Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Limestone classification (depositional texture)
Document related concepts
no text concepts found
Transcript
What is limestone? Limestone = a biochemical sedimentary rock made up mostly of calcium carbonate Mineral Crystal system Formula Remarks Calcite Rhombohedral CaCO3 Dominant limestone mineral, especially in rocks older than Cenozoic Aragonite Orthorhombic CaCO3 Dominant mineral in Recent carbonate sediments; alters readily to calcite How do limestones form? Most limestones are simply the cemented remains of marine shells Limestone “anatomy” Grains Skeletal particles, ooids, peloids Lime mud Microscopic crystals produced by calcareous algae and through abrasion of larger particles Cement Inorganically precipitated CaCO3 crystals Skeletal grains ooids peloids Lime mud Calcite cement Factors affecting precipitation of CaCO3 in sea water Factor Type of change Physical effect Effect on CaCO3 Temperature Increase Loss of CO2, increase in pH Increase precipitation Pressure Decrease Loss of CO2, increase in pH Increase precipitation Salinity Decrease Decrease activity of “foreign” cations Increase precipitation Photosynthesis Removes CO2 from sea water; pH increases Increase precipitation Bacterial activity Catalyzes CaCO3 precipitation Increase precipitation Where do limestones form? Because CaCO3 precipitates most readily in warm, well lit, agitated water of normal marine salinity…..most limestones form in shallow, tropical depositional environments e.g., Bahamas, central America, Persian Gulf, NW shelf of Australia, Great Barrier Reef, Malaysia, Indonesia, etc. Modern CaCO3 depositional environments *Note: Although cool water carbonates Are forming in many places, they are highly prone to dissolution and therefore do not become major limestone accumulations Caicos Platform Reef tract Quiet water high-energy sand shoals Prevailing winds North America during the Devonian Period Iowa during the Devonian Period What are limestone products? Whole rock Crushed limestone Dolomitic limestone Burned lime (calcium oxide) High calcium lime Dolomitic lime Hydrated lime (calcium hydroxide) How is limestone used? Construction Soil stabilization Flue Gas Desulfurization Steel Production (flux for blast furnaces) Glass Production Water Treatment Waste Treatment Paper Production (filler) Chemical Production Masonry, Mortars and Other Building Materials
Related documents