Ian S Mc Callum
Systematic study of the major families of volcanic and plutonic igneous rocks with emphasis on tectonic setting, phase relations, geochemistry, and models of their origin and evolution throughout geologic time. Laboratory emphasizes thin-section study of rocks using transmitted and reflected light. Prerequisite: ESS 312.
Why are active volcanoes restricted to certain parts of the earth? Why is the magma erupted from Hawaii different from that erupted at Mount St. Helens? Why is the magma erupted at Mount Vesuvius different from magma anywhere else on earth? Why are some volcanoes more explosive than others? What processes have produced the great batholiths of the Sierra Nevada Range and the Peruvian Coastal Range? What do the great layered intrusions like the Bushveld and Stillwater Complexes have in common? What caused the huge outpourings of lava that formed the basalts of the Columbia River Plateau fourteen million years ago? Where in the earth’s mantle do the voluminous magmas that erupt at ocean ridges originate? How do basalts from the Moon and meteorites differ from terrestrial basalts? These and a myriad other questions will be addressed in this class. Students will also learn how to identify, describe and interpret a wide variety of common igneous (volcanic and plutonic) rocks using modern petrographic microscopes and a comprehensive set of thin sections and polished thin sections. The emphasis in lectures will be on modern ideas regarding the origin and evolution of the major classes of igneous rocks. We are fortunate in having an excellent textbook written by a former UW student, John Winter. John’s book was published in 2001 and is titled “An introduction to igneous and metamorphic petrology.” In order to make the class as interactive as possible reading in the textbook will be assigned.
Student learning goals
General method of instruction
About half of the lectures (3 hours per week) will use the “talking head” approach since this is still the most efficient way to transmit important basic information to a group of students. The other half will involve interactive discussion based on assigned reading. In order to encourage student participation I will ask each student to lead the discussion on a particular topic. The lab (four hours a week) will involve a short (approximately 30 minute introduction) with the remaining time devoted to hands-on microscopy of our extensive and comprehensive thin section and polished section collection. We have an excellent television/microscope system that will be used extensively to demonstrate petrographic features in the thin sections.
Important prerequisites for this class are ESS 212 (Earth Materials) and ESS 312 (Geochemistry). It would also be helpful (but not essential)if students have completed ESS 438 (Optical Mineralogy). The first 2-3 weeks in lab will be spent reviewing the optical properties of the important mineral groups.
Class assignments and grading
There will be four homework sets due at regular intervals during the quarter. Also, starting in week 3 there is a weekly lab assignment that involves writing a complete petrographic description of a selected sample. Students will also keep a lab notebook. Selected reading in the textbook is also required. There is a required 2-3 day field trip. Field trip itinerary: Seattle to Omak via Hwy 20 and 97 (stops to look at Mt. Baker flows, Chilliwack batholith, Shuksan blueschist terrane, Skagit gneiss terrane, Golden Horn batholith, Methow graben exposures, granites and metamorphic rocks of the Okanagan Highlands terrane. Omak to Seattle via Hwys 97 and 2 (stops to look at Chelan Gneiss terrane, Columbia Plateau basalts, Mt. Stuart batholith, Chiwaukum metamorphic terrane, and plutonic rocks of the Cascade Arc near Mt. Index).
Grade breakdown: Final examination (lecture )—30%. Final exam (lab)—20%. Homework assignments—20%. Weekly lab assignment—25%. Class participation—5%. The final lecture examination will consist of four questions selected from a list of ten questions that will be provided to students at least two weeks before the final exam.