EarthRef.org Reference Database (ERR) -- Macdonald & Katsura 1961

In July 1960 a boring in the lava crust of Kilauea Iki crater furnished continuous core samples and well cuttings to a depth of 19.5 ft. where liquid lava was encountered. Chemical and petrographic - analysis were made of 6 samples of the lava core; 2 samples of the liquid lava; a surface lava sample; and 2 samples of lava and a sample of Pelee's hair formed in the early stages of eruption. The analyses indicate the existence in Hawaii of completely liquid tholeiitic magma that is undersaturated in silica at least to the degree of containing nearly 10% normative olivine. The different composition of the samples confirm the dominance of crystal differentiation in the tholeiitic suite, involving primarily the movement of magnesian olivine, with small amounts of pyroxene and calcic plagioclase. The composition of one of the liquid lava samples indicates that at least marginal members of the alkalic suite can be derived from undersaturated tholeiitic magma, and the possibility is suggested of the derivation of the alkalic basalts, in general, from such a magma. The derivation appears to be accomplished by crystallization differentiation, controlled by the separation of pyroxene. However, it is realized that other processes of differentiation, such as volatile transfer of alkalies and thermodiffusion, may be operative.