GEOL 1610 1st EditionLecture 5Outline of Last Lecture I. This Dynamic Earth- plate tectonicsII. The historical perspectiveIII. What causes all this?IV. Developing the TheoryV. Ocean floor mappingVI. Magnetic stripping and polar reversesVII. Sea Floor SpreadingVIII. Concentration of earthquakesIX. Divergent boundariesOutline of Current Lecture I. Tectonic Context of VolcanoesII. Three Tectonic Settings for VolcanoesIII. Rift Valleys- a special case for volcanoesIV. What defines the nature of a volcanic eruption?V. Products of volcanic eruptionsVI. Volcanoes: Behavior, properties, and classificationVII. Products of Mafic and Volcanic EruptionsVIII. Mafic Lava- Main PointsIX. Shield VolcanoesX. Felsic Magma and lava- Main PointsXI. Products of Felsic Volcanic EruptionXII. Volcanoes of Rift ValleysXIII. What are the main intrusive igneous bodies?Current LectureI. Tectonic Context of Volcanoesa. Convergent Boundariesi. Island Arcsii. Continental Arcsb. Divergent Boundariesi. Rift Valleysii. Oceanic Ridgesc. Intraplate Activityi. Island arcsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Subduction margins of ContinentsII. Three Tectonic Settings for Volcanoesa. Island arcsb. Subduction margins of ContinentsIII. Rift Valleys- a special case for volcanoesa. Bimodal Volcanismb. Rifts evolves into mid-ocean ridgesIV. What defines the nature of a volcanic eruption?a. Viscosityi. SiO2 content (rhyolite 70% basalt 50%)ii. Correlates positively with viscosityb. Violatiles (dissolved gas + water)i. H2O, CO2, SO2ii. Decrease viscosity, increase explosivenessc. Temperature of the lavai. Hot lava flows farther (lower viscosity)V. Products of volcanic eruptionsa. Lavai. Flows across surfaceb. Pyroclasticsi. Particles ejected into airii. From ash to bombsc. Gassesi. Usually very poisonous and hotVI. Volcanoes: Behavior, properties, and classificationa. Mafic Volcanoesi. Shield volcanoesii. Cinder (scoria) Conesiii. Fissure Eruptions- Basalt Plateausb. Felsic and Intermediate Volcanoesi. Composite cones (stratovolcanoes)ii. CalderasVII. Products of Mafic and Volcanic Eruptionsa. Basaltic Lavai. Pahoehoe, aaii. Pillow Basalts, Flood Basaltsb. Pyroclasticsi. Size: mostly small bombsii. Behavior: bubbles and spitsiii. Deposits: scoria conesVIII. Mafic Lava- Main Pointsa. “Gentle eruptions”b. BasaltThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. Low viscosityd. Lots of lavae. Little ashf. Long flowsg. “shield” volcanoesIX. Shield Volcanoesa. Steamounts-Islandsi. Kilavea, Mauna Loaii. Lava tubesiii. Steep-walled calderaiv. Late eruption stage1. More viscous2. More pyroclasticsb. Cinder (scoria) conesi. Deep Crater, Steep Slopesii. Smalliii. Short-livediv. Lapilli dominate ash and bombsX. Felsic Magma and lava- Main Pointsa. High viscosityb. Eruptionsi. Violentii. Variableiii. Lots of Ashiv. Little Lavav. Granatic to intermediate (andesitic)XI. Products of Felsic Volcanic Eruptiona. Lavai. Usually rhyolite/andestite flowsii. Porphry common alsob. Pyroclastic+ Gapsesi. Size- lots of ash, some lapilli, rare bombsii. Behavior: Nuee Ardente, Laharsiii. Deposits: Tuff, welded tuffc. Composite cones (stratovolcanoes)i. Tallest, symmetricalii. Mainly andesitic (but variable)iii. Interbedded lavas and pyroclasticsiv. Fissure eruptions, parasitic conesv. Nuee ardent eruptions commond. Calderasi. Collapse, Crater typeii. Huge eruptionsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iii. Lake formation1. Yellow stone 1.4 and 0.6 Million years agoiv. Mawwaiian type1. Slow Subsidencev. Post eruption collapse1. Mt. Mazama 7,800 years agoXII. Volcanoes of Rift Valleysa. Bimodal volcanism (mafic and felsic)b. Evolves to mafic only with sea floor spreadingXIII. What are the main intrusive igneous bodies?a. Batholiths, Laccoliths, Dikes, Pipes-necks These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a