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magma-and-other-volcanic-materials.pptxreal
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- 3. Let’s Review… ❖Compare andcontrast magma and lava. ❖What plate boundaries will result in formation of a volcano?
- 4. Magma • has awide range of compositions, but silica (SiO2) always dominates the mix. • has high temperatures. • fluid—it has the ability to flow. Most magma actually is a mixture of liquid (often referred to as melt) and solid mineral grains.
- 5. Composition of Magmasand Lavas • The composition of magmas and lavas is controlled by the most abundant elements in the Earth—Si, Al, Fe, Ca, Mg, Na, K, H, and O. • chemical composition (largely silica dioxide - SiO2 ) and gas content (largely water vapor and CO2). • SiO2 content controls the viscosity of a magma
- 6. Viscosity of Magmasand Lavas • The internal property of a substance that offers resistance to flow is called viscosity. • The more viscous a magma, the less easily it flows. • Viscosity of a magma depends on temperature and composition (especially the silica and dissolved-gas contents).
- 7. Types of Magma •Basaltic, containing about 50 percent SiO2. • Andesitic, about 60 percent SiO2. • Rhyolitic, about 70 percent SiO2.
- 9. Magma Type Chemical Composition Temperature (degrees C) Viscosity Gas Content Basaltic45-55% SiO2; High in Fe, Mg, Ca; Low in K, Na. 1000 - 1200 Low Low Andesitic 55-65% SiO2; Intermediate Fe, Mg, Ca, Na, K 800-1000 Intermediate Intermediate Rhyolitic 65-75% SiO2; Low in Fe, Mg, Ca; High in K, Na 650-800 High High
- 11. Types of volcanicdeposits (photos from USGS) Volcanoes also vary in terms of the types of deposits that they produce. Lava: Hot (up to 1200 degrees C), fluid,molten rock that flows along the land surface.
- 12. Lava can flowlike viscous water, including forming lava falls.
- 13. Pahoehoe: Lava witha ropelike surface texture due to partial cooling as the lava flowed. Relatively hot, low viscosity lava.
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- 15. A thick depositof pahoehoe lava
- 16. Aa: Blocky, roughlava flow. Due to high viscosity lava that flowed pushing chunks of solid and semi-solid blocks. www.volcanovideo.com/Movies/p8vdclp.htm
- 17. Lava tube: Atube formed by cooling and solidifying of the lava walls while fluid lava continued to flow inside.
- 18. Pillows: A formof closed lava tube (with a bulbous end) that forms when a lava flows into water (e.g., a lake or ocean) and cools very rapidly.
- 19. Pyroclastic material: ✔Debris formedby a volcanic explosion. ✔Results when magma is very viscous. ✔ Rapidly moving volcanic material. ✔ Speeds up to 200km/h ✔ May contain hot, poisonous gases Tephra: ✔The general term for all pyroclastic material that is ejected from a volcano. Different terms apply according to the size of the tephra.
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- 21. Ash: tephra thatis finer than 2 mm in diameter.
- 22. Lapilli: from 2mm to 64 mm in diameter. Blocks: hard fragments greater than 64 mm in diameter.
- 23. Bombs: soft, partiallymelted fragments greater than 64 mm in diameter.
- 24. Tuff: A depositmade up of ash. Welded tuff: A deposit of pyroclastic material that was laid down while still very hot and particles become fused together. Ash fall: Fallout of very fine ash from the air. Volcanic ash fall during mid-day with the eruption of Mount Pinatubo in the Philippines.
- 25. Ash flow: Pyroclasticdebris that flows downslope. Lahar: A water saturated slurry of ash and other volcanic debris that flows downslope.
- 26. Nuée Ardente (glowingcloud): A hot, gaseous cloud of ash that flows down slope. http://volcano.und.nodak.edu/vwdocs/volc_images/ Flow speeds can reach 160 km/hr and temperatures can exceed 600 degrees C.
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- 28. What are thesigns of an impending Volcanic Eruption?
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- 32. What are thetypes of Geothermal power plant?