Chapter 3: Day 6: Rock Processing Flashcards
Lithification
Processes by which sediments are transformed into sedimentary rocks
Compaction
Increased pressure from overlying sediment
Cementation
Binding together of sediments. By Calcite, Silica, and Iron Oxide
Fossils
Traces or remains of prehistoric life. Are the most important inclusions. Help determine past environments. Used as time indicators. Used for matching rocks from different places
New Rock From Old
. Form from preexisting igneous, sedimentary, or metamorphic rocks
. Take place due to temperatures and pressures unlike those in which it formed
. Leads to changes in mineralogy, texture, and chemical composition
. Often progresses incrementally
What are 3 Degrees of Metamorphism?
. Exhibited by rock texture and mineralogy
. Low-grade, slight changes (e.g., shale becomes slate)
. High-grade, obliteration of original features (e.g., shale becomes gneiss)
What are 4 Metamorphic Agents?
. Heat
. Pressure (stress)
. Confining pressure—from burial
. Differential stress—occurs during mountain building
Chemically active fluids
. Mainly water and other volatiles
. Promote recrystallization by enhancing ion migration
Foliation Texture
. Flat arrangement of mineral grains or structures
. Minerals are perpendicular to the compressional force/force of being squeezed in together
. Is formed where metamorphic rocks has differential stress that squeezes the rock together.
What are 4 Common Solutions of Foliation
slate, phyllite, schist, gneiss
Nonfoliated texture
. Contain equidimensional crystals
. Resembles a coarse-grained igneous rock
What are 2 Common Solutions of Nonfoliated texture
quartzite, marble
Metallic Mineral Resources
Produced by Igneous and Metamorphic processes. Most important ore deposits are generated from hydrothermal (hot-water) solutions
Examples of Metallic Mineral Resources
Gold, silver, copper, mercury, lead, etc.
Pegmatites
. Form fluid-rich environment, have unusually large crystals
. Vein deposits in fractures or bedding planes
. Disseminated deposits that are distributed throughout the rock
Non-Metallic Mineral Resources
. Make use of the material’s Nonmetallic elements
. Physical and/or chemical properties
Two broad groups of Non-Metallic Mineral Resources
. Building materials (e.g., limestone, gypsum)
. Industrial minerals (e.g., fluorite, corundum, sylvite)
Energy Resources
Coal, Oil, Natural Gas, and Oil trap
Coal
. It is used to set it on fire, produce energy, and give electricity and heat to buildings and homes.
. It is a very important fossil fuel that is used for since the Industrial Revolution. It uses energy when plants get from the sun before it turns into coal. This is why coal produces energy when it burned for fossil fuel.
. It’s form from plant matter where it changes in swampy environment where oxygen in water is very low due to muddy substance. It makes plant matter difficulty to break down. The plant matter builds and compress into hard material.
Types:
. Peat (Partially altered plant material)
. Lignite (If is compressed, it turns soft and brown)
. Bituminous (If is more compressed, it turns soft and black where it leaves black soot when rubbing on fingers)
. Anthracite (If is metamorphosed in the mountain building, it turns hard, black, and brassy luster where it don’t leave soot. It burns at hottest temperature.
Oil and Natural Gas
More than 60 percent of U.S.-consumed energy. Remains of marine plants and animals
Source rock
Where oil and natural gas originate
Oil trap
A place where oil can be lodged in the rock and not escape.
Two Basic Features of Oil Trap
. Reservoir rock: Rock that has a lot of empty pore space.
. Cap rock: s impermeable so the oil can’t flow through it and keeps them from surface escape.
What are 4 Common traps
. Anticlines: Classic petroleum trap. The strata are bowed upwards like a dome shape. Water is more dense of oil and gas, so the oil rises on top of the water. Nothing rises up to the cap rocks.
. Salt Domes: It has the salt dome when salt is under high pressure it will flow like a liquid, kind of like the blobs. It will pierce up through overlying sedimentary layers. It could create several oil traps.
. Faults: It creates traps if a cap rock is faulted up against another cap rock, and there’s a reservoir rock beneath.
. Stratiagraphic: It would occur if of change in sea level where a porous sedimentary unit ends up getting deposited on top of an impermeable unit and then the situation reverses and the impermeable unit is deposited back on top again.