Klasifikasi berdasar komposisi mineralogi

Williams, Turner, dan Gilbert (1954)A. Kelompok GabroIndeks warna 40 70 %Plagioklas lebih basa dari Ab1An1Mengandung CPX, OPX dan OLVAlkali felspar dan kuarsa < 10 %Yang banyak foids disebut gabro alkalinNama : gabro, diabas (dolerit) dan basal (dibedakan berdasar lokasi pembekuan, tekstur dan struktur).

Mode: % of each mineral in rockMust add up to 100%Quick ID of major mineralsChoose which diagram to name your rock

QAPF diagramAnorthosite: >90% plagGabbro >35% mafic minerasDiorite

B. Kelompok UltramafikIndeks warna > 70 %Nama : pikrit, peridotit, dunit, piroksenitBatuan alterasi : serpentinitC. Kelompok DioritIndeks warna < 40 %SiO2 52 66 %Tabel hal. 93Nama : Diorit, andesitBatuan alterasi : propilit

KELOMPOK DIORIT, MONZONIT & SIENIT

TeksturAlkali felspar < 1/3 total felsparAlkali felspar >1/3 < 2/3 total felsparAlkali felspar > 2/3 total felsparTipe-tipe FelspatoidButir halusAndesitTrasi andesitTrasitPonolitButir kasarDioritMonzonitSienitFelspatoidal sienit

D. Kelompok Granit Tabel hal 121 Norm Q 10 % Nama : Dasit, Riolit, Granit, Pegmatit, Granodiorit, Obsidian, Perlit, Pitchstone

KELOMPOK GRANODIORIT. ADAMELIT & GRANIT

TeksturAlkali felspar > 1/8 < 1/3 total felsparAlkali felspar > 1/3 < 2/3 total felsparAlkali felspar > 2/3 total felsparButir halusDasitRiodasitRiolitButir kasarGranodioritAdamelitGranit

Other names:Porphyry: porphyritic rockAplite: uniformly fine-granite phaneritic light colored granite (sugary)Pegmatite: phaneritic with highly variable grain size (can be large).Quartz-richGranitoid909060602020Alkali Fs.Quartz SyeniteQuartzSyeniteQuartzMonzoniteQuartzMonzodioriteSyeniteMonzoniteMonzodiorite(Foid)-bearingSyenite5103565(Foid)-bearingMonzonite(Foid)-bearingMonzodiorite90Alkali Fs.Syenite(Foid)-bearingAlkali Fs. Syenite10(Foid)Monzosyenite(Foid) Syenite(Foid)Monzodiorite(Foid) GabbroQtz. Diorite/Qtz. Gabbro510Diorite/Gabbro/Anorthosite(Foid)-bearingDiorite/Gabbro60(Foid)olitesQuartzoliteGraniteGrano-dioriteTonaliteAlkali Feldspar GraniteQAPF60

(c)

Mafic rocks: plag, pyroxene, olivineNorite: gabbro with more opx than cpxTop and bottom fields at 10% tick marksSide fields at 5% tick marks(c)

Ultramafic rocks: opx, cpx, olivineIf cant tell opx vs. cpx use general names of pyroxenite and peridotite

Aphanitic rocksBased % from phenocrystsNeed to normalize A and PNot the most definite way to name rockFigure 2-3. A classification and nomenclature of volcanic rocks. After IUGS.

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.

Rock with 70% X, 20% Y, 10% ZPlot mineral composition of triangle diagramFigure 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.

Figure out % of each mineralReduce to 3 minerals of choice and normalizeIn rock:X=9%Y=2.6%Z=1.3%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.

In rock:X=9%Y=2.6%Z=1.3%Of these 3:X=70%Y=20%Z=10%X+Y+ZX/(X+Y+Z)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.

Of these 3:X=70%Y=20%Z=10%X/(X+Y+Z) =70Now normalize %Y and ZZ/(Z+Y) and Y/(Z+Y)20/30 (67%) for Y10/30 (33%) for ZFigure 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.