文档介绍：Major Elements “Wet-chems”: gravimetric/volumetric Major Elements Modern Spectroscopic Techniques Figure 8-1. The geometry of typical spectroscopic instruments. From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. Major elements: usually greater than 1% SiO2 Al2O3 FeO* MgO CaO Na2O K2O H2O Minor elements: usually - 1% TiO2 MnO P2O5 CO2 Trace elements: usually < % everything else Element Wt % Oxide Atom % O
Si
Al
Fe
Ca
Mg
Na
Abundance of the elements in the Earth’s crust A typical rock analysis Wt. % Oxides to Atom % Conversion Oxide Wt. % Mol Wt. Atom prop Atom % SiO 2
TiO 2
Al 2 O 3
Fe 2 O 3
FeO
MnO
MgO
CaO
Na 2 O
K 2 O
H 2 O +
(O)
Total
Must multiply by # of cations in oxide Table Chemical analyses of some representative igneous rocks Peridotite Basalt Andesite Rhyolite Phonolite SiO2
TiO2
Al2O3
Fe2O3
FeO
MnO
MgO
CaO
Na2O
K2O
H2O+
Total
CIPW Norm Mode is the volume % of minerals seen Norm is a calculated “idealized” mineralogy Variation Diagrams How do we display chemical data in a meaningful way? Bivariate (x-y) diagrams Harker diagram for Crater Lake Figure 8-2. Harker variation diagram for 310 analy