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 Clastic RocksChemical Rocks vs.
Difference: Texture Clastic Texture vs. Chemical (Crystalline Texture)
Gravel Sized Detrital Rocks (Subdivided Based on Grain Roundness) Breccia Conglomerate
Maturity Mature Well 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 Greywacke
Clastic Sedimentary Rock ID
Compacted and cemented from detrital sediments Formation processes: Transportation, deposition, compaction, and cementation Fossil-fuel bearing rocks Classified based on particle size Shale: The most abundant clastic rocks Clastic Sedimentary Rocks (Keynotes )
Chemical Sedimentary Rocks (Names based primarily on composition) Basic Rock Name Limestone Chert Rock Salt Rock Gypsum Peat or Coal Composition Calcite Quartz (silica) Halite Gypsum “Carbon” / Plant Remains
Chemical Rocks (Names based mainly on composition) Limestones Crystalline Limestone Chalk Fossiliferous Limestone
Chemical Rocks (cont.) Evaportites Rock Gypsum Rock Salt Coal Chert
Precipitated from chemical solutions and/or accumulated chemical, biological matter Classified based on composition and texture :Limestone: The most abundant nonclastic sedimentary rocks Common texture: Crystalline, microcrystalline, skeletal, oolitic, massive Chemical Sedimentary Rocks (Keynotes)