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An Introduction to Geology Sedimentary Rocks. Back to the Rock Cycle.

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Presentation on theme: "An Introduction to Geology Sedimentary Rocks. Back to the Rock Cycle."— Presentation transcript:

1 An Introduction to Geology Sedimentary Rocks

2 Back to the Rock Cycle

3 Sedimentary processes 1. Weathering 2. Transportation 3. Deposition 4. Lithification A. Existing rocks B. Biological materials C. Chemical precipitates OF

4 Sedimentary processes

5 Common sedimentary minerals Quartz Feldspars Micas Calcite

6 Hand specimens First impressions?

7 Weathering Physical / Mechanical

8 Weathering Chemical / Biological

9 Weathering = clasts

10 Transportation

11 Transport mechanisms Rivers = fluvial Seas = marine Mississippi delta

12 Transport mechanisms AEOLIAN (wind) Can only transport small grains GLACIAL (ice) Huge volumes of sediment

13 Transportation Proximity + velocity = grain size

14 Transport time = maturity Textural maturity:

15 Transport time = maturity Mineralogical maturity:

16 Deposition Transportation into basins

17 Lithification Deposition (+ deposition + deposition) = burial Burial = compaction + cementation

18 Compaction Stylolites in chalk

19 Cementation Mineral precipitation into pore spaces: e.g. calcite, quartz, haematite e.g. calcite, quartz, haematite

20 Hand specimens Second impressions?

21 Sedimentary rocks Grain size ClassificationExample >2 mm RudaceousConglomerate Particle size, shape and composition

22 Conglomerate

23 Sedimentary rocks Grain size ClassificationExample >2 mm RudaceousConglomerate mm ArenaceousSandstone Particle size, shape and composition

24 Sandstone

25 Sedimentary rocks Grain size ClassificationExample >2 mm RudaceousConglomerate mm ArenaceousSandstone mm ArgillaceousSiltstone Particle size, shape and composition

26 Siltstone

27 Sedimentary rocks Grain size ClassificationExample >2 mm RudaceousConglomerate mm ArenaceousSandstone mm ArgillaceousSiltstone <0.004 mm ArgillaceousClaystone Particle size, shape and composition

28 Claystone Bituminous shales, Saltwick Nab, near Whtby

29 Sedimentary rock types 1. Clastic (or detrital)

30 Sedimentary rock types 1. Clastic (or detrital)

31 Sedimentary rock types 2. Biogenic (or organic)

32 Sedimentary rock types 2. Biogenic (or organic)

33 Sedimentary rock types 3. Chemical (precipitates)

34 Hand specimens What sedimentary rock type is your specimen?

35 Sedimentary structures Bedding

36 Sedimentary structures Cross-bedding

37 Sedimentary structures Cross-bedding

38 Sedimentary structures Ripple marks

39 Sedimentary structures Mud cracks

40 Sedimentary structures Shell beds

41 Sedimentary structures Trace fossils

42 Sedimentary UK

43 Next week Under Pressure:Metamorphic Rocks


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