FeMiddlemost {GCDkit} | R Documentation |
Auxiliary function performing adjustment of the iron-oxidation ratio as proposed by Middlemost (1989).
FeMiddlemost(anhydrous = TRUE)
anhydrous |
logical; should be returned major-element analyses recast to anhydrous basis? |
This function performs an adjustment of the iron-oxidation ratio for individual volcanic rock types as proposed by Middlemost (1989).
The classification is based on TAS classification (Le Bas et al. 1986, Le Maitre et al. 1989).
The Fe2O3/FeO ratios for individual rock types, based on Verma et al. (2002) (Fig. 1), are as follows:
foidite, Na2O+K2O<= 3 | 0.15 |
foidite, 3 < Na2O+K2O<= 7 | 0.2 |
foidite, 7 < Na2O+K2O<= 10 | 0.3 |
foidite, Na2O+K2O> 10 | 0.4 |
picrobasalt | 0.15 |
basalt | 0.2 |
basaltic andesite | 0.3 |
andesite | 0.35 |
dacite | 0.4 |
rhyolite | 0.5 |
trachybasalt | 0.3 |
basaltic trachyandesite | 0.35 |
trachyandesite | 0.4 |
trachyte/trachydacite | 0.5 |
tephrite/basanite, Na2O+K2O<= 6 | 0.2 |
tephrite/basanite, Na2O+K2O> 6 | 0.3 |
phonotephrite | 0.35 |
tephriphonolite | 0.4 |
phonolite | 0.5 |
If the parameter 'anhydrous
' is set, returned are the major-element
data recast to 100 % anhydrous basis.
A matrix with adjusted whole-rock chemical data.
No permanent changes to either 'WR
' or 'WRanh
' are made.
Vojtech Janousek, vojtech.janousek@geology.cz
Le Bas M J, Le Maitre R W, Streckeisen A & Zanettin B (1986) A chemical classification of volcanic rocks based on the total alkali-silica diagram. J Petrology 27: 745-750 doi: 10.1093/petrology/27.3.745
Le Maitre R W et al (1989) Igneous Rocks: A Classification and Glossary of Terms, 1st edition. Cambridge University Press
Middlemost E A K (1989) Iron oxidation ratios, norms and the classification of volcanic rocks. Chem Geol 77: 19-26 doi: 10.1016/0009-2541(89)90011-9
Verma S P, Torres-Alvarado I S, Sotelo-Rodriguez Z T (2002) SINCLAS: standard igneous norm and volcanic rock classification system. Comput and Geosci 28: 711-715 doi: 10.1016/S0098-3004(01)00087-5