Sedimantoloji Karbonatlara Bakış ( İngilizce İçerik ) - 2 Calcitic & Aragonitic Ooids Great Salt LakeGrapestones GrapestonesGrapestones GrapestonesPellets PelletsPellets PelletsSkeletal Particles Skeletal Particles - - Mineralogy Mineralogy ? Calcite commonly containing less than 4 mole % magnesium ? Some foraminifera, brachiopods, bryozoans, trilobites, ostracodes, calcareous nannoplankton & tintinnids ? Magnesian calcite, with 4-20 mole % magnesium ? Echinoderms, most foraminifera, & red algaeSkeletal Particles Skeletal Particles - - Mineralogy Mineralogy ? Aragonite tests ? Corals, stromatoporoids, most molluscs, green algae, & blue-green algae. ? Opaline silica ? sponge spicules & radiolariansDrafted by Waite 99, after James 1984)Foraminifera ForaminiferaAfter Scholle After Scholle Foraminifera ForaminiferaBrachiopod BrachiopodBrachiopods BrachiopodsBryozoan BryozoanBryozoan BryozoanTrilobite Trilobite Remains Remains Ostracod Ostracod Remains Remains Calcispher Calcispher es esCrinoid CrinoidRed Calcareous Red Calcareous Algae AlgaeSurface Water Organic Productivity Surface Water Organic Productivity ? Marine algae & cyanobacteria base of marine food chain ? Fed by available nitrogen and phosphorus ? Supplied in surface waters by deep water upwellingSurface Water Organic Productivity Surface Water Organic Productivity ? Vertical upwelling drives high biological productivity at: ? Equator ? Western continental margins ? Southern Ocean around Antarctica ? Produce biogenous oozesDeep Water Carbonate Deposits Deep Water Carbonate Deposits ? Deep water pelagic sediments accumulate slowly (0.1-1 cm per thousand years) far from land, and include: ? abyssal clay from continents cover most of deeper ocean floor ? carried by winds ? ocean currents ? Oozes from organisms' bodies; not present on continental margins where rate of supply of terriginous sediment too high & organically derived material less than 30% of sediment Carbonate Compensation Depth Carbonate Compensation Depth - - CCD CCD ? Deep-ocean waters undersaturated with calcium carbonate & opalline silica. ? Biogenic particles dissolve in water column and on sea floor ? Pronounced for carbonates ? Calcareous oozes absent below CCD depthCarbonate Compensation Depth Carbonate Compensation Depth - - CCD CCD ? CCD varies from ocean to ocean ? 4,000 m in Atlantic. ? 500 - 1,500 m in Pacific ? Siliceous particles dissolve more slowly as sink & not so limited in distribution by depth ? Nutrient supply controls distribution of siliceous sedimentsAfter James, 1984Naming Naming and and describing describing Limestones LimestonesCarbonate Cement Fabrics Carbonate Cement Fabrics ? Crust or rims coat grains, ? Syntaxial overgrowth: ? optical continuity with skeletal fabric ? Echinoid single crystals ? Brachiopod multiple crystals ? Blocky equant: ? final void fillIsopachus Marine CementMeniscus Cement