Volcanoes, Plate Tectonics and Igneous Rocks
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A presentation on Volcanoes, Plate Tectonics and Igneous Rocks for high school use. Compiled by James Campbell with resources from the Geological Society of the UK which has wealth of useful material.
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Volcanoes, Plate Tectonics and Igneous Rocks
- 3. Volcanic bombs: large lumps of rock and molten blobs of magma thrown out from the volcano Ash, steam & gas: material erupted from the volcano Geyser: vent that shoots steam and boiling water into the air Sill: flat sheet of igneous rock formed underground Ash, steam & gas Crater Secondary vent Volcanic bombs Lava Sills Magma chamber Geysers Conduit Main vent Dykes
- 4. • Magma collects in magma chamber • As magma is added the pressure increases causing fractures • Magma is less dense than surrounding solid rock so rises • Erupts on the surface through a volcano as lava, ash and gas
- 5. Outer core (liquid) Inner core (solid) • Plates are made from the lithosphere • The lithosphere is broken up into tectonic plates which move around on top of the asthenosphere • Lithosphere is rigid and brittle so can fracture and buckle • Asthenosphere is solid rock but is plastic and can flow
- 8. Plates moving AWAY from each other Volcanoes Magma New ocean crust David Karnå / CC by 3.0 Iceland LithosphereAsthenosphere (lower mantle)
- 9. Magma Plate melts Volcano Plate is subducted Oceanic and Continental plates Mount St. Helens, Washington, USA Oceanic crust ~2.9 g/cm3 Continental crust ~2.7 g/cm3
- 10. Oceanic and oceanic plates Older oceanic plate Younger oceanic plate Oceanic island arc Magma Plate melts Plate is subducted Ocean trench Mount Mayon, Philippines
- 11. Magma Hot spot Active volcano Older extinct volcanoes Plate moving over hotspot Kilauea, Hawaii Plate moving OVER a HOTSPOT Kilauea, Hawaii
- 13. Lava fountain, Hawaii Ash cloud, Aleutian Islands Volcanic bomb Effusive Explosive Pyroclastic flow, Monserrat (British Geological Survey) Lava lake, Nyiragongo
- 14. Olympus Mons on Mars Shallow slopes made from lavaRunny basalt magma Kilauea lava lake, Hawaii Wolf Volcano, Galapagos Islands Erta Ale Volcano, Ethiopia Photo: filippo_jean/CC-By-2.0
- 15. Steep slopes made from lava and ash Sticky magma Mount St. Helens, Washington, USA Mount Fuji, Japan Mayon Volcano, PhilippinesCotopaxi, Ecuador
- 16. ´A´a lava, Guatemala Photo: Librex/CC-By-2.0Pahoehoe lava, Hawaii Columnar joints, Isle of Mull Pillow lava, Cornwall
- 17. IGNEOUS ROCKS
- 19. Magma Rock images: Sandatlas.org Basalt columns, Isle of Mull Basalt Andesite Basalt with olivine crystals Obsidian Pumice
- 21. Gabbro under the microscope Gabbro Granite MAGMA Diorite Rock images: Sandatlas.org
- 23. • Mid Atlantic Ridge – divergent plate boundary • North American and Eurasian plates moving apart at 25mm/year • Iceland also lies above a ‘hotspot’ • Eyjafjallajökull is in Iceland's Eastern Volcanic Zone • 200km thick ice cap
- 24. David Karnå / CC by 3.0 Fissure eruption at Fimmvörðuháls Ash column after explosive eruption Explosive eruption at Eyjafjallajökull 20th March 2010 10km high plume Boaworm / CC by 3.0
- 25. • European airspace was closed from 15-21 April 2010. 107,000 flights were cancelled, airline industry lost £1.1 billion (International Air Transport Association) • Many industries relying on air freighted products were badly affected → shortages of imported fruits, flowers and electronic hardware • River levels raised by 3m • Agricultural land, roads, bridges and buildings damaged by flooding • 800 people were evacuated
- 27. • Mount Nyiragongo is in the Democratic Republic of Congo • Part of East African Rift Valley, a developing divergent plate boundary • Crater contains persistent lava lake • The lava emitted in eruptions at Nyiragongo is often unusually fluid (nephelinite - very low SiO2 content)
- 29. • Nyiragongo erupted on 17th January 2002 • 13km fissure opened up on the south side of the volcano • Lava flows reached speeds of 60km/hr in the direction of Goma and Lake Kivo • 14-34 million m3 of lava • Eruption of lava stopped after ~12 hours but lava continued to flow towards and into Lake Kivo for a 3 days • 45 fatalities in first 24 hours due to lava flows and CO2 asphyxiation
- 30. THE PRESENTER A huge thank you and acknowledgements to the Geological Society of the UK from which this material was chiefly drawn https://twitter.com/JAHC1 https://www.linkedin.com/in/jamesahcampbell/ https://www.slideshare.net/JamesAHCampbell1 https://www.youtube.com/JamesCampbell_JAHC James Campbell has spent over 30-years in the diamond industry in a variety of leadership roles both in major and junior companies. He is currently Managing Director of Botswana Diamonds plc and also a Non-Executive Director of Shefa Gems ATM. Previously he held leadership roles at Rockwell Diamonds Inc, Stellar Diamonds plc, Lucara Diamond Inc, African Diamonds plc, West African Diamonds plc and De Beers where he spent over 20-years with notable appointments including General Manager Exploration and Nicky Oppenheimer's Personal Assistant. James is also Chairman of the leadership development Non-Profit Organisation Common Purpose SA. James holds a degree in Mining & Exploration Geology from the Royal School of Mines (Imperial College, London) and an MBA with distinction from Durham University. James is a Fellow of the IOM3, SAIMM and IODSA. He is also a C.Eng (UK), C.Sci (UK) and Pr.Sci.Nat.