Major elements: usually greater than 1%
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Bu səhifədəki naviqasiya:
Trace elements: usually
Mode
Example: AFM diagram Example: AFM diagram
Extrapolate BA B and further to low SiO2
Can chemistry be used to distinguish families
Early on it was recognized that some chemical parameters were very useful in regard to distinguishing magmatic groups
Major elements: usually greater than 1%
Major elements: usually greater than 1%
SiO2 Al2O3 FeO* MgO CaO Na2O K2O H2O
Minor elements: usually 0.1 - 1%
TiO2 MnO P2O5 CO2
Trace elements: usually
< 0.1%
everything else
Mode
is the volume %
of minerals seen
Mode
is the volume % of minerals seen
Norm
is a calculated “idealized”
mineralogy
Example:
AFM diagram
Example: AFM diagram
(alkalis-FeO*-MgO)
Harker diagram
Harker diagram
Smooth trends
Model with 3 assumptions:
1 Rocks are related by FX
2 Trends =
liquid line of descent
3 The basalt is the parent magma from which the others are derived
Extrapolate BA B and further to low SiO2
Extrapolate BA B and further to low SiO2
K2O is first element to 0 (at SiO2 = 46.5)
Can chemistry
be used to distinguish
families
of magma types?
Can chemistry be used to distinguish
families
of magma types?
Early on it was recognized that some chemical parameters were very useful in regard to
distinguishing magmatic groups
Early on it was recognized that some chemical parameters were very useful in regard to distinguishing magmatic groups
Total Alkalis (Na2O + K2O)
Silica (SiO2)
and silica saturation
Alumina (Al2O3)
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