GEOL 1001 Chapter : Chapter 10
Document Summary
Sediments, time, and stratigraphic record: properties of sediments and sedimentary rocks, chemical weathering, new minerals produced, dissolved salts go into solutions, mechanical weathering, particle sizing, erosion and deposition, materials moved, sediments accumulate in different environments. Evaporate basins: fresh water-salt, gypsum, anhydrite, marine water- calcite(limemuds), minerals, ex. Clastic diagenesis: compaction, grain rearrangement into denser clusters, reduced porosity, water expulsion, cementation- after burial, during compaction, groundwater precipitation, redox changes and ion exchange, alteration, authigenic growth of new minerals, unstable mineral breakdown to form clay. Intermediate: marl (mudstone with 35- 65% carbonate, common non-clastic/ low terrigenous content. Bioturbation: disturbance produced by burrowing organism, burrow mottled fabrics, roots of plants- same effect. Desiccation features: mud cracks-intertidal; supratidal environments, record of alternating wet-dry environments. Lithification- filling or final pore spaces- forms rock: replacement-secondary effects, dolomization-forms dolomite, silicification-forms chert. Cherts: nodules, layers or beds of colloidal silicia, usually diagenetic, sometimes primary, deep-sea radiolarian beds, deep sea sponge spicules, shallow water diatoms.
