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GEOLOGY BY NUMBER : solving petrology problems with quantitative skills

GEOLOGY BY NUMBER : solving petrology problems with quantitative skills. Jennifer M. Wenner Geology Department University of Wisconsin Oshkosh. GEOLOGY BY NUMBER. µ = µ inf e Ea /RT * [1+A( m T + b )] -2.5. The research question:.

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GEOLOGY BY NUMBER : solving petrology problems with quantitative skills

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  1. GEOLOGY BY NUMBER:solving petrology problems with quantitative skills Jennifer M. Wenner Geology Department University of Wisconsin Oshkosh

  2. GEOLOGY BY NUMBER µ = µinf eEa/RT* [1+A(mT + b)]-2.5

  3. The research question: • How is continental crust formed? (especially in continental arcs since they best approximate “average continental crust”)

  4. Observations • Continental arcs are sites of voluminous continental crustal addition

  5. Observations • The major rock type in continental arcs is grano-diorite (although there are close associations of mafic and felsic rocks).

  6. Observations • Field and chemical observations suggest that two (or more) distinct magmas were interacting to generate a variety of different rocks

  7. Hypothesis • Average continental crust is formed by mixing basaltic magmas and granitic magmas to make GRANODIORITE!

  8. Problems (perceived?) • Early calculations suggested that physical properties (melting temperature, viscosity and density) limit the abilities of magmas to mix.

  9. VISCOSITY CALCULATIONS • µ =µ0(1+A)-2.5(Marsh, 1981) •  = mT + b(empirical data) • µ = µ0[1+A(mT + b)]-2.5 • µ0 = µinf eEa/RT(theoretical -- Arrhenius) • µ =µinf eEa/RT* [1+A(mT + b)]-2.5

  10. VISCOSITY CALCULATIONS-- students need to be able to: • µ =µ0(1+A)-2.5(Marsh, 1981) •  = mT + b • µ = µ0[1+A(mT + b)]-2.5 • µ0 = µinf eEa/RT • µ =µinf eEa/RT* [1+A(mT + b)]-2.5 • Manipulate others’ equations • Use and evaluate empirical data • Assess a model’s assumptions • Discern rate and order of magnitude • Use tools such as Excel

  11. GEOCHEMICAL ANALYSIS

  12. GEOCHEMISTRY --students need to be able to: • Read and interpret graphs • Recognize and assess sources of error • Approximate slope / shape of data • Articulate meaning of data with reference to quantitative chemical concepts (i.e., KD values, µ, eNd) • Use computer programs (i.e., Excel, etc.)

  13. Petrology and Petrography

  14. Petrology and Petrography-- students need to be able to: • Express scale (including features at a variety of scales) • Assess changes/ contrasts in rates (i.e., cooling/crystallization, tectonic, diffusion) • Recognize different orders of magnitude

  15. Field work

  16. Field work -- Students need to be able to: • Approximate distances / height / scale • Estimate slope • Calculate angles and plot structural data on a map • Determine magnetic declination • Visualize 3-D from a 2-D map

  17. Approximation and/or estimation of: Rates Slope / shape of curve Distances / angular relationships Order of magnitude Appreciation of the power of graphical solutions Assessment of assumptions Spatial relations Statistics, sources of error, data analysis Use of technologic tools such as Excel Others? Important quantitative skills

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