Sedimantoloji Karbonatlara Bakış ( İngilizce İçerik ) - 3 Influx of Influx of Magnesium Magnesium Rich Rich Continental Continental Ground Ground Waters Waters Influx of Influx of sea water sea water Evaporation Evaporation of mixed of mixed Waters Waters 1. Aragonite 1. Aragonite 2. Gypsum 2. Gypsum 3. Anhydrite 3. Anhydrite 4. Dolomite 4. Dolomite 5. Halite 5. Halite accumulate accumulate in this order in this orderStylolites ? Dissolution seam(A), ? Stylolite (B), ? Highly serrate stylolite (C) ? Deformed stylolite (D). A few grains are shown schematically to emphasize the change in scale from the previous figure (after Bruce Railsback ) Two-dimensional cross-sectonal views ofStylolites Stylolites ? Tangential (A) ? flattened (B) ? concavo-convex (C) ? sutured (D) (after Bruce Railsback) Intergranular contacts as seen in thin sectionStylolites Stylolites Stylolites Stylolites After Bruce RailsbackLecture Conclusions Lecture Conclusions ? Photosynthesis, warm temperatures & low pressures in shallow water control carbonate distribution ? Carbonate sediment types indicate depositional setting ? Most mud lime mud has a bio-physico-chemical originLecture Conclusions Lecture Conclusions ? Ooid, intraclast, pellet, and pisoid grains have bio- physico-chemical origin ? Mineralogy & fabric separate foram’s, brach’s, bryozoan, echinoids, red calc’ algae, corals, green calc’ algae, and molluscan skeleletal grains ? CCD controls deepwater ooze distribution ? Mineralogy & fabric separate foram’s, brach’s, bryozoan, echinoids, red calc’ algae, corals, green calc’ algae, and molluscan skeleletal grainsLecture Conclusions Lecture Conclusions ? CCD controls deepwater ooze distribution ? Folk & Dunham are best way to classify carbonates ? Most diagenesis, dolomitization, & cementation of carbonates takes place in near surface crust & trace elements can be used in this determination ? Stylolites develop through burial & solution/compactionEnd of the Lecture Lets go for lunch!!!Global Climate Cycles Global Climate Cycles Global Climate Cycles Global Climate Cycles Global climatic cycles, referenced to geologic periods (yellow), megasequences (light purple), sea level cycles (blue), & volcanic output (dark purple). (Redrawn & modified L. Waite, 2002 after Fischer, 1984)Frakes et al. (1992) have alternating cold & warm states ("cool" & "warm" modes) at comparable time scales to Fischer (1984) cycles but propose older portion of Mesozoic greenhouse (Middle Jurassic to Early Cretaceous) has a cool climate, & presence of seasonal ice at higher latitudes (after L. Waite, 2002) Phanerozoic Global Climate History Phanerozoic Global Climate History Phanerozoic Global Climate History Phanerozoic Global Climate HistoryCopied from Steven Wojtal of Oberlin CollegeCO CO 2 2 - - Temperature & Pressure Effect! Temperature & Pressure Effect! ? Carbonate precipitation favored by high temperatures, low pressure and breaking waves. ? Solubility of carbon dioxide increases with depth and drops in temperature ? CO 2 + 3H 2 O = HCO 3 -1 + H 3 O +1 + H 2 O = CO 3 -2 + 2H 3 O +1CO CO 2 2 - - Temperature & Pressure Effect! Temperature & Pressure Effect! ? At higher pressure CO 2 dissolves & is released at lower pressures ? HCO 3 -1 and CO 3 -2 are more stable at higher pressures but less stable at lower pressures ? HCO 3 -1 and CO 3 -2 reach higher concentrations in colder waters but lower concentration at warm watersCopied from Steven Wojtal of Oberlin CollegeCalcium Carbonate Calcium Carbonate - - Solubilty Solubilty ? Note behavior of calcium carbonate: CaCO 3 = Ca +2 ? Concentration of carbonate ion (CO 3 -2 ) is buffered by amount of CO 2 in solution ? Increasing pressure elevates concentrations of HCO 3 -1 & CO 3 -2 (products of solubility reaction) in sea water ? CaCO 3 is more soluble at higher pressuresCalcium Carbonate Calcium Carbonate - - Solubilty Solubilty ? Similar effect occurs with decreasing temperature ? CaCO 3 is more soluble in cool waters than warm waters ? CaCO 3 is increasingly soluble at depth in colder waters but precipitates in warm shallow waters Copied from Steven Wojtal of Oberlin CollegeCopied from Suzanne O'Connell Wesleyan CollegeCopied from Suzanne O'Connell Wesleyan College