EXAM 2 igneous

EXAM 2 igneous - Up from the Inferno: Magma and Igneous...

Info iconThis preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon
Up from the Inferno: Magma and Igneous Rocks Igneous Rocks
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Igneous Rocks Solidified molten rock (which freezes at high temp). 1,100°C to 650°C. Depends on composition. Earth is mostly igneous rock. Magma – Subsurface melt. Lava – Melt at the surface. Magma erupts via volcanoes.
Background image of page 2
Igneous Rocks Melted rock can cool above or below ground. Intrusive igneous rocks – Cool slowly underground. Extrusive igneous rocks – Cool quickly at the surface. Lava – Cooled liquid. Pyroclastic debris – Cooled fragments. Ash. Fragmented lava. There are many varieties of igneous rocks.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 below ground above ground Igneous rocks Most COMMON rock type on earth as all mantle, ocean crust and most continental crust Formed from the cooling and consolidation of magma Volcanic (extrusive) cooled on the surface (lava) Plutonic (intrusive) cooled below the surface (magma)
Background image of page 4
First we need to have magma…. .
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 MAGMA PROPERTIES * Completely or partially molten material, which cools to form an igneous rock * Liquid portion called the melt (magma or lava) * Hot 600-1200 o C * Lose heat as crystallize (freeze) * Chemical composition - magma have different compositions * Silica content controls viscosity and therefore flow * Volatile content controls melting temperature – high volatiles lowers melting temperature * Magma less dense than rock so rises
Background image of page 6
Magma Formation Why does magma form? Earth is hot inside. Why? Planetesimal and meteorite accretion Gravitational compression Differentiation Radioactive decay
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Role of Heat
Background image of page 8
Magma Formation Geothermal gradient – Earth is hot inside. Crustal temperature (T) increases 25°C / km with depth. At the base of the lithosphere T ~ 1,280 °C. Geothermal gradient varies from place to place.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Partial melting occurs in the crust & upper mantle Melting is from… Pressure release Volatile addition Heat transfer Magma Formation
Background image of page 10
Magma Formation Pressure release. Base of the crust is hot enough to melt mantle rock. Due to high pressure, the rock does not melt. A drop in pressure initiates “ decompressional melting.”
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Role of Pressure Pressure increases with depth Melting occurs at higher temps with depth because of confining pressure the greater the pressure, the higher the melting point When confining pressure drops, decompression melting occurs Occurs when rock ascends as a result of convective upwelling (recall that the mantle is solid, but flows at very slow rates. mixture of solid + melt peridotite Decompression melting
Background image of page 12
Addition of Volatiles Adding volatiles to hot, dry rocks initiates melting Adding volatiles to hot, dry rocks initiates melting Volatiles cause rocks to melt at lower T Volatiles cause rocks to melt at lower T Important subduction process Important subduction process Volatiles Volatiles  are elements or compounds that are gas or liquid at  are elements or compounds that are gas or liquid at temperatures and pressures on the Earth’s surface.
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 14
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/26/2011 for the course ECON 0146010010 taught by Professor Allisonfranzese during the Spring '11 term at Rutgers.

Page1 / 89

EXAM 2 igneous - Up from the Inferno: Magma and Igneous...

This preview shows document pages 1 - 14. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online