An iron-rich montmorillonite in a sediment core from the northeastern Pacific

Abstract

A sediment core section nearly 230 cm long (190–420 cm below the sea bottom) from the northeastern Pacific is largely composed of smectite. X-Ray, thermal, i.r. and chemical analyses indicate the smectite to be an iron-rich montmorillonite (SiO 2, 51·66%; TiO 2, 0·58%; Al 2O 3, 8·13%; Fe 2O 3, 14·08%; FeO, 0·51%, MnO, 0·29%; MgO, 4·21%, CaO, 0·15%; Na 2O, 1·21%; K 2O, 0·71%; H 2O +, 6·74%; H 2O−, 10·13%; total 98·40%). The hypothesis that the Fe-smectite could have been formed by the interaction of hydrothermal solutions and seawater is by circumstantial evidence.