Biogenous ooze

Biogenous ooze is marine sediment that accumulates on the seafloor and is a byproduct of the death and sink of the skeletal remains of marine organisms. Biogenous ooze consists of organic compounds, usually in the form of microorganism tests that fall from closer to the ocean surface to the ocean floor after death. For marine sediment to receive this classification, it must be composed of more than 30% skeletal material which also includes teeth and shells. The two primary types of ooze are siliceous, which is composed primarily of silica (), and calcareous or carbonate, which is mostly calcium carbonate (). In an area in which biogenous is the dominant sediment type, the composition of microorganisms in that location determines to which category it is classified. The primary types of microorganisms used to classify ooze are radiolarians and diatoms (siliceous), and coccolithophores and foraminifera (calcareous). The presence of these organisms can lead to sub-classifications based upon their dominance. Along some areas of terrigenous sediment are siliceous ooze. This is due to siliceous ooze being more abundant in areas of cooler, more nutrient rich water. The nutrients allow for the abundant growth of microorganisms, and silica dissolves slower in cooler water, allowing adequate time for deposition. Radiolarians and diatoms are the primary plankton used to classify siliceous ooze. Radiolaria is a part of a diverse group of plankton with transparent skeletons and come in a variety of shapes. They range in size from . They are most abundant in regions near the equator as well as subpolar regions. Diatoms are single-celled siliceous algae that are a major part of phytoplankton. They come in pinnate and centric shapes and range in size from . Siliceous oozes lean towards dissolution in warmer waters with lower pressures, meaning they are best preserved in deep ocean. Calcareous sediments are more common in the deep ocean, comprising about half of its surface area. However, the deepest parts of the ocean are dominated by abyssal clay instead.