Igneous Petrology: Phase Diagrams

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Match the phase diagram element with its correct definition:

Liquidus = The temperature at which crystallization begins for a given composition. Solidus = The temperature below which all material is completely solid. Eutectic point = The specific temperature and composition at which the liquid solidifies into two solid phases simultaneously. Invariant point = A point at which the system has no degrees of freedom.

Match the variables in the Gibbs Phase Rule to their definitions:

F = Variance (degrees of freedom) C = Number of components in the system P = Number of phases present 2 = Accounts for Temperature and Pressure

Match the phase diagram region with the possible phases:

Above the liquidus line = Only liquid phase exists Between liquidus and solidus lines = Liquid and solid phases coexist At the Eutectic point = Two solid phases form simulataneously from a liquid Below the solidus line = Only solid phases exist

Match the term related to binary eutectic systems with its description:

Eutectic composition = The specific mixture of components that melts at the lowest temperature. Liquidus line = The boundary above which only liquid is stable. Solidus line = The boundary below which only solids are stable. Tie line = Connects the compositions of phases in equilibrium at a specific temperature Signup and view all the answers

Match the system variance with its correct definition:

F = 0 = Invariant point; the system has no degrees of freedom. F = 1 = Univariant line; the system has one degree of freedom. F = 2 = Divariant field; the system has two degrees of freedom. Variance = Number of degrees of freedom Signup and view all the answers

Match the phase diagram component with its description:

Phase = A physically and chemically homogeneous portion of a system. System = The sum of the components that are being investigated. Component = The chemical constituents of a system (e.g., minerals in a rock). Crystallization path = The sequence of changes that a magma undergoes upon cooling Signup and view all the answers

Match the description with the phase diagram application:

Crystallization sequence = Predict the order in which minerals will crystallize from a cooling magma. Phase proportions = Determine the amount of each phase present at a given temperature and composition using the lever rule. Equilibrium conditions = Define the temperature and pressure at which different mineral assemblages are stable. Phase Stability = Indicates the stable phases under certain temperature, pressure, and compositional conditions Signup and view all the answers

Match the rule/law with its correct usage/description in phase diagrams:

Lever Rule = Used to determine the proportions of each phase in a two-phase region. Gibbs Phase Rule = Defines the relationship between the number of phases, components, and degrees of freedom in a system. Liquidus line = Indicates the temperature above which a substance is completely liquid Solidus line = Indicates the temperature below which a substance is completely solid Signup and view all the answers

Match the following phase diagram features with their definitions:

Solidus = The temperature below which a substance is completely solid. Liquidus = The temperature above which a substance is completely liquid. Eutectic Point = The point on a phase diagram where a liquid transforms directly into two solid phases. Peritectic Point = The point on a phase diagram where a solid phase transforms into a liquid phase and another solid phase. Signup and view all the answers

Match the application of phase diagrams to their descriptions in igneous petrology:

Magma Crystallization = Predicts the order in which minerals crystallize from a magma as it cools. Fractional Crystallization = Models changes in magma composition as certain minerals are removed. Magma Differentiation = Explains how different rock types form from single magma source. Geothermometry = Estimates the temperatures at which a cooling rock formed. Signup and view all the answers

Match the system type with its corresponding definition:

Binary Eutectic System = Two components that form a mixture with the lowest melting point at a specific composition. Binary System with Congruent Melting Compound = A compound melts directly into a liquid of the same composition. Binary System with Incongruent Melting Compound = A compound melts into a liquid and another solid phase with different compositions. Ternary System = System consisting of three components. Signup and view all the answers

Match the following terms related to solid solutions with their correct descriptions:

Complete Solid Solution = Two minerals can mix in any proportion in the solid state. Partial Solid Solution = Limited range of compositions over which two minerals can mix. Solid Solution = The ability of one mineral to substitute one or more elements into its crystal structure. Immiscibility Gap = A range of composition where two minerals will not form a solid solution. Signup and view all the answers

Match the following limitations of phase diagrams with their explanations:

Equilibrium Conditions = Phase diagrams assume equilibrium, which may not always be achieved in nature. Simplified Systems = Phase diagrams often represent only binary or ternary systems, not complex natural magmas. Absence of Volatiles = Phase diagrams typically don't account for volatiles like water, affecting melting points. Ideal Mixing = Phase diagrams may assume ideal mixing, which is often not the case in natural systems. Signup and view all the answers

Match the following terms related to ternary phase diagrams to their definitions:

Isotherm = A line on a phase diagram connecting points of equal temperature. Cotectic Line = A line on a ternary phase diagram representing the equilibrium between a liquid and two solid phases. Ternary Eutectic Point = The point on a ternary phase diagram where three solid phases coexist in equilibrium with a liquid phase at the lowest melting temperature. Tie Line = A line connecting the compositions of two phases that are in equilibrium with each other. Signup and view all the answers

Match the type of melting with its description.

Congruent Melting = A solid melts directly into a liquid of the same composition. Incongruent Melting = A solid melts into a liquid and another solid phase with different compositions. Eutectic Melting = A mixture of solids melts at a lower temperature than any of the pure constituents. Partial Melting = The process by which only part of a solid rock melts. Signup and view all the answers

Match the following terms to their descriptions relating to crystal formation in igneous rocks:

Zoning = Variation in composition within a single crystal, often reflecting changes in magma composition during growth. Reaction Rim = A surrounding of one mineral by another, indicating a reaction between the two. Exsolution Lamellae = Thin parallel intergrowths of two different minerals that form upon cooling from a solid solution. Skeletal Crystal = A crystal that has grown rapidly with edges growing faster than the center. Signup and view all the answers

Associate types of phase diagrams with appropriate description:

Binary Phase Diagram = A graph showing the equilibrium relationships between phases in a two-component system. Ternary Phase Diagram = A triangular graph showing the equilibrium relationships between phases in a three-component system. P-T Diagram = A graph showing the stability fields of different phases as a function of pressure and temperature for a single component. Activity-Composition Diagram = Diagram showing the stability of mineral assemblages as a function of the activities of components. Signup and view all the answers

Match the following processes with their impact of magma composition:

Fractional Crystallization = Changes magma composition by removing early-formed crystals, leading to residual liquid enrichment. Assimilation = Alters magma composition through incorporation of surrounding wall rocks. Magma Mixing = Modifies magma composition by blending two or more chemically distinct magmas. Zone Refining = A process where repeated melting and crystallization results in the purification of a substance. Signup and view all the answers

Igneous Petrology

Study of the origin, composition, texture, and classification of igneous rocks.

Phase Diagram

Graphical representation of phase equilibrium as a function of T, P, and composition.