What are the different types of seafloor sediments, and what are the factors that control the distribution of each major sea sediment type? Where does each major seafloor sediment type tend to accumulate in greatest quantity (i.e., discuss the distribution of these sediments)?
To understand the different types of seafloor sediments and their distribution, you need to consider several factors such as the source of sediments, transportation mechanisms, and depositional conditions. Here are the four major types of seafloor sediments and their distributions:
1. Lithogenous Sediments: Lithogenous, or terrigenous, sediments primarily originate from the continents. They are derived from weathering and erosion of rocks on land and are transported to the ocean via rivers, wind, or glacial activity. These sediments include materials like sand, silt, and clay. The distribution of lithogenous sediments is influenced by factors such as proximity to land, strength of currents, and topography of the seafloor. They tend to accumulate near continental margins, river outflows, and areas with strong coastal currents.
2. Biogenous Sediments: Biogenous sediments are composed of the remains of marine organisms. These sediments include materials like shells, coral fragments, and microscopic planktonic organisms (such as foraminifera and diatoms) that produce calcite or silica skeletons. The distribution of biogenous sediments is primarily controlled by factors such as biological productivity, ocean currents, and depth. They tend to accumulate in areas with high productivity, such as upwelling zones, where nutrient-rich waters foster the growth of marine organisms. Biogenous sediments are most abundant in the deep-sea, especially in regions with slow sedimentation rates.
3. Hydrogenous Sediments: Hydrogenous sediments form through chemical processes in the ocean. These sediments are derived from dissolved substances that precipitate out of seawater, building up layers over time. Examples of hydrogenous sediments include manganese nodules, evaporites, and phosphorites. The distribution of hydrogenous sediments depends on factors such as water chemistry, temperature, and pressure. For instance, manganese nodules tend to accumulate on the abyssal plains of the deep-sea, while evaporite deposits form in restricted basins with high rates of evaporation.
4. Cosmogenous Sediments: Cosmogenous sediments are derived from extraterrestrial sources, such as meteorites or interplanetary dust particles. These sediments are relatively rare compared to other types. Their distribution is influenced by factors like meteorite impacts, atmospheric circulation, and ocean currents. Cosmogenous sediments can be found worldwide but are more concentrated in areas with a higher influx of extraterrestrial material, such as deep ocean basins and polar regions.
In summary, the distribution of seafloor sediments is influenced by various factors specific to each sediment type. Understanding these factors, including the source, transportation mechanisms, and depositional conditions, helps us explain the accumulation patterns of different sediment types on the seafloor.