Igneous and Metamorphic Petrology Quiz
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Questions and Answers

What process occurs when magma melts surrounding rock and alters its composition during its ascent?

  • Differentiation
  • Mixing of Magmas
  • Partial Melting
  • Assimilation (correct)
  • Which of the following processes is responsible for the crystallization of minerals from magma in the mantle?

  • Mixing of Magmas
  • Differentiation (correct)
  • Assimilation
  • Partial Melting
  • What mechanism enables different magmas with varying compositions to combine in the mantle?

  • Assimilation
  • Mixing of Magmas (correct)
  • Differentiation
  • Partial Melting
  • During which process is magma generated near the Earth's surface due to melting at lower temperatures than surrounding rock?

    <p>Partial Melting (B)</p> Signup and view all the answers

    What is a key difference between the processes of magma generation on Earth and the Moon?

    <p>Earth has a more dynamic environment leading to more complex generation processes. (B)</p> Signup and view all the answers

    What defines igneous rocks?

    <p>Rocks formed by cooling and solidification of magma or lava (A)</p> Signup and view all the answers

    Which term refers to the processes of rock formation?

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

    What is the primary factor influencing the composition of magma?

    <p>Temperature (B)</p> Signup and view all the answers

    Which process cannot occur in a vacuum?

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

    Which component is most commonly associated with magma?

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

    What is considered the 'compound liquid' in geological terms?

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

    Which temperature is significant for the radiation process in rocks?

    <p>Above 1200°C (C)</p> Signup and view all the answers

    What is the term for the description and classification of rocks?

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

    What is the primary source of heat affecting the melting of rocks in the solid earth?

    <p>Solar radiation (B)</p> Signup and view all the answers

    Which process is NOT a factor that generates magma?

    <p>Cooling of the lithosphere (D)</p> Signup and view all the answers

    Which radioactive element has a half-life greater than $10^9$ years contributing to heat production in Earth?

    <p>Uranium-238 (D)</p> Signup and view all the answers

    What occurs at the mid-ocean ridge during the crustal geothermal process?

    <p>Formation of new crust (B)</p> Signup and view all the answers

    What causes the increase in temperature required for rock melting?

    <p>Release of heat from radioactive decay (B)</p> Signup and view all the answers

    How does the movement of a down going slab generate heat for melting?

    <p>By causing friction at the plate boundaries (B)</p> Signup and view all the answers

    What is a likely consequence of a decrease in pressure beneath the Earth's surface?

    <p>Phase change allowing magma generation (B)</p> Signup and view all the answers

    What process contributes to the initial heating of Earth's interior during core formation?

    <p>Short-lived radioisotope decay and accretionary heat (A)</p> Signup and view all the answers

    Flashcards

    Igneous Petrology

    The study of igneous rocks and the processes involved in their formation.

    Petrography

    The description and classification of rocks.

    Petro-genesis

    The conditions under which rocks were formed.

    Magma

    Molten rock found beneath the Earth's surface.

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    Lava

    Molten rock that has reached the Earth's surface.

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    Igneous Rock

    Rock formed from the cooling and solidification of magma or lava.

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    Magma composition

    Chemically complex and mainly consists of silicate solutions with some metal oxides/sulfides.

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    Magma generation

    Magma formation due to elevated temperatures exceeding rock melting points, by radiation, conduction or convection.

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    Sources of Heat for Melting Rocks

    Solar radiation, core movement, and radioactive decay are key sources of heat that can melt rocks.

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    Subduction Zone Melting

    Melting of rocks occurs when oceanic lithosphere sinks into the asthenosphere in a subduction zone.

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    Heat Increase for Magma Generation

    Increasing the temperature of rock raises its melting point, causing rocks to melt forming magma.

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    Pressure Decrease and Magma

    Decreasing pressure can cause phase changes in rocks, fostering magma formation.

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    Crustal Geothermal Gradients

    Temperature variations within Earth's crust, influencing rock melting in different locations, like mid-ocean ridges and trenches.

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    Global Heat Flow

    Movement of heat within Earth's mantle, with warmer areas near mid-ocean ridges compared to cratons.

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    Bowen's Reaction Series

    Sequence of mineral crystallization from cooling magma, with surface-enriched minerals in the lower part of the series.

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    Core Formation

    Earth's core formed from the sinking of iron-rich material, releasing heat and causing widespread melting.

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    Magmatic Differentiation

    A process where a single magma body changes its composition due to the removal or addition of minerals.

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    Crystal Settling

    The process of heavier minerals crystallizing from magma and sinking to the bottom of the magma chamber.

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    Partial Melting

    The process where only a portion of a rock melts, producing magma with a different composition than the original rock.

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    Assimilation

    The process where magma incorporates surrounding rock into its composition.

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    Magma Mixing

    The process where two magmas with different compositions merge, creating a new, hybrid magma.

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    Study Notes

    Course Information

    • Course number: Geol. 402
    • Course title: Igneous and Metamorphic Petrology
    • Instructor: Dr. Adnan Khan, Assistant Professor, Department of Geology
    • Recommended textbook: Petrology: Igneous, Sedimentary, and Metamorphic by Harvey Blatt and Robert J. Tracy

    Petrology Overview

    • Petrology is the study of rocks, encompassing igneous, sedimentary, and metamorphic rocks.
    • This includes their genetic distribution, classification, and formation processes.

    Igneous Petrology

    • The scientific study of igneous rocks
    • Two key components:
      • Petrogenesis: The processes of rock formation
      • Petrography: The description of rocks, including their classification

    Nature of Magma

    • Magma is a naturally occurring, hot fluid within the Earth.
    • It's a molten substance at high temperatures.
    • It is called magma until it erupts on the surface, at which point it is called lava.

    Magma Composition

    • Magma is chemically complex, containing molecular building blocks for minerals.
    • Mostly composed of silicates, along with oxides and sulfides of metals.
    • Always contains water and other gases held in solution by pressure, with heat as the principle factor.

    Magma Generation

    • Magma forms when temperatures at depth in the Earth exceed the melting temperatures of rocks.
    • This can occur through three primary processes, or a combination of them.

    Sources of Heat for Melting Rocks

    • Solar radiation: Minor heat source (50,000 times less potent than other sources)
    • Core movement: Significantly contributes to melting by heat transfer
    • Radioactive decay (U, U, Th, K, and Rb): A substantial heat source, contributing up to 50-100% of the Earth's internal heat.

    Factors Generating Magma

    • Increase of heat: Raises melting temperature, causing rocks to melt and form magma.
    • Decrease of pressure: Causes phase change in rock, generating magma.

    Processes Generating Magma

    • Radiation: Emission of EM energy from hot bodies into surrounding bodies. Increasingly important at very high temperatures (>1200°C).
    • Conduction: Transfer of kinetic energy via atomic vibrations. More efficient if the surface area of the enclosure is larger.
    • Convection: Movement of material with contrasting temperatures, due to different densities. Crucial in magma generation.

    Magma Evolution

    • Differentiation: Separation of substances with different chemical compositions within a magma body.
    • Partial Melting: Different minerals melt at different temperatures, resulting in magmas with different compositions depending on what minerals are present and the conditions.
    • Assimilation: Incorporation of surrounding country rock into a magma body, altering its chemical composition.
    • Mixing of Magmas: The mixing of two or more magmas with different compositions, which can create a new, intermediate composition.

    Bowen's Reaction Series (diagram illustrated)

    • This series describes the order in which minerals crystallize from a cooling magma.

    Global Heat Flow Models (diagram illustrated)

    • Global heat flow patterns are shown with warmer areas over spreading ridges and colder areas over cratons.

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    Related Documents

    Petrology Lecture 1 PDF

    Description

    Test your knowledge on the principles of igneous and metamorphic petrology, focusing on the study of rocks, their classification, and formation processes. Explore key concepts such as petrogenesis and the nature of magma. Ideal for students in Geology 402.

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