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Sedimentary rocks Modified from and

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Presentation on theme: "Sedimentary rocks Modified from and"— Presentation transcript:

1 Sedimentary rocks Modified from and

2 Relative abundances of major rock types exposed at the Earth's surface. Why a sedimentary rock study is important for ENGINEERS ?

3 Sedimentary Rocks Weathering Erosion Transport Deposition Sediments Lithification

4 Weathering The sediments that make up sedimentary rocks are produced by: Mechanical & Chemical Weathering

5 Mechanical Weathering Thermal stress Frost weathering Hydroric action Biological weatering

6 Chemical Weathering Oxidation (rusting) Dissolution (Acid rain)

7 Mineral Stability

8 Products of Weathering Lithic (Rock) Fragments (granite, basalt, schist, etc.) Dissolved Ions (Calcium, Potassium, Sodium, etc.) Rust Minerals (Hematite, Goertite, etc.) Clay Minerals (Bentonite, Montmorillonite, etc.) Residual Minerals (Quartz, Orthoclase, Muscovite, etc.)

9 Erosion & Transport Water Wind Ice Gravity

10 Deposition

11 Lithification Sediment Rock

12 Cementation Typical Cement: Calcite Quartz

13 Sedimentary Rocks Identification Note: Use the same terms to describe sediments & sedimentary rocks. Only difference is lithification!

14 Rock Identification is based on: Composition What minerals make up the rock? Texture What is the shape, size and orientation of the mineral grains that make up the rock? Major Difference: Crystalline vs. Clastic

15 Types of Sedimentary Rocks Clastic RocksChemical Rocks vs.

16 Difference: Texture Clastic Texture vs. Chemical (Crystalline Texture)

17 Clastic Rock Composition Clastic Rocks Lithic Fragments Quartz Clay Minerals Fossil Fragments Rust Minerals Orthoclase Muscovite / Biotite

18 Clastic Rock Texture Clastic Texture Grain Size Grain Sorting Grain Rounding Sediment Maturity

19 Grain Size

20 Detrital Rock Names (Based Primarily on Grain Size) Sand Sized: Sandstone Gravel Sized:Conglomerate Siltstone Shale Mud Sized: Mudstone

21 Grain Size Factors : Deposition Energy (environment) and Transportation Path

22 Sorting Sorting Factor : Deposition Energy (environment)

23 Grain Roundness Roundness Factor : Transportation path (environment)

24 Gravel Sized Detrital Rocks (Subdivided Based on Grain Roundness) Breccia Conglomerate

25 Maturity Mature Well Sorted Well Rounded All Quartz Immature Poorly Sorted Angular grains Mixed Composition including clay

26 Sandstones (Subdivided based on maturity) Quartz Sandstone Arkose (Sandstone) Lithic Sandstone Greywacke

27 Clastic Sedimentary Rock ID





32 Compacted and cemented from detrital sediments Formation processes: Transportation, deposition, compaction, and cementation Fossil-fuel bearing rocks Classified based on particle size Shale: The most abundant clastic rocks Clastic Sedimentary Rocks (Keynotes )

33 Chemical Sedimentary Rocks (Names based primarily on composition) Basic Rock Name Limestone Chert Rock Salt Rock Gypsum Peat or Coal Composition Calcite Quartz (silica) Halite Gypsum “Carbon” / Plant Remains

34 Chemical Rocks (Names based mainly on composition) Limestones Crystalline Limestone Chalk Fossiliferous Limestone

35 Chemical Rocks (cont.) Evaportites Rock Gypsum Rock Salt Coal Chert

36 Precipitated from chemical solutions and/or accumulated chemical, biological matter Classified based on composition and texture :Limestone: The most abundant nonclastic sedimentary rocks Common texture: Crystalline, microcrystalline, skeletal, oolitic, massive Chemical Sedimentary Rocks (Keynotes)

37 Chemical Sedimentary Rock ID





42 Exercises P48

43 Exercises P50

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