Low temperature basalt alteration by sea water: an experimental study at 70°C and 150°C

Geochimica et Cosmochimica Acta
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Abstract

Basaltic glass and diabase were reacted with seawater at 70°C at 1 bar and 150°C at 500 bars to determine fluid composition and alteration mineralogy. All experiments were performed at a water/ rock mass ratio of 10.

The changes in seawater chemistry depended on temperature and crystallinity of the basalt. The experiment at 70°C produced a slight but continuous loss of Mg, Na and K and enrichment of Ca and SiO2in the seawater while pH decreased slowly. At 150°C, in contrast, Mg and SO4 were quickly and quantitatively removed while Ca, SiO2, Na, K, Fe, Mn and Ba were added to the seawater. pH rose to values between 5.5 and 6.5 after an initial drop to lower values. Basalt glass reacted more extensively at 150°C than diabase.

Smectite was the major alteration product (iron-rich saponite) at 150°C for both the glass and diabase experiments. Smectite from the diabase experiment was well crystallized while that from the glass experiment was poorly crystallized. The smectites are similar to smectites found in altered oceanic ophiolitic basalts.

Publication type Article
Publication Subtype Journal Article
Title Low temperature basalt alteration by sea water: an experimental study at 70°C and 150°C
Series title Geochimica et Cosmochimica Acta
DOI 10.1016/0016-7037(79)90006-1
Volume 43
Issue 12
Year Published 1979
Language English
Publisher Elsevier
Description 11 p.
First page 1937
Last page 1947
Online Only (Y/N) N
Additional Online Files (Y/N) N
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