Melt Properties

Updates/questions?

• Labs:• Field trip:18th or 19th?

• Last lecture’s 3 remaining slides in lab

Today’s topics:1. Magma properties

Melt properties - Internal variables

Composition

Majority of Earth’s minerals are …?

Bill White’s

Geochemistry book

Silicates

http://visionlearning.com/library/modules/mid140/Image/VLObject-3539-060516120522.jpg

Networks

http://visionlearning.com/library/modules/mid140/Image/VLObject-3539-060516120522.jpg

Bridging Oxygen

www.uwgb.edu/dutchs/PETROLGY/NesoSoro.HTM

http://visionlearning.com/library/modules/mid140/Image/VLObject-3539-060516120522.jpg

NBO/T•NBO/T change with melt composition….why?

Mysen, 1983

Rhyolite Basalt

Structure in Melt

Carmichael et al., 1974

Breaking the polymers

Carmichael et al., 1974

www.origins.rpi.edu/claycatalyzed.html

Effect of volatiles

Polymerization and Viscosity

• What will move more easily:

a) Shorter chain polymers?

b) 3D networks?

• What does that mean w.r.t. rock types?

Viscosity

Viscosity

http://video.google.com/videosearch?ndsp=18&um=1&hl=en&client=firefox-a&rls=org.mozilla:en-US:official&q=viscosity&ie=UTF-8&sa=N&tab=iv#ndsp=18&um=1&hl=en&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=viscosity&ie=UTF-8&sa=N&tab=iv&start=10

Viscosity

Viscosity, composition, temperature

Scarfe., 1986

Decreasing SiO2

Viscosity and pressure

Scarfe., 1986

Viscosity and H2O

Scarfe., 1986

Lava types and viscosityUSGS

Ctein

Viscosity regimes

Regimes related to temperature w.r.t. Tg

T >> Tg Viscosity very low,

follows power law: (T) = o(T-Tc)-

~2, Tc = critical T (> Tg)

T ~ Tg Intermediate viscosity,

follows exponential: (T) =

Aeexp(Be/(TSconf))

Ae~0.003, S from experiments, Be from fit

T << Tg: Very high viscosity: sample turned into

glass

(Bottinga et al., 1995)

Rheology and time

Webb & Dingwell, 1995

Glass Transition