W2-3 Rock cycle

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Questions and Answers

What primary role does the biosphere play in the transformation of fresh rock into regolith?

  • It shields rocks from the effects of the hydrosphere and atmosphere.
  • It contributes to tectonic uplift, exposing new rock surfaces.
  • It facilitates the breakdown of rocks through the actions of living organisms and organic acids. (correct)
  • It directly melts exposed rocks through geothermal activity.

How does the chemical weathering process primarily affect the stability of minerals found in igneous and metamorphic rocks when they are exposed at Earth's surface?

  • It causes them to become more resistant to surface conditions by increasing their hardness.
  • It chemically alters them into new, more stable minerals that are in equilibrium with surface conditions. (correct)
  • It instantaneously transforms them into more stable minerals through intense heat and pressure.
  • It encases them in protective layers that prevent further degradation.

Under what specific conditions does pressure reduction lead to the disintegration of rocks, contributing to the formation of regolith?

  • When the overlying material is removed by erosion, decreasing the pressure on the rock and causing it to expand and fracture. (correct)
  • When rocks are rapidly cooled, causing them to contract and develop surface cracks.
  • When rocks are deeply buried and subjected to extreme confining pressures from overlying strata.
  • When tectonic forces compress rocks, leading to internal stresses and eventual breakage.

How does the process of frost wedging contribute to the physical weathering of rocks?

<p>By the expansion of freezing water in cracks and crevices, exerting pressure that widens the openings and splits the rock. (B)</p> Signup and view all the answers

In what specific way does physical weathering enhance the effects of chemical weathering on rocks?

<p>By breaking rocks into smaller pieces, thereby increasing the surface area available for chemical reactions. (B)</p> Signup and view all the answers

What is the underlying mechanism by which weak carbonic acid facilitates chemical weathering?

<p>It donates hydrogen ions that react with minerals, breaking them down and forming new compounds. (D)</p> Signup and view all the answers

How does the removal of potassium ions (K+) from a feldspar crystal during chemical weathering influence the crystal's structure and composition?

<p>It leaves an insoluble residue of clay minerals, altering the original feldspar crystal. (C)</p> Signup and view all the answers

What critical distinction differentiates sediment from regolith, based on their role in Earth's surface processes?

<p>Regolith is weathered material that remains in place, while sediment is transported weathered material. (B)</p> Signup and view all the answers

What is the most significant implication of the continuous removal of weathered particles by agents like water, wind, and ice?

<p>It exposes fresh rock surfaces, promoting further weathering and landscape evolution. (B)</p> Signup and view all the answers

What characteristic fundamentally distinguishes clastic sediments from chemical sediments?

<p>Clastic sediments are transported as solid particles, while chemical sediments are transported in solution and precipitate out. (B)</p> Signup and view all the answers

How does the presence of calcium carbonate shells in sediments indicate a biochemical origin?

<p>Calcium carbonate shells are formed by living organisms and indicate biogenic activity. (B)</p> Signup and view all the answers

What is the crucial role of compression and time in the lithification process that transforms sediment into sedimentary rock?

<p>They reduce pore space and allow cementation, binding the sediment particles together. (D)</p> Signup and view all the answers

How are the textures and compositions of conglomerate and sandstone fundamentally different, relating to their formation environments?

<p>Conglomerate is formed from rounded gravel in high-energy environments, while sandstone is formed from sand-sized particles in various energy settings. (A)</p> Signup and view all the answers

What key feature distinguishes shale or mudstone from siltstone in terms of particle size and depositional environment?

<p>Shale and mudstone are composed of the finest particles deposited in low-energy environments, while siltstone is composed of slightly coarser particles. (A)</p> Signup and view all the answers

How does the concept of the rock cycle relate to the interaction between the geosphere, hydrosphere, atmosphere, and biosphere?

<p>The rock cycle is driven by interactions among all Earth systems, which contribute to the weathering, erosion, deposition, and lithification of rocks. (B)</p> Signup and view all the answers

What is the most significant consequence of diagenesis on sediments undergoing lithification?

<p>Alteration of sediment composition and texture through low-temperature and low-pressure changes. (C)</p> Signup and view all the answers

How does the process of recrystallization contribute to the lithification of sediment?

<p>By rearranging crystals of less stable minerals into more stable forms, enhancing rock strength and stability. (B)</p> Signup and view all the answers

Why is the presence of fossils considered a significant indicator of sedimentary rock origin?

<p>Fossils provide definitive evidence of the environments and life forms present during sediment deposition. (D)</p> Signup and view all the answers

How does the sorting of sediments influence the characteristics of the resulting sedimentary rock?

<p>Well-sorted sediments typically indicate a consistent energy environment, leading to more uniform rock properties. (B)</p> Signup and view all the answers

How does the process of compaction facilitate lithification?

<p>By applying weight that reduces pore space and forces grains into closer contact, aiding cementation. (B)</p> Signup and view all the answers

Where would you most likely find locations of clastic sediment deposits?

<p>Troughs, rift valleys, trenches, and basins controlled by plate tectonics. (D)</p> Signup and view all the answers

According to the course material, what primary factor dictates the downslope movement of rock and the flow of fluids during mass wasting events?

<p>The force of gravity. (A)</p> Signup and view all the answers

What role does cementation play in the transformation of sediment into sedimentary rock?

<p>It binds sediment grains together through the precipitation of minerals from pore fluids. (D)</p> Signup and view all the answers

How do earthquakes contribute to mass wasting?

<p>By triggering landslides on unstable slopes. (D)</p> Signup and view all the answers

In the context of sediment transport, what distinguishes 'saltation' from 'surface creep'?

<p>Saltation refers to particles moving in short jumps or bounces, while surface creep involves slow rolling or sliding along the surface. (B)</p> Signup and view all the answers

How do volcanic eruptions instigate mass wasting events?

<p>Volcanic eruptions can deposit unstable material on slopes and trigger lahars. (C)</p> Signup and view all the answers

How does the relative water velocity affect the transportation of sediment within a stream?

<p>Higher water velocity allows for the transport of larger particles and increases the amount of sediment that can be carried. (D)</p> Signup and view all the answers

During sediment transport in a stream, under what conditions are larger particles most likely to be transported as part of the bed load?

<p>During periods of high discharge and stream power. (D)</p> Signup and view all the answers

How does long-term suspension differ from short-term suspension in sediment transport?

<p>Long-term suspension involves particles that remain suspended for extended periods due to their small size. (A)</p> Signup and view all the answers

What is 'bedding' in sedimentary rocks, and how does it form?

<p>A banded appearance that results from sediment deposition in layers. (C)</p> Signup and view all the answers

How would the absence of water fundamentally change the process of chemical sediment formation?

<p>It would inhibit the dissolution and transportation of ions, preventing the formation of chemical sediments. (D)</p> Signup and view all the answers

How does the principle of original horizontality most directly influence the interpretation of geological history in regions with intensely folded strata?

<p>It indicates that the strata were originally deposited horizontally and subsequently deformed. (C)</p> Signup and view all the answers

In regions undergoing significant tectonic activity, how might the principle of stratigraphic superposition be used to determine relative ages of rock layers when faulting is present?

<p>Faults displace layers, but the original sequence from bottom to top still indicates relative age unless overturning has occurred. (A)</p> Signup and view all the answers

How can the analysis of lateral continuity aid in predicting the extent and volume of a potential aquifer in a region with complex geological structures?

<p>By tracing the thinning of permeable layers to estimate the aquifer's boundaries and recharge rates. (D)</p> Signup and view all the answers

What challenges arise in applying stratigraphic correlation to determine the age equivalence of sedimentary rocks across vast distances with few shared fossils or marker beds?

<p>Changes in depositional environments lead to different sedimentary characteristics, complicating direct comparisons. (D)</p> Signup and view all the answers

Under what complex scenario might the principles of cross-cutting relationships and superposition be simultaneously applied to determine the age of a dike intrusion within a sequence of faulted sedimentary layers?

<p>If the dike cuts the sedimentary layers but is offset by the faults, it is older than the faults but younger than the layers. (C)</p> Signup and view all the answers

How does the presence of an angular unconformity specifically challenge the direct application of stratigraphic superposition in determining the age sequence of rock layers?

<p>It represents a time gap where some rock record is missing, requiring careful consideration of the missing interval when determining relative ages. (C)</p> Signup and view all the answers

How can one differentiate between a disconformity and a paraconformity in sedimentary rocks, and why is this distinction crucial for accurate geological interpretations?

<p>Disconformities show clear erosional surfaces, while paraconformities are identified by time gaps without physical evidence, making age determination more complex. (C)</p> Signup and view all the answers

What complex depositional and diagenetic processes influence the preservation of fossils in mudstone compared to sandstone, considering their relative porosity and permeability?

<p>Mudstone's lower permeability prevents fluid flow, reducing fossil alteration, while sandstone's porosity leads to greater alteration. (C)</p> Signup and view all the answers

How does the presence of rounded clasts in conglomerate versus angular clasts in breccia provide insights into the energy levels and transport distances of their respective depositional environments?

<p>Rounded clasts indicate high energy and long transport, while angular clasts mean low energy and short transport. (A)</p> Signup and view all the answers

How does the transformation of shale into slate during low-grade metamorphism illustrate changes in texture and mineral alignment under differential stress?

<p>The platy minerals in shale realign perpendicularly to the direction of maximum stress, creating a foliation in slate. (C)</p> Signup and view all the answers

What are the limitations of using color as the primary method of stratigraphic correlation across sedimentary basins with varying redox conditions and organic matter content?

<p>Color variations may reflect differences in mineral composition and oxidation state rather than age equivalence. (A)</p> Signup and view all the answers

How might the principle of lateral continuity be applied to predict subsurface reservoir geometries in petroleum exploration, particularly in complex deltaic environments?

<p>By mapping the thinning and pinching out of sand bodies to define potential reservoir limits and flow barriers. (D)</p> Signup and view all the answers

How can the detailed petrographic analysis of sandstone, including its grain size, sorting, and mineral composition, be used to reconstruct the tectonic setting and weathering history of its source region?

<p>Mature sandstones with well-rounded grains suggest high-energy, stable tectonic settings, while immature sandstones indicate active settings with rapid uplift and erosion. (B)</p> Signup and view all the answers

How does the development of foliation in metamorphic rocks, such as the transformation of shale to schist, reflect the interplay between differential stress, mineral alignment, and metamorphic grade?

<p>Differential stress causes platy minerals to align perpendicularly, intensifying with metamorphic grade and creating a layered texture. (D)</p> Signup and view all the answers

What conditions are most conducive to metasomatism?

<p>Abundant pore fluids involved in metamorphism. (D)</p> Signup and view all the answers

What is the primary significance of differential stress in metamorphism?

<p>It implies direction and is recorded in metamorphic rock textures. (A)</p> Signup and view all the answers

What metamorphic feature results from extreme differential stress?

<p>Parallel alignment of minerals/foliation. (D)</p> Signup and view all the answers

How does confining pressure and directed stress relate to foliation?

<p>Confining pressure inhibits foliation; directed stress encourages parallel alignment. (B)</p> Signup and view all the answers

What is a critical result of metamorphism?

<p>The creation of new stable mineral assemblages. (D)</p> Signup and view all the answers

How do changing temperature and pressure conditions primarily alter rocks?

<p>Through mechanical deformation or chemical recrystallization. (D)</p> Signup and view all the answers

What is the primary cause of chemical reactions and recrystallization in contact metamorphism?

<p>High temperatures from magma intrusion. (D)</p> Signup and view all the answers

Why does burial metamorphism occur?

<p>Burial to depths with increased temperatures. (C)</p> Signup and view all the answers

What is responsible for the differential stress, mechanical deformation and recrystallization found in regional metamorphism?

<p>Mountain range formation. (C)</p> Signup and view all the answers

How are metamorphic rocks classified?

<p>By rock texture and mineral assemblage. (C)</p> Signup and view all the answers

How does plate tectonics directly influence metamorphism?

<p>By explaining the regional distribution of metamorphic facies. (B)</p> Signup and view all the answers

What is a derivative of shale in metamorphic rock classification?

<p>Slate (D)</p> Signup and view all the answers

What determines rock properties once rock is heated, even to partial melting, and becomes magma?

<p>Cooling and crystalization. (C)</p> Signup and view all the answers

What determines crystal size?

<p>Rate of Cooling. (B)</p> Signup and view all the answers

What is mafic rock?

<p>Rock that contains little silica. (D)</p> Signup and view all the answers

What conditions during fractional crystallization would lead to the most significant changes in the composition of the remaining magma?

<p>Rapid removal of early-formed crystals and continuous injection of magma with a distinctly different composition. (B)</p> Signup and view all the answers

How does the presence of existing crystal structures within a magma chamber influence the textures of newly formed igneous rocks during subsequent cooling phases?

<p>It can promote heterogeneous nucleation, leading to porphyritic textures with varied grain sizes. (A)</p> Signup and view all the answers

If a section of the Earth's crust experiences both uplift and increased denudation, which factor would primarily determine whether the land surface in that area is elevated or lowered over time?

<p>The balance between the rate of uplift and the rate of denudation. (C)</p> Signup and view all the answers

How would increased rates of both uplift and denudation in a mountainous region most likely affect the sediment composition and deposition patterns in the adjacent lowlands?

<p>Increase sediment flux, promoting deposition of poorly sorted, coarse-grained sediments closer to the source. (A)</p> Signup and view all the answers

How might alternating layers of welded tuff and agglomerate provide insights into the eruptive history of a volcano?

<p>They suggest cyclical variations in eruptive intensity, transitioning between ash-rich and bomb-rich phases. (B)</p> Signup and view all the answers

In a region experiencing significant tectonic activity and volcanism, how are the principles of uplift, isostasy, and denudation intertwined to shape the landscape?

<p>Tectonic uplift initiates landscape change, with isostatic adjustments modifying the effects of denudation, leading to a dynamic equilibrium. (B)</p> Signup and view all the answers

How does the long-term interplay between tectonic activity and climate variability influence the formation and preservation of specific geological features?

<p>Tectonic events initiate change, but climate mediates the rate and style of denudation, affecting long-term feature preservation. (D)</p> Signup and view all the answers

What is the most significant difference between the cooling process of volcanic rock and plutonic rock?

<p>Volcanic rock cools rapidly on the Earth's surface, while plutonic rock cools slowly within the Earth's crust. (B)</p> Signup and view all the answers

When considering the cooling rates of igneous rocks, how does the Bowen's reaction series relate to the resulting mineral composition?

<p>Minerals that crystallize early in Bowen's series are more likely to be found as phenocrysts in porphyritic rocks, having had time to grow larger before the rest of the melt cooled rapidly. (A)</p> Signup and view all the answers

Concerning fractional crystallization, how does the removal of early-formed crystals from a magma affect the composition of the remaining melt, and what implication does this have for the diversity of igneous rocks?

<p>It enriches the melt in elements that were not incorporated into the early-formed crystals, leading to a wider range of igneous rock compositions. (A)</p> Signup and view all the answers

Which of the following scenarios would most likely result in the formation of a porphyritic igneous rock?

<p>Slow cooling at depth followed by rapid cooling at the surface. (D)</p> Signup and view all the answers

How does the principle of isostasy specifically relate to the long-term erosional processes in a mountain range?

<p>Erosion unloads the mountain range, leading to isostatic uplift and continued exposure of deeper rocks. (D)</p> Signup and view all the answers

How can pyroclastic rocks provide specific insights into the explosivity and volcanic processes of past eruptions?

<p>The grain size distribution and composition directly reflect the magma's viscosity, gas content, and fragmentation efficiency during eruption. (A)</p> Signup and view all the answers

What are the effects of the continuous and ongoing contest between internal and external forces on the Earth's surface?

<p>Constant changes of the Earth's surface reflect the ongoing contest between internal forces that raise the lithosphere and external forces that wear it down. (A)</p> Signup and view all the answers

How is the rate of denudation related to uplift rates and the overall relief of a landscape?

<p>Uplift rates and denudation rates are directly proportional. If the rate of uplift is very high, denudation cannot counteract the change in landform, yielding increased altitude and relief. (D)</p> Signup and view all the answers

Flashcards

Weathering

Breakdown of rocks into smaller pieces by physical and chemical processes.

Regolith

Layer of loose, unconsolidated material covering bedrock.

Mechanical weathering

Physical disintegration of rocks into smaller fragments.

Pressure reduction

Disintegration of rock due to pressure release.

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Frost wedging

Water freezes in cracks, expands, and breaks rocks.

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Salt wedging

Salt crystals grow in rock pores, causing disintegration.

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Chemical Weathering

Chemical alteration of minerals into more stable forms.

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Carbonic acid weathering

Weak carbonic acid dissolves minerals in rocks.

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Erosion

The transportation of weathered material by wind, water, or ice.

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Sediment

Accumulated transported regolith.

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Deposition

The location where sediment accumulates.

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Clastic Sediment

Sediment made of broken rock and minerals.

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Chemical Sediment

Sediment formed from dissolved substances.

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Biogenic Sediment

Sediment from biochemical reactions in water.

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conglomerate

Gravel cemented

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Mass wasting

The downslope movement of rock and regolith controlled by gravity.

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Lithification

The process by which sediment or regolith becomes solid rock.

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Bedding

A banded appearance in sedimentary rocks resulting from sediment deposition in layers.

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Process of lithification

A multi-step process that transforms sediment into sedimentary rock.

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Compaction

The process where sediment accumulates, causing the pile to grow thicker.

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Cementation or Recrystallization

The process where particles adhere to each other through mineral precipitation or crystal growth.

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Diagenesis

Low-temperature and low-pressure changes that happen to sediment after deposition.

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Sorting

The way particles in sediment vary in size; can be well sorted or poorly sorted.

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Stream Load

Material transported downstream by a body of water.

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Bed load

Heavy sediment (sand, pebbles, boulders) that moves along the stream bed.

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Suspended load

Sediment (silt and clay) carried within the water column.

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Surface creep

The state when material rolls/slides/creeps to move along the surface.

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Saltation

A process where grains bounce or hop along the stream bed.

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Dissolved load

Dissolved ions transported in a body of water.

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Clastic Sediment Deposition

Low-lying areas where clastic sediments are deposited, often controlled by plate tectonics.

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Clastic Sedimentary Rock

Rock formed from lithified clastic sediment.

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Breccia

Sedimentary rock with angular clasts larger than 2 mm.

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Sandstone

Sedimentary rock made of clasts (0.5 - 2 mm).

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Siltstone

Sedimentary rock with silt and clay-sized particles.

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Shale

Rock with clay-sized particles that splits easily into sheets.

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Mudstone

Shale that does not split into sheets.

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Chemical Sedimentary Rock

Rock from lithified chemical sediment via mineral precipitation.

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Evaporite

Rock formed by evaporation.

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Banded Iron Formation

Rock formed during atmospheric shift from O2-poor to O2-rich.

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Limestone

Rock of lithified shells/skeletal material from sea organisms.

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Chert

Rock containing tiny quartz particles from siliceous skeletons.

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Original Horizontality

Sediments are deposited in horizontal layers.

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Stratigraphic Superposition

Order of strata from bottom to top indicates deposition sequence.

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Lateral Continuity

Sediment extends horizontally, thinning laterally.

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Pore Fluids in Metamorphism

Fluids trapped in rock pores accelerate reactions during metamorphism.

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Metasomatism

Metamorphism with abundant pore fluids, altering the rock's composition.

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Heat Sources for Metamorphism

Heating from burial, intrusions, or collisions can induce metamorphism.

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Stress (in Metamorphism)

Force applied in a specific direction during metamorphism, more informative than pressure.

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Differential Stress

Stress that is unequal in different directions

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Mineral Alignment

Parallel alignment of minerals under differential stress, creating striped or planar patterns (gneiss or foliation).

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New Mineral Assemblages

New minerals formed during metamorphism, stable under the new conditions.

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Metamorphic Processes

Rock transformation from changing temperature/pressure, either mechanical or chemical.

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Contact Metamorphism

Occurs when magma intrudes rock, causing localized high-temperature alteration.

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Burial Metamorphism

Results from deep burial, typically at temperatures exceeding 150°C.

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Regional Metamorphism

Occurs over large areas due to differential stress and recrystallization during mountain formation.

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Rock Texture (Metamorphic)

Metamorphic rocks are classified by this, along with mineral content.

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Shale's Metamorphic Sequence

Shale transforms via metamorphism into slate, phyllite, schist, then gneiss.

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Metamorphic Facies

States that mineral assemblage depends on temperature, pressure, and rock composition.

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Plate Tectonics and Metamorphism

Explains the distribution of metamorphic facies and associated rocks.

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Volcanic rock

Rocks formed from rapid cooling of lava, leading to small mineral grains.

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Glass (Volcanic)

Rapidly cooled lava that solidifies into a non-crystalline solid.

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Pyroclastic Rock

Rock formed from volcanic fragments, transitional between igneous and sedimentary.

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Welded Tuff

Pyroclastic rock formed from fused volcanic ash.

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Agglomerate (Tephra)

Bomb-sized pyroclastic tephra.

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Tuff (Tephra)

Lapilli or ash-sized pyroclastic tephra.

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Plutonic Rock

Rocks formed from slow cooling of magma, leading to large crystals.

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Coarse Grained Texture

Igneous rock with coarse grains due to slow cooling.

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Pegmatite

Extremely coarse-grained intrusive igneous rock.

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Porphyry

Igneous rock with a mix of large and small grains.

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Fractional Crystallization

Process that contributes diversity to igneous rocks.

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Denudation

The destructive effects of weathering, erosion, and mass wasting due to gravity and the sun's energy.

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Drivers of Earth's Surface Changes

Uplift, isostasy, and volcanism caused by Earth's internal heat energy.

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Landform development

They are controlled by process, climate, lithology, relief and time

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Landscape Timeframes

Earth's landscape features evolve over extended periods.

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Study Notes

New Rock from Old

  • Metamorphic rocks undergo changes in texture, mineralogy, or both while in the solid state.
  • Low-grade metamorphism occurs between 150°C–550°C and at low pressure.
  • High-grade metamorphism occurs above 550°C and at high pressure.
  • Other factors, including fluids, time, and stress, also play an important role in metamorphism.
  • Fluids trapped in the pores between rock grains heat up during metamorphism and speed up chemical reactions.
  • Abundant pore fluids involved in metamorphism is called metasomatism.
  • Rock can be heated by burial, exposure to igneous intrusions, or collision.
  • Each of these can be associated with different pressures, so metamorphism can rarely be due only to temperature.
  • Stress implies direction and is a more useful term than pressure.
  • Metamorphic rocks record differential stress in their textures.
  • Differential stress is stress that is not equal in all directions.
  • Differential stress commonly produces the parallel alignment of certain minerals which gives the rock a stripey pattern(gneiss) or planar fabric(foliation).
  • Metamorphism also produces new mineral assemblages that are stable at the new pressure and temperature.
  • The processes that result from changing temperature and pressure are either mechanical deformation or chemical recrystallization, or both.
  • Different kinds of metamorphism reflect the importance of the two processes.
  • Contact metamorphism occurs where magma intrudes rock; high temperatures cause chemical reactions and recrystallization.
  • Burial metamorphism occurs when buried sediment attains temperatures greater than 150°C, causing recrystallization.
  • Regional metamorphism involves differential stress, mechanical deformation, and recrystallization from mountain range formation.
  • Classification of metamorphic rocks is based on rock texture and mineral assemblage.
  • Classification primarily names the metamorphic derivatives of:
  • Shale -> slate -> phyllite -> schist -> gneiss
  • Basalt -> greenschist -> amphibolite -> granulite
  • Limestone -> marble
  • Sandstone -> quartzite
  • For a given range of temperature and pressure and for a given rock composition, the assemblage of minerals formed during metamorphism is always the same, according to the concept of metamorphic facies.
  • Plate tectonics explains the regional distribution of metamorphic facies and regionally metamorphosed rock.

From Rock to Magma and Back Again

  • When rock is heated to the point of melting, even partial melting, it becomes magma, which will become igneous rock.
  • Cooling and crystallization determine the properties of the igneous rock.
  • Crystals grow in an interlocking texture.
  • The rate of cooling determines crystal size.
  • Rocks that contain a lot of silica are called felsic; rocks that contain little silica are called mafic.
  • When magma or lava solidifies, the mineral assemblage is the same for both intrusive and extrusive rock; however, the texture is different.
  • Rapid cooling creates volcanic rock.
  • Volcanic rocks have a fine-grained texture because lava cools so rapidly that minerals do not have time to grow large.
  • Some lava cools so rapidly that it forms glass.
  • Pyroclastic rock is transitional between igneous and sedimentary rock, forming tephra.
  • Fused ash forms welded tuff.
  • Bomb-sized tephra is called agglomerate.
  • Lapilli or ash-sized tephra is called tuff.
  • Slow cooling creates plutonic rock.
  • Intrusive igneous rock tends to be coarse-grained because magma within the crust cools slowly, enabling crystal growth.
  • Extremely coarse-grained rock is called pegmatite.
  • A mixture of large and small grains is called porphyry.
  • There is a diversity of igneous rocks that arise from the three principal magma compositions.
  • Fractional crystallization contributes to the diversification of igneous rocks.
  • Crystallization is halted, the crystals are separated from the melt, or the melt is injected with additional magma.

The Rock Cycle, Tectonic Cycle, and Earth’s Landscapes

  • The major components of the Earth system meet at the land surface.
  • Constant changes to Earth’s surface reflect the ongoing competition between internal forces that raise the lithosphere and external forces that wear it down.
  • Uplift, isostasy, and volcanism are driven by Earth’s internal heat energy.
  • Gravity and the Sun’s energy drive denudation, i.e. the destructive effects of weathering, erosion, and mass wasting.
  • The progressive sculpting of the land into varied relief is the net result.
  • Uplift and denudation rates both vary over time.
  • Landform development in any given location is controlled by process, climate, lithology, relief, and time.
  • Major landscape features of Earth have developed over long time intervals.
  • Change may be started by a tectonic event, a large sea level change, or a shift in climate.
  • Landscapes never achieve a state of equilibrium; Earth's surface has always been dynamic.

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