Fig 5.12 WHERE DO SEDIMENTS ORIGINATE? WEATHERING OF PRE-EXISTING ROCKS

HOW ARE SEDIMENTS MOVED? (ERODED/TRANSPORTED) water wind ice gravity

WHERE DO SEDIMENTS ACCUMULATE?

75% OF SURFACE ROCKS ARE SEDIMENTARY.

JUST LIKE IGNEOUS ROCKS: TEXTURE MEANS SIZE OF GRAINS Fine-grained Coarse- grained

Sedimentary 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 DEPOSITION

WATER SORTS SEDIMENTS ACCORDNG TO SIZE, SO TEXTURE TELLS US ABOUT ENERGY OF E.O.D. Increasing energy = Increasing particle size

Layered nature of sedimentary rocks reflects depositional processes

What are SOURCES of sediments for sedimentary rocks?

Mechanical Weathering

Chemical Weathering KAlSi 3 O 8 + H + + HCO H 2 O ►► Potassium feldspar Al 2 Si 2 O 5 (OH) 4 + K + + HCO SiO 2 Clay mineral Carried away in solution Introduced in solution

Products 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 RX

Conglomerate & breccia very coarse-grained detrital rocks formed in high-energy environments conglomerate breccia

Sandstone* a coarse-grained detrital rocks formed in a medium to high-energy environment. * composition of grains is commonly quartz

Shale* a fine-grained detrital rock formed in a low-energy environment (most common sedimentary rock). * Composition of grains is almost always clay

Limestone* a chemical rock formed in a variety of environments, often with the assistance of organisms (most common chemical sedimentary rock). *composition is always calcite (CaCO 3 ), grain size is variable

Solution of calcite CO 2 + H 2 0 ► H 2 CO 3 CaCO 3 + H 2 CO 3 ► Ca (HCO 3 ) - Weathering Chemical Weathering Processes : solid solution solution solution 29

CaCO H + + (CO 3 ) 2- Ca (HCO 3 ) - Formation of Limestone Precipitation of Calcite solid solution solution solution 30

Rock 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 cycle

Non-metallic mineral resources are concentrated in sedimentary rocks. Examples? What processes concentrate these materials?

Limestone Quarry

Crushed 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 KAlSi 3 O 8 + H + + HCO H 2 O ►► Potassium feldspar Al 2 Si 2 O 5 (OH) 4 + K + + HCO SiO 2 Clay mineral Carried away in solution Introduced in solution