Which term denotes sediment of biological origin, consisting of calcareous or siliceous residues?

• A. Clay
• B. Biogenous Sediment
• C. Authigenic Sediment
• D. Calcareous ooze

Answer: (B)

Biogenous sediment is the sediment formed from the remains of living organisms, specifically from materials like calcium carbonate or silica that make up shells and tests. When organisms such as foraminifera, coccolithophores, diatoms, or radiolarians die, their calcareous or siliceous remains accumulate on the ocean floor, creating this type of sediment. It includes both calcareous and siliceous components, which is why it’s the best-fitting term for sediment of biological origin made up of those residues.

Calcareous ooze is a subset of this idea, consisting only of calcium carbonate remains, so it’s narrower. Clay is largely derived from weathering and erosion of rocks (not biological). Authigenic sediment forms in place through chemical precipitation during diagenesis, not from biological shells or tests.