There are three kinds of sea floor sediment: terrigenous, pelagic, and hydrogenous. Terrigenous sediment is derived from land and usually deposited on the continental shelf, continental rise, and abyssal plain.

1) Terrigenous Sediments: These sediments originate from the continents from erosion, volcanism and wind transported material. These are the most abundant sediments. 2) Biogenous Sediments: These are sediments derived from critters. *These include calcareous (most skeletons) and silicious (diatoms) compositions.

Sediments are also classified by origin. There are four types: lithogenous, hydrogenous, biogenous and cosmogenous. Lithogenous sediments come from land via rivers, ice, wind and other processes. Biogenous sediments come from organisms like plankton when their exoskeletons break down.

ocean gyres

Red clay, also known as abyssal clay however, is mostly located in the ocean and is formed from a combination of terrigenous material and volcanic ash. In terms of size, terrigenous particles are generally larger than abyssal clay particles so they sink faster.

In marine systems, lithogenic particles are refractory assemblages of crustally-derived minerals that transit the water column largely unaltered. Each year, large quantities—1 Pg (Ginoux et al., 2004, Mahowald et al., 2009)—of crustally-derived particles cycle through the world oceans.

Lithogenic Sediments: Detrital products of pre-existing rocks (igneous, metamorphic, sedimentary) and of volcanic ejecta and extraterrestrial material. Also products of alteration during early chemical reactions within freshly deposited sediment.

Hydrogenous sediments are sediments directly precipitated from water. Examples include rocks called evaporites formed by the evaporation of salt bearing water (seawater or briny freshwater).

Examples of lithogenous sediment include volcanogenic sediments, glacial marine sediments, and abyssal clays. Volcanogenic sediments are found near convergent volcanic arcs or hot spots.

Sources of terrigenous sediments include volcanoes, weathering of rocks, wind-blown dust, grinding by glaciers, and sediment carried by rivers or icebergs.

The term neritic is used to described the shallow part of the ocean near a coast and overlying the continental shelf. Neritic sediments are generally shallow water deposits formed close to land. They are dominated by lithogenous sources and are typically deposited quickly.

Evaporites are hydrogenous sediments that form when seawater evaporates, leaving the dissolved materials to precipitate into solids, particularly halite (salt, NaCl). In fact, the evaporation of seawater is the oldest form of salt production for human use, and is still carried out today.

Oceanography test 2

Lithogenous is the most common neretic deposit because neretic deposits are close to the shore, where lithogenous sediments are created. biogenous oozes are the most common pelagic deposit because pelagic areas are the most productive area of the ocean, where the most biogenous ooze is created.

Give examples of lithogenous sediment found in each. Neritic (of the coast) deposits are found on continental shelves and in shallow water near islands; these deposits are generally coarse grained. Pelagic (of the sea) deposits are found in the deep-ocean basins and are typically finer-grained materials.

Diatomaceous Earth • Siliceous ooze lithifies into diatomaceous earth. • Diatomaceous earth. has many. commercial uses.

Most deep ocean sediments are silt and mud. Most sediments form as rocks are broken down into smaller particles such as sand and clay.

Cosmogenous sediment is derived from extraterrestrial sources, and comes in two primary forms; microscopic spherules and larger meteor debris. These high impact collisions eject particles into the atmosphere that eventually settle back down to Earth and contribute to the sediments.

Terrigenous sediment is derived from continental sources transported by rivers, wind, ocean currents, and glaciers. It is dominated by quartz, feldspar, clay minerals, iron oxides, and terrestrial organic matter.

pelagic sediment

Siliceous oozes predominate in two places in the oceans: around Antarctica and a few degrees of latitude north and south of the Equator. At high latitudes the oozes include mostly the shells of diatoms.

Red and brown clays Red clay, also known as either brown clay or pelagic clay, accumulates in the deepest and most remote areas of the ocean. It covers 38% of the ocean floor and accumulates more slowly than any other sediment type, at only 0.1–0.5 cm/1000 yr.

Oil and natural gas are the two major energy sources obtained from the ocean floor. Drilling on the ocean floor has already been done and the most abundant oil and natural gas producers are North Sea, Gulf of Mexico, Atlantic Ocean (near Brazil and West Africa), Arabian Gulf, and South East Asian Seas.