Geology 7133 – Carbonates: geochemistry, petrology, & sedimentology

Instructor: Dr. Huiming Bao (Phone: 8-3419)

Office: E338 Howe-Russell, LSU

E-mail: bao@lsu.edu

Website: http://www.geol.lsu.edu/bao/carbonates

Pre-requirements: Earth system history and Geochemistry or permission of the instructor

Our first meeting will be announced soon via email. If you want to be included in the mailing list, send me your email address. I would like to begin the class early, because I will be out of town for a field trip during the later half of the October.

Objectives

Carbonates are ions or salts of carbonic acid (CO₃^2-). Carbonate ions are the most important ions in ocean chemistry (e.g., links to global carbon cycle). Carbonate rocks are the most studied chemical sediments by geologists. Students will learn basic knowledge on ion chemistry, mineralogy, petrology, depositional settings, diagenesis, and elemental & isotope geochemistry that are associated with carbonate rock records. The focus is to interpret various signals stored in the carbonate rocks in the context of global carbon cycle, ocean chemistry, climate, and plate tectonics in the past.

Structure

There will be lectures, in-class discussions, and laboratory exercises (total ~ 6 hours), student presentations. Reading assignments and problem sets are distributed. Laboratory session includes identifying carbonates in thin sections and in hand specimen, and reconstructing the evolution of a Paleozoic carbonate platform as a case study.

I will assign a topic of my choice to each of you as your term paper topic.

Grading

45%: A (late) mid-term exam (mid-November) that covers the materials in lectures, in-class and lab exercises, and problem sets.

30%: term paper

25%: Class engagement and presentations

Reference books and reading materials

There will be no designated textbook. I recommend the following books for reading. In addition, we will be reading and discussing papers from recent literature on theme topics (see syllabus for examples). Reference books and copies of key reference papers will be distributed in class or on reserve in E338 Howe-Russell.

Books

Reeder, R.J., ed., 1983, Carbonates: Mineralogy and Chemistry: Reviews in Mineralogy, v. 11, 394 p.

Tucker, M. E., and V. P. Wright, 1990, Carbonate Sedimentology: Blackwell, 482 p.

Demicco, R. V., and Hardie, L. A., 1994, Sedimentary Structures and Early Diagenetic Features of Shallow Marine Carbonate Deposits: SEPM Atlas Series, No. 1, 263 p.

Morse, J.W. and F.T. Mackenzie, 1990, Geochemistry of Sedimentary Carbonates, Elsevier, Amsterdam, 707 pp.

Schlesinger, W. H., 1997, Biogeochemistry: An Analysis of Global Change. Academic Press; 2 edition 588 p.

Papers

(Will hand out in class)

Syllabus (will be modified):

Week 1

Various Occurrences of Carbonate Rocks and their records of past global biogeochemical changes

Week 2

Basics of Aquatic Chemistry related to carbonate mineral precipitation and dissolution

Carbonate equilibrium and kinetics in aqueous solutions

Problem set I out

Week 3

Mineralogy and petrology, Mg (Sr)/Ca ratio

Problem set I due and Problem set II out

Week 4:

Classification of carbonate rocks and depositional settings

Problem set II due

Week 5

Hand-specimen and thin-section skill (in the Petrology lab)

Problem set III out

Week 6

Carbonate diagenesis and porosity

Problem set III due and IV out

Week 7:

Major carbonate facies belts from tidal flats to the deep sea

(Chapters in Tucker and Wright, 1990)

Carbonate platform models

Evolution and Drowning of carbonate platforms

Problem set IV due and V out

Week 8:

Non-marine carbonates

Week 9:

Review of isotope geochemistry concepts

d¹³C and d¹⁸O of calcite – equilibrium and kinetics

Problem set V due

Mid-term exam

Week 10:

Carbon cycles, perturbations, interpreting carbon-isotope excursion

Carbonates and organic carbon

Calcification and PCO₂

Interpreting carbon-isotope excursion: carbonates and organic matter

Week 11:

Sulfate reduction coupled with carbonate precipitation

Methane generation coupled with carbonate precipitation

Fall Break

Week 12

Hand-specimen and thin-section skill (in our Petrology lab)

Student-chaired Discussion session I --- Carbonate facies, reef-complex

Week 13:

Student-chaired Discussion session II – Sedimentary models of carbonate deposition systems

Evolution and Drowning of carbonate platforms

Week 14:

Earth system transition during Carboniferous and Permian

Student-chaired Discussion session III – Carbonate deposition in Neoproterozoic ice ages

Week 15:

Carbonate deposition in Neoproterozoic ice ages

Aragonite seas and calcite seas

Student-chaired Discussion session IV - Aragonite seas and calcite seas

Week 16:

Student-chaired Discussion session V - Plate tectonic control of seawater chemistry and carbonate sedimentation

Student-chaired Discussion session VI – Secular trend of carbonate precipitation on Earth

Week 17:

Review

Final term paper due at 5:00 pm on Dec. 13, 2006.