Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Igneous rocks - Global Change
Document related concepts
Transcript
The Diversity and Cycle of Rocks Rock Cycle Rock cycle: describes dynamical transformation of rocks between the 3 rock types • IGNEOUS, METAMORPHIC, SEDIMENTARY Where are we going? • What is the Earth made of? (Of what is the Earth made?) • When compounds organize into crystalline structures….Minerals, otherwise amorphous! • Minerals combine to form Rocks Abundance of Elements in the Earth’s Crust • 98% of the mass of crustal minerals is from 8 elements Crystals of a Mineral Aragonite - CaCO3 Minerals Mineral: building blocks of rocks • Naturally occurring • Homogenous • Inorganic solid (biominerals okay) • Fixed crystalline structure • Definable chemical composition Quartz (SiO2) Crystal Structure is defined by the ordering of atoms which form a crystal lattice This arrangement produces distinct and and identifying properties of the mineral. -Cleavage -Hardness -Crystal Habit Cleavage Mineral Properties • • • • • • • • Crystal Form or Habit Cleavage Hardness Color Luster Specific Gravity Streak Other Features • • • • • • • • Natural Shape Broken Shape Soft or Hard Clear to Colored Metallic or NonDensity=mass/volume Color of powder Reaction with acid Crystal Form or Habit Polymorphs – many shapes • Same chemical composition i.e., mineral composed of Carbon • Different arrangement of atoms in the crystalline structure C: Diamond versus Graphite CaCO3: Aragonite versus Calcite Bonding of Atoms into an Ordered Crystalline Structure Arrangement of Atoms Defines Crystal Properties Valence of the Silicate Ion or Tetrahedron The basic building block of all silicates More Complex Silicate Minerals Pyroxene SiO3-2 Amphibole Si4O11-6 Micas Seriously Complex Tectosilicates – Framework Structure •Quartz •Feldspars Common Earth Minerals • • • • • • Olivine Pyroxenes Amphiboles Micas Feldspars Quartz • • • • • • Isolated Single Chain Double Chain Sheets Framework Framework Sequence of Crystallization Bowen’s Reaction Series EXTRUSIVE INTRUSIVE Igneous Rocks Igneous rocks: most abundant rock type • Formed from freezing of magma at temperatures between about 650-1100 °C • Intrusive rocks - Slow cooling within the Earth • Extrusive (volcanic) rocks - Erupted on the Surface Addition of Water Results in Partial Melting Formation of Felsic and Intermediate Magmas Igneous Rocks Igneous rocks: classified by mineral size and composition • Intrusive rocks - Crystallized slowly - Minerals are larger • Extrusive rocks - Crystallized rapidly - Minerals are smaller IGNEOUS ROCKS – RATE OF COOLING Intrusive Granite Extrusive Obsidian Glass Rhyolite Rocks Types Rocks: aggregates of minerals • Rock types are categorized by their genesis • Igneous rocks: crystallized from (partly) molten material • Metamorphic rocks: recrystallized under intense temperature and/or pressure • Sedimentary rocks: lithified fragments of pre-existing rock or formed from biological/chemical precipitation IGNEOUS ROCKS METAMORPHIC ROCKS SEDIMENTARY ROCKS RELATIVE ABUNDANCE OF ROCK TYPES SUMMARY
