Presentation on theme: "Chapter 6.1 Formation of Sedimentary Rocks. Vocabulary Texture- the size, shape, and crystal size Sediment- Pieces of solid material that have been deposited."— Presentation transcript:
Vocabulary Texture- the size, shape, and crystal size Sediment- Pieces of solid material that have been deposited on Earth’s surface by wind, water, ice, gravity, or chemical precipitation. Lithification- physical and chemical process that transform sediments into sedimentary rocks.
Vocabulary Cont. Cementation-when mineral growth cements sediment grains together into rock. Cross-bedding- bedding in which the particle sizes become progressively heavier and coarser towards the bottom layers. Graded bedding- bedding formed when inclined layers of sediment move forward across horizontal surface. Bedding- horizontal layering of sedimentary rocks.
Weathering Produces clastic sediment Physical Processes Minerals in rock are chemically unchanged. Rock fragments break off. Occurs when Earth’s crust is exposed Chemical Processes Minerals in rocks are chemically changed. Occurs through
Erosion and Transport Wind Moving Water Gravity Glaciers
Process of Lithification Lithification begins when the weight of overlaying sediments forces sediment grains closer together. Water in pressed out. The grains are then compacted together. Sediments that are buried will experience high temperatures and will have cementation.
Section 6.2 Vocab Clastic: sediments having particles ranging in size from boulders to microscopic particles, which often have worn surfaces and rounded corners. Clastic Sedimentary Rock: sedimentary rocks formed from deposits of loose sediments Porosity: the percentage of open spaces between grains in a rock Evaporite: chemical sedimentary rocks that form as a result of crystal grains precipitating out of a supersaturated body of water Reservoir: a subsurface area of rock that has enough porosity to allow for the accumulation of oil, natural gas, or water
Clastic sedimentary rocks Coarse-grained Type of fragments: gravel size Types of rock formed: conglomerate, breccia Formed by: high-energy flows of water Medium Grained Type of fragments: sand Type of rock formed: sandstone Formed by: stream and river channels, beaches, deserts Fine-grained Type of fragments: silt and mud Type of Rock formed: siltstone, shale
Medium-grained clastics Porosities as high as 30-40% -When pore spaces connected it allows for water to move through sandstone Can hold reservoirs of oil, natural gas, and groundwater Fine-grained clastics Very low porosity Form barrier to the movement of groundwater and oil Chemical Sedimentary Rocks
Sequence ___ Thick layers of evaporites can accumulate as evaporation removes freshwater. ___ Water evaporates and leaves behind dissolved minerals. ___ Minerals are dissolved and carried into lakes and oceans by chemical weathering. ___ Layers of chemical sedimentary rocks called evaporites form. ___ The concentration of minerals reaches the saturation point. ___ Crystal grains precipitate out of the solution and settle on the bottom. 1 2 3 4 5 6
Biochemical Sedimentary Rocks What forms them The remains of the once-living animals and plants Where they form Shallow-water environments Swamps and coastal areas How limestone forms Organisms use calcium carbonate in seawater to make their shells. Calcium carbonate precipitates out of the water and crystallizes between the grains of calcium sediment during lithification. How Coal forms Thick layers of vegetation accumulate. The layers are buried and compressed and are lithified into coal.
Importance of Sedimentary Rocks Provide Information about Sedimentary Rocks Provide Resources Past Animals and plants Bedrock Ancient Rivers, lakes, And shorelines Uranium Phosphate And iron Oil, natural Gas, and coal Building materials
Real-World Connection A company want to drill a new oil well. They know that a layer of oil containing shale is located beneath a thick layer of siltstone. Describe challenges the company might face. The siltstone has low porosity, so the oil will not flow though it. The company would have to drill though the siltstone to reach the oil-containing shale. If the layer of siltstone is too thick, the company might not be able to drill deep enough to reach the oil.
Intrusive- Igneous rocks that cool slowly beneath Earth’s surface Regional Metamorphism- Belts of metamorphic rock covering large areas Contact Metamorphism- Metamorphism that occurs when molten rocks come in contact with solid rocks. Hydrothermal Metamorphism- Metamorphism caused when very hot water reacts with rocks and alters its chemistry and mineralogy. Foliated- Metamorphic rocks containing wavy layers and bands of minerals. Nonfoliated- Metamorphic rocks composed of minerals with blocky shapes. Rock Cycle- The continuous cycle of changing and remaking rocks.
Causes of Metamorphism Conditions necessary for metamorphism High Pressure 1. Materials being buried alive 2. Igneous intrusion Low Pressure Can be caused by 1.Weight of the rocks above 2.Compressive forces during mountain building
Types of Metamorphism I.Regional Metamorphism A. Occurs when high temperatures and pressure affect large regions of Earth’s crust. B. Geologists can divide metamorphic rock belts into zones based on the mineral groups found in the rocks. II. Contact Metamorphism A. Occurs when magma comes in contact with solid rock. B. Can result in zones of different mineral surrounding an intrusion. III. Hydrothermal Metamorphism A. Occurs when very hot water reacts with rock and changes its chemistry and mineralogy. B. Can result in dissolved minerals, break down of minerals, and deposits of new minerals.
Metamorphic Texture TextureShape of crystals How formedExamples FoliatedFlat, needlelike High pressure during metamorphism Schist, gneiss NonfoliatedblockyNo pressure during metamorphism Quartzite, marble PorphyroblastVery largeReorganization of atoms during metamorphism garnet
Mineral Changes Like in fractional crystallization. Minerals in solid rock are stable at certain temperatures and pressures. During metamorphism. The minerals in rock change into new minerals. The new minerals are stable under the new temperatures and pressure conditions. These kinds of changes are called solid- state alterations. Compare mineral changes in metamorphism to changes in fractional crystallization. Name the process of mineral change in metamorphism.
Composition Changes Hot fluid movie in and out of rock during metamorphism. This can change the original composition of the rock. Chemical changes often happen during contact metamorphism near igneous intrusions. Hydrothermal fluids move into the surrounding rocks and change their mineralogy, texture and chemistry.
Synthesize Rocks are constantly changing from one type through internal and external processes. A rock’s age tells when it took its present form. A geologist says that a certain rock us 500 million years old. Tell if this can be true, and why or why not.
Other Metamorphic is Latin of “Changed form” James Hutton proposed the rock cycle in the 1700’s