Sedimentary Rocks Sediments Lithification Deposition Transport Erosion Weathering

From Sediment to Rock Most sedimentary rocks are formed through a series of processes: erosion, deposition, compaction, and cementation.

Weathering Mechanical & Chemical 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 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 2mm 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 Immature Mature Well Sorted Poorly Sorted Well Rounded All Quartz Immature Poorly Sorted Angular grains Mixed Composition including clay

Sandstones (Subdivided based on maturity) Quartz Sandstone Arkose (Sandstone) Lithic 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) 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) Crystalline Limestone Limestones Fossiliferous Limestone Chalk

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

Chemical Sedimentary Rock ID

Sedimentary Rocks on Earth