rochas Ígneas
TRANSCRIPT
![Page 1: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/1.jpg)
Rochas Ígneas
![Page 2: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/2.jpg)
![Page 3: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/3.jpg)
http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Rocks/Rocks8.html
![Page 4: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/4.jpg)
Outra versão do Ciclo de Rocha …
http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Metrocks/Metrocks2.html
![Page 5: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/5.jpg)
Fusão Parcial e MagmaE.g., fusão parcial resulta enriquecimento em Sílica
Fusão Parcial MagmaEnriquecido: O, Si, Al, Na, K, Empobrecido: Ca, Fe, Mg Pobre em: O, Si, Al, Na, K, (< 50%)
Rico em: Ca, Fe, Mg (> 50%)
See Kehew, Fig 3-6
![Page 6: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/6.jpg)
Formação de Magma• Como são as rochas fundidas?
– 1. Aquecimento ■ 2. Redução de pressão– 3. Aumento do conteúdo de água– 4. Increased silica content
• Onde as rochas fundem?– Zonas de subducção (Silicosos
e intermediários) – Plumas Mantélicas (“Hot Spots”) não somente em limites divergentes
(Máficos)
Hot andHigh Pressure
Hot andLow Pressure
![Page 7: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/7.jpg)
Intrusivo vs. Extrusivo (Rochas silicosas)
• Silicoso (félsico) Magmas– Frio (<700oC)– Viscoso (não flui facilmente)– Gasoso (steam of H2O and C02)
• Silicoso (Rochas)– Usualmente intrusiva, grão
grosseira, rochas ácidas (Granito) a intermediária (Diorito) rochas formam plutons
– Se extrusiva, grão fino formada por vulcões explosivos
Riolito ou Andesito
See Kehew, Fig 3-40
![Page 8: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/8.jpg)
Rocha Ígnea IntrusivaE.x., Granito (Ácido):
Pobre em: Fe, Mg, Ca, (<20%) Rico em: Silica (>70%)
Quartz
Na Plagioclase
Biotite
![Page 9: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/9.jpg)
Vulcanismoácido
• Magma ácido• Alta viscosidade• Gasoso• Erupsão
explosiva • Inclinação
abrupta, vulcões em forma de cone
![Page 10: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/10.jpg)
Extrusive vs. Intrusive
(Mafic Rocks)• Mafic Magmas
– Hot (>1000oC)– Non-Viscous (runny, flows easily)– “Dry” (no H2O or C02)
• Mafic Rocks– Usually Extrusive, Fine-grained, Mafic (Basalt) rock forms oceanic
crust, Shield Volcanoes and Basalt Floods
– If Intrusive, course-grained mafic rocks are formed Gabbro.
– If intrusive, Dikes and Sills more common
See Kehew, Fig 3-40
![Page 11: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/11.jpg)
E.g., Vulcanismo Máfico, Hawai
Vulcões “Hot Spot”
![Page 12: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/12.jpg)
Hawaii 10.3
12.0 20.6
Midway 27.2 19.9 43.4
42.4
48.1 55.2
56.2 59.6
0-5
Current PlateMotion
HawaiUma longa cadeia de vulcões inativas
• Idade das ilhas, em milhões de anos
![Page 13: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/13.jpg)
Tipos de Erupção (Mafic Volc.)
• Tipos de Erupção– Fluxo de lava– Fontes de lava – Erupção em fissura
• Textura da rocha– Afanítica– Porfirítica – Vesicular– Vidro (Obsidiana)
![Page 14: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/14.jpg)
Textura (Extrusiva, Rochas máficas
• Ahah (Rubbley)– Maior parte sólida
quando flui• Pahoehoe (Ropey)
– Maior parte líquida quando flui
![Page 15: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/15.jpg)
![Page 16: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/16.jpg)
Desastre associado a rochas vulcânicos
• Baseado em
– Tipo de vulcanismo– Terremotos– História dos fluxos– Zonas de “rift”– Inclinação
![Page 17: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/17.jpg)
Sill Máfico: Intrudido entre camadas
• Magma máfico é menos viscoso e mais quente
• Não forma plutons mas
• Corta ao longo de camadas (Sills) ou mesmo cortar camadas (Diques)
![Page 18: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/18.jpg)
Classificação de rochas ígneas Ácido Intermediário Máfico
Granito Diorito Gabro Riolito Andesito Basalto
(Porphyritic)
Intr
usiv
eEx
trus
ive
![Page 19: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/19.jpg)
Intrusiva (Plutonica)Extrusiva (Volcanica)
Min
eral
Per
cent
age
Continental Crust Oceanic Mantle Crust
Classificação de rochas ígneas
![Page 20: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/20.jpg)
Igneous Rocks and Silicates
The Igneous Rock Classification parallels the systematicSilicate Mineral Classification
Frame- Double Single Iso. work Sheet Chain Chain
Fig.
3-6
Min
eral
Per
cent
age
![Page 21: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/21.jpg)
Granito
• Cores claras, grão grosseira, sem padrões
• Quartzo, feldspato, mica e hornblenda
• Frequentemente usada em edifícios e monumentos
![Page 22: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/22.jpg)
Basalto
• Cores escuras, grão fina, extrusivo
• Formeda onde a lava alcança a superfície
• Mais abrangente das rochas ígneas
• Frequentemente usada em edifícios e monumentos
![Page 23: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/23.jpg)
Gabbro
• Dark-colored, coarse- grained intrusive
• Similar composition to basalt—plagioclase feldspar with some pyroxene and olivine
http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Slideshow/Igrocks/Igrock8.html
![Page 24: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/24.jpg)
Obsidian
• Natural volcanic glass• Forms when lava cools
very quickly• Usually dark, but small
pieces may be clear• Fractures along curved
(conchoidal) surface• Used as spear and
arrow points, knives
http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Slideshow/Igrocks/Igrock7.html
![Page 25: Rochas Ígneas](https://reader034.vdocuments.pub/reader034/viewer/2022042610/5706383f1a28abb8238f0eb8/html5/thumbnails/25.jpg)
Pumice and other igneous rocks
• Light colored, frothy (many air spaces)
• Same minerals as in granite, but finer in grain size
For more about igneous rocks: http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Igrocks/Igrocks1.html