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Marine Sediments Outline:

Marine Sediments Outline:  Discuss classification of sedimentary rocks as clastic or chemical, and divisions by size. Discuss where silica oozes, carbonates, red clays, terrigenous sediments, and ice rafted sediments occur, and why they have this distribution.

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Marine Sediments Outline:

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  1. Marine Sediments Outline: •  Discuss classification of sedimentary rocks as clastic or chemical, and divisions by size. • Discuss where silica oozes, carbonates, red clays, terrigenous sediments, and ice rafted sediments occur, and why they have this distribution. • Discuss what the vertical sequence of rock types can tell about the history of the location. • Discuss the importance of rads, diatoms, forams, and coccoliths in the ocean sediments. • Understand the purpose and operations of the ocean drilling programs (DSDP, ODP, and IODP)

  2. Sediment transport changes • Smaller • Rounder • Less mineral diversity (more quartz) • Size sorting (segregation)

  3. Rock Facies Symbols (ss, sh, ls) Transgression, regression—”seas come in, seas go out”

  4. Phi scale • Gravel: < -1 • Sand: -1 to 4 • Silt: 4 to 8 • Clay: 8 to 10 • Colloid: >10 Initiation of transport Bed load, suspended load Settling velocity Porosity/permeability Dropstone, erratics Heavy minerals Quartz Two types of clay

  5. Open University text, early 1990’s

  6. Dutkiewicz and others, 2015

  7. Uncompacted at the seafloor ( porosity ~ 0.9) the vertical rate of accumulation is 220 m/My or 22 cm/ky, When compacted at a depth of several hundred meters (porosity ~ 0.5) about 45 m/My or 4.5 cm/ky, Full compaction about 22 m/My or 2.2 cm/ky. Mean age of ocean floor is 59 My, the mean sediment thickness exceeds 1.2 km. Spatial variability in accumulation is great, • mid-gyre, central north Pacific (~1 m/My) • some coastal instantaneous rates >1000 m/My (obviously this is not a steady state condition; frequent events occur to erode and redeposit this material in deeper water).

  8. Age depth curve • CCD • Current latitude ≠ depositional latitude

  9. Coccolith Diatom Foram Rad CaCO3 SiO2 CaCO3 SiO2 High lat Low Lat (smaller)

  10. Paleozoic Rads

  11. Diatom (swimming pool filters)

  12. Coccolith (Nannofossils)

  13. Emiliania huxleyi type A Scale bar 1 micron

  14. (recent example) Foram: Peneroplis planatus

  15. Saharan Dust off West AfricaThe image above was made using Moderate Resolution Imaging Spectroradiometer (MODIS) data from both the Terra and Aqua satellites, acquired on January 28, 2003. Stitched together, the composite scene shows a large plume of Saharan Desert dust blowing westward from Africa toward the open Atlantic. The dust (light brown pixels) can be easily distinguished from the brighter white clouds in the image. The west African shoreline can be seen to the right of the image. Full-resolution scene, available at 500 meters per pixel.

  16. Sept 2015

  17. Deep sea drilling

  18. Not used, not testable

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