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Precipitation of Secondary Phases from the Dissolution of Silicate GlassesBasaltic and anorthositic glasses were subjected to aqueous weathering conditions in the laboratory where the variables were pH, temperature, glass composition, solution composition, and time. Leached layers formed at the surfaces of glasses followed by the precipitation of X-ray amorphous iron and titanium oxides in acidic and neutral solutions at 25 C over time. Glass under oxidative hydrothermal treatments at 150 C yielded a three-layered surface; which included an outer smectite layer, a Fe-Ti oxide layer and an innermost thin leached layer. The introduction of Mg into solutions facilitated the formation of phyllosilicates. Aqueous hydrothermal treatment of anorthositic glasses (high Ca, low Ti) at 200 C readily formed smectite, whereas, the basaltic glasses (high Ti) were more resistant to alteration and smectite was not observed. Alkaline hydrothermal treatment at 2000e produced zeolites and smectites; only smectites formed at 200 C in neutral solutions. These mineralogical changes, although observed under controlled conditions, have direct applications in interpreting planetary (e.g., meteorite parent bodies) and terrestrial aqueous alteration processes.
Document ID
20110011368
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Ming, Douglas W. (NASA Johnson Space Center Houston, TX, United States)
Golden, D. C. (Hernandez Engineering, Inc. Houston, TX, United States)
Date Acquired
August 25, 2013
Publication Date
October 31, 2004
Subject Category
Geophysics
Report/Patent Number
JSC-CN-157
Meeting Information
Meeting: Soil Science Society of American Annual Meeting
Location: Seattle, WA
Country: United States
Start Date: October 31, 2004
End Date: November 5, 2004
Funding Number(s)
OTHER: 344-43-AB
Distribution Limits
Public
Copyright
Public Use Permitted.

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