Marine Sediments and Sedimentation

What is Sediment? Sediment is any loose material which can be transported by a liquid that eventually settles at the bottom of the liquid Consists of organic and inorganic matter from a number of biological and geological activities: Erosion of rock Volcanic eruptions Activity of living organisms Marine sediment has a variety of size, shapes, and colors

Characteristics of Marine Sediment Marine sediment color ranges from red and dark brown to creamy white Organic sediment (white) Iron oxide (red, brown) Clay deposits (blue, green) Particle size ranges from 0.004 - 256 mm Marine sediment characteristics vary geographically Thickness of sediment layer Source of sediment

Sediment Size Sediment is classified by particle size ranging from large boulders to fine clay Most marine sediment is found at the smaller end of the spectrum as sand, silt, and clay The smaller the sediment size, the easier it is for it to be carried by streams, waves, and currents

Sediment Source Marine sediment can be classified by origin Marine sediment can be classified into four categories: Terrigenous Biogenous Hydrogenous Cosmogenous

Terrigenous sediment Derived from land Terrigenous sediments are the most abundant sediment Formation is a part of cycle that moves through different parts of the Earth Erosion of land masses runs off into oceans and accumulates on the ocean floor Clay is one type of terrigenous sediment 38% of ocean floor is covered in clay

Biogenous Sediment Derived from the remains of marine organisms Plankton, coral, mollusks (high levels of CaCO3) After organisms die, the hard structures fall to the bottom of the ocean Over millions of years, fossil fuels are formed Ooze is a type of biogenous sediment that contains 30% organic material Primarily composed of dead microorganisms

Prominent examples are manganese and phosphorous nodules Hydrogenous Sediment Cosmogenous Sediment Hydrogenous sediment is formed from minerals that have precipitated from dissolved minerals Originate from submerged rock, hydrothermal vents, and river runoffs Prominent examples are manganese and phosphorous nodules Cosmogenous sediment originate from the cosmos or outer space Dust from asteroids and comets can build up on ocean floor Microtektites – small particles formed from the impact of an asteroid