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- Chapter 28: Met of Pelites - Whitman College
Chapter 28: Metapelites Figure 28 5 AFM compatibility diagram (projected from Ms) for the biotite zone, greenschist facies, above the chloritoid isograd The compositional ranges of common pelites and granitoids are shaded Winter (2010) An Introduction to Igneous and Metamorphic Petrology Prentice Hall Chapter 28: Metapelites Figure 28 6
- Chemographic Diagrams - University at Buffalo
Another figurative AKF to show where minerals plot Al-poor rocks contain biotite, and may contain an amphibole if sufficiently rich in Mg and Fe, or microcline if not Rocks richer in Al contain andalusite and cordierite * * * All 9 is clearly too complex
- PowerPoint Presentation
Amphibole begins to form The original basaltic magma becomes andesitic magma As temperatures cool to 800 C and silica increases further, the sheet silicate biotite forms Andesitic magma now evolves into rhyolitic magma Quartz forms last at low temperatures Muscovite mica and potassium feldspar also form at this temperature
- Igneous Rocks - USGS
Common rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite (and other micas), augite, and the calcium rich plagioclase feldspars Common mafic rocks include basalt (extrusive) and gabbro (intrusive) as pictured Mafic lava, before cooling, has a lower viscosity than felsic or intermediate lava due to its lower silica content
- Intrusive Igneous Rocks, part 2
* Mafic Mineralogy of Granodiorite Hornblende is the most common mafic mineral, followed by biotite Hornblende may occur in prisms or in ragged plates Pyroxene is rare * Monzonite Intrusive igneous, plutonic The feldspar in these rocks is between ⅓ and ⅔ microcline or orthoclase, with the remainder being plagioclase P (A+P) is 35-65 Q = 0-5
- Chapter 21: Metamorphism
Biotite, which is an important pelitic mineral that is often indicative of both grade and composition, does not appear Although our assemblage plots as a 3-phase sub-triangle, other pelitic assemblages plot on the A-F edge, and most of the area of the diagram is wasted The ACF diagram is more useful for mafic rocks Figure 28-5 (p 640)
- Magmatic Differentiation, Assimilation Magma Mixing
” and then “Hornblende ”, then “ Biotite ”, with the falling temperature Continuous Series: At lowering of temperature (cooling starts), first plagioclase to crystallized is rich in Ca (Ca-Plagioclase) As the reaction goes on and temperature drops, the crystals become more and more sodic (unless remove from the melt)
- Chemistry of Igneous Rocks
Melts Liquid composed of predominantly silica and oxygen Like water, other ions impart greater conductivity to the solution Si and O is polymerized in the liquid to differing degrees – how ‘rigid’ this network may be is uncertain… Viscosity of the liquid increases with increased silica content, i e it has less resistance to flow with more SiO2… related to polymerization?? There is
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