1. Sediments and Sedimentary Rocks Tom Bean/DRK L - 6: cd/EM - E

2. Sedimentary rocks 5 % by volume of the upper crust 75% by area of continental areas Often the only record of geologic events: e.g. The Himalayas will someday be sandstone

3. Sedimentary Stages in the Rock Cycle

4. 2 KINDS OF SEDIMENTARY ROCKS A. DETRITAL & CLASTIC - Rock resulting from the consolidation of loose sediment that has been derived from previously existing rocks and accumulated in layers B. CHEMICAL - Rock formed by the precipitation of minerals from solution by either organic or inorganic processes

5. Transport and deposition of clastic sediments Movement of sediment by wind, ice or water (GEOLOGIC AGENTS). Mode of transport produces distinctive deposits. Deposit as layers - beds/strata

6. Transport affects the sediment in several ways - Sorting Sorting : measure of the variation in the range of grain sizes in a clastic rock or sediment Well-sorted sediments indicate that they have been subjected to prolonged water or wind action. Poorly-sorted sediments are either not far- removed from their source or deposited by glaciers.

7. Sorting Well-sortedPoorly-sorted

8. Rex Elliott Well-sorted Sand

9. Poorly-sorted Sand Rex Elliott

10. Transport affects the sediment in several ways - SHAPE Roundness Roundness : measure of how rounded the corners are Sphericity Sphericity : measure of how much it is like a sphere * Sorting, roundness, and sphericity all increase with LENGTH of transport.

11. Sorting Roundness

13. Types of detrital rocks Largely based on the size of the particles, which may be anything. Conglomerate (poorly sorted/round) Breccia (poorly sort/angular) Sandstone(quartzite, arkose, greywacke) Mudstone Siltstone Shale - most common rock on continents

14. Conglomerate Breck Kent

15. Sandstone Breck Kent

16. Shale D. Cavagnaro/Visuals Unlimited

17. SEDIMENTARY ROCKS CHEMICAL ROCK- Rock formed by the precipitation of minerals from solution by either organic or inorganic processes

18. Types of chemical sedimentary rocks LimestoneCaCO 3 ChertSiO 2 SaltNaCl, KCl GypsumCaSO 4 2H 2 O Coalaltered organic debris

19. Breck Kent Limestone

20. Breck Kent Halite

21. Breck Kent Chert

22. Fossiliferous Limestone Peter Kresan

23. Chemical environments: Evaporites Restricted environments such as Mediterranean Sea & Texas coast Minerals precipitate according to solubility. Gypsum Halite CaSO 4 2H 2 O NaCl

24. One Model for the Formation of Evaporites

25. Chemical environments: Carbonates Clear water — away from big rivers (or volcanoes) Warm water — subtropical to tropical Shallow water -- two reasons: Organic:sunlight only penetrates to about 100 m Inorganic: CCD so carbonates dissolve

26. Foraminifer in the Eye of a Needle Chevron Corporation

27. Coral Reef Surrounding Volcanic Island Jean-Marc Truchet/Tony Stone Worldwide

28. Common Sedimentary Environments

29. Clues to interpreting sedimentary depositional environments Sedimentary structures Sorting, roundness, sphericity Sequence & kinds of beds

30. Sedimentary structures Particular structural features can give information about the environment of deposition. Structures also help determine if a bed is right-side-up — important in deformed rocks

31. Peter Kresan Cross-bedded Sandstone

32. Turbidity currents Varves record annual cycles in glacial lakes S. C. Porter

33. Raymond Seiver Modern Rippled Sand

34. Reg Morrison/Auscape Ancient Ripple-marked Sandstone

35. Fig. 7.9

36. MODERNANCIENT Mudcracks

37. Chip Clark Bioturbation Tracks and Tunnels

38. From Peat to Coal

39. The end