EarthRef.org Reference Database (ERR) -- Hay & Iijima 1968

Hay, R.L. and Iijima, A. (1968). Nature and origin of palagonite tuffs of the Honolulu Group on Oahu, Hawaii. In: Studies in Volcanology - A memoir in honor of Howel Williams. Geological Society of America, Boulder. 331-376.

Tephra deposits (alkali basalt to melilite nephelinite) of the Honolulu Group on Oahu are middle to late Pleistocene. Some deposits are fresh, but most are zeolitic palagonite tuff. Pyroclastic deposits are generally zoned from clayey soil 3-8 feet thick, down into relatively fresh tuff from 15-40 feet thick, underlain by palagonite tuff 60 or more feet thick. The amount of authigenic minerals in tuffs is generally proportional to the amount of palagonite and indicates that minerals are related to the palagonitization process. Reaction of sideromelane with cold ground water accounts for the vertical zoning from surface tuffs down into palagonite. The sharp interface between unaltered sideromelane and palagonite suggests that palagonite formed by a microsolution-precipitation mechanism