On distinguishing basaltic lavas of circum-oceanic and oceanic-island type by means of discriminant functions

Abstract

The basaltic lavas of the oceanic-island environment are much richer in titania than those found on the landward flanks of the great deeps margining the open oceans. Exceptions to this rule are rare; examination of a large body of data indicates that the efficiency of a classification based solely on TiO ₂ content would be nearly 93 percent. Neither any other single oxide nor any unweighted combination of oxides other than TiO ₂ approaches the efficiency of TiO ₂ . Extensive discriminant function calculations indicate: (1) Weighted linear combinations which include TiO ₂ may be a slight improvement over TiO ₂ alone. (2) Any combination of oxides which does not include TiO ₂ is far less effective than TiO ₂ alone.