1 / 10

Chapter 3 Section 2 Igneous Rocks

Chapter 3 Section 2 Igneous Rocks. From the core of the continents to nearly all of the oceanic crust—igneous is everywhere!. IGNEOUS ROCKS. magma lava. “fire” rocks. cooling. andesite. pumice. Formed from cooled/hardened _________ or ______

anise
Download Presentation

Chapter 3 Section 2 Igneous Rocks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 3 Section 2 Igneous Rocks From the core of the continents to nearly all of the oceanic crust—igneous is everywhere!

  2. IGNEOUS ROCKS magma lava “fire” rocks cooling andesite pumice Formed from cooled/hardened _________ or ______ Are called _______________ [ignis Latinfire] The rate of __________ determines the size of the mineral’s crystals. basalt

  3. INtrusive: below groundcools slower many many &large crystals Ex: granite, gabbro

  4. Intrusive Igneous • Visible due to erosion & weathering • Magma= mainly silicon & oxygen • Gases: water vapor (gases trapped) • Magma less dense than surrounding rock moves towards surface & cools • Elements combine minerals form & ‘grow’ crystals! • Example: • Granite • Cumberlandite

  5. Intrusive Igneous: Cumberlandite • Only found in Cumberland, RI (official state rock) • 4-acre lot in Blackstone Valley (Iron Mine Hill) & trace amts. Narr. Bay • Dense & prone to rust (iron  magnetic); titanium, transitions to peridotite (intr. coarse ign.) • Formed 1.5 bya  volcanic activity • Valuable  cannon and farm tools 18th/19th cent.

  6. Obsidian EXtrusive: above groundcools quicker f e w &small crystals Air bubbles are sometimes trapped (pumice, scoria) Basalt

  7. Extrusive Igneous Basalt • Magma = below ground// Lava= above ground • Lava most gases escaped • Lava hardens extrusive igneous rock • Extruded onto surface • Example: Rhyolite, Basalt

  8. Classifying Igneous Rocks • Classification based on two major characteristics: • Texture: appearance based on size, shape & arrangement of crystals • Composition: proportions of light and dark minerals

  9. Classification: Texture • Coarse-grained: slow cooling large crystals • Allows charged atoms (ions) to move large distances within magma & link together (crystallize) • Fine-grained: rapidcooling  small crystals • Ions lose motion and quickly combine; all compete for available ions • Glassy: lava on surface little time for ions to crystallize randomly distributed  glassy appearance (tiny crystals) • Porphyritic: different-sized minerals experience different rates of cooling • Large crystals (phenocrysts) may be surrounded by fine grained minerals • Minerals don’t crystallize @ same rate (location and melting point.)

  10. Classification: Composition • Granitic: light-colored silicates (quartz & feldspar) • 70 % silica • 10 % dark silicate minerals (i.e. biotite mica, amphibole) • Major component of continental crust • Ex: rhyolite = extrusive granitic rock • Basaltic: contain many dark silicate materials (plagioclase feldspar) • Rich in magnesium and iron • Iron  darker and denser than granitic rocks • Ex: gabbro = intrusive basaltic rock • Andesitic: composition between granitic and basaltic • Volcanic rock = andesite: • At least 25 % dark silicates (amphibole, pyroxene, biotitemica) • Dominant mineral plagioclase feldspar :type of feldspar dark w/ridges (striations) • Ultramafic: composed almost entirely of dark silicate minerals • Rare @ Earth’s surface • Ex: peridotite—upper mantle composition

More Related