Based on principal organisms the calcareous oozes are further divided into:

Question

Accepted Answer

Based on principal organisms, calcareous oozes are further divided into **Pteropod and Globigerina ooze**.

Here's why Option 3 is correct and the others are incorrect:

*   **Option 3: Pteropod and Globigerina ooze (Correct)** Calcareous oozes are primarily composed of calcium carbonate (CaCO3). The two main types of organisms that contribute significantly to this type of ooze are foraminifera (specifically, *Globigerina* is a very common genus) and pteropods. *Globigerina* are planktonic foraminifera with shells made of calcium carbonate. Pteropods are small, swimming sea snails, also with calcium carbonate shells. Therefore, a classification based on the dominant organisms would logically separate calcareous oozes into those dominated by *Globigerina* and those dominated by pteropods, or a mixture of both.

*   **Option 1: Red clay and Globigerina ooze (Incorrect)** Red clay is a type of deep-sea sediment that is *not* calcareous. It's primarily composed of fine-grained clay minerals and is found in areas where the accumulation of biogenic material (like calcareous or siliceous shells) is very slow. While *Globigerina* ooze *is* calcareous, red clay is a distinct sediment type, and the two are not subdivisions of calcareous ooze based on principal organisms.

*   **Option 2: Diatom and Radiolarian ooze (Incorrect)** Diatoms and radiolarians are organisms with shells made of silica (SiO2), not calcium carbonate. Oozes formed from their remains are classified as *siliceous* oozes, not calcareous oozes. Therefore, they cannot be subdivisions of calcareous ooze.

*   **Option 4: Pteropod and Radiolarian ooze (Incorrect)** While pteropods *do* contribute to calcareous oozes, radiolarians contribute to *siliceous* oozes. A classification of calcareous oozes would not include radiolarians as a principal organism.