Minerals
Igneous Rocks
Metamorphic Rocks/Metamorphism
Sedimentary Rocks
Volcanos
100
What are the 6 characteristics of a mineral?
1) Naturally occurring
2) Solid
3) Have a crystalline structure
4) Inorganic
5) Definite chemical composition
6) Homogenous
100
What is the difference between magma and lava?
Magma - Molten rock INSIDE earth's crust.
Lava - Molten rock on earth's SURFACE.
100
What are the causes of metamorphism?
Metamorphism takes place in response to changes in temperature, pressure, application of compression and shear, and/or interaction with hydrothermal fluids.The process involves reactions that take place without melting, and it can produce new textures and new minerals.
100
What are the differences between clastic/detrital, biological, organic, and chemical sedimentary rocks? Give examples of each.
1) Clastic/Detrital - Loose rock fragments (clasts) cemented together.
Rock Examples: conglomerate, breccia, sandstone, shale, mudstone
2) Chemical - Minerals that crystallize/precipitate directly from water.
Rock Examples: gypsum, halite, carbonates
3) Biochemical - Made of sediments derived from the shells of once-living organisms.
Rock Examples: limestone, coquina, chert
4) Organic - Rich on organic carbon from once living organisms/plants.
Rock Examples: coal, peat, oil shale
100
Describe what viscosity is.
Viscosity is the ability of a substance to resist flow. Higher viscosity means higher SiO2 (silica) content. Lower viscosity means lower SiO2 (silica) content.
200
What are the psychical properties that are used when identifying minerals?
1) Color
2) Luster
3) Streak
4) Hardness
5) Crystal Habit (shape)
6) Cleavage vs. Fracture
7) Acid Test (HCL)
8) Specific Gravity (Density)
200
What rate affects the size of crystals that form in an igneous rock?
RATE OF COOLING
Slow cooling = coarse grains (granite, gabbro)
Fast cooling = fine grains (basalt, rhyolite)
200
How does foliation develop in metamorphic rocks?
Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied.
200
What are some common sedimentary structures?
1) Bedding - Bedding is a primary sedimentary structure that refers to the arrangement of sedimentary layers or strata within a rock. It is formed by the deposition of sediments over time in horizontal or nearly horizontal layers, each representing a distinct episode of sedimentation.
2) Ripple marks - cm-scale ridges, directly reflect flow velocity and grain size. Sedimentary structures that develop on the surface of sedimentary layers as a result of the action of moving fluids, such as water or wind.
3) Crossbedding - Created by ripple and dune migration. Characterized by inclined layers or beds within a larger sedimentary sequence. These inclined layers are typically at an angle to the main horizontal bedding plane of the surrounding sedimentary rock.
4) Graded Bedding - Produced from turbidity currents. Base of structure is coarse grained and continuously gets finer as you move up the structure.
5) Mud cracks -Indicate alternate wet and dry terrestrial conditions. Sediments "dry out" and crack.
200
Describe the different types of lava flows and their characteristics.
300
Explain the processes that form minerals.
1) Crystallization - Freezing or cooling of a “liquid” (solidification of a melt).
2) Precipitation - ions dissolved in water bond together and separate. Solution is saturated with dissolved ions and new mineral form. (Minerals filling empty space, fractures or cavities. Ex. Geode)
300
What are intrusive rocks? What are extrusive rocks?
Intrusive (Plutonic) - Cooled beneath the surface.
Extrusive (Volcanic) - Cooled above the surface.
HELPFUL HINT:
INtrusive = cooled IN earth's crust
EXtrustive = cooled OUTSIDE earth's crust
300
What types of metamorphism occur at each plate boundary? List metamorphic rocks that form in these regions.
1) Divergent plate boundaries (Hydrothermal Metamorphism)
This occurs when seawater infiltrates through cracks in the oceanic crust and is heated by magma chambers beneath mid-ocean ridges. The hot water reacts with the surrounding rocks, altering their mineralogy and creating hydrothermal metamorphic rocks.
Rock Examples: serpentinite, chlorite schist
2) Convergent plate boundaries (Regional Metamorphism, Contact Metamorphism)
Regional Metamorphism - Intense pressure and temperature conditions associated with the subduction of one tectonic plate beneath another. (subduction zones, orogeny)
Contact Metamorphism - Occurs when rocks are subjected to high temperatures and moderate pressures due to being in close proximity to an igneous intrusion, such as a magma chamber. The heat from the intrusion causes the surrounding rocks to recrystallize and undergo changes in mineralogy and texture.
Rock Examples: slate, marble, gneiss, phyllite
3) Transform plate boundaries (Dynamic Metamorphism)
Shearing and deformation along transform plate boundaries result in dynamic metamorphism, where rocks are subjected to intense pressure and shearing forces.
Rock Examples: migmatite, granulite
300
How does transport and erosion effect sediments.
300
What are pyroclastic materials and their characteristics.
Pyroclastic rocks are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroclasts. Pyroclastic rocks are a type of volcaniclastic deposit, which are deposits made predominantly of volcanic particles. Classified by size.
1) Ash (<2 mm)
2) Lapilli (2 to 64 mm)
3) Bombs & Blocks (>64 mm)
400
Describe Felsic vs. Mafic
Felsic - Continental crust, lighter color, 68-77% SiO2.
Key Minerals: quartz, feldspar
Key Rocks: granite, rhyolite
Mafic - Oceanic crust, darker color, 48-52% SiO2.
Key Minerals: magnesium, ferric iron
Key Rocks: basalt, gabbro
400
Describe the texture of a porphyritic rock and how it forms.
Porphyritic textures develop when conditions during cooling of a magma change relatively quickly. The earlier formed minerals will have formed slowly and remain as large crystals, whereas, sudden cooling causes the rapid crystallization of the remainder of the melt into a fine grained (aphanitic) matrix.
400
Describe the main types of metamorphism.
1) Contact Metamorphism: This occurs when rocks are subjected to high temperatures and moderate pressures due to being in close proximity to an igneous intrusion, such as a magma chamber. The heat from the intrusion causes the surrounding rocks to recrystallize and undergo changes in mineralogy and texture. Contact metamorphism typically affects a relatively small area around the intrusion and is characterized by a zone of alteration called a contact aureole. The minerals formed are often characteristic of the temperature and pressure conditions present.
2) Regional Metamorphism: This type of metamorphism occurs over large areas and is associated with the intense pressure and temperature conditions found deep within the Earth's crust during mountain-building processes or tectonic plate collisions. Regional metamorphism typically produces significant changes in both mineralogy and texture, resulting in the formation of foliated or non-foliated rocks. Foliated rocks exhibit a layered or banded appearance due to the alignment of mineral grains, while non-foliated rocks lack this layering.
3) Dynamic Metamorphism (or Cataclastic Metamorphism): This occurs along fault zones or other areas of intense shearing and deformation, where rocks are subjected to high pressures and temperatures due to tectonic forces. Dynamic metamorphism results in the mechanical fracturing and recrystallization of rocks, often producing finely crushed or granulated textures. The mineralogy of dynamically metamorphosed rocks may remain relatively unchanged, but the texture can be significantly altered due to the deformation.
400
How are sedimentary rocks classified?
1) Clastic/Detrital - grain size, roundness, sorting, composition.
2) Chemical - Hardness, Precipitation (carbonates (HCL test), quartz SiO2), Evaporites.
3) Biochemical/Biogenic - presence of shells, ooids.
4) Organic - Presence of organic material (peat, coal)
400
Describe the 4 types of volcanos.
1) Sheild Volcanos - Built by successive flows from central vent and fissure zones. Fluid lava travels long distances. Creates a broad, shield-shaped edifice many 10’s of km in circumference.
2) Stratovolcanoes (Composite Volcanos) - Erupts fluid lava flows and explosive pyroclastic material. Makes the biggest & prettiest mountains (Mt. Shasta, Mt. Fuji, Vesuvius)
3) Cinder Cone - Cone shaped, center vent filled with rock fragments. Successive layers of ejected material, pyroclastic material.
4) Volcanic Dome - Viscous plug squeezes up like toothpaste and blocks vent. Gas builds up in underlying magma and may lead to explosive eruption to clear blocked vent.
500
Define the term atomic bonding. Describe the 2 types of atomic bonding that occur in minerals.
Atomic Bonding - The geometry of the atomic packing and the nature of chemical bonding determine the mineral properties.
Ionic bonding - Transfer of electrons.
Covalent bonding - The sharing of electrons. Strongest bond type.
500
What two criteria are used to classify igneous rocks?
1) Texture - Is dependent on cooling rate.
Aphanitic: fine crystals (cannot see with the naked eye). Rapid cooling (volcanic).
Rock Examples: Basalt, Rhyolite
Phaneritic: coarse crystals easily seen with the naked eye. Slow cooling (plutonic).
Rock Examples: Granite, Gabbro
2) Composition - Is dependent on the source material.
Ultramafic - 38 to 45% silica (peridotite)
Mafic (Mg and Fe-rich) - 45 to 52% silica (basalt, gabbro)
Intermediate - 52 to 66% silica (diorite)
Felsic (Feldspar and silica) - 66 to 76% silica (rhyolite, granite)
***BOWENS REACTION SERIES***
500
List the progression of metamorphic rocks from original depositions to the highest grade of metamorphism, i.e., shale–slate–phyllite–schist–gneiss. In what tectonic setting do these form?
These metamorphic rocks typically form in convergent plate boundary settings where intense pressure and temperature conditions associated with tectonic processes like mountain-building or subduction lead to metamorphism. The specific tectonic setting can vary, but convergent plate boundaries, where plates collide and undergo compression, are most commonly associated with the formation of high-grade metamorphic rocks like schist and gneiss.
500
Describe some depositional environments and the expected sediments within those environments.
1) Desert Environments - Sand-dune environments develop where there is an abundance of wind-blown, well-sorted sand.
2) Glacial Environments - Ice carries and dumps every grain size. A common feature of this environment is glacial till, a poorly sorted mixture of gravel, sand, silt, and clay.
3) Lake Environments - Gravels and sands near shore Well-sorted muds Finely laminated shales.
4) Evaporitic Environments - Evaporites (Created from evaporated water). Evaporation triggers deposition of chemical precipitates. Examples include halite (rock salt) and gypsum.
5) Shallow Marine Clastic Environments - Coastal beaches (Surf zone). Sediments are constantly being processed by waves. Well-sorted, well-rounded medium sand. (Coquina, Siltstone, Mudstone)
6) Shallow Marine Carbonate Environments - Biochemical precipitation of calcium carbonate that comes from once living critters. (oolite limestone)
7) Deep-Marine Environments - The skeletons of planktonic organisms make chalk or chert; fine silt and clay lithifies into shale.
500
Describe what fall, flow and surge deposits are.
Fall: formed from material explosively ejected from the vent.
Flow: gravity-controlled surface flows which travel as high particle concentration gas-solid dispersions.
Surge: gravity-controlled surface flow which travels as expanded, turbulent low particle concentration gas-solid dispersion.