Example Exercises and Activities

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   Physical and Chemical Variations Along the Central American Volcanic Arc
   Kent Ratajeski
   
   The Central American volcanic arc displays large arc-parallel variations in chemical composition that yield important clues concerning the complex origin of magmas in subduction zones. In this exercise, students use data compiled by researchers for the NSF MARGINS program to compare heights, volumes, and geochemical compositions of 39 Quaternary volcanic centers along the Central American arc, together with crustal thicknesses, to assess the possible sources of the magmas and the petrologic processes that have modified them prior to eruption.


2. Global Geochemistry of Mid-Ocean Ridge Basalts
   Kent Ratajeski
   
   Geological processes at the mid-ocean ridges are responsible for the bulk of the Earth's heat loss and volcanic activity. The compositions of materials erupted at these locations, dominantly mid-ocean ridge basalts (MORB's), have profound implications for the inner workings of the Earth's mantle, the construction of oceanic crust, and global plate tectonics. In this exercise, students replicate a portion of a classic paper on MORB geochemistry [Klein and Langmuir, 1987] , but using a much larger global geochemical dataset downloaded from the PETDB database. Through a series of activities and questions, students are encouraged to think about the petrologic and geodynamic processes controlling the composition of Earth's most abundant volcanic rocks.


3. Volcanic Fields of North America
   Kent Ratajeski and Brian Stogner
   
   In this activity, students gather gather data from selected North American volcanic fields which were active during the Cenozoic. Geographic, age, and geochemical data from each volcanic field are easily obtained from the North American Volcanic and Intrusive Rock Database (NAVDAT). Students are asked to compare and contrast the geochemical and age data, classify the field by geochemical criteria, and make hypotheses for the similarities and differences that they observe. This exercise provides a broad overview of the volcanic history of North America as well as opportunities to explore features of individual volcanic fields.


4. Volcanic Landforms and Magma Composition
   Kent Ratajeski
   
   Magma composition is an important control on the geomorphology of lava flows and volcanoes. In this exercise, students investigate this relationship by studying several classic examples of diverse volcano types in the western United States. Students use the interactive Google Earth software to determine the size and shape of the selected volcanoes, and then use the North American Volcanic and Intrusive Database (NAVDAT) to gather whole-rock geochemical data to test the nature of the relationship between magma composition and volcano geomorphology.


5. Cenozoic Volcanic History of the Western United States
   Kent Ratajeski
   
   In this activity, students view a Quicktime video animation based on data from the North American Volcanic and Intrusive Rock Database (NAVDAT) to learn about the history of volcanism in the western U.S. during the last 65 million years. Students are guided through the complex data-rich animation with a series of instructions and study questions which highlights time-space-composition relationships and links to plate tectonics.


6. Sr Isotopic Compositions of Mafic Volcanic Rocks, Western United States
   Kent Ratajeski
   
   In this exercise, students use whole-rock Sr isotopic compositions of volcanic rocks in the western United States to explore variability in mantle sources. The isotopic data are obtained from the North American Volcanic and Intrusive Database (NAVDAT) and analyzed using an interactive plotting and mapping tools at the NAVDAT website.


7. Igneous Rock Compositions and Plate Tectonics
   Allen Glazner and Kent Ratajeski
   
   This is a group assignment that uses the GEOROC database to examine the function of plate tectonics in generating petrologic diversity. Use Excel to produce variation diagrams of major-element data and chondrite-normalized REE plots to quantify similarities and differences of samples from the same and different plate tectonic settings. Identify and analyze the chemical trends to make petrologic interpretations.


8. Crystallization-Differentiation of Basaltic Magma
   Kent Ratajeski
   
   Use a 'precompiled' Excel spreadsheet containing analyses from the GEOROC database, supplemented by other data, to produce variation diagrams of major-element data, and graphs illustrating time-space-compositional relationships. Identify and analyze the chemical trends to make petrologic interpretations. Use surface samples and drill core data from the Kilauea Iki lava lake as the case study.


9. Compositional Diversity in Volcanic Suites
   Kent Ratajeski
   
   Guided by step-by-step tutorials, request specific datasets from the GEOROC database and use Excel to produce variation diagrams of major- and trace-element data. Analyze the chemical trends to make petrologic interpretations. Use data from the caldera-producing volcanoes at Yellowstone and Crater Lake as a case study.