Seafloor Sediments, Essay Example

There are three min types of ocean sediments, each distinguished from the other by the process of formation, mass composition distribution on the seafloor.

Terrigeneous Sediments

These are sediments which originate from soil and rock material eroded from land, due to physical and chemical weathering processes (Lesitsyn and Kennett 27). The weathered rock material is then eroded and transported by wind and water (rivers) to the ocean. River water deposit rock and soil sediments near sea mouth regions such as deltas, estuaries and bays. Consequently, these sediments tend to accumulate along the continental margins (shoreline). Terrigeneous rock material makes about 75% of ocean sediments, with concentrated accumulations piling up to 10km along continental rises. However, some sediments of this type accumulate in the deep sea due to the action of wind and ocean currents. An example of terrigeneous sediments is ‘red clay,’ a fine-grained and reddish-brown sediment in the deep ocean, sometimes referred to as pelagic sediment.

Biogenic Sediments

These are particles derived from marine organisms such as clams and corals found in the shallow and warm sea water. In addition, microscopic shells of single-celled animals and plants decompose into biogenic sediments, which eventually settle and accumulate in the deep ocean (Bridge and Demicco 85). Biogeneous sediments of this type consist of shells rich in silicon and calcium, mainly derived from algae and protozoans. Nonetheless, only about 30% of biogenic sediments originate from plant/animal remains, while the rest is non-biogenic (i.e. terrigeneous material-mud).

Hydrogenous Sediments

Hydrogenous sediments form as a result of sea water precipitation on the ocean floor. Sea water contains minerals such manganese, which precipitate to form manganese nodules (Hurst 2010) as a result of chemical reactions. Similarly, dissolved salt ions, e.g. Sodium chloride may precipitate as a result of sea water evaporation, and form hydrogenous sediments such as halite and gypsum- from Calcium sulfates.

Works Cited

Bridge, J., and Demicco, Robert. “Biogenic and Chemogenic Sediment Production.” Earth surface processes, landforms and sediment deposits. London: Cambridge University Press, 2008.

Hurst, Steve. Lecture 12: Ocean Sediments II. University of Illinois, Dept. of Geology. October 31 2010 <http://ijolite.geology.uiuc.edu/02Fallclass/geo117/lectures/Lect12.html>

Lesitsyn, Aleksandr, and Kennett, James. “The Formation of Sedimentary Material on Land.” Oceanic sedimentation: lithology and geochemistry. New York: American Geophysical Union, 1996.