Geochronology & Thermochronology
GEOS 474A/574A
Spring 2016

Syllabus

Details: M,W: 10:00 am to 11:30 pm; 3 units, regular grades, cross listed for undergrads (474) and grads (574). 
Instructors:  Peter Reiners and Mihai Ducea: reiners (at) email.arizona.edu; ducea (at) email.arizona.edu.
Office Hours: As arranged in and after class.
Readings: Readings will be assigned from chapters and current papers, copies of which will be provided, but buying either the Faure & Mensing or Dickin texts listed at the end of this syllabus is also recommended.
Course website: http://www.geo.arizona.edu/~reiners/geos474-574/
Prerequisites: Physical Geology (GEOS 251), Mineralogy (GEOS 306), Chemistry (CHEM 151, 152), Geochemistry (GEOS 400). Recommended: Calculus (MATH 124/125, 129).

Course Rationale and Logistics

Much of earth and planetary science relies on radioactive decay and growth of naturally occurring nuclides and their use as chronometers to understand the timing of events and rates of processes, and the use of radiogenic isotopes as tracers for understanding a wide range of phenomena. This course will introduce students to the fundamentals of geochronology and thermochronology, diffusion in minerals and heat in the Earth, trace element behavior, and differentiation and recycling processes in the Earth and other solar system objects. The approach will be lectures to supplement readings, and active participation in, and leading of, discussions of modern work in current papers. This will assume familiarity with basic geology, mineralogy, chemistry, geochemistry, and a little bit of calculus (see prerequisites).

There will be approximately 8 problem sets throughout the course. Each graduate student will present and lead one ~20-30 minute discussion on a paper assigned to him/her. All students will complete a final project consisting of a paper (and, for graduate students, a presentation) describing their work on either: a) original geochronologic analysis and interpretations using facilities at UA, or b) innovative modeling, synthesis, or reinterpretation or previously published data. Students will present a written (2-3 page) proposal by the end of February describing their planned project, its motivation, significance, methods, and anticipated results.

Grading will follow this formula: Graduate Students: Problem sets: 50%; Final Paper and Presentation: 30%; In-class presentations and participation: 20%. Undergraduate Students: Problem sets: 50%; Final Paper: 30%; In-class presentations and participation: 20%.Grades will be assigned according to the following percentage scheme: A ≥ 90%, B ≥ 80%, C ≥ 70%, D ≥ 60%, E ≥ 50%.

Tentative Schedule
This schedule is subject to change.

Date

Topic

Primary Presenter

Wed 13 Jan:

Nucleosyn., nuclear systematics, decay/growth

PR

Mon 18 Jan: MLK Day; no class

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Wed 20 Jan:

More fundamentals; trace elements, mixing, analytical methods

MD

Mon 25 Jan:

Isochrons, errors, and interpretation

MD

Wed 27 Jan:

Diffusion

PR

Mon 1 Feb:

More Diffusion

PR

Wed 3 Feb:

Closure

PR

Mon 8 Feb:

Rb/Sr

MD

Wed 10 Feb:

Sm/Nd

PR

Mon 15 Feb:

Rb/Sr and Sm/Nd geochron examples

PR, MD

Wed 17 Feb:

Sm/Nd and Lu/Hf geochron: garnet

MD

Mon 22 Feb:

Re/Os

MD

Wed 24 Feb:

Pt/Re/Os

PR

Mon 29 Feb:

Sr-Nd-Os geodynamics examples

PR

Wed 2 Mar:

(U-Th)/Pb

PR

Mon 7 Mar:

(U-Th)/Pb geochron: zirc/ap etc.

GG

Wed 9 Mar:

(U-Th)/Pb sedimentary geochron

MD

Mon 14 Mar: SB, no class

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Wed 16 Mar: SB, no class

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Mon 21 Mar:

U-series

PR

Wed 23 Mar:

K-Ar

PR

Mon 28 Mar:

40Ar/39Ar

PR

Wed 30 Mar: (AB mtg)

K-Ca

MD

Mon 4 Apr:

40Ar/39Ar

PR

Wed 6 Apr:

Lu-Hf in zircon

GG

Mon 11 Apr: Utah trip

fission track

BC

Wed 13 Apr:

(U-Th)/He

PR

Mon 18 Apr:

modeling thermal/exhum histories

PR

Wed 20 Apr:

Tectonic applications

MD

Mon 25 Apr:

Tectonic applications

MD

Wed 27 Apr:

Cosmogenic dating

TJ

Mon 2 May:

Final Presentations

 

Wed 4 May:

Final Presentations

 

Books and other resources:
Bill White's books Geochemistry and Isotope Geochemistry, both published by Wiley, are highly recommend. You can also find the lecture notes (which can be downloaded as pdf’s) for his Isotope Geochemistry course at Cornell here.
Two other good books:
·Radiogenic Isotope Geology, 2nd Ed., by A. P. Dickin, 2005, Cambridge University Press, 492 pp.
·Isotopes: Principles and Applications, 3rd Ed., by G. Faure and T.M. Mensing, 2005, John Wiley & Sons, 897 pp. The older (2nd Ed.) (1986) version of this book is ok too.
Other hyperuseful references:
·Geochronology and Thermochronology by the 40Ar/39Ar Method, 2nd Ed., by McDougall, I., and Harrison, T.M., 1999, Oxford University Press, 269 pp.
·Geodynamics, 2nd Ed., by Turcotte, D.L., and Schubert, G., 2002, Cambridge University Press, 456 pp.

Policies
·Absence policies: Attendance at all lectures and discussions are required, however, the following kinds of excused absences will be permitted: 1) All holidays or special events observed by organized religions will be honored for those students who show affiliation with that particular religion, 2) Absences pre-approved by the UA Dean of Students (or Dean's designee) will be honored.
·Policies regarding Academic Integrity will be followed and are available at: http://deanofstudents.arizona.edu/policies-and-codes/code-academic-integrity.
·Policies against threatening behavior by students: http://policy.web.arizona.edu/education-and-student-affairs/threatening-behavior-students.
·Students with Disabilities: If you anticipate issues related to the format or requirements of this course, please meet with me so we can discuss ways to ensure your full participation in the course. If you determine that formal, disability-related accommodations are necessary, it is important that you be registered with Disability Resources (621-3268; drc.arizona.edu) and notify me of your eligibility for reasonable accommodations. I can then plan how best to coordinate your accommodations. More info: http://drc.arizona.edu/learn/index.html
·Information contained in the course syllabus, other than the grade and absence policies, may be subject to change with reasonable advance notice, as deemed appropriate by the instructor.



Problem Sets
Handed out in class.

Resources
Isotopic Abundances and Masses
One version of Chart of Nuclides
More Tables of Isotopes and other useful isotope information: http://ie.lbl.gov/toi.htm
White Isotope Geochemistry Course
White Geochemistry Text

Discussion Papers
These will be updated as needed. Below are useful and interesting papers on some of the topics we'll be covering and from which you can choose for discussion leading.

Extinct radionuclides stuff
Wadhwa and Lugmair, 1996
, GCA, Caldera eucrite dating
Allegre et al., 1983, Nature, Age of the atmosphere
Boyet et al., 2010, EPSL, Dating a bunch of eucrites and the initial 146Sm/144Nd
McKeegan and Davis, 2007, in the modestly named: Treatise on Geochemistry, Nothing mechanically useful, but good review of early solar system chronology

Rb-Sr stuff
Sobolev et al., 2011
, Nature, Sr isotopes in Hawai'ian melt inclusions; also Armienti and Gasperini comment
Davidson et al, 2005
, Geology, Rb/Sr isochrons in magmatic systems
Ague and Baxter 2007, EPSL, Short duration metamorphic events
Carlson 2002, Am Min, Scales of equilibration during metamorphism
Austrheim 1987, EPSL, Eclogitization by fluids
Glodny et al., 2008, GCA, Rb-Sr geochron in Western Gneiss region
Patel et al., 1999, JMG, Laramie Range Rb-Sr systematics in metamorphism

Sm-Nd stuff
Jackson and Carlson, 2011
Nature, Holy crap, did they actually find the real primitive mantle?
Caro et al., 2006
GCA, 142Nd/144Nd in terrestrial rocks
Bennett et al., 1993 EPSL, Archean highly depleted mantle
Moorbath et al., 1997 Chem Geol, Extreme Nd-isotope heteorgeneity in Archean--fact or fiction etc
Moorbath, 2005 Applied Geochemistry, review of Hadean-Archean transition etc
Frost 1993 Geology, Nd isotopes in the Wyoming province
Bowring and Housh 1995 Science, Early Earth mantle Nd isotopes, including Comment from Moorbath & Whitehouse and reply from B&H
Boyet and Carlson 2005, Science Earth has higher epsilon142Nd than chondrites
Boyet and Carlson 2006, EPSL, implications of the above

U-Pb stuff
Rasbury et al., 1998
, Geology, Dating paleosols with U/Pb
Blackburn et al., 2012
, Science, Really long-term exhumation rates from deep crustal xenolith thermochronology
Cole et al., 2005
, GSAB, Dating tufa from Miocene lakes using U/Pb
Blackburn et al., 2011
, CMP, Lithosphere-scale (the vertical way) thermal histories from high-T U/Pb thermochronology
Mattinson, 2005
Chem Geol, CA-TIMS analyses
Wilde et al., 2001 Nature, really frickin old zircs, etc.
Bouvier et al., 2008 EPSL, are Martian basaltic shergottites really old or really young now? (If they're old there will be trouble, and if they're young it will be double...so you gotta let me know...)

Os stuff
Coggon et al., 2012
Chem Geol, OMFG: PGM LA-ICP-MS Pt-Os dates!
Shirey and Richardson, 2011
Science, Vestiges of the beginning of the Mr. Wilson Cycle from diamonds and their reduced sulfur secrets.
Brandon et al., 2003
EPSL, 186Os/188Os in various igneous suites and core contributions?
Peucker-Ehrenbrink and Ravizza, 2000 Terra Nova, the marine Os isotope record
Lassiter and Hauri, 1998 EPSL, Os isotope constraints on the origins of Hawai'ian tholeiitic magmas
Creaser et al., 2002 GCA, Re-Os dating black shales
Bizimis et al., 2007 EPSL, Os and Hf evidence for ancient mantle lithosphere beneath Hawai'i (WTF!)
Hauri, 2002 PTRSLsA, Os isotopes and mantle convection
Kogiso et al., 2004 GCA, Length scales of mantle heterogeneities from Os isotopes in OIBs
Alves et al., 2002 EPSL, Os isotope mixing arrays in arc magmas
Chesley et al., 2004 EPSL, Re-Os system and mantle metasomatism
Schoenberg et al., 2002 Nature, W isotopes in Isua metasediments and the LHB
Schersten et al., 2004 Nature, W isotopes in Hawai'ian magmas and constraints on core contributions

U-series stuff
Paces et al., 2010
EPSL, U-series dating, climate, groundwater, opal, a dangerous combination
Schmitt et al., 2011 EPSL, U-series on zircons in MORs, cooling rates, eruption ages, residence times, etc.
Schmitt et al., 2011 AREPS, Review of U-series dating of accessory magmatic phases, and insights therefrom
Ludwig et al., 1991
Geology, 234U/238U of corals on drowned Hawai'ian reefs
Wagner et al., 2010 Natty Geosci, U-Th dating of speleothem in Cave of the Bells and paleoclimate
Wagner et al., 2010 supplementary data
Turner et al., 2001 Science, ultrafast source-to-eruption movement of arc subduction signature from 226Ra/230Th

Ar stuff
Bissig and Riquelme, 2010,
EPSL, Ar-Ar dating of supergene minerals, Andean uplift and climate, and mineral resources, wow.
Guillou et al., 2010,
Quaternary Geochron, unspiked K-Ar dates, Icelandic volcanism, and climate fluctuamatations
Kelly, 2002
RiMGs, K/Ar and Ar/Ar dating review
Harrison and Zeitler, 2005 RiMGs, Fundamentals of noble gas geochronology
Kelley and Wartho, 2000 Science, phlogopite Ar/Ar ages in mantle xenoliths
Renne et al., 2001 EPSL, invasion of the Permian bacteria! (and dating evaporites)


Last updated: 4 January 2016