Ch 02 igneous classification
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The document discusses different classification schemes for igneous rocks. It provides figures that classify igneous rocks based on their mineralogical composition and textures. Figure 2-1 shows how to plot mineral components on ternary diagrams. Figures 2-2 and 2-3 classify phaneritic, gabbroic, ultramafic, and volcanic rocks based on their mineralogy. Figure 2-4 classifies volcanic rocks based on their total alkalis and silica content. Figure 2-5 classifies pyroclastic rocks based on material type and size of fragments.
Ch 02 igneous classification
- 1. Classification of Igneous RocksClassification of Igneous Rocks Figure 2-1a. Method #1 for plotting a point with the components: 70% X, 20% Y, and 10% Z on triangular diagrams. An Introduction to Igneous and Metamorphic Petrology, John Winter, Prentice Hall.
- 2. Classification of Igneous RocksClassification of Igneous Rocks Figure 2-1b. Method #2 for plotting a point with the components: 70% X, 20% Y, and 10% Z on triangular diagrams. An Introduction to Igneous and Metamorphic Petrology, John Winter, Prentice Hall.
- 3. Classification ofClassification of Igneous RocksIgneous Rocks Figure 2-2. A classification of the phaneritic igneous rocks. a. Phaneritic rocks with more than 10% (quartz + feldspar + feldspathoids). After IUGS. The rock must contain a total of at least 10% of the minerals below. Renormalize to 100% (a) Quartz-rich Granitoid 9090 6060 2020Alkali Fs. Quartz Syenite Quartz Syenite Quartz Monzonite Quartz Monzodiorite Syenite Monzonite Monzodiorite (Foid)-bearing Syenite 5 10 35 65 (Foid)-bearing Monzonite (Foid)-bearing Monzodiorite 90 Alkali Fs. Syenite (Foid)-bearing Alkali Fs. Syenite 10 (Foid) Monzosyenite (Foid)Syenite (Foid) Monzodiorite (Foid)Gabbro Qtz. Diorite/ Qtz. Gabbro 5 10 Diorite/Gabbro/ Anorthosite (Foid)-bearing Diorite/Gabbro 60 (Foid)olites Quartzolite Granite Grano- diorite Tonalite AlkaliFeldsparGranite Q A P F 60
- 4. Classification of Igneous RocksClassification of Igneous Rocks Figure 2-2. A classification of the phaneritic igneous rocks. b. Gabbroic rocks. c. Ultramafic rocks. After IUGS. Plagioclase OlivinePyroxene Gabbro Troctolite Olivine gabbro Plagioclase-bearing ultramafic rocks 90 (b) Anorthosite OlivineOlivine ClinopyroxeneClinopyroxeneOrthopyroxeneOrthopyroxene LherzoliteLherzolite Harzburgite WehrliteWebsterite OrthopyroxeniteOrthopyroxenite ClinopyroxeniteClinopyroxenite Olivine Websterite PeridotitesPeridotites PyroxenitesPyroxenites 90 40 10 10 DuniteDunite (c)
- 5. Classification ofClassification of Igneous RocksIgneous Rocks Figure 2-3. A classification and nomenclature of volcanic rocks. After IUGS. (foid)-bearing Trachyte (foid)-bearing Latite (foid)-bearing Andesite/Basalt (Foid)ites 10 60 60 35 65 10 20 20 60 60 F A P Q Rhyolite Dacite Trachyte Latite Andesite/Basalt Phonolite Tephrite
- 6. Classification of Igneous RocksClassification of Igneous Rocks Figure 2-4. A chemical classification of volcanics based on total alkalis vs. silica. After Le Bas et al. (1986) J. Petrol., 27, 745-750. Oxford University Press.
- 7. Classification of Igneous RocksClassification of Igneous Rocks Figure 2-5. Classification of the pyroclastic rocks. a. Based on type of material. After Pettijohn (1975) Sedimentary Rocks, Harper & Row, and Schmid (1981) Geology, 9, 40-43. b. Based on the size of the material. After Fisher (1966) Earth Sci. Rev., 1, 287-298.