Chemical and Mineralogical Changes During Basalt-Seawater Interaction: Site 223, Leg 23, D.S.D.P., North-West Indian Ocean

C. Th. Papavassiliou* and M. E. Cosgrove
Department of Geology, The University, Southampton, SO9 5NH
*Present address: Laboratory of Mineralogy and Petrology, University of Athens, Ano Ilissia (Panepistimioupolis), Athens, Greece.

Abstract: The development of low- and hightemperature alteration products in a 23 m section of ocean-floor basalts is described. Analcime, calcite and dioctahedral smectite are ubiquitous. Trioctahedral smectite, smectite-chlorite mixed layers, chabazite and scolecite occur in the deeper sections with Fe3+ oxides/hydroxides progressively becoming more abundant in the upper regions. The upper layers of the sequence show marked chemical reduction. High-temperature chemical changes include Na and Mg enrichment accompanied by Ca and Fe2+ losses. Superimposed low temperature changes include gains in Fe3+ K, Li, and Rb, and losses in Na, Ca, and Fe2+ Many trace elements also show consistent behaviour.

Mineralogical Magazine; June 1981 v. 44; no. 334; p. 141-146; DOI: 10.1180/minmag.1981.044.334.03
© 1981, The Mineralogical Society
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