Lecture-10-F10 - EAS 111: 10/4/10 • Today: Igneous rocks...

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Unformatted text preview: EAS 111: 10/4/10 • Today: Igneous rocks part 1 – basics and intrusive rocks - Next time: Volcanoes and hazards • This week, and the next couple of weeks: – Bring your textbooks to lab – it will help! – Keep up on your reading in Chapter 5 & 6 • FYI: Final Exam scheduled: Monday 12/13 10:20 AM – 12:20 PM – right here • Next Monday 10/11 – October Break – no class! We DO have lecture Weds 10/14. • Next week – October Break – NO LABS! Earth and Atmospheric Sciences 111 Fall 2010 Igneous Processes I - Igneous Rocks and Textures -Plate Margin Types and the Associated Igneous Rocks - Magma generation, movement and emplacement Lecture 10 What Can Happen to a Rock? Weathering Erosion and transport Deposition 01.06.a1 01.06.a1 a iiall Bur Bur Solidification ft liift Upl Up ifftt plli Up U Melting Deformation Deformation and metamorphism metamorphism Observe these igneous rocks and devise a way to classify them them 05.02.a1 Observe these textures of igneous rocks 05.01.a Observe these other textures of igneous rocks 05.01.a Some Useful New Terms Intrusive (Plutonic) Extrusive (Volcanic) Magma Lava Cools slowly underground (1000s to millions of years) Reaches the surface, cools quickly (seconds to 1000s of years) Molten rock underground Molten rock at the surface Eruption as lava or ash Forming Forming Igneous Rocks Rocks Forms magma chamber (solidifies or rises) Accumulates into rising magma body Partial melting of source 05.03.a1 Settings of Large Magma Chambers Observe these settings where large magma chambers Observe form, and propose causes of melting for each site form, Subduction beneath Subduction continent continent Continental Continental collision collision Mid-ocean ridge Oceanic hot spot Continental hot spot 05.11.b1 Irregular Plutons 05.11.c Batholith 05.11.c Fast cooling Slow cooling Cooling Rate and Texture 05.10.b Slow then fast Moderate cooling 05.10.c1 Granite Diorite Gabbro Peridotite 05.02.b1-8 Felsic Rhyolite Intermediate Andesite Mafic Basalt Ultramafic Ultramafic lava CPS: Igneous Rock Texture CPS: A magma formed from partial melting of the continental crust but cooled entirely deep underground would be…? entirely A. Felsic and coarse grained B. Mafic and coarse grained C. Felsic and fine grained Felsic D. Mafic and fine grained Mafic Magma Injected as Sheets Dike Sill 05.12.a Decompression 05.06.c EAS 111: Earth Science News Team led by Purdue professor first to record key event that breaks continents apart Dec.11, 2008 - Nature CPS: Melting Rocks CPS: What was the likely composition of the rock injected in the dike observed in this study? this Felsic because it was probably the result of Felsic decompression melting of the mantle decompression B. Mafic because it was probably the result of Mafic decompression melting of the mantle decompression C. Intermediate because it was related to waterIntermediate added melting from subduction D. Intermediate because of the heating from friction from the separating plates caused melting melting A. Gabbro 05.02.b1-8 Mafic Basalt How could melting occur along a divergent boundary How (mid-ocean ridge)? (mid-ocean 05.06.a1 05.06.c2 Solid asthenosphere Solid rises to fill gap rises Decompression Decompression melting melting How could melting How occur in a continental rift? rift? 05.06.c Decompression Crustal Heating Granite Gabbro 05.02.b1-8 Felsic Rhyolite Mafic Basalt 05.10.c1 Role of Source Area Cont inent al Cr ust Man tle Melting Melting continental crust forms felsic or intermediate magma magma 05.03.b2 Melting mantle Melting forms mafic magma magma Magmatism with Hot Spots Oceanic island Rising Rising mantle plume plume 05.08.a Crustal Crustal melting and caldera in continent Huge basalt flows on continents continents Melting in a Ocean-Ocean Convergent Boundary Melting (Subduction Zone) (Subduction Mostly Mostly intermediate rocks rocks 05.07.a Add water to Add hot mantle hot Diorite 05.02.b1-8 Intermediate Andesite 05.10.c1 How could melting occur along an ocean-continent How convergent boundary? convergent Mostly intermediate Mostly and some felsic rocks and Mafic magma Mafic melts crust melts Adding water Adding melts mantle melts 05.07.b1 Granite Diorite 05.02.b1-8 Felsic Rhyolite Intermediate Andesite 05.10.c1 Viscosity: Resistance to Flow Low viscosity: lava Low spreads out spreads High High viscosity: lava piles up up Higher temp. Higher and fewer silica chains silica Lower temp. Lower and abundant silica chains silica 05.09.c1 EAS 111: Assignments for 10/6/09 • Reading in Exploring Geology Chapter 6: – 6.1, 6.2, 6.3, 6.4 • Basaltic igneous rock and volcanoes – 6.7, 6.8 • Intermediate igneous rock and composite volcanoes – 6.10, 6.11, 6.12 • Large calderas, general volcanic hazards ...
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