111-32 - GY 111 Lecture Notes D Haywick(2008-09 1 GY 111...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
GY 111 Lecture Notes D. Haywick (2008-09) 1 GY 111 Lecture Notes Metamorphism 3: Contact Metamorphism Lecture Goals : A) Metamorphic Aureoles B) Isograds C) Index minerals and metamorphic grade Reference: Press et al., 2004, Chapter 9; Grotzinger et al., 2007, Chapter 6; GY 111 Lab manual Chapter 4 A) Metamorphic Aureoles Contact metamorphism is induced by plutons as they pass upward through the lithosphere and crust toward the surface of the Earth, or by other magma-filled intrustions like dikes and sills. These bodies all contain molten rock (magma) which heats the enclosing parent rock to high temperatures and therefore induces heat only metamorphism. As previously discussed, heat only metamorphism is called contact metamorphism. Unlike regional metamorphism, contact metamorphism is generally localized to the immediate vicinity of the intrusion. In fact, there is a zone of metamorphism that surrounds the intrusion like a halo or an envelop which is officially called a metamorphic aureole (see cartoon at the top of the next page and the image to the left from http://newterra.chemeketa.edu). Within the aureole, metamorphic grade of the parent rock varies from high nearest the intrusion, to low someway from the contact. The width of the metamorphic aureole (or the width of the zone of contact metamorphism) depends on several factors such as the size and
Background image of page 1

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

View Full DocumentRight Arrow Icon
GY 111 Lecture Notes D. Haywick (2008-09) 2 temperature of the intrusion (dikes and sills are small and therefore induce “thin” aureoles whereas large bodies like plutons and batholiths induce “thick” aureoles), the amount of time the parent rocks were in contact with the intrusion and the type of parent rock. Some rocks conduct heat more readily or are more susceptible to heat than others. Contact metamorphism is relatively easy to
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/04/2012 for the course GLY 111 taught by Professor Haywick during the Fall '11 term at S. Alabama.

Page1 / 5

111-32 - GY 111 Lecture Notes D Haywick(2008-09 1 GY 111...

This preview shows document pages 1 - 3. Sign up to view the full document.

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