1. Sedimentary Rocks Sedimentary rocks are products of mechanical and chemical weathering of preexisting rocks They account for about 5% (by volume) of Earth’s outer 15 kilometers The account for 90% of the upper ½ kilometer Contain evidence of past environments Provide information about sediment transport by one of the geologic fluids Often contain fossils

2. Sedimentary rocks are important for economic considerations because they may contain Coal Petroleum and natural gas Sources of iron, aluminum, and manganese Natural fertilizers Materials for concrete and bitumen

3. Types of sedimentary rocks Sediment originates from mechanical and/or chemical weathering Rock types are based on the source of the material Detrital or clastic rocks – transported sediment as solid particles Chemical rocks – sediment that was once in solution

4. What is a sediment? A material deposited by one of the geologic fluids (wind, water, ice) at the earth’s surface.

5. Types of Sediments Clastics –Materials transported and deposited by wind, water, or ice Chemical –Materials deposited by chemical precipitation Biologic – Parts of living organisms

6. Clastic or Detridal Pieces of solid stuff transported ad deposited by a geologic fluid Size and amount is controlled by –Fluid Density, viscosity –Velocity

8. Generalized Geologic Map

9. Evaporites Reduce the volume by 44% (CaMg)CO3 (Limestone - Dolomite) 2.2 g/cm3 81% (CaMg)SO4 (Gypsum) 2.6 g/cm3 91% (Na,K)Cl (Rock Salt) 1.8 g/cm3

11. Sedimentary Sequence in the Mediterranean Basin Clastics Cycle 3 Salt Gypsum Limestone Clastics Cycle 2 Salt Gypsum Limestone Clastics Cycle 1 Salt Gypsum Limestone

12. Clastics 2.0 g/cm3 Limestone 2.2 g/cm3 Gypsum 2.6 g/cm3 Salt 1.8 g/cm3

14. Biologic Parts of living organism –Rock Forming organisms (coral, algae) limestones Organic Rocks from dead organisms Plants(coal) Fragments of organisms –(oozes, muds, fossils) limestones

15. Rock forming Organisms Coral Blue-Green algee

16. Dead Coral

17. Distribution of reefs Clear warm water Normal salinity

18. Dead organisms Plants –Swamps (anoxic) –Peat –lignite –subbituminous –bituminous –superbituminous Shells –Fragments

19. Shells

20. Coal Swamp Burpee Museum, Rockford, Illinois

21. Major Coal U.S. Basins

22. Sedimentary environments A geographic setting where sediment is accumulating The environment determines the nature of the sediments that accumulate (grain size, grain shape, etc.)

23. Types of sedimentary environments Continental –Dominated by stream erosion and deposition –Glacial –Wind (eolian) Marine –Shallow (to about 200 meters) –Deep (seaward of continental shelves)

24. Types of sedimentary environments Transitional (shoreline) –Tidal flats –Lagoons –Deltas

25. Sedimentary Environments..\POG Lect\sed environments.jpg

26. Sedimentary Facies Different sediments often accumulate adjacent to one another at the same time Each unit (called a facies) possesses a distinctive set of characteristics reflecting the conditions of a particular environment The merging of adjacent facies is a gradual transition

27. Sedimentary Facies

28. Big Bend, Texas

29. Sedimentary structures Strata, or beds (most characteristic of sedimentary rocks) Bedding planes that separate strata

30. Sedimentary structures Cross-bedding Graded beds Ripple marks Mud cracks Fossils