81.%20Sedimentary%20Rocks

81.%20Sedimentary%20Rocks - Sedimentary Rocks Lecture 8...

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Unformatted text preview: Sedimentary Rocks Lecture 8 Sedimentary Rocks Lecture 8: Sedimentary Rocks Page 1 of 14 Lecture 8: Sedimentary Rocks Geologic Laws Uniformitarianism Uniformitarianism Original Horizontality Original Superposition Superposition – Present is the key to the past – Units originally deposited horizontally – Oldest unit is on the bottom Cross-Cutting Relationships Cross Superposition Original Horizontality Lecture 8: Sedimentary Rocks Page 2 of 14 Lecture 8: Sedimentary Rocks Cross-Cutting Relationships Sedimentary Materials Particles Particles – Physical Weathering = Clastic Chemicals Chemicals – Chemical Weathering = Chemicals (ions/cations) Organics Organics Organic materials, In-place and Clastic Lecture 8: Sedimentary Rocks Page 3 of 14 Lecture 8: Sedimentary Rocks Clastic Sedimentary Minerals Quartz Quartz – Weathered remains of igneous rocks Clay (Kaolinite, Illite, Smectite) Clay – Weathered remains of AlSiO based minerals Oxides (Hematite, Corundum, Rutile) Oxides – Weathered remains of Igneous/metamorphic rocks Conglomerate Conglomerate Boulders to Clay Coarse grained Poorly Sorted Lecture 8: Sedimentary Rocks Page 4 of 14 Lecture 8: Sedimentary Rocks Sandstone Sand Sizes Well Graded Poorly Graded Lecture 8: Sedimentary Rocks Page 5 of 14 Lecture 8: Sedimentary Rocks Claystone, Mudstone, Shale Silt and clay size Lecture 8: Sedimentary Rocks Page 6 of 14 Lecture 8: Sedimentary Rocks Clay Mineralogy Clastic Sedimentary Rocks Regional Extent = Local/Regional – Regional Unpredictable Geologic Names Geologic Rock Substance Properties Rock – Conglomerate: Very High Energy, Poorly Sorted, Very Coarse, Angular to Rounded – Sandstone: High to Medium Energy, Well to Poorly Sorted, Angular to Rounded – Shale: Low energy, Very Fine, Rounded to Platey (But you can’t see them anyway) can’ – Strength: Very Low to Very High – Deformation: Variable Lecture 8: Sedimentary Rocks Page 7 of 14 Lecture 8: Sedimentary Rocks Engineering Properties What is the mineralogy of a sandstone? How should I Know? Lecture 8: Sedimentary Rocks Page 8 of 14 Lecture 8: Sedimentary Rocks Chemical Sedimentary Minerals Carbonates Carbonates – Calcite (CaCO3), Dolomite (Ca MgCO3) MgCO – Precipitated from saturated fluids – Produced by organic processes Evaporites (Salts) Evaporites – Gypsum (CaSO4), Halite (NaCl) – Precipitated from saturated fluids Clastic Limestone In-Place Limestone Precipitated Limestone Lecture 8: Sedimentary Rocks Page 9 of 14 Lecture 8: Sedimentary Rocks Evaporites Chemical precipitate from Supersaturated Fluids Lecture 8: Sedimentary Rocks Page 10 of 14 Lecture 8: Sedimentary Rocks Chemical Sedimentary Rocks Carbonate (Limestone) Carbonate – – – – Low to High Energy May contain fossils Medium to High Strength Variable deformation characteristics Evaporites (Salts) Evaporites – – – – Very Low Energy Arid environment Low to Very Low Strength Plastic deformation Lecture 8: Sedimentary Rocks Page 11 of 14 Lecture 8: Sedimentary Rocks Engineering Properties Organic Sedimentary Rocks Coal and Lignite Coal – Anaerobic wetland environment – Very Low Energy – Dominantly Carbon material Lecture 8: Sedimentary Rocks Page 12 of 14 Lecture 8: Sedimentary Rocks Coal Coal Swamp Coal Mine Lecture 8: Sedimentary Rocks Page 13 of 14 Lecture 8: Sedimentary Rocks Classification of Sedimentary Rocks Break Lecture 8: Sedimentary Rocks Page 14 of 14 Lecture 8: Sedimentary Rocks ...
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This note was uploaded on 04/16/2011 for the course GEOL 320 taught by Professor Mathewson during the Spring '11 term at Texas A&M.

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