Sedimentary, my dear Watson Lab 6 Sedimentary, my dear Watson

Weather and Sediment Chemical weathering – chemical decomposition or dissolution of a material (into a solution). Physical weathering – physical decomposition of a material (into grains or clasts).

Weather and Sediment Sediment – loose grains/chemical residues or rocks, minerals, plants & animals Erosion – transport of weathered sediments

Sedimentary Rocks Form when: Sedimentary rocks are classified by: Sediments collect, compact & harden: Lithification Mineral crystals precipitate from an aqueous solution Sedimentary rocks are classified by: Composition Texture

Sedimentary Composition Detrital (siliciclastic) – Rock or mineral fragments Quartz, feldspar, clay, or lithic fragments Chemical – Precipitated from aqueous solution Calcite, dolomite, halite, gypsum, iron bearing minerals, chert Biochemical (bioclasts) – Grains are remains of organisms See page 116 in lab manual

Sedimentary Textures Grain size: Deposits Precipitates Gravel size > sand sized > silt sized > clay sized Precipitates Crystalline > microcrystalline

Sedimentary Textures Grain shape: Describes the smoothness of the edges of grains Well rounded to angular

Sedimentary Textures Grain arrangement: See page 111 in lab manual Describes sorting of the grains Poorly sorted, moderately sorted, well sorted See page 111 in lab manual

Depositional environment?? Detrital? Precipitates? Biochemical/bioclasts?