epsc 221: general geology
TRANSCRIPT
![Page 1: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/1.jpg)
EPSC 221:GENERAL GEOLOGY
Lab 2:Igneous Rocks
![Page 2: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/2.jpg)
• Geologists organize rocks based on:- COMPOSITION- TEXTUREà mineralogy
Igneous Rocks—Definitions
![Page 3: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/3.jpg)
• Texture is controlled by:- cooling time- nucleation opportunity
• Phaneritic = coarse grain
• Aphanitic = fine grain
Phaneritic
Aphanitic
Igneous Rocks—Texture
![Page 4: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/4.jpg)
• If the crystals vary in size severely, the texture is Porphyritic- phenocrysts- ground mass
Porphyritic
Igneous Rocks—Texture
![Page 5: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/5.jpg)
• Vesicular textures indicate a bubbly magma
Vesicular
Igneous Rocks—Texture
![Page 6: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/6.jpg)
• Glassy textures indicate an incredibly rapid cooling- ground mass
Glassy
Igneous Rocks—Texture
![Page 7: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/7.jpg)
• Fragmental textures- pyroclastic flows- ash deposits
• welded together by heat Fragmental
Igneous Rocks—Texture
![Page 8: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/8.jpg)
Ultramaficperidotite Mafic
gabbro Felsicrhyolite
Intermediatediorite
• based on silica content (composition)• can be roughly determined by color
Igneous Rocks—Composition
![Page 9: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/9.jpg)
Important Minerals
Potassium Feldspar Plagioclase Feldspar Olivine Pyroxene
Quartz AmphiboleMicas
Igneous Rocks—Composition
![Page 10: EPSC 221: GENERAL GEOLOGY](https://reader031.vdocuments.site/reader031/viewer/2022012020/616895f1d394e9041f70daa8/html5/thumbnails/10.jpg)
Volcanic/Extrusive Plutonic/Intrusive
Igneous Rocks—Setting