library(StatDA)
data(chorizon)
x=chorizon[,c("Al2O3","CaO","Fe2O3","K2O","MgO","MnO","Na2O","P2O5","SiO2","TiO2")]
x1=x/x[,"TiO2"]
x1.obj=log10(x1[,1:9])
pdf("fig-10-8.pdf",width=9,height=4.5)
par(mfrow=c(1,2),mar=c(4,4,2,2))
plot(x1.obj[,"SiO2"],x1.obj[,"Al2O3"],xlab="log10(SiO2/TiO2)",ylab="log10(Al2O3/TiO2)",
pch=3,cex=0.7,cex.lab=1.2)
plot(x1.obj[,"Na2O"],x1.obj[,"K2O"],xlab="log10(Na2O/TiO2)",ylab="log10(K2O/TiO2)",
pch=3,cex=0.7,cex.lab=1.2)
dev.off()