Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16What are SOURCES of sediments for sedimentary rocks? Slide Number 18Chemical WeatheringSlide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Chemical WeatheringFig 5.12 WHERE DO SEDIMENTS ORIGINATE? WEATHERING OF PRE-EXISTING ROCKSHOW ARE SEDIMENTS MOVED? (ERODED/TRANSPORTED) • water • wind • ice • gravityWHERE DO SEDIMENTS ACCUMULATE?75% OF SURFACE ROCKS ARE SEDIMENTARY.JUST LIKE IGNEOUS ROCKS: •TEXTURE MEANS SIZE OF GRAINS Fine-grained Coarse- grainedSedimentary Rocks: Form in surface environments (75% of earth’s surface)  Classified according to texture (in part)  Reflect conditions of environment of formation  Accumulate in layers over time (can be “read” like pages in a book)JUST LIKE IGNEOUS ROCKS: •TEXTURE IN SEDIMENTARY ROCKS IS A MEANS TO CLASSIFY ROCKS • BUT ALSO TELLS US ABOUT FORMATION OF ROCK … • TEXTURE RELATES TO ENERGY OF ENVIRONMENT OF DEPOSITIONWATER SORTS SEDIMENTS ACCORDNG TO SIZE, SO TEXTURE TELLS US ABOUT ENERGY OF E.O.D. Increasing energy = Increasing particle sizeLayered nature of sedimentary rocks reflects depositional processesWhat are SOURCES of sediments for sedimentary rocks?Mechanical WeatheringChemical Weathering KAlSi3O8 + H+ + HCO3- + H2O Potassium feldspar Al2Si2O5(OH)4 + K+ + HCO3- + SiO2 Clay mineral Carried away in solution Introduced in solutionProducts from mechanical /chemical wxg Solids (residuals) Dissolved minerals From chem. wxg (in solution) secondary minerals from chemical wxg (clays, iron oxides) Primary minerals from mechanical wxg (quartz sand) Minerals + organics = SOIL DETRITAL (CLASTIC) SED RX CHEMICAL SED RXConglomerate & breccia very coarse-grained detrital rocks formed in high-energy environments conglomerate brecciaSandstone* a coarse-grained detrital rocks formed in a medium to high-energy environment. * composition of grains is commonly quartzShale* a fine-grained detrital rock formed in a low-energy environment (most common sedimentary rock). * Composition of grains is almost always clayLimestone* a chemical rock formed in a variety of environments, often with the assistance of organisms (most common chemical sedimentary rock). *composition is always calcite (CaCO3), grain size is variable• Solution of calcite • CO2 + H20 H2CO3 • CaCO3 + H2CO3 Ca 2+ + 2 (HCO3)- Weathering Chemical Weathering Processes: solid solution solution solution 29• CaCO3 + 2 H+ + (CO3)2- Ca 2+ + 2 (HCO3)- Formation of Limestone Precipitation of Calcite solid solution solution solution 30Rock Salt: a chemical rock formed from evaporation of water (evaporite)Sedimentary processes and life processes are intermingled Fossils are evidence of past life. They are concentrated in sedimentary rocks.• What are fossil fuels? •Coal •Oil •Natural gas All are organic materials with C-H bonds Fossils fuels are concentrated in sedimentary rocks.Geologic requirements for oil production: • source rock • reservoir rock • trap• What is proposed relationship between fossil fuels and global warming?Global carbon cycleGlobal mean surface temperature during the last few decades of the 20th century is higher than any comparable period than during the last 400 years. --National Academy of ScienceNon-metallic mineral resources are concentrated in sedimentary rocks. • Examples? • What processes concentrate these materials?Limestone QuarryCrushed stone • Price: $6.80 per ton • Volume: 1.1 billion tons • Value? • Relative cost of development? Copper • Price: $3,230 per ton • Volume: 2.2 million tons • Value? • Relative cost of development?Chemical Weathering KAlSi3O8 + H+ + HCO3- + H2O Potassium feldspar Al2Si2O5(OH)4 + K+ + HCO3- + SiO2 Clay mineral Carried away in solution Introduced in