GEOL 1 Lecture Notes - Lecture 7: Oceanic Crust, Partial Melting, Peridotite

0 views2 pages
19 Oct 2020
Jeff Koo
Geol 1
Physical Geology
Spring 2019
4 Units
Bowen’s Reaction Series
Shows temperature from low to high
High temperature-first minerals to crystalize
Low temperature- that can stay liquid
Gold has a very low melting point- similar to quartz- the last things that crystalizes
How do we make different rocks? - the mantle comes up
- Kind of the same thing
Partial melting: melt part of the rock,
and fractional crystallization: big thig of magma and cool it down and you start crystalizing
from the top-down
Partial melting: as a rock heats up and begins to melt, Bowen’s reaction series operates from the
bottom up. The most silica-rich end of the rock’s composition begins melting first
What’s the bottom line? Magma tends to be more silica-rich than the parent rock that it was
generated from
Let’s look at compostions:
Peridotite: 45% silica, rich in FE, Mg, Ca
Basalt/ gabbro: 50% silica, rich in Fe, Mg, Ca
Andesite/ diorite: 60% silica,
Starting with the mantle: peridotite: 45% silica, rich in Fe, Mg, Ca partially melts along rising
plumes in convection cells in the mantle
- The mantle is made of peridotite
Basalt/ gabbro: 50% silica, rich in Fe, Mg, Ca- it forms oceanic crust- and eventually bump into
another oceanic crust and gets subducted back in
Now we have oceanic crust: eventually it subducts under other oceanic crust
There, partial melting occurs (remember adding water?)
Basalt/ Gabbro: 50% silica, rich in Fe, Mg, Ca
Andesite/ diorite: 60% silica, mix of cations
Now we have a volcanic arc: typically, these are andesitic volcanoes
Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.