Lithification Sediments Deposition Transport Erosion Weathering Sedimentary Rocks

Lithification Sediments Deposition Transport Erosion Weathering Sedimentary Rocks

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

Mechanical Weathering

Chemical Weathering

Mineral Stability

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

Deposition

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!

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

Types of Sedimentary Rocks Detrital Rocks Chemical Rocks vs.

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

Detrital Rock Composition Detrital Rocks • Lithic Fragments • Quartz • Clay Minerals • Fossil Fragments • Rust Minerals • Orthoclase • Muscovite / Biotite

Detrital Rock Texture Clastic Texture • Grain Size • Grain Sorting • Grain Rounding • Sediment Maturity

Grain Size • Gravel 2 mm • Sand 1/16 mm • Mud - Silt 1/256 mm • Mud - Clay

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

Sorting

Grain Roundness

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

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

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

Sandstones Under a Scope

Detrital Sedimentary Rock ID

Chemical Rock Texture Crystalline Texture • Coarse • Fine

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

Chemical Sedimentary Rock ID

Sedimentary Rocks on Earth