NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
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Sea Floor and Sediments (contd.)
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Notes on Topic:
The notes represent summaries of key issues
for each topic
They emphasize the terminology used to describe
the various phenomena.
| 3. Sediments: |
| Learning Objectives: |
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Characteristics and global occurrence of different sediment types.
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Sources for sediment: lithogenous, biogenous, hydrogenous, cosmogenous.
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| Sediment Particles: |
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Three different major sources
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Lithogenous (rock fragments)
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formed by physical weathering processes on land (terrigenous)
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from volcanism (e.g. ashes)
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often altered by chemical weathering
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Biogenous (biogenic), or ooze:
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hard skeletal parts, shells (tests), bones, teeth of marine organisms
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Hydrogenous:
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| Hydrogenous Sediments: |
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Formed as particles or coatings
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Manganese (Mn, Fe, Co, Cu, Ni) nodules grow slowly (1 - 10 mm/Ma)
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may form on teeth, etc. where sediments accumulate slowly
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Also, carbonates, evaporites (salt), phosphorites.
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| Cosmogenous Sediments: |
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Particles from space,
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dust, tektites and meteorite fragments (3 x 1010g/a),
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characterized by chemistry (Fe, or Fe-rich)
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| Biogenous Ooze: |
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Biological material from surface waters
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comprises >30% of sediment
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diluted by other particles
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calcareous or siliceous
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deep ocean undersaturated in calcite and silica
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Carbonate dissolves in deep ocean at low temperatures and high pressures
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carbonate compensation depth (CCD ~4km), or lysocline
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Calcareous oozes dominate shallower regions of open ocean
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absent in deep ocean basins
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Formed from foraminifera, (microscopic animals), pteropods (snails)
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coccolithophores (calcareous plants), coccoliths of microscopic plants.
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Silica dissolves slowly
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Diatomaceous oozes from diatoms (plants) under nutrient-rich waters
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N. Pacific and Antarctica
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Radiolarian oozes from radiolaria (microscopic animals)
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| Red Clay: |
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Very fine oxidized, lithogenous sediment
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Department
of Geological Sciences,
1001
E. Tenth Street, Bloomington, IN 47405-1403
Phone:
(812) 855-5582 Last updated: 7 October 2000
Comments:
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Copyright
2000, The Trustees of Indiana University
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