SEAFLOOR SEDIMENTS Lithogenous Biogenous Hydrogenous Cosmogenous

General patterns Review shape of typical ocean floor Lots of sediments near continents Few sediments at ocean ridges – Why?

Lithogenous (1) From weathering and erosion of continents Some relatively close to continental mass ◦ Beach sediments ◦ River sediments ◦ Glacial debris ◦ Graded bedding from turbidity currents

Turbidity currents and graded bedding Turbidity currents and graded bedding

Lithogenous (2) Some found on abyssal plain ◦ Wind-blown debris ◦ Red clays

Biogenous sediments (1) Remains of formerly living organisms (shells and reef material) Silica rich: radiolarians, diatoms Calcium carbonate rich: ◦ forams, coccolithophores, reefs ◦ carbonate compensation depth

RADIOLARIAN

DIATOMS

FORAMS

COCCOLITHS

Biogenous (2) Difficult to accumulate biogenous oozes Productivity of that area of the ocean Destruction as “shells” fall to seafloor Additional CCD for carbonate sediments Dilution by other sediments

Hydrogenous sediments Evaporites Manganese nodules Phosphorite nodules Metal sulfides

Manganese Nodules

Cosmosgenous sediments Meteorites Tektites Random distribution and relatively insignificant TEKTITES

MAP OF SEDIMENTS IN OCEAN Student version

Resources from the seafloor What is accessible? What is owned by whom? What is economically valuable?