousness of organisms at the ocean surface, the dissolution rate after they reach the ocean bottom, and the rate of accumulation of terrigenous materials. Other factors that contribute to the accumulation at the bottom are scouring currents and temperature, and pH conditions in the overlying water column through which the hard parts fall.