Please read over the questions carefully and answer the questions and label the corresponding diagram (attached image) Show your calculations and plot each rock on the appropriate blank classification diagram on the back of this page. Label your plotted points with the corresponding question number and label the corners of the diagram. 1. You're studying a uniformly fine-grained (1-2mm) igneous rock. Your point-count modal analysis of a thin section indicates 30.6% plagioclase, 28.9% quartz, 25.5% microcline, 8.2% muscovite, and 5.8% biotite. Collectively, zircon and apatite (accessory minerals) make up only 1.0% of the rock. What is the rock name? 2. You're studying a medium- to coarse-grained (4-10 mm) igneous rock. Based on the hand sample, you estimate that the rock contains 30% alkali feldspar, 30% nephaline, 15% hornblende, 15% plagioclase, and 10% biotite. Accessory minerals are negligible. What is the rock name? 3. You're studying a coarse-grained (5-10 mm) igneous rock. The hand sample contains equal proportions of black pyroxene and dark-gray plagioclase. There is little else in the rock. This is substantiated by thin section study. Microprobe analyses indicate that the pyroxene is augite and that the plagioclase is Anz (bytownite). What is the rock name? 4. While mapping in the Ariège region of the French Pyrenees, you discover an outcrop of an unusual igneous rock. The rock is quite coarse-grained and is dark colored with patches of dark green, due to abundant olivine. You estimate that the rock contains approximately 50% olivine, 45-50% pyroxene, and no more than about 5% garnet. In thin section, the pyroxene is identified as mostly orthopyroxene (about 30% of the rock), but there's also considerable clinopyroxene present (15-20% of the rock). What is the rock name? 5. Your description of a pyroclastic rock indicates that it's dominated by accretionary lapilli (80%) that you interpret as having formed in the eruptive column, but also contains substantial (20%) volcanic ash. What is the rock name? 6. While hiking the slopes of El Chichón volcano in Mexico, you discover an outcrop of microcrystalline (0.1-0.5 mm) volcanic rock. You perform whole-rock geochemical analysis of the rock, and find it contains 57.6 wt% SiOz, 18.3 wt% Al203, 6.4wt% Fe203, 7.3wt% CaO, 4.3 wt% NazO, 3.1 wt% MgO, 2.5w% K20, and trace amounts of other compounds. What is the rock name?
Please read over the questions carefully and answer the questions and label the corresponding diagram (attached image)
Show your calculations and plot each rock on the appropriate blank classification diagram on the back of this page. Label your plotted points with the corresponding question number and label the corners of the diagram.
1. You're studying a uniformly fine-grained (1-2mm) igneous rock. Your point-count modal analysis of a thin section indicates 30.6% plagioclase, 28.9% quartz, 25.5% microcline, 8.2% muscovite, and 5.8% biotite. Collectively, zircon and apatite (accessory minerals) make up only 1.0% of the rock.
What is the rock name?
2. You're studying a medium- to coarse-grained (4-10 mm) igneous rock. Based on the hand sample, you estimate that the rock contains 30% alkali feldspar, 30% nephaline, 15% hornblende, 15% plagioclase, and 10% biotite. Accessory minerals are negligible.
What is the rock name?
3. You're studying a coarse-grained (5-10 mm) igneous rock. The hand sample contains equal proportions of black pyroxene and dark-gray plagioclase. There is little else in the rock. This is substantiated by thin section study. Microprobe analyses indicate that the pyroxene is augite and that the plagioclase is Anz (bytownite).
What is the rock name?
4. While mapping in the Ariège region of the French Pyrenees, you discover an outcrop of an unusual igneous rock. The rock is quite coarse-grained and is dark colored with patches of dark green, due to abundant olivine. You estimate that the rock contains approximately 50% olivine,
45-50% pyroxene, and no more than about 5% garnet. In thin section, the pyroxene is identified as mostly orthopyroxene (about 30% of the rock), but there's also considerable clinopyroxene present (15-20% of the rock).
What is the rock name?
5. Your description of a pyroclastic rock indicates that it's dominated by accretionary lapilli (80%) that you interpret as having formed in the eruptive column, but also contains substantial (20%) volcanic ash.
What is the rock name?
6. While hiking the slopes of El Chichón volcano in Mexico, you discover an outcrop of microcrystalline (0.1-0.5 mm) volcanic rock. You perform whole-rock geochemical analysis of the rock, and find it contains 57.6 wt% SiOz, 18.3 wt% Al203, 6.4wt% Fe203, 7.3wt% CaO, 4.3 wt% NazO, 3.1 wt% MgO, 2.5w% K20, and trace amounts of other compounds.
What is the rock name?
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