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Sedimentary Rocks. Lithification. Sediments. Deposition. Transport. Erosion. Weathering. From Sediment to Rock. Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, and cementation . Weathering.
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Sedimentary Rocks Lithification Sediments Deposition Transport Erosion Weathering
From Sediment to Rock • Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, and cementation.
Weathering The sediments that make up sedimentary rocks are produced by: Mechanical & Chemical Weathering
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.)
Erosion & Transport Water Wind Ice Gravity
Lithification Sediment Rock
Cementation • Typical Cement: • Calcite • Quartz
Sedimentary Rocks Identification Note: Use the same terms to describe sediments & sedimentary rocks. Only difference is lithification!
CompositionWhat minerals make up the rock? TextureWhat is the shape, size and orientation of the mineral grains that make up the rock?Major Difference:Crystalline vs. Clastic Rock Identification is based on:
Types of Sedimentary Rocks Detrital Rocks Chemical Rocks vs.
Difference: TextureDetrital (Clastic Texture)vs.Chemical (Crystalline Texture)
Detrital Rock Composition • Detrital Rocks • Lithic Fragments • Quartz • Clay Minerals • Fossil Fragments • Rust Minerals • Orthoclase • Muscovite / Biotite
Clastic Texture Grain Size Grain Sorting Grain Rounding Sediment Maturity Detrital Rock Texture
Grain Size • Gravel2mm • Sand1/16 mm • Mud - Silt1/256 mm • Mud - Clay
Detrital Rock Names(Based Primarily on Grain Size) Gravel Sized: Conglomerate Sand Sized: Sandstone Mud Sized: Mudstone Siltstone Shale
Gravel Sized Detrital Rocks(Subdivided Based on Grain Roundness) Conglomerate Breccia
Maturity • Immature • Poorly Sorted • Angular grains • Mixed Compositionincluding clay • Mature • Well Sorted • Well Rounded • All Quartz
Sandstones(Subdivided based on maturity) Quartz Sandstone Arkose (Sandstone) Lithic Sandstone Greywacke
Crystalline Texture Coarse Fine Chemical Rock Texture
Chemical Sedimentary Rocks(Names based primarily on composition) • Composition • Calcite • Quartz (silica) • Halite • Gypsum • “Carbon” / Plant Remains • Basic Rock Name • Limestone • Chert • Rock Salt • Rock Gypsum • Peat or Coal
Chemical Rocks(Names based mainly on composition) Limestones Crystalline Limestone Fossiliferous Limestone Chalk
Chemical Rocks (cont.) Evaportites Chert Rock Salt Rock Gypsum Coal