igneous petrology francis 2013. lectures: tues & thurs: 11:30 - 12:30 pm lab: thursday...

IgneousPetrology

Francis 2013

Lectures: Tues & Thurs: 11:30 - 12:30 pm Lab: Thursday 2:30-5:30pm Room: FDA 315

Documents: www.eps.mcgill.ca/~courses/c423/

Topics: The Nature of Silicate MeltsReview of Thermodynamics and Simple Phase Diagrams

Phase Equilibria in Complex Systems at elevated P-TRole of VolatilesBehaviour of Trace ElementsImplications of IsotopesCrust / Mantle Reservoirs Fractionation ProcessesMid-Ocean Ridge Basalts Ocean Island Basalt Suites Flood Basalt VolcanismCalc-Alkaline Magmatism Ultra-Potassic and Carbonatitic Magmatism Troctolite - Anorthosite Magmatic SuitesKomatiites and Archean Greenstone - Tonalite Terranes Magmatism on the Moon, Venus, and Mars

Grading: Final Theory Exam 50% Lab Reports 50%

TA’s: Grant Cox - FDA 311 ([email protected]) Ryan Libbey - FDA 312

([email protected])Jason Coumans - FDA 202a

([email protected])

Igneous Petrology: EPSC 423A, 2013 [email protected]

http://www.eps.mcgill.ca/~courses/c423/

Labs – reports worth 50% A typed report will be required for each lab, typically due the following Thursday

before the next Lab.

You Will Work in Teams of ~2

1. Review of Common Rock Forming Minerals2. Meteorites and the Mantle3. Volcanic Textures, Cooling Rates, and Primary Magmas 4. Classification of Basalts: Baffin Island and Fort Selkirk5. Plutonic Equivalents: The Monteregian Hills (with associated field trip)6. Small Intrusions – the Dash Dyke7. Large Layered Intrusions – Muskox, Bushveld, Raudot. 8. Graphical & Numerical Analysis of Crystal Fractionation 9. Eocene Calc-Alkaline Volcanism10. Eocene Granitoid Plutonism11. Kimberlites, carbonatites, and other exotica12. Precambrian greenstones and granitoids

NB: Get Microscope and download AlphaMelts program during the first lab, Thursday, Sept. 5.All questions such as: my microscope does not work, where are the thin sections, who has the rock samples, etc. should be directed to the TA’s.

Francis, Igneous Petrology EPSC 423A, 2013

Mount St. Hilaire

RougemontMount

Yamaska

Field Trip Saturday, Oct. 5

The Monteregian Hills

References on Reserve in PSE Library and/or my Office

Theory:

Winter, J.D.; 2001: An Introduction to Igneous and Metamorphic Petrology. Prentice

Hall, QE461.W735 2001.

Philpotts,A.R., & Ague, J.J.; 2009: Priciples of Igneous and Metamorphic Petrology.

Cambridge University Press, QE461.P572

Ehlers, E.G.; 1972: The Interpretation of Geological Phase Diagrams. Freeman, San Francisco, QE364 E35

Rocks in Thin Section:

Nesse, W.D., 2004: Introduction to Optical Mineralogy, 348p. Oxford University, Press, QE369.06 N47

Williams, H., Turner, F.J., & Gilbert, C.M.; 1982: Petrography: An introduction to the study of rocks in thin section. Freeman, San Francisco, QE434 W73.


Required Component of Course Outlines Jane Everett, Dean of Students.

Integrity:

McGill University values academic integrity. Therefore all students must understand the meaning and consequences of cheating, plagiarism and other academic offences under the Code of Student Conduct and Disciplinary Procedures (seewww.mcgill.ca/students/srr/honest/ for more information).

Language:

In accord with McGill University’s Charter of Students’ Rights, students in this course have the right to submit in English or in French any written work that is to be graded.


https://excas.campus.mcgill.ca/owa/redir.aspx?C=094627021e0646b0a2042b5ef14a64b1&URL=http%3A%2F%2Fwww.mcgill.ca%2Fstudents%2Fsrr%2Fhonest%2F

Igneous Petrology

The study of rocks that form by the:crystallization of a cooling melt (“liquid”) or magma

Fundamental challenge : to understand high temperature

crystal-liquid processes

by studying cold solid rocks


Solid(xyl) Liquid(liq)

Cxyli / Cliq

i = Ki

Elemental partitioning between coexisting solid and liquid

followed by the physical separation of solid(s) and liquid 0livine

glass

K

constanttemperature

Diversity of igneous rocks reflects the action of

crystal – liquid fractionation

processes at high temperature

(Fe/Mg)oliv / (Fe/Mg)liq ~ 0.3


Two Kinds of Igneous Rocks:

Basalt/gabbro: dark or mafic rocks dominated by Fe-Mg silicates, such as olivine, and pyroxenes.

Constitute the oceanic crust.

Granitoids: light or felsic rocks dominated by feldspar and quartz that

Constitute the continental crust.

Black/Dark

White/Light

Basalt

Granite

Igneous Rocks reflect magmatic processes in an evolving Earth


Composition of the Sun and the Cosmic Abundances of the Elements:

The Sun constitutes 99.98 wt.% of the solar system, thus the chemical composition of the Sun is also that of the solar system.

To determine the proportion of the elements in the Sun, we make use of the energy levels between the electron orbitals of the atoms of the different elements. The electromagnetic spectra of the Sun was noted to contain dark lines in 1802 by Wollaston and later studied by Fraunhofer (early 1800's), indicating adsorption at selective wavelengths or energies. Radiation emerging from the Sun's interior passes though the gas of its photosphere (outermost visible layer), in which the different elements selectively absorb radiation whose wavelength corresponds to the difference in the energy (E = hc/) levels of its electron orbitals. The intensity of the absorption lines is a measure of the proportion of each element.

Solar Spectrum


Major Elements

Chondritic Meteorites have the same solid composition as the Sun ~ Solar System

O, Si, Mg, Fe constitute more than 91% of Condensed Sun’s Composition

The Sun constitutes 99.98 wt.% of the solar system, thus the chemical composition of the Sun is also that of the solar system.


>92%

Mantle Xenoliths:

Olivine – rich Peridotite nodules of the Earth’s mantle brought to the surface by volcanoes.


Sun BulkSilicateEarth (~68 wt.%) + Fe-metal core (~31 wt.%)

The Earth’s upper mantle is similar in composition to BSE, and is composed of a rock called peridotite, which consists largely of the minerals olivine and orthopyroxene

basalt orgranite crust

Fe-Nimetallic

core

peridotite mantle

SiO2 + MgO + FeO ~ 91%

Sun - Chondritic Meteorites - Earth’s Mantle

~


Mantle Xenoliths

Chondritic Meteorite

+ IronMetal

Iron


peridotite mantle

olivine

feldspar

= Sun


Terrestrial Planets


Fe-Nimetallic

core

peridotite mantle Crust represents only ~0.7

wt.% of the Earth


SiO2 45.2 49.4 60.3

TiO2 0.7 1.4 1.0

Al2O3 3.5 15.4 15.6

MgO 37.5 7.6 3.9 FeO 8.5 10.1 7.2 CaO 3.1 12.5 5.8 Na2O 0.6 2.6 3.2

K2O 0.1 0.3 2.5

Total 99.2 99.3 99.5

Cations normalized to 100 cations Si 38.5 46.1 56.4 Ti 0.5 1.0 0.7 Al 3.6 16.9 17.2 Mg 47.6 10.6 5.4 Fe 6.0 7.9 5.6 Ca 2.8 12.5 5.8 Na 0.9 4.7 5.8 K 0.1 0.5 3.0 O 140.2 153.0 161.3

Mineralogy (oxygen units, XFe3+ = 0.10) Quartz 0.0 0.0 13.0 Feldspar 13.2 57.3 64.3 Clinopyroxene 6.7 25.7 5.9 Orthopyroxene 18.3 4.1 14.7 Olivine 59.9 9.9 0.0 Oxides 1.8 3.0 2.0

Mantle Ocean Continent crust crust

Oceanic crust - MORB basalt p

Continental crust - granite eFrancis, Igneous Petrology EPSC 423A, 2013

Solid Source Refractory Solid + Liquid Restite

Refractory Mantle + Oceanic Crust

Cpx-rich PeridotiteLherzolite

Olivine-rich Peridotite + Basalt Harzburgite

Partial Melting of the Mantle

Fertile Mantle

Whole = Σ Parts

Lever Rule: p/R = x/y

y

x

R

amount of basalt (P) infertile mantle = x/(x+y)

~ 15-20%


Parent Magma Crystal Cumulate + Residual Magma

Volcanic RocksPlutonic or

Intrusive Rocks

Mafic Magma Gabbroic Cumulate + Felsic Magma

Volcanic rocks approximate the compositions of magmatic liquids. They represent aliquots of liquid that have escaped to the surface. The compositional variation observed in the liquids that the volcanic rocks represent is produced by varying degrees of crystal fractionation of a largely “gabbroic” mineral assemblage that now comprises plutonic intrusions.

Crystal Fractionation of Basalt

Whole = Σ Parts

Lever Rule: e/C = x/y

y

x

amount of granitein basalt = x/(x+y) ~ 10%

C


Continental Crustal GranitoidsSecond Stage Melting of Basalt

The majority of crustal granitoids are, however, thought to be liquids

produced at the eutectic point e by the second stage melting of silica-saturated basaltic/gabbroic mafic crust, consisting largely of pyroxene and plagioclase.

e


SiO2 45.2 49.4 60.3

TiO2 0.7 1.4 1.0

Al2O3 3.5 15.4 15.6

MgO 37.5 7.6 3.9 FeO 8.5 10.1 7.2 CaO 3.1 12.5 5.8 Na2O 0.6 2.6 3.2

K2O 0.1 0.3 2.5

Total 99.2 99.3 99.5

Cations normalized to 100 cations Si 38.5 46.1 56.4 Ti 0.5 1.0 0.7 Al 3.6 16.9 17.2 Mg 47.6 10.6 5.4 Fe 6.0 7.9 5.6 Ca 2.8 12.5 5.8 Na 0.9 4.7 5.8 K 0.1 0.5 3.0 O 140.2 153.0 161.3

Mineralogy (oxygen units, XFe3+ = 0.10) Quartz 0.0 0.0 13.0 Feldspar 13.2 57.3 64.3 Clinopyroxene 6.7 25.7 5.9 Orthopyroxene 18.3 4.1 14.7 Olivine 59.9 9.9 0.0 Oxides 1.8 3.0 2.0

Mantle Ocean Continent crust crust

Oceanic crust - MORB basalt p

Continental crust - granite e

Spectrum of Igneousliquids


igneous petrology francis 2013. lectures: tues & thurs: 11:30 - 12:30 pm lab: thursday...

Documents

igneous petrology epsc

metamorphic petrology

priciples of igneous

pm lab

coumans fda

dean of students

lab reports50

grant cox fda