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Chapter 20 Ocean Basins

Chapter 20 Ocean Basins. Section 3 Ocean-floor Sediments Notes 20-3. Ocean-floor Sediments. Coarse gravel and sand are found close found close to the shore Heavier and harder to move Fine particles are carried farther into the deep ocean

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Chapter 20 Ocean Basins

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  1. Chapter 20Ocean Basins Section 3 Ocean-floor Sediments Notes 20-3

  2. Ocean-floor Sediments • Coarse gravel and sand are found close found close to the shore • Heavier and harder to move • Fine particles are carried farther into the deep ocean • Bottom sediments in deep ocean are finer than sediments in shallow water • Core samples: drill into layers or scoop up sediments

  3. Ocean Core Samples

  4. Sources of Deep Ocean Sediments • Most are made from materials that settle slowly from ocean water above • Inorganic Sediments • From rivers • Most are on the shore or continental shelf • Occasionally they slide down the continental slope • May move billions of kg of material • Causes turbidity currents

  5. Sources of Deep Ocean Sediments • Some are from volcanic eruptions • Icebergs carry sediments from their place of origin across the ocean • As it melts the sediments fall out • Meteorites also fall to the ocean floor • Even if most of it burns up, the ash falls to the ocean

  6. Iceberg

  7. Sources of Deep Ocean Sediments • Organic Sediments • Remains of marine plants or animals • Most common substances are • Silica (SiO4) • Comes from microscopic organisms: radiolaria and diatoms • Calcium carbonate (CaCO3) • Comes from the skeletons of foraminifera, corals and clams

  8. Radiolaria

  9. Diatoms

  10. Foraminifera

  11. Sources of Deep Ocean Sediments • Chemical Deposits • During chemical reactions solid materials can be formed • Nodules: lumps of minerals • Manganese oxide, nickel oxide and iron oxide • Phosphorite

  12. Physical Classification of Sediments • Two types of sediments • Mud: fine silt and clay sized particles • Red clay is common on the abyssal plain • 40 % clay, some silt, sand ad organic material • Can be gray, blue, green or yellow-brown • Ooze: soft, organic material • 40% of floor is covered with ooze • 30% of ooze is made of organic material • Diatoms, radiolaria, foraminifera • Rest is mud

  13. Physical Classification of Sediments • Two types of ooze: • Calcareous ooze: mostly calcium carbonate • Never found below 4,500 m • It dissolves in deep, cold water • Siliceous ooze: mostly silicon dioxide • Comes from radiolaria and diatoms • Found in cold, nutrient rich ocean water (Antarctica)

  14. Homework Section Review Pg. 401 #1-3

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