Marine Sediments Eroded particles and fragments of dust, dirt and other debris that have settled out of the water and accumulated on the sea floor.

Provide Clues  To past global climate change  Movements of ocean floor plates  Ocean circulation patterns  Nutrient supplies for marine organisms

Sedimentary Rocks  Over time sediments are “lithified” turned to stone  1 centimeter of rock = 1000 years  More than 50% of rocks found on land were formed on the sea floor

Classification  Type , composition, Source and location found  Composition includes- worn rock, living organisms, Dissolved minerals, and outer space particles

Lithogenous  Derived from preexisting rock  Comes from land masses and volcanic Islands  Weathering- Break rock into smaller pieces by: Water, temperature, wind and chemical effects  Erosion-Transport of pieces of rock carried from continents to oceans by rivers, wind, glaciers, and gravity  Deposition- sediments settle in bays or lagoons along shore, river mouth deltas, along Beaches, on the continental shelf, and carried to deep ocean by turbidity currents. Microscopic particles blown across ocean settle on abyssal plains

Composition  Quartz (SiO2) Major component of all rocks found on land  Beach sand = Quartz same composition as glass  Texture -classified as Boulders, cobbles, pebbles, granules, sand, silt and clay  Sorting- Measure of uniformity of grain sizes

Biogenous Sediments  Remains of hard parts of living organisms  Macroscopic- Larger particles, shells, Bones, Teeth from fish – Whales – Corals  Microscopic- need a microscope to see well  Algae and Protozoans produce tiny Shells called “tests” that sink after the animal dies  Form deposits called “oozes” on the sea floor fine grained mushy material, has the consistency of toothpaste  Biogenous ooze must be 30% biogenous by weight which means 70% lithogenous clay

Biogenous Composition  Two main types - Calcium Carbonate CaCO3 or calcite, and Silica SiO2- NH2O or opal Silica Tests- 2 types of organisms Diatoms- microscopic Algae  Planktonic-Free floating, Photosynthetic  Found in upper sunlit surface area  Most have two halves to their tests, fit together like a petri dish  Tests are preforated to allow nutrients in and wastes out  70,000 species identified, live few days to 1 week, reproduce sexually and asexually  Main ingredient of Diatomaceous earth, 3000 ft thick sediment layers Radiolarians- Microscopic protozoans  Silica shell with long spikes or rays  Well developed symmetry “snow flakes of the Ocean”  Rely on external food sources- Bacteria and other plankton

Biogenous Composition Calcium Carbonate Tests- 2 significant organisms Foraminifers- Single celled protozoans, relatives of radiolarians, may be microscopic to macroscopic. Ingest their own food Produce calcium carbonate test which is chambered or segmented, Some resemble beach shells Coccolithophores-algae, single celled Produce thin plates or shields of calcium 20-30 overlap to form spherical test Photosynthesize so remain near surface 10-100 times smaller than diatoms so often called nannoplankton When organism dies plates accumulate on ocean bottom Calcerous ooze- white deposit called chalk “write on blackboard” Chalk cliffs of Dover, England, Formed during the cretaceous period (creta= chalk)  

Chalk cliffs of Dover

Additional Biogeneous Sediments Limestones-most contain fossil marine shells others form directly from seawater  Bahama Bank, Great Barrier Reef- Australia are carbonate deposits which occur in shallow warm water  Limestone deposits form bedrock underlying Florida  Percolation of groundwater in limestone creats caverns and sinkholes Stromatomatolites- Cyanobacteria produce deposits by trapping sediments in mucous and cementing it into rock  Found in Shark Bay, Australia and Eluthera, Bahamas  Three Billion year old stromatolites hundreds meters high

Hydrogenous Sediments  Derived from the dissolved material in water  Precipate- change from the dissolved to the solid state  A change in conditions ex. Temperature, pressure, chemicals causes oversaturation and then precipitation Manganese nodules-rounded lumps of manganese, baseball size, growth rate 5mm/year Phosphate deposites-on continental shelf shallower than 100 meters.coat rocks form nodules.Phosphate mines on land/fertilizer Carbonates-aragonite and calcite precipitate out of seawater on beaches,have layers like onion Metal sulfides-formation associated with hydrothermal vents, iron, nickel, copper, zinc, silver Evaporites- restricted areas with high evaporation, Highly concentrated water,Salts calcium hydrates anhydrate and gypsum

Cosmogenous Sediments – two types Microscopic Spherules-small globular masses composed of either silicate rock or iron and nickel  Constantly rain down on earth  300,000 metric tones reach surface each year Macroscopic Meteor Debri- associated with impact sites of meteors  Irridium dust layer coats surface from large impacts