Verma {GCDkit} | R Documentation |
Plots data stored in 'WR
' (or its subset) into discrimination plots proposed by
Verma et al. (2006) for (ultra-) basic rocks (SiO2 < 52 wt. %).
Verma(FeMiddlemost=NULL)
FeMiddlemost |
logical, should be iron adjusted according to Middlemost (1989)? |
Suite of five diagrams for discrimination of geotectonic environment of ultrabasic and basic rocks (SiO2 < 52 wt. %), proposed by Verma et al. (2006). It is based on log-transformed concentration ratios of major-element oxides. Note that prior to the transformation, the analyses are recast to 100% anhydrous basis. Each diagram is a plot of two discriminant functions, DF1 and DF2, respectively in x- and y-axes. Only samples with SiO2 < 52 wt. % are plotted. To work properly, the major element analysis should be complete (SiO2, TiO2, Al2O3, Fe2O3, FeO, MnO, MgO, CaO, Na2O, K2O, P2O5). Following the recommendation by Verma et al. (2006), prior to the plotting can be performed an adjustment of the iron-oxidation ratio as proposed by Middlemost (1989) (see 'FeMiddlemost').
For the Fe2O3/FeO ratios implemented for individual rock types (based on TAS classification), see Verma et al. (2002) (Fig. 1).
Following geotectonic settings may be deduced:
Abbreviation used | Environment |
IAB | island arc basic rocks |
CRB | continental rift basic rocks |
OIB | ocean-island basic rocks |
MORB | mid-ocean ridge basic rocks |
None.
This function uses the plates concept. The individual plots can be selected and their
properties/appearance changed as if they were stand alone Figaro-compatible plots.
See Plate
, Plate editing
and
figaro
for details.
Vojtech Janousek, vojtech.janousek@geology.cz
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
Verma S P, Guevara M, Agrawal S (2006) Discriminating four tectonic settings: Five new geochemical diagrams for basic and ultrabasic volcanic rocks based on log-ratio transformation of major-element data. Journal of Earth System Science 115: 485-528. doi: 10.1007/BF02702907
FeMiddlemost Agrawal Plate Plate editing plotPlate figaro
#plot the diagrams plotPlate("Verma")