MARINE SEDIMENTS

Trujillo and Thurman, 10^th, Chapter 4; be sure to read boxes 4.2 (diatoms) and 4.3 (Cretaceous – Tertiary Boundary), omit box 4.1

Objectives: Students should be able to

1. describe the formation of the four major sediment types

2. discuss areas of the ocean where specific sediments dominate and the reasons they are found in these areas

3. list specific examples of each of the major sediment types

4. discuss how sediments can be used to tell the geologic or climatic history of the area

5. discuss several resources that come from the seafloor

LITHOGENOUS: from erosion of continents; size, sorting, rounding important

· Found close to continents: river sources, beach sediments, turbidites, glacial debris

· Found on abyssal plains: red clays, fine-grained quartz sand from deserts

BIOGENOUS: from remains of organisms; composition important

· Calcium carbonate: coccolithophores, foraminifera, reefs; carbonate compensation depth (CCD)

· Silica: diatoms, radiolarians

· Controls on where we find oozes: productivity of area, destruction as sinks to bottom, dilution with other sediments

HYDROGENOUS: precipitates from seawater

· Manganese nodules

· Phosphates

· Metal sulfides

· Evaporites

COSMOGENOUS: from outer space; very minor

· Tektites: pieces from impacts

· Meteorites

DISTRIBUTION: Know where in oceans one is likely to find these different types of sediments.

RESOURCES FROM THE SEAFLOOR (be sure to read on own)

· Sand and gravel

· Petroleum: oil and gas

· Phosphates

· Salt deposits

· Manganese nodules

· Methane hydrates