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Geol 4110 Class 5 - Metamorphic Rocks and Deformation 2/23/08 Class will not meet this week. Rather, you should expect to come to the classroom to work on the homework exercise on your own time. Before attempting the homework, you should read through the Primer on Metamorphic Rock Handout and view the Powerpoint (from the website). Handouts Primer on Metamorphic Rocks Other Ideas for Metamorphic Rock Exercises (MMEW handouts) Download Powerpoint on Metamorphic Rocks and Deformation Homework - Classification of Metamorphic Rocks (10 pts) There are as many ways to classify rocks as there are rocks. Their are several general approaches to classifying rocks. One is to group rocks by their physical attributes, another is to group them by their chemical attributes, and a third way is to classify them by their interpreted mode of origin (their petrogenesis). For metamorphic rocks, physical classification and genetic classifications are the most common. We will make attempts to classify a suite of 18 metamorphic rocks by these two methods. Part I. Physical Classification Develop a 3-tiered classification scheme based on physical attributes of your own choosing. Make the attributes either/or. Possible attributes include: color (dark/light), luster(shiny/dull), foliation (yes/no), grain size (coarse/fine), banding (yes/no). See the flow chart on the next page as an example of such a 3-tiered scheme. (Do not use this exact flow chart for your scheme) Part II. Genetic Classification Genetic classifications of metamorphic rocks typically involve interpretations of the protolith (what the rock started out as) and the degree of metamorphism. Write in the matrix below the appropriate sample number. Protolith Quartz Sandstone Low Grade Quartzite: ____________ ____________ same Limestone Marble: ____________ ____________ same Conglomerate Metaconglomerate: ___________ ___________ Shale, Siltstone Slate: ____________ ____________ Graywacke Metagraywacke: _____________ Basalt Greenstone: _____________ High Grade Schist: ____________ ____________ Gneiss: ____________ ____________ Amphibolite: _____________ 15 Samples S123 3811 4003 4329 2107 3305 10 3000 4011 4317 3386 3804 3073 2307 GFL 46A Classification by Physical Characteristics 1) 2) BANDING COARSE NO BANDING FINE 3) DARK LIGHT DARK ________ _______ ________ LIGHT COARSE FINE DARK LIGHT DARK LIGHT ________ _______ _______ _______ _______ ______ _______ ________ _______ _______ _______ _______ ______ ________ _______ ________ _______ _______ _______ _______ ______ ________ _______ ________ _______ _______ _______ _______ ______
